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18 pages, 5924 KiB

Open AccessArticle

Poly(3-hydroxybutyrate) Production from Lignocellulosic Wastes Using Bacillus megaterium ATCC 14581

by Lacrimioara Senila, Emese Gál, Eniko Kovacs, Oana Cadar, Monica Dan, Marin Senila and Cecilia Roman

Polymers 2023, 15(23), 4488; https://doi.org/10.3390/polym15234488 - 22 Nov 2023

Cited by 1 | Viewed by 989

Abstract

This study aimed to analyze the production of poly(3-hydroxybutyrate) (PHB) from lignocellulosic biomass through a series of steps, including microwave irradiation, ammonia delignification, enzymatic hydrolysis, and fermentation, using the Bacillus megaterium ATCC 14581 strain. The lignocellulosic biomass was first pretreated using microwave irradiation [...] Read more.

This study aimed to analyze the production of poly(3-hydroxybutyrate) (PHB) from lignocellulosic biomass through a series of steps, including microwave irradiation, ammonia delignification, enzymatic hydrolysis, and fermentation, using the Bacillus megaterium ATCC 14581 strain. The lignocellulosic biomass was first pretreated using microwave irradiation at different temperatures (180, 200, and 220 °C) for 10, 20, and 30 min. The optimal pretreatment conditions were determined using the central composite design (CCD) and the response surface methodology (RSM). In the second step, the pretreated biomass was subjected to ammonia delignification, followed by enzymatic hydrolysis. The yield obtained for the pretreated and enzymatically hydrolyzed biomass was lower (70.2%) compared to the pretreated, delignified, and enzymatically hydrolyzed biomass (91.4%). These hydrolysates were used as carbon substrates for the synthesis of PHB using Bacillus megaterium ATCC 14581 in batch cultures. Various analytical methods were employed, namely nuclear magnetic resonance (¹H-NMR and¹³C-NMR), electrospray ionization mass spectrometry (EI-MS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA), to identify and characterize the extracted PHB. The XRD analysis confirmed the partially crystalline nature of PHB. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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14 pages, 2647 KiB

Open AccessArticle

Characterization of Cellulose-Degrading Bacteria Isolated from Silkworm Excrement and Optimization of Its Cellulase Production

by Hao Li, Minqi Zhang, Yuanhao Zhang, Xueming Xu, Ying Zhao, Xueping Jiang, Ran Zhang and Zhongzheng Gui

Polymers 2023, 15(20), 4142; https://doi.org/10.3390/polym15204142 - 19 Oct 2023

Cited by 2 | Viewed by 2323

Abstract

An abundance of refractory cellulose is the key limiting factor restricting the resource utilization efficiency of silkworm (Bombyx mori) excrement via composting. Screening for cellulose-degrading bacteria is likely to provide high-quality strains for the safe and rapid decomposition of silkworm excrement. [...] Read more.

An abundance of refractory cellulose is the key limiting factor restricting the resource utilization efficiency of silkworm (Bombyx mori) excrement via composting. Screening for cellulose-degrading bacteria is likely to provide high-quality strains for the safe and rapid decomposition of silkworm excrement. In this study, bacteria capable of degrading cellulose with a high efficiency were isolated from silkworm excrement and the conditions for cellulase production were optimized. The strains were preliminarily screened via sodium carboxymethyl cellulose culture and staining with Congo red, rescreened via a filter paper enzyme activity test, and identified via morphological observation, physiological and biochemical tests, and phylogenetic analysis of the 16S rDNA sequence. Enzyme activity assay was performed using the 3,5-dinitrosalicylic acid method. DC-11, a highly cellulolytic strain, was identified as Bacillus subtilis. The optimum temperature and pH of this strain were 55 °C and 6, respectively, and the filter paper enzyme activity (FPase), endoglucanase activity (CMCase), and exoglucanase activity (CXase) reached 15.40 U/mL, 11.91 U/mL, and 20.61 U/mL. In addition, the cellulose degradation rate of the treatment group treated with DC-11 was 39.57% in the bioaugmentation test, which was significantly higher than that of the control group without DC-11 (10.01%). Strain DC-11 was shown to be an acid-resistant and heat-resistant cellulose-degrading strain, with high cellulase activity. This strain can exert a bioaugmentation effect on cellulose degradation and has the potential for use in preparing microbial inocula that can be applied for the safe and rapid composting of silkworm excrement. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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18 pages, 15746 KiB

Open AccessArticle

Research on Properties of PBAT/CaCO₃ Composite Films Modified with Titanate Coupling Agent

by Zhekun Liu, Fantao Meng, Xianggang Tang, Chengzhuang Su, Qinglin Mu and Guannan Ju

Polymers 2023, 15(10), 2379; https://doi.org/10.3390/polym15102379 - 19 May 2023

Cited by 3 | Viewed by 1893

Abstract

High cost, low crystallinity, and low-melt strength limit the market application of the biodegradable material poly (butylene adipate-co-terephthalate) (PBAT), which has become a major obstacle to the promotion of PBAT products. Herein, with PBAT as resin matrix and calcium carbonate (CaCO₃) [...] Read more.

High cost, low crystallinity, and low-melt strength limit the market application of the biodegradable material poly (butylene adipate-co-terephthalate) (PBAT), which has become a major obstacle to the promotion of PBAT products. Herein, with PBAT as resin matrix and calcium carbonate (CaCO₃) as filler, PBAT/CaCO₃ composite films were designed and prepared with a twin-screw extruder and single-screw extrusion blow-molding machine designed, and the effects of particle size (1250 mesh, 2000 mesh), particle content (0–36%) and titanate coupling agent (TC) surface modification of CaCO₃ on the properties of PBAT/CaCO₃ composite film were investigated. The results showed that the size and content of CaCO₃ particles had a significant effect on the tensile properties of the composites. The addition of unmodified CaCO₃ decreased the tensile properties of the composites by more than 30%. TC-modified CaCO₃ improved the overall performance of PBAT/CaCO₃ composite films. The thermal analysis showed that the addition of titanate coupling agent 201 (TC-2) increased the decomposition temperature of CaCO₃ from 533.9 °C to 566.1 °C, thereby enhancing the thermal stability of the material. Due to the heterogeneous nucleation of CaCO₃, the addition of modified CaCO₃ raised the crystallization temperature of the film from 97.51 °C to 99.67 °C and increased the degree of crystallization from 7.09% to 14.83%. The tensile property test results showed that the film reached the maximum tensile strength of 20.55 MPa with the addition of TC-2 at 1%. The results of contact angle, water absorption, and water vapor transmission performance tests showed that TC-2 modified CaCO₃ increased the water contact angle of the composite film from 85.7° to 94.6° and decreased the water absorption from 13% to 1%. When the additional amount of TC-2 was 1%, the water vapor transmission rate of the composites was reduced by 27.99%, and the water vapor permeability coefficient was reduced by 43.19%. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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14 pages, 8756 KiB

Open AccessArticle

A Circular Approach for the Valorization of Tomato By-Product in Biodegradable Injected Materials for Horticulture Sector

by Alain Bourmaud, Kolja Konschak, Coralie Buffet, Méline Calatraba, Anton Loïc Rudolph, Antoine Kervoëlen, Basile Gautherot, Estelle Bonnin and Johnny Beaugrand

Polymers 2023, 15(4), 820; https://doi.org/10.3390/polym15040820 - 07 Feb 2023

Viewed by 1342

Abstract

This study focuses on the use of tomato (Solanum lycopersicum L.) by-product biomass from industrial plants as reinforcement for designing a range of new degradable and biobased thermoplastic materials. As a novel technique, this fully circular approach enables a promising up-cycling of [...] Read more.

This study focuses on the use of tomato (Solanum lycopersicum L.) by-product biomass from industrial plants as reinforcement for designing a range of new degradable and biobased thermoplastic materials. As a novel technique, this fully circular approach enables a promising up-cycling of tomato wastes. After an in-depth morphological study of the degree of reinforcement through SEM and dynamic analysis, mechanical characterization was carried out. Our mechanical results demonstrate that this circular approach is of interest for composite applications. Despite their moderate aspect ratio values (between 1.5 and 2), the tomato by-product-reinforced materials can mechanically compete with existing formulations; PBS-Tomato fiber, for example, exhibits mechanical performance very close to that of PP-flax, especially regarding strength (+11%) and elongation at break (+6%). According to the matrix and particle morphology, a large range of products—biobased and/or degradable, depending on the targeted application—can be designed from tomato cultivation by-products. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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15 pages, 4426 KiB

Open AccessArticle

Physico-Chemical Characterization of Keratin from Wool and Chicken Feathers Extracted Using Refined Chemical Methods

by Sara Mattiello, Alessandro Guzzini, Alessandra Del Giudice, Carlo Santulli, Marco Antonini, Giulio Lupidi and Roberto Gunnella

Polymers 2023, 15(1), 181; https://doi.org/10.3390/polym15010181 - 30 Dec 2022

Cited by 7 | Viewed by 4510

Abstract

In this work, the characteristic structure of keratin extracted from two different kinds of industrial waste, namely sheep wool and chicken feathers, using the sulfitolysis method to allow film deposition, has been investigated. The structural and microscopic properties have been studied by means [...] Read more.

In this work, the characteristic structure of keratin extracted from two different kinds of industrial waste, namely sheep wool and chicken feathers, using the sulfitolysis method to allow film deposition, has been investigated. The structural and microscopic properties have been studied by means of scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), and infrared (IR) spectroscopy. Following this, small-angle X-ray scattering (SAXS) analysis for intermediate filaments has been performed. The results indicate that the assembly character of the fiber can be obtained by using the most suitable extraction method, to respond to hydration, thermal, and redox agents. The amorphous part of the fiber and medium range structure is variously affected by the competition between polar bonds (reversible hydrogen bonds) and disulfide bonds (DB), the covalent irreversible ones, and has been investigated by using fine structural methods such as Raman and SAXS, which have depicted in detail the intermediate filaments of keratin from the two different animal origins. The preservation of the secondary structure of the protein obtained does offer a potential for further application of the waste-obtained keratin in polymer films and, possibly, biocomposites. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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11 pages, 1897 KiB

Open AccessArticle

Effect of Tannin Furanic Polymer in Comparison to Its Mimosa Tannin Extract on the Growth of Bacteria and White-Rot Fungi

by Jonas Eckardt, Gianluca Tondi, Genny Fanchin, Alexander Lach and Robert R. Junker

Polymers 2023, 15(1), 175; https://doi.org/10.3390/polym15010175 - 29 Dec 2022

Viewed by 1431

Abstract

Tannins are well-known to protect plants from bacteria and fungi, but nothing is known about its effects on microorganisms once they are copolymerized. Therefore, a study was conducted to evaluate the effect of a tannin–furanic polymer in comparison with industrial mimosa tannin extract [...] Read more.

Tannins are well-known to protect plants from bacteria and fungi, but nothing is known about its effects on microorganisms once they are copolymerized. Therefore, a study was conducted to evaluate the effect of a tannin–furanic polymer in comparison with industrial mimosa tannin extract on the in vitro growth of two strains of bacteria, Bacillaceae and Pseudomanadaceae, and two white-rot fungi, Trametes versicolor and Agrocybe aegerita. Results have highlighted that the tannin polymer did not inhibit the growth of tested bacteria and even favored the growth of Bacillaceae without extra glucose. The growth of both fungi was enhanced by mimosa tannin and its polymer at low concentrations (<1%), while concentrations above 10% had a growth-inhibiting effect, which was slightly less strong for the polymer compared to the tannin against Trametes versicolor. These findings highlighted that tannin–furanic polymers can be tolerated by certain microorganisms at low concentration and that their inhibitory effect is similar or slightly lower than that of the pristine tannin extract. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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15 pages, 4087 KiB

Open AccessArticle

Micromechanical Deformation Processes and Failure of PBS Based Composites Containing Ultra-Short Cellulosic Fibers for Injection Molding Applications

by Laura Aliotta, Mattia Gasenge, Vito Gigante and Andrea Lazzeri

Polymers 2022, 14(21), 4499; https://doi.org/10.3390/polym14214499 - 24 Oct 2022

Cited by 1 | Viewed by 1441

Abstract

The use of biobased thermoplastic polymers has gained great attention in the last years as a potential alternative to fossil-based thermoplastic polymers. Biobased polymers in fact offer advantages not only in terms of reduced dependence on fossil resources but they also lower the [...] Read more.

The use of biobased thermoplastic polymers has gained great attention in the last years as a potential alternative to fossil-based thermoplastic polymers. Biobased polymers in fact offer advantages not only in terms of reduced dependence on fossil resources but they also lower the CO₂ footprint in accordance with sustainability and climate protection goals. To improve the properties of these materials, reinforcement with biobased fibers is a promising solution; however, it must be kept in mind that the fibers aspect ratio and the interfacial adhesion between the reinforcement and the matrix plays an important role influencing both physical and mechanical properties of the biocomposites. In this paper, the possibility of producing composites by injection molding, based on polybutylene succinate and ultra-short cellulosic fibers has been explored as a potential biobased solution. Thermo-mechanical properties of the composites were investigated, paying particular attention to the local micromechanical deformation processes, investigated by dilatometric tests, and failure mechanisms. Analytical models were also applied to predict the elastic and flexural modulus and the interfacial properties of the biocomposites. Good results were achieved, demonstrating the that this class of biocomposite can be exploited. Compared to pure PBS, the composites with 30 wt.% of cellulose fibers increased the Young’s modulus by 154%, the flexural modulus by 130% and the heat deflection temperature by 9%. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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16 pages, 6424 KiB

Open AccessEditor’s ChoiceArticle

Biochar Particles Obtained from Agricultural Carob Waste as a Suitable Filler for Sustainable Biocomposite Formulations

by Giulia Infurna, Luigi Botta, Marco Maniscalco, Elisabetta Morici, Giuseppe Caputo, Salvatore Marullo, Francesca D’Anna and Nadka Tz. Dintcheva

Polymers 2022, 14(15), 3075; https://doi.org/10.3390/polym14153075 - 29 Jul 2022

Cited by 4 | Viewed by 1836

Abstract

In the context of sustainable and circular economy, the recovery of biowaste for sustainable biocomposites formulation is a challenging issue. The aim of this work is to give a new life to agricultural carob waste after glucose extraction carried out by a local [...] Read more.

In the context of sustainable and circular economy, the recovery of biowaste for sustainable biocomposites formulation is a challenging issue. The aim of this work is to give a new life to agricultural carob waste after glucose extraction carried out by a local factory for carob candy production. A pyrolysis process was carried out on bio-waste to produce biofuel and, later, the solid residual fraction of pyrolysis process was used as interesting filler for biocomposites production. In this work, biochar particles (BC) as a pyrolysis product, after fuels recovery of organic biowaste, specifically, pyrolyzed carobs after glucose extraction, were added on poly(butylene-adipate-co-terephthalate), (PBAT), at two different concentrations, i.e., 10 and 20 wt%. The BC have been produced using three pyrolysis processing temperatures (i.e., 280, 340 and 400 °C) to optimize the compositions of produced solid fractions and biofuels. The resulting particles from the pyrolysis process (BC280, BC340 and BC400) were considered as suitable fillers for PBAT. Firstly, the BC particles properties were characterized by elemental composition and spectroscopy analysis, particle size measurements and evaluation of radical scavenging activity and efficiency. Moreover, PBAT/BC composites were subjected to analysis of their rheological and thermal behavior, morphologies and mechanical properties. In addition, accelerated weathering, monitored by both tensile test and spectroscopic analysis, was carried out, and obtained results show that the biochar particles can exert a beneficial effect on photo-oxidation delay of PBAT matrix. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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Review

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25 pages, 690 KiB

Open AccessReview

A Comprehensive Study on Starch Nanoparticle Potential as a Reinforcing Material in Bioplastic

by Herlina Marta, Claudia Wijaya, Nandi Sukri, Yana Cahyana and Masita Mohammad

Polymers 2022, 14(22), 4875; https://doi.org/10.3390/polym14224875 - 12 Nov 2022

Cited by 6 | Viewed by 3135

Abstract

Starch can be found in the stems, roots, fruits, and seeds of plants such as sweet potato, cassava, corn, potato, and many more. In addition to its original form, starch can be modified by reducing its size. Starch nanoparticles have a small size [...] Read more.

Starch can be found in the stems, roots, fruits, and seeds of plants such as sweet potato, cassava, corn, potato, and many more. In addition to its original form, starch can be modified by reducing its size. Starch nanoparticles have a small size and large active surface area, making them suitable for use as fillers or as a reinforcing material in bioplastics. The aim of reinforcing material is to improve the characteristics of bioplastics. This literature study aims to provide in-depth information on the potential use of starch nanoparticles as a reinforcing material in bioplastic packaging. This study also reviews starch size reduction methods including acid hydrolysis, nanoprecipitation, milling, and others; characteristics of the nano-starch particle; and methods to produce bioplastic and its characteristics. The use of starch nanoparticles as a reinforcing material can increase tensile strength, reduce water vapor and oxygen permeability, and increase the biodegradability of bioplastics. However, the use of starch nanoparticles as a reinforcing material for bioplastic packaging still encounters obstacles in its commercialization efforts, due to high production costs and ineffectiveness. Full article

(This article belongs to the Special Issue Biodegradable Polymer Composites)

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