The Impact of the COVID-19 Pandemic on the Amount of Plastic Waste and Alternative Materials in the Context of the Circular Economy

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

To my knowledge the data given are original.

 

 ABSTRACT

Under the Abstract:

It is stated that

“……. Here, a biodegradable nonwoven fabric produced using spunbonded technology is presented. Here, a biodegradable alternative to polypropylene materials is presented. The nonwoven fabric was produced using spunbonded technology……”

Since the wording is not proper, this part must be corrected.

INTRODUCTION

Introduction should be rewritten in a comprehensive way, by quoting clearly what this study adds to the existing knowledge as there are quite studies on biodegradability of Polybutylene succinate.

 

The Introduction starts with the following sentence:

“Plastics are chemically manufactured polymers [1]…..”

This quote does not need a reference.

 

Besides, similar to the above given example in the text some reference usages are not proper. Another example:

“…..Plastics are used in virtually all industries, including: in clothing, nonwoven industry, medical supplies, water bottles, food packaging, electrical goods and building materials [2–5]….”

Such a part does not need references.

 

It is stated that:

“……Literature data shows that since 1950, global plastic pollution has amounted to 8.3 billion million tons. The COVID-19 pandemic has….”

Which literature data is this? The authors should give the literature.

 

It is stated that:

“…..Currently, plastic waste management mainly involves landfilling and incineration [12]…”

What about plastic recycling?

 

Figure 1 is not supporting the text. In Figure 1, “Produkt” should be corrected.

 

2. Covid - problem with waste management

 

What is y axis in Figure 2 and Figure 3? It is hard to understand where the numbers are in the y axis. Also under the introduction part it is stated that:

“…..The COVID-19 pandemic has caused an increase in the amount of plastic waste [6]……”

It will be helpful to give Figure 2 and 3 with data obtained before the Covid-19.

 

It is stated that:

“…. Scientists estimated that during the pandemic, humanity used about 3 million disposable masks per month, making a total of as many as 130 billion masks. Assuming that a disposable surgical mask weighs about 3.5 grams, it turned out that the total weight of masks used every month exceeded 450 tons….”

Who are the scientists? References should be given.

 

Unabbreviated form of PPE should be given before the abbreviation.

 

Some parts of the text require references. A couple of examples are given below:

“…..As experts emphasize, in the first half of the pandemic, the import of masks to the European Union more than doubled. An additional 170,000 tons of masks were then imported to Europe an average of 0.75 masks per person per day. At the same time, local production increased. One of the effects of the coronavirus pandemic was an increased demand for personal protective equipment, most of which are filtering half-masks or disposable protective masks, made of plastic and intended for single use. Experts pointed out that due to the demand for personal protective equipment during the Covid 19 pandemic, more and more waste was generated. The production of masks has almost equaled the scale of plastic bottle production, of which approximately 43 billion pieces are produced worldwide each month….”

“….According to scientific research, plastic production has quadrupled over the last 40 years and if this trend continues, plastic production will be responsible for 15% of greenhouse gas emissions by 2050. That's as much as all forms of transport currently do. Other studies show that 8 million tons of plastic now end up in the oceans annually, and this amount continues year after year….”

 

4. Materials and Methods

It is stated that:

“…..The nonwoven fabric was composed of polybutylene succinate (Bionolle™ 1001 MD) and produced directly from the polymer using the spun-bonded technique….”

The production flow-chart should be explained by denoting all the inputs. What is the source of polybutylene succinate? Is it bio based or petroleum origin?

 

“….Figure 8. Molas mass distribution (MMD)…”

 

Must be “Molar mass distribution”.

5. Results and discussion

No need to have the following part at the end of this heading as these issues are indicated earlier:

“……The number of plastic wastes has significantly increased during COVID-19 pandemia and plays an important role in environmental pollution [33]. An unprecedented increase in using single-use plastics (SUPs) and personal protective equipment (PEE) was noticed. Behind these numbers there are tons of waste, which is not managed and poses a direct threat to ecosystems. According to the literature [33,34] the amount of plastic waste produced worldwide was estimated at 1.6 million tons per day. The data revealed that 3.4 billion facemasks were disposed of daily globally…..”

 It is a known fact that Polybutylene succinate is biodegradable. The results obtained in this paper about the biodegradability should be compared with literature. Also, as indicated before in Introduction part the literature on biodegradability of Polybutylene succinate should be discussed.

 

A Conclusion part should be introduced.

 

 

 

Comments on the Quality of English Language

English should be improved.

Author Response

Replies to comments and suggestions

Quality of English Language

 Extensive editing of English language required

English language was edited for proper grammar and overall style.

Introduction should be rewritten in a comprehensive way, by quoting clearly what this study adds to the existing knowledge as there are quite studies on biodegradability of Polybutylene succinate.

As recommended by the reviewer, the introduction was remodeled, information on the biodegradability of polybutylene succinate was added and the importance of the research conducted by the authors was emphasized.

 „… PBS is characterized by good processability. As the literature shows, composites made of natural fibers based on PBS are completely biodegradable and have good mechanical properties [28,29]. In recent years, there has been an increase in the use of bioplastics like PBS, which has raised awareness about the environmental issues caused by non-renewable and non-biodegradable plastics, as well as the rapid depletion of fossil fuel resources. The biodegradability of PBS is an attractive feature of this polymer and therefore gives it an advantage in single-use applications. This polymer can degrade at a high rate in a short period of time and has also been listed as compostable [30]. Therefore, it was proposed as an element of personal protective equipment. A cheap source from which PHA can be obtained is waste paper [31]. PHAs are an alternative to synthetic plastics due to their physicochemical properties comparable to those of synthetic plastics and their biodegradable and biocompatible nature [32,33].”

„In the current environmental problems related to large amounts of plastic waste, working on environmentally friendly solutions is of great importance. Therefore, the authors undertook research aimed at producing spun-bonded nonwoven fabric from the PBS polymer, which is described in the article. The purpose of this article is to provide inspiration for the desire to replace plastics with biodegradable polymers and thus reduce the amount of harmful polymer waste on the environment. The article cites statistical data on the production of plastics, definitions of biodegradation, degradation and composting processes. The importance of biodegradation is discussed.”

The Introduction starts with the following sentence:

“Plastics are chemically manufactured polymers [1]…..”

This quote does not need a reference.

Rephrase the sentence and leave the literature reference.

Besides, similar to the above given example in the text some reference usages are not proper. Another example:

“…..Plastics are used in virtually all industries, including: in clothing, nonwoven industry, medical supplies, water bottles, food packaging, electrical goods and building materials [2–5]….”

Such a part does not need references.

 According to the authors, mentioning the literature is not an error. Due to the reference to specific industries, the authors left literature references. If the reviewer believes that they should be removed, the authors will leave the text without literature references.

It is stated that:

“……Literature data shows that since 1950, global plastic pollution has amounted to 8.3 billion million tons. The COVID-19 pandemic has….”

Which literature data is this? The authors should give the literature.

 Literature references were introduced according to the reviewer's suggestion.

It is stated that:

“…..Currently, plastic waste management mainly involves landfilling and incineration [12]…”

What about plastic recycling?

 The entry was changed to Actually, plastic waste management includes landfilling, incineration, recycling and energy recovery and literature references were introduced.

Figure 1 is not supporting the text. In Figure 1, “Produkt” should be corrected.

 Corrected as per reviewer's suggestion.

2. Covid - problem with waste management

What is y axis in Figure 2 and Figure 3? It is hard to understand where the numbers are in the y axis. Also under the introduction part it is stated that:

“…..The COVID-19 pandemic has caused an increase in the amount of plastic waste [6]……”

It will be helpful to give Figure 2 and 3 with data obtained before the Covid-19.

 According to the reviewer's suggestion, data from before the Covid 19 pandemic (2018) was added to charts 2 and 3, and the axis markings were introduced in the charts.

It is stated that:

“…. Scientists estimated that during the pandemic, humanity used about 3 million disposable masks per month, making a total of as many as 130 billion masks. Assuming that a disposable surgical mask weighs about 3.5 grams, it turned out that the total weight of masks used every month exceeded 450 tons….”

Who are the scientists? References should be given.

 According to the reviewer's suggestion, the authors add a literature reference to the source text.

Unabbreviated form of PPE should be given before the abbreviation.

 The reviewer's suggestion was followed. The unabbreviated form of PPE is given before the abbreviation.

Some parts of the text require references. A couple of examples are given below:

“…..As experts emphasize, in the first half of the pandemic, the import of masks to the European Union more than doubled. An additional 170,000 tons of masks were then imported to Europe an average of 0.75 masks per person per day. At the same time, local production increased. One of the effects of the coronavirus pandemic was an increased demand for personal protective equipment, most of which are filtering half-masks or disposable protective masks, made of plastic and intended for single use. Experts pointed out that due to the demand for personal protective equipment during the Covid 19 pandemic, more and more waste was generated. The production of masks has almost equaled the scale of plastic bottle production, of which approximately 43 billion pieces are produced worldwide each month….”

“….According to scientific research, plastic production has quadrupled over the last 40 years and if this trend continues, plastic production will be responsible for 15% of greenhouse gas emissions by 2050. That's as much as all forms of transport currently do. Other studies show that 8 million tons of plastic now end up in the oceans annually, and this amount continues year after year….”

 Footnotes have been added as suggested by the reviewer

4. Materials and Methods

It is stated that: 

“…..The nonwoven fabric was composed of polybutylene succinate (Bionolle™ 1001 MD) and produced directly from the polymer using the spun-bonded technique….” 

The production flow-chart should be explained by denoting all the inputs. What is the source of polybutylene succinate? Is it bio based or petroleum origin? 

Information was added and it was introduced to detail the spun-bonded technique: 

The spun-bonded technique consists of introducing the polymer into the extruder through a feeder. To process polyesters like PLA or PBS, it is necessary to reduce the water content level to ppm. [65,66]. The polymer is melted in the extruder's heating zone. The extruders can be single or twin-screw with various arrangements. The temperature gradient should be adapted to the polymer, taking into account the melting and decomposition temperature and the melt flow coefficient. If the temperature is too low, it can cause blockage in the extruder system. Conversely, if the temperature is too high, the viscosity of the polymer will increase, leading to improper fiber formation and material degradation. Therefore, careful selection of the melt temperature is important [67]. The polymer melt is filtered and fed to the spinning head where it is formed into fibers. Depending on the head used as well as its parameters, e.g. number of holes, diameter and length of holes, fibers with different properties can be obtained, e.g. diameter, degree of primary crystallization. The filaments are next drawn in the spinning channel under the influence of hot air and collected on the belt under vacuum. At this stage, the fibers are loosely laid and only pre-bonded into the webbing. It is necessary to use a calendar at a certain temperature to bond the fibers into a nonwoven [68,69]. The parameters of the process are shown below.

  

 

“….Figure 8. Molas mass distribution (MMD)…”- corrected 

Must be “Molar mass distribution”. 

5. Results and discussion

No need to have the following part at the end of this heading as these issues are indicated earlier: 

“……The number of plastic wastes has significantly increased during COVID-19 pandemia and plays an important role in environmental pollution [33]. An unprecedented increase in using single-use plastics (SUPs) and personal protective equipment (PEE) was noticed. Behind these numbers there are tons of waste, which is not managed and poses a direct threat to ecosystems. According to the literature [33,34] the amount of plastic waste produced worldwide was estimated at 1.6 million tons per day. The data revealed that 3.4 billion facemasks were disposed of daily globally…..” 

The paragraph has been moved to part 2 and correlated with data on plastic production. 

 It is a known fact that Polybutylene succinate is biodegradable. The results obtained in this paper about the biodegradability should be compared with literature. Also, as indicated before in Introduction part the literature on biodegradability of Polybutylene succinate should be discussed. 

A literature review was added and the obtained results were discussed (Results and Discussion). 

A Conclusion part should be introduced. 

coreccted  

 

For your convenience, changes made to the article are marked in red.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The present work focuses on a biodegradable nonwoven fabric produced using a PBS bionolle™ 1001MD and spunbonded technology. In the current form, unfortunately the study cannot be accepted for publication. The contribution for the aim of the study is not satisfying indeed the topic needs a more detailed data and deep discussion.

In the introduction and in the text some references are missing, as in the sentence” Literature data shows that since 1950, global plastic pollution has amounted to 8.3 billion million tons” or “According to scientific research, plastic production has quadrupled over the last 40 years and if this trend continues, plastic production will be responsible for 15% of greenhouse gas emissions by 2050.” and so on. Moreover, in the introduction it will be better add information about recycling.

The Materials and Methods sections need to be rewritten: the supplier of PBS is missing, some parameters of the manufacturing process have to be added, no data are reported about the physic-mechanical characterization (equipment, how the test was carried out, the obtained curve...). The biodegradation test on Cotton (100%), used as reference, and on PP are not described, although in the text we found the sentence: “Simultaneously the biodegradability of polypropylene facemask reached 0% ± 0.0”; it will be better showing the photo documentation also for these samples in the results. In the biocompatibility testing the CO₂ amount is not specified, such as data on cell culture medium; in addition, 24H must be 24h. in the SEM analysis specification is declared that electron-beam-accelerating voltage is 5 KV, but in the images is 10KV.

Also, in the Results and discussion sections, comments and descriptions must be improved: “good physico-mechanical properties” is a meaningless sentence. The percentage of the extracts of a material in contact with the cells is not claimed, and the figure 9 is not clear and not well commented; in addition, the images seem to be at different magnitude. Experiments supporting the sentence” The produced nonwoven fabric can be used as the first protective layer of a face mask, providing a barrier to larger particles.” are absent.

Comments on the Quality of English Language

 Moderate editing of English language required

Author Response

Replies to comments and suggestions

Quality of English Language

Moderate editing of English language required

English language was edited for proper grammar and overall style.

Comments and Suggestions for Authors 

 

The present work focuses on a biodegradable nonwoven fabric produced using a PBS bionolle™ 1001MD and spunbonded technology. In the current form, unfortunately the study cannot be accepted for publication. The contribution for the aim of the study is not satisfying indeed the topic needs a more detailed data and deep discussion. 

 

The authors of the article made changes to the text, providing detailed data and conducted a deeper analysis. Any changes made to the text are marked in red to facilitate verification.

 

In the introduction and in the text some references are missing, as in the sentence” Literature data shows that since 1950, global plastic pollution has amounted to 8.3 billion million tons” or “According to scientific research, plastic production has quadrupled over the last 40 years and if this trend continues, plastic production will be responsible for 15% of greenhouse gas emissions by 2050.” and so on. Moreover, in the introduction it will be better add information about recycling. 

 

As suggested by the reviewer, literature references and information about recycling have been added.

It is estimated that that since 1950, global plastic pollution has amounted to 8.3 billion million tons [5–7].

Plastic and other harmful products are ending up in our oceans, damaging the environment. Scientific research has shown that plastic production has quadrupled in the past 40 years. If this trend continues, plastic production will be responsible for 15% of greenhouse gas emissions by 2050. [45].

 

The Materials and Methods sections need to be rewritten: the supplier of PBS is missing, some parameters of the manufacturing process have to be added, no data are reported about the physic-mechanical characterization (equipment, how the test was carried out, the obtained curve...). The biodegradation test on Cotton (100%), used as reference, and on PP are not described, although in the text we found the sentence: “Simultaneously the biodegradability of polypropylene facemask reached 0% ± 0.0”; it will be better showing the photo documentation also for these samples in the results. In the biocompatibility testing the CO2 amount is not specified, such as data on cell culture medium; in addition, 24H must be 24h. in the SEM analysis specification is declared that electron-beam-accelerating voltage is 5 KV, but in the images is 10KV. 

Information was added and a point was introduced to detail the spun-bonded technique: 

The spun-bonded technique consists of introducing the polymer into the extruder through a feeder. To process polyesters like PLA or PBS, it is necessary to reduce the water content level to ppm. [65,66]. The polymer is melted in the extruder's heating zone. The extruders can be single or twin-screw with various arrangements. The temperature gradient should be adapted to the polymer, taking into account the melting and decomposition temperature and the melt flow coefficient. If the temperature is too low, it can cause blockage in the extruder system. Conversely, if the temperature is too high, the viscosity of the polymer will increase, leading to improper fiber formation and material degradation. Therefore, careful selection of the melt temperature is important [67]. The polymer melt is filtered and fed to the spinning head where it is formed into fibers. Depending on the head used as well as its parameters, e.g. number of holes, diameter and length of holes, fibers with different properties can be obtained, e.g. diameter, degree of primary crystallization. The filaments are next drawn in the spinning channel under the influence of hot air and collected on the belt under vacuum. At this stage, the fibers are loosely laid and only pre-bonded into the webbing. It is necessary to use a calendar at a certain temperature to bond the fibers into a nonwoven [68,69]. The parameters of the process are shown below.

 

Biodegradability- the description has been extended to include missing data on polypropylene and cotton masks (reference material). The obtained results have also been added to Figure 9.

Biocopatibilty-corrected 

Biocompatibility testing was also carried out in accordance with the standard [70]. The study was conducted on L922 (mouse fibroblast) cell lines from Sigma Aldrich. The cell cultures before analysis took 49 days in medium Minimum Essential Medium -MEM Eagle with Earle's Salts Base with supplement Fetal Bovine Serum (FBS) (Biological Industries, Israel). Incubation with the test material was carried out over 24h at a temperature of 37°C and 5% CO2. The density of cultured cells was 104 cells/well. The incubation plates were applied with solutions of 100% polyethylene extract, which is the negative control, 100% exact of the test material and its dilution in the range of 50-0.1%, and 0.01% Triton X-100 solution, which is the position control. The results were developed based on the absorbance value measured at the analytical wavelength of 450nm. Absorbance was measured on a BioTek Synergy H1 microplate reader (Agilent Technologies, USA).

 

 

electron-beam-accelerating voltage –corrected  

  

Also, in the Results and discussion sections, comments and descriptions must be improved: “good physico-mechanical properties” is a meaningless sentence. The percentage of the extracts of a material in contact with the cells is not claimed, and the figure 9 is not clear and not well commented; in addition, the images seem to be at different magnitude. Experiments supporting the sentence” The produced nonwoven fabric can be used as the first protective layer of a face mask, providing a barrier to larger particles.” are absent. 

In the Results and discussion section, in accordance with the reviewer's suggestion, the comments "good physico-mechanical properties" have been corrected.

Additionally, Figure 9 (currently 13) has been commented. Regarding the image quality, it was taken from an external report. The contractor is an accredited laboratory and ensures that the test was performed in accordance with applicable standards. We do not have access to other image quality.

Protective and medical face masks are usually made of three layers of nonwovens material with filtration properties. The outer layers are most often layers of nonwoven fabric produced using the spun-bonded technique. The spun  bonded nonwoven  is a barrier to particles larger than 1um. The heart of the mask is non-woven fabric, produced using melt-blown technology, constituting the inner layer of the mask. This nonwoven filters small particles of pollution, usually up to 1 μm in size. Therefore, the authors suggested that the nonwoven  described in the article may be a component of a protective/medical face masks. This information is widely known, therefore no literature references are provided. The statement "The produced nonwoven fabric can be used as the first protective layer of a face mask, providing a barrier to larger particles" is only a suggestion of the authors of the article.

 

For your convenience, changes made to the article are marked in red.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Line 21 missing dot after desired

Line 21-23, please rephrase, English must be improved

 

The introduction goes thorou every aspect impacted by the research, but it can be reduced. Also, an extensive english revision is required.

 

Line 33 please rephrase, English must be improved

Line 43-46 plastics are polymeric materials that pose a threat to the environment and are not broken down by microorganisms: This statement is not true. Many kinds of plastics are biodegradable, other has low biodegradability. The Authors also talk abut them in the following sentences. Introduction must be improved with exhamples an needd to be deeply detailed   I suggest the authors to revise the bibliografic research (for example please read: https://doi.org/10.1007/s11356-018-1234-9; https://doi.org/10.3390/ma14174782; https://doi.org/10.3390/ma14113069; https://doi.org/10.1016/j.foodres.2020.109625; https://doi.org/10.1016/j.foodres.2020.109625; https://doi.org/10.3390/polym13081200; https://doi.org/10.3390/polym13091436; https://doi.org/10.1016/j.biortech.2021.124685; https://doi.org/10.1016/j.biortech.2021.124985;https://doi.org/10.1007/s10924-020-01870-0 and many others)

Line 45: These materials introduce pollution into the environment in the form of microplastics: not all of them. Please Make exhaustive examples.

Lines 83-87: NOt clear, English must be improved

Line 115-116: Please cite which report

Line 134-135 Experts pointed out that due to the 134

demand for personal protective equipment during the Covid 19 pandemic, more and more waste was generated. Could you please give references and numbers? 

Lines 154-170: all these statements need to be proved by references

Lines 171-172: why are them an alternative?

Lines 194-196 Additionally, the incorporation of biodegradable materials aligns with the broader goal of conserving natural resources and reducing the reliance on petrochemical

derived raw materials: I'm not sure that this statement is copletely true. Fossil based plastic can be biodegradable, as well as PLA that requires the exploitation of filed for its production. 

Line 220-223: English must be improved, suggestion: As the consumption of a wide range of polymers has increased in almost all areas of application, there is a need to identify the most ecological way to manage them, especially at the end of the product's life cycle. 

 

Table 1: can you compare the data reported to a reference material? are them in line? whay are them good?

Table 2: the table is splitted in two pages, I suggest the authors to report the layout error to the editorial board.

Table 3: same as table 2

 

Conclusions: can be improved. The Authors states that: Reducing the number of products that introduce microplastic pollution into the environment can be reduced by using biodegradable materials. Please note that biodegradable doesn't mean that non microplastics are generated, but only that they are not persistent.

In general, the paper is unbalanced between introduction and results. The authors present some interesting results, but spend very few words on their interpretation, without giving them the importance they deserve. 

Comments on the Quality of English Language

An extensive english revision is required, especially in the introductory paragraphs

Author Response

Replies to comments and suggestions

Quality of English Language

 Extensive editing of English language required 

English language was edited for proper grammar and overall style.

Comments and Suggestions for Authors 

Line 21 missing dot after desired 

The sentence ending with a period has been rephrased.

Line 21-23, please rephrase, English must be improved 

 The reviewer's suggestions have been followed.

The challenge was to create environmentally friendly materials for personal protective equipment. One of the alternatives to polypropylene materials is a biodegradable nonwoven produced using spun-bonded technology.

The introduction goes thorou every aspect impacted by the research, but it can be reduced. Also, an extensive english revision is required. 

 The introduction was reformatted and the English language was corrected.

The change is marked in red for convenience.

Line 33 please rephrase, English must be improved 

The sentence on line 33 has been reformatted. Changed to: Polymers are chemical substances with a very high molecular weight, they are divided into thermosetting or thermoplastic [1].

Line 43-46 plastics are polymeric materials that pose a threat to the environment and are not broken down by microorganisms: This statement is not true. Many kinds of plastics are biodegradable, other has low biodegradability. The Authors also talk abut them in the following sentences. Introduction must be improved with exhamples an needd to be deeply detailed   I suggest the authors to revise the bibliografic research (for example please read: https://doi.org/10.1007/s11356-018-1234-9; https://doi.org/10.3390/ma14174782; https://doi.org/10.3390/ma14113069; https://doi.org/10.1016/j.foodres.2020.109625; https://doi.org/10.1016/j.foodres.2020.109625; https://doi.org/10.3390/polym13081200; https://doi.org/10.3390/polym13091436; https://doi.org/10.1016/j.biortech.2021.124685; https://doi.org/10.1016/j.biortech.2021.124985;https://doi.org/10.1007/s10924-020-01870-0 and many others) 

In accordance with the reviewer's recommendations, the cited content was modified and the literature was re-analyzed based on the literature references cited above.

These materials also introduce pollutants into the environment in the form of microplastics, mesoplastics [12,13] and nanoplastics [14–16]. Microplastics and nanoplastics are of greatest concern because they can move in the environment, have the ability to release the chemicals they contain, and can also migrate through animal tissues and thus enter living organisms, including humans [17]. Li et al. [18] discussed the sources, occurrence of plastics and their impact on the marine environment. Karapanagioti et al. [19] discussed the dangers of plastic debris to marine animals. An alternative to traditional polymer materials are biodegradable polymers, which enable production within the principles of a circular economy. Currently, leather is trendy as an alternative to synthetic materials. Vanessa Gatto et al. described a collagen stabilization method mediated by 2-chloro-4,6-diethoxy-1,3,5-triazine (CDET) and tert-amine. The authors obtained good quality leather with environmentally friendly parameters [20]. Due to the durability of polymer materials and their large amount of waste, a significant portion accumulates in the environment. As the literature shows, a significant part of waste is generated by packaging materials [21][22][23]. Currently, many activities are undertaken to recycle plastic materials such as PP, PE, PET, or PS.) [21]. Actually, plastic waste management includes landfilling, incineration, recycling and energy recovery [24]. The burning of waste materials causes the emission of dangerous gases, and plastic waste landfills contribute to the contamination of groundwater [25]. An alternative to traditional polymer materials are biodegradable polymers, which enable production within the principles of a circular economy. Good examples are environmentally friendly biopolymers, such as polybutylene succinate (PBS) [26], polyhydroxyalkanoate (PHA) and polyhydroxybutyrate (PHB) [27]. PBS is characterized by good processability. As the literature shows, composites made of natural fibers based on PBS are completely biodegradable and have good mechanical properties [28,29]. In recent years, there has been an increase in the use of bioplastics like PBS, which has raised awareness about the environmental issues caused by non-renewable and non-biodegradable plastics, as well as the rapid depletion of fossil fuel resources. The biodegradability of PBS is an attractive feature of this polymer and therefore gives it an advantage in single-use applications. This polymer can degrade at a high rate in a short period of time and has also been listed as compostable [30]. Therefore, it was proposed as an element of personal protective equipment. A cheap source from which PHA can be obtained is waste paper [31]. PHAs are an alternative to synthetic plastics due to their physicochemical properties comparable to those of synthetic plastics and their biodegradable and biocompatible nature [32,33].

Line 45: These materials introduce pollution into the environment in the form of microplastics: not all of them. Please Make exhaustive examples. 

Corrected according to the reviewer's instructions. Text added and supported by literature.

These materials also introduce pollutants into the environment in the form of microplastics, mesoplastics [12,13] and nanoplastics [14–16]. Microplastics and nanoplastics are of greatest concern because they can move in the environment, have the ability to release the chemicals they contain, and can also migrate through animal tissues and thus enter living organisms, including humans [17]. Li et al. [18] discussed the sources, occurrence of plastics and their impact on the marine environment. Karapanagioti et al. [19] discussed the dangers of plastic debris to marine animals. An alternative to traditional polymer materials are biodegradable polymers, which enable production within the principles of a circular economy. Currently, leather is trendy as an alternative to synthetic materials. Vanessa Gatto et al. described a collagen stabilization method mediated by 2-chloro-4,6-diethoxy-1,3,5-triazine (CDET) and tert-amine. The authors obtained good quality leather with environmentally friendly parameters [20].

Lines 83-87: NOt clear, English must be improved 

Corrected according to the reviewer's instructions. The English language has been improved.

The literature and media have reported extensively on the amount of plastic produced and the negative impact of polymer waste on the environment. However, there is still a lack of detailed data regarding the amount of microplastics that enter the environment as plastics decompose. This area requires further research by scientists.

 

Line 115-116: Please cite which report 

Corrected according to the reviewer's instructions. Literature reference added.

 According to literature, the Covid-19 pandemic has had a significant impact on nature. [36]

Line 134-135 Experts pointed out that due to the 134 demand for personal protective equipment during the Covid 19 pandemic, more and more waste was generated. Could you please give references and numbers?  

Corrected according to the reviewer's instructions. Literature reference added.

There was also an increase in local production. The demand for personal protective equipment, such as filtering half-masks or disposable protective masks made of plastic and intended for single-use, significantly surged during the pandemic. [39–41].

Lines 154-170: all these statements need to be proved by references 

Corrected according to the reviewer's instructions. Literature reference added.

The most common protective materials are nonwoven materials made of petroleum-based polymers, such as polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET) [42–44]. Plastic and other harmful products are ending up in our oceans, damaging the environment. Scientific research has shown that plastic production has quadrupled in the past 40 years. If this trend continues, plastic production will be responsible for 15% of greenhouse gas emissions by 2050. [45]. Currently, all forms of transport contribute the same amount of plastic waste as other sources. Studies indicate that eight million tons of plastic waste are dumped into the oceans annually, and this trend continues each year. [46]. However, personal protective equipment poses an even greater risk than ordinary plastic. Plastic gloves or bags may be mistaken as food by sea turtles or jellyfish, leading to their death. This can result in the decomposition of animals in the water, which increases the level of harmful substances in the water. [47]. An additional factor is that many personal protective equipment contains viruses, fungi and bacteria [48]. Such products may decompose and pollute the environment in the form of microplastics, which, despite their small size, constitute a very dangerous pollution of ecosystems. During the Covid-19 pandemic, the focus has been on ensuring public health and safety. However, it is crucial to recognize that the pandemic has also highlighted the significance of the waste issue. The improper disposal of hazardous waste can have severe consequences on human health, oceans, and the environment. Unfortunately, many regions across the globe lack the infrastructure to effectively handle such waste, making it a global concern. [49–52].

Lines 171-172: why are them an alternative? 

Changes made as below:

Products made from biodegradable polymers derived from biomass offer a sustainable and eco-friendly alternative to traditional plastics. These materials possess similar functional properties as plastics but are designed to break down naturally without harming the environment once they are no longer needed.

Lines 194-196 Additionally, the incorporation of biodegradable materials aligns with the broader goal of conserving natural resources and reducing the reliance on petrochemical derived raw materials: I'm not sure that this statement is copletely true. Fossil based plastic can be biodegradable, as well as PLA that requires the exploitation of filed for its production.  

Changes made as below:

Biodegradability is defined as a process of biological decomposition of materials. Simpler substances such as carbon dioxide, water, and ammonia are the products of the process. Bacteria and fungi (yeasts and molds) are among the microorganisms responsible for biodegradation.

Sentence was corrected- biodegradable polymers were placed with biopolymers 

Line 220-223: English must be improved, suggestion: As the consumption of a wide range of polymers has increased in almost all areas of application, there is a need to identify the most ecological way to manage them, especially at the end of the product's life cycle.  

  Sentence was rewritten according to the suggestion.  

Table 1: can you compare the data reported to a reference material? are them in line? whay are them good? 

The obtained nonwoven was characterized by physico-mechanical parameters listed in Table 1. A spun-bonded nonwoven must have the appropriate parameters to be effective in its application. Breaking force, for example spun-bonded nonwoven made from non-biodegradable polymers, i.e. linear low-density polyethylene was 33N [71]. In the commercial market, nonwoven fabrics made of spun-bonded polypropylene are available with a braking force of 10-200 N and an elongation of 50-300%, depending on their surface density. Different nonwoven fabrics are used based on the application. The newly developed biononwoven has similar physico-mechanical parameters as commercially available products.   

Table 2: the table is splitted in two pages, I suggest the authors to report the layout error to the editorial board. 

Thank you for your attention. This has changed since changes were made to the article

Table 3: same as table 2 

  Changes have been made

Conclusions: can be improved. The Authors states that: Reducing the number of products that introduce microplastic pollution into the environment can be reduced by using biodegradable materials. Please note that biodegradable doesn't mean that non microplastics are generated, but only that they are not persistent. 

In general, the paper is unbalanced between introduction and results. The authors present some interesting results, but spend very few words on their interpretation, without giving them the importance they deserve.  

Changes were made to the article and the results were discussed in more details.

 

For your convenience, changes made to the article are marked in red.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

It is very hard to track the reviews performed according to the comments of the reviewer as in there is no Authors Response to Reviewers Comments. Such a document should be added by quoting exactly the part of the manuscript changed depending on the reviewers’ comments.

 

The subject of the manuscript is within the scope of Sustainability, but it must undergo a drastic revision before being considered for publication.

 

To my knowledge the data given are original.

 

The whole document including the references is found to have 41 % similarity according to plagiarism check.

 

The text must be revised by eliminating the reference lumps and presenting the references individually or inserting only the essential references. Some examples are:

“…..many regions across the globe lack the infrastructure to effectively handle such waste, making it a global concern. [49–52]….”

“….The demand for personal protective equipment, such as filtering half-masks or disposable protective masks made of plastic and intended for single-use, significantly surged during the pandemic. [39–41]….”

“….The inclusion of biopolymers is in line with the broader objective of conserving natural resources and reducing dependence on petrochemical-derived raw materials. [55–57]….”

 

INTRODUCTION

 

The manuscript still has some problems related to reference usage. A couple of examples are given below:

 

The Introduction starts with the following sentence:

“Polymers are chemical substances with a very high molecular weight, they are divided into thermosetting or thermoplastic [1].…..”

This quote is a known thing that is not stated for the first time by “Proshad, R.; Kormoker, T.; Islam, M.S.; Haque, M.A.; Rahman, M.M.; Mithu, M.M.R. Toxic Effects of Plastic on Human Health and Environment: A Consequences of Health Risk Assessment in Bangladesh. Int. J. Heal. 2017, 6, 1, 479”. Therefore it does not need a reference.

 

There are parts of the manuscript that does not contain scientific references. Rather than using scientific references the information given in web sites are used. As an example, it is stated that:

“……their death. This can result in the decomposition of animals in the water, which increases the level of harmful substances in the water. [47]. An additional….”

Reference 47 is not a scientific one. Besides this sentence indicates “harmful substances”, what kind of harmful substances are these?

 

It is stated that:

“….The improper disposal of hazardous waste can have severe consequences on human health, oceans, and the environment. Unfortunately, many regions across the globe lack the infrastructure to effectively handle such waste, making a global concern. [49–52]….”

Since plastic wastes are not considered as hazardous wastes, it is hard to understand the significance of this part. Also, 4 different references are used to support this quote, that is not really about the subject. So, this can be given as another example of improper usage of references.

 

Instead of using

“…..by packaging materials [21][22][23]….”

“……by packaging materials [21-23]….” should be inserted.

 

Figure 1 should be explained in the text.

 

Is life cycle of biodegradable polymers in the circular economy different from non-biodegradable ones? If yes, how?

 

2. Covid - problem with waste management

 

It is stated that:

“…..The distribution of plastics production in individual years of the Covid-19 pandemic depending on the type of raw material is shown in Figures 2 and 3. There is an enormous amount of unmanaged waste that directly threatens ecosystems. According to the literature It is estimated that globally, 1.6 million tons of plastic waste and 3.4 billion face masks are produced and disposed of every day, respectively [33,34]…..”

The titles of the Figures are:

Figure 2. World production of plastics during the Covid-19 pandemic and immediately before the outbreak of the Covid-19 pandemic

Figure 3. European production of plastics during the Covid-19 pandemic and and immediately before the outbreak of the Covid-19 pandemic

However, the bars given in the figures seem not much different during covid, before and after covid. As indicated in the previous comments, it will be helpful to give Figure 2 and 3 with data obtained before and after the Covid-19. Also, the data presented in these figures are not discussed in the text. Therefore, it might be beneficial to get rid of these figures or else leave the figures and evaluate the data shown, in the text.

Two “and” appearing in the title of Figure 3 should be corrected.

 

 

Figure 8 is not mentioned in the text. All of a sudden it appeared in the text. Before giving a figure, it should be introduced in the text by denoting what it shows. After the figure, it must be evaluated in the text as well.

 

It is stated that:

“…. Scientists estimated that during the pandemic, humanity used about 3 million disposable masks per month, making a total of as many as 130 billion masks. ….”

Who are the scientists? References should be given.

 

6. Summary

 

Not a Summary but a Conclusion part should be introduced. Conclusion should give the concluding remarks obtained from this study.

 

It is stated that:

“…..However the amount of waste turns out to be significant and problematic for the environment after pandemic. Air pollution affects not only the environment but also the economy, adversely affecting the implementation of sustainable development goals. Plastic waste harms….”

It is hard to understand why authors use a sentence about air pollution here?

 

The following part is given under Summary:

“……Therefore, alternatives based on polymers of natural origin or that degrade more rapidly are being sought [83–85]. Currently, there are discussions and numerous studies on whether biodegradable or renewable materials are a better solution. Studies show a variety of data both favorable to bio-based plastics and unfavorable. [86–88]……”

This part should be moved to Introduction.

Comments on the Quality of English Language

Minor editing of English language is required.

Author Response

Dear Reviewer,

 

 

Replies to comments and suggestions:

 

1. It is very hard to track the reviews performed according to the comments of the reviewer as in there is no Authors Response to Reviewers Comments. Such a document should be added by quoting exactly the part of the manuscript changed depending on the reviewers’ comments.

 

References to reviewers' comments in the first round have been entered into the publication in red. The authors decided that this method should be readable.  

In addition, in response to the reviewers we included a feedback note with suggestions regarding what has been improved. Thank you for your opinion, we will try to be more detailed next time. 

2. The whole document including the references is found to have 41 % similarity according to plagiarism check. 

 

Plagiarism refers to the research methodology which we use and it has been used in other publications. Descriptions of research methods have been corrected to compensate for this percentage. 

3. The text must be revised by eliminating the reference lumps and presenting the references individually or inserting only the essential references. Some examples are: 

 

“…..many regions across the globe lack the infrastructure to effectively handle such waste, making it a global concern. [49–52]….” 

 

“….The demand for personal protective equipment, such as filtering half-masks or disposable protective masks made of plastic and intended for single-use, significantly surged during the pandemic. [39–41]….” 

 

“….The inclusion of biopolymers is in line with the broader objective of conserving natural resources and reducing dependence on petrochemical-derived raw materials. [55–57]….” 

 

 

The authors left literature references to the quoted fragments. The authors' goal was to show the scale of the problem and support it with literature references.

 

4. The manuscript still has some problems related to reference usage. A couple of examples are given below: 

References to reviewers' comments in the first round have been entered into the publication in red. The authors decided that this method should be readable.  

 

5. The Introduction starts with the following sentence: 

 

“Polymers are chemical substances with a very high molecular weight, they are divided into thermosetting or thermoplastic [1].…..” 

 

This quote is a known thing that is not stated for the first time by “Proshad, R.; Kormoker, T.; Islam, M.S.; Haque, M.A.; Rahman, M.M.; Mithu, M.M.R. Toxic Effects of Plastic on Human Health and Environment: A Consequences of Health Risk Assessment in Bangladesh. Int. J. Heal. 2017, 6, 1, 479”. Therefore it does not need a reference. 

The authors agree with the reviewer's suggestion. The literature reference to the sentence “Polymers are chemical substances with a very high molecular weight, they are divided into thermosetting or thermoplastic” has been removed. 

 

6. There are parts of the manuscript that does not contain scientific references. Rather than using scientific references the information given in web sites are used. As an example, it is stated that: 

 

“……their death. This can result in the decomposition of animals in the water, which increases the level of harmful substances in the water. [47]. An additional….” 

 

Reference 47 is not a scientific one. Besides this sentence indicates “harmful substances”, what kind of harmful substances are these? 

 

Scientific references have been added to the quoted fragments 

 

7. It is stated that: 

 

“….The improper disposal of hazardous waste can have severe consequences on human health, oceans, and the environment. Unfortunately, many regions across the globe lack the infrastructure to effectively handle such waste, making a global concern. [49–52]….” 

 

Since plastic wastes are not considered as hazardous wastes, it is hard to understand the significance of this part. Also, 4 different references are used to support this quote, that is not really about the subject. So, this can be given as another example of improper usage of references. 

The entry and literature references have been removed. 

 

8. Instead of using 

 

“…..by packaging materials [21][22][23]….” 

 

“……by packaging materials [21-23]….” should be inserted. 

 

 The entry has been corrected according to the reviewer's suggestion 

 

9. Figure 1 should be explained in the text. 

The figure shows the circulation of biopolymers from biological sources (e.g. chitosan, cellulose, starch or polylatide). The product life cycle begins when the raw material is obtained. After undergoing manufacturing processes such as synthesis, modification, and conversion into usable material, the product eventually becomes waste. This step is a key point in a circular economy. When a product is discarded in a landfill, its life comes to an end. Non-biodegradable polymers, when reused as raw material, e.g. re-PET, also fit into the circular economy. But it is still not a common practice. Unfortunately, in many parts of the world today, this is still the primary method of utilization. The concept of the circular economy involves looking at waste not as something to discard, but as a valuable resource that can be repurposed. This can be achieved by processing it into new functional material or allowing it to decompose, such as in compost, which adds organic matter to the soil for use in agriculture. This approach helps to create a more sustainable system of production and consumption. Such a management system, which treats waste as a source of biomass or as a renewable material, is supported in Europe. The data shows that Europe is the region with the lowest percentage of landfill waste.  

 

10. Is life cycle of biodegradable polymers in the circular economy different from non-biodegradable ones? If yes, how? 

 

11. Added, Explanation in the text of the Figure 1 description 

 

2. Covid - problem with waste management 
3. It is stated that: 

“…..The distribution of plastics production in individual years of the Covid-19 pandemic depending on the type of raw material is shown in Figures 2 and 3. There is an enormous amount of unmanaged waste that directly threatens ecosystems. According to the literature It is estimated that globally, 1.6 million tons of plastic waste and 3.4 billion face masks are produced and disposed of every day, respectively [33,34]…..” 

 

The titles of the Figures are: 

 

Figure 2. World production of plastics during the Covid-19 pandemic and immediately before the outbreak of the Covid-19 pandemic 

 

13. Figure 3. European production of plastics during the Covid-19 pandemic and and immediately before the outbreak of the Covid-19 pandemic 

However, the bars given in the figures seem not much different during covid, before and after covid. As indicated in the previous comments, it will be helpful to give Figure 2 and 3 with data obtained before and after the Covid-19. Also, the data presented in these figures are not discussed in the text. Therefore, it might be beneficial to get rid of these figures or else leave the figures and evaluate the data shown, in the text. 

 

Two “and” appearing in the title of Figure 3 should be corrected. 

Corrected  Figure 2 and 3, and added descriptions to them. 

 

 

14. Figure 8 is not mentioned in the text. All of a sudden it appeared in the text. Before giving a figure, it should be introduced in the text by denoting what it shows. After the figure, it must be evaluated in the text as well. 

Corrected according to the Reviewer's suggestion 

 

15. It is stated that: 

 

“…. Scientists estimated that during the pandemic, humanity used about 3 million disposable masks per month, making a total of as many as 130 billion masks. ….” 

 

Who are the scientists? References should be given. 

 

Corrected according to the Reviewer's suggestion 

 

 

16. Not a Summary but a Conclusion part should be introduced. Conclusion should give the concluding remarks obtained from this study.

 

It is stated that: 

 

“…..However the amount of waste turns out to be significant and problematic for the environment after pandemic. Air pollution affects not only the environment but also the economy, adversely affecting the implementation of sustainable development goals. Plastic waste harms….” 

 

It is hard to understand why authors use a sentence about air pollution here? 

The entry was changed to: Pollution affects not only the environment but also the economy, adversely affecting the implementation of sustainable development goals. Plastic waste harms health and has become a serious global environmental problem. The COVID-19 pandemic has led to increased demand for single-use products, increasing demand in an already out-of-control area.   

  

 

The following part is given under Summary: 

 

“……Therefore, alternatives based on polymers of natural origin or that degrade more rapidly are being sought [83–85]. Currently, there are discussions and numerous studies on whether biodegradable or renewable materials are a better solution. Studies show a variety of data both favorable to bio-based plastics and unfavorable. [86–88]……” 

 

This part should be moved to Introduction. 

The Reviewer's recommendations were followed and the indicated fragment was moved to the introduction. 

 

Comments on the Quality of English Language 

Minor editing of English language is required. 

The article was checked for correctness of the English language.

 

All changes for round two are marked in blue in the manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The study cannot be accepted for publication.

The contribution for the aim of the study is still not satisfying and the revised form is still lacking necessary data and information, so the paper is poorly organized.

In the introduction section, information about recycling have not been appropriately added.

References 37 and 41 are not reference.

Methods used to obtain mechanical properties are still missing and obtained data are poorly explained; (equipment, how the test was carried out, the obtained curve...)

The production method is descriptive and too superficial, moreover some data are not reported: a single or twin extruder was used for production? Polymer was dried before extrusion and if yes, how many time and what was the used temperature for?

In the revised version is reported” Conversely, if the temperature is too high, the viscosity of the polymer will increase, leading to improper fiber formation and material degradation.”

Note that the viscosity of the polymer usually will decrease, increasing temperature.  

 

Pictures about the biodegradation test on Cotton (100%), used as reference, and on PP was not added.

Regarding the image quality of figure 13, it would be better to have original images, not coming from a report.

Finally, the suggestion of the authors that produced nonwoven fabric can be used as the first protective layer of a face mask, is not supported by experimental data.

Comments on the Quality of English Language

 Moderate editing of English language required

Author Response

Dear Reviewer,

 

 

Replies to comments and suggestions:

 

In the introduction section, information about recycling have not been appropriately added. 

 

The co-authors made changes to the introduction. Recycling information added 

Fasteners were introduced as follows: 

To reduce the amount of plastic waste, two main strategies can be used, i.e. the use of biodegradable materials and recycling. According to EU legislation and Briassoulis and colleagues, the best alternative for valorization of post-consumer polymer waste from fossil fuels as well as biopolymers followed by chemical recycling is mechanical recycling. 

 

References 37 and 41 are not reference. 

According to the reviewer's suggestion, the literature items have been changed. Literature references have been changed. 

Methods used to obtain mechanical properties are still missing and obtained data are poorly explained; (equipment, how the test was carried out, the obtained curve...) 

Added 

“‘Physico-mechanical properties of nonwovens were determined under environmental conditions (20±2°C and RH 65±4%) according to PN-EN ISO 139:2006. For the material, the thickness was determined under PN-EN ISO 9073-2:2002. The TILMET - 64 thickness gauge was used for the work constructed at University of Technology, Łódź, Poland with a pressure of 0.5 kPa. The surface density was applied based on PN-EN 29073-1:1994. The breaking force, elongation and tear strength was determined according to PN-EN 29073-3:1994. The measurements were made on the tenacity tester Instron model 5544 (UK).”  

 

 

The production method is descriptive and too superficial, moreover some data are not reported: a single or twin extruder was used for production? Polymer was dried before extrusion and if yes, how many time and what was the used temperature for? 

We have added some information but it is a patented prduct we do not want to share full information.  

“The biopolymer was extruded using a single-screw extruder with the temperature of heating zones in the range of 165-240°C. The melted polymer at 240°C was pressed through the spinning head. The fibers from the head were directed to a 9/17 cm channel, where the fibers were stretched at a draw ratio of 1,500Pa in the chamber. The stretched fibers, after passing through the forming channel, were deposited in the form of a web on a transport grid with a 24 Hz fleece pickup vacuum.  This web was then thermally bonded using two calenders, with calender I operating at 50°C and calender II at 60°C.” 

In the revised version is reported” Conversely, if the temperature is too high, the viscosity of the polymer will increase, leading to improper fiber formation and material degradation.” 

 

Note that the viscosity of the polymer usually will decrease, increasing temperature.   

 

corrected, instead of viscosity there was a mistake because it was about the melt flow index  - brachylogy 

“Conversely, if the temperature is too high, the melt flow index of the polymer will increase as a result of decrease of viscosity, leading to improper fiber formation and material degradation.” 

  

 

Pictures about the biodegradation test on Cotton (100%), used as reference, and on PP was not added. 

Unfortunately, photodocumentation for the PP mask and Cotton was not made. The authors used Cotton as a reference material. The authors' intention was not to present a visual comparison, but to present a summary of the results obtained. Thank you for this comment. For subsequent research, photodocumentation will be prepared and presented in a publication. It is worth noting that achieving 100% biodegradability for Cotton does not make it possible to provide photodocumentation after the process. At the same time, the weight loss for the PP mask was negligible, so visually the mask did not change compared to the initial sample.   

 

 

Regarding the image quality of figure 13, it would be better to have original images, not coming from a report. 

unfortunately we don't have any better images 

 

Finally, the suggestion of the authors that produced nonwoven fabric can be used as the first protective layer of a face mask, is not supported by experimental data. 

It was pointed out that biobased nonwoven has similar prametry to PP nonwovens: 

“The obtained nonwoven was characterized by physico-mechanical parameters listed in Table 1. A spun-bonded nonwoven must have the appropriate parameters to be effective in its application. Breaking force, for example spun-bonded nonwoven made from non-biodegradable polymers, i.e. linear low-density polyethylene was 33N  [89] . In the commercial market, nonwoven fabrics made of spun-bonded polypropylene are available with a braking force of 10-200 N and an elongation of 50-300%, depending on their surface density. Different nonwoven fabrics are used based on the application. The newly developed biononwoven has similar physico-mechanical parameters as commercially available products  [90,91].” 

But we added more information abautSMS composite    

 

 Comments on the Quality of English Language 

Minor editing of English language is required. 

The article was checked for correctness of the English language.

 

 

All changes for round two are marked in blue in the manuscript.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

In my opinion, the corrections and additional explanations made by you during the revision are relevant and exhaustive. The present form is a very well written paper, with interesting perspectives and results.

 

Author Response

Thank you for your positive opinion. I believe that the article will be useful to many researchers.

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

In the present form the article could be accepted for publication, although a question is still without answer that is: Polymer was dried before extrusion and if yes, how many time and what was the used temperature for.

Author Response

Dear Reviewer,

Replies to comments and suggestions:

In the present form the article could be accepted for publication, although a question is still without answer that is: Polymer was dried before extrusion and if yes, how many time and what was the used temperature for.

 

Thank you for your positive opinion. Required information has been added to the manuscript. They are marked in yellow in the text of the publication.

The polymer was dried in a rotary dryer (Fourné Maschinenbau, Germany) during 13 hours at a temperature of 55±5°C.

Author Response File: Author Response.docx