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Article

Efficient Use of Secondary Raw Material from the Production of Polyamide Construction Products

by
Tomasz Olszewski
*,
Danuta Matykiewicz
*,
Mateusz Barczewski
and
Jacek Andrzejewski
Faculty of Mechanical Engineering, Poznan University of Technology, Piotrowo 3, 61-138 Poznan, Poland
*
Authors to whom correspondence should be addressed.
Processes 2024, 12(7), 1304; https://doi.org/10.3390/pr12071304
Submission received: 20 May 2024 / Revised: 14 June 2024 / Accepted: 20 June 2024 / Published: 23 June 2024
(This article belongs to the Section Environmental and Green Processes)
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Versions Notes

Abstract

:
This study aimed to assess the possibility of using post-production waste and the impact of the conditioning method on the mechanical and thermomechanical properties of polyamide injection molded parts. Samples containing 5, 10, and 15 wt.% of ground post-production waste were produced using injection molding technology. The rheological properties by oscillatory rheometry, the melt mass flow rate (MFR), and the thermal stability by thermogravimetric analysis (TGA) of polymer mixtures containing recycled fraction were determined. The samples were conditioned under the following conditions: 24 h and 14 days in distilled water, in a climatic chamber, and aged in a xenon-light-accelerated aging chamber. Then, the impact and static tensile strength and heat deflection temperature (HDT) were assessed. The results show that the addition of post-production waste in the form of grinding does not significantly affect the mechanical and thermomechanical properties of the finished products. This research provides valuable information regarding the possibility of using secondary materials for manufacturing high-performance construction products. Moreover, it was proven that the process of conditioning polyamide samples in a climatic chamber was the most effective and significantly increased the impact strength of the tested material.

1. Introduction

The large-scale production of plastic products and their practical use in every branch of industry and everyday life mean that these materials, after use, pose a threat to waste management around the world [1]. Polyamide 6 (PA6) and polyamide 6.6 (PA6.6) are a group of crystalline thermoplastic materials commonly known under the commercial name Nylon [2]. Due to its properties and durability, and the availability of various types, polyamide is still widely used and modified to produce durable elements for construction, automotive, and utility applications [3,4]. Therefore, the world’s demand for polyamides of different types is increasing every year. Considering the increased interest in these materials, the related waste management problems become crucial [5,6].
According to Plastics Europe, in 2022 the production of plastic in Europe alone has reached the level of 58.7 Mt, of which only 3.2% was produced by the mechanical recycling of pre-consumer goods [7]. As the demand for plastic is still growing, the reduction of production waste has a significant impact on the reduction of greenhouse gas emissions, dependence on finite petroleum resources, disposal of plastic wastes in the environment, and, last but not least, the profitability of plastic processing companies [8,9,10].
The reduction process can generally be applied to materials, energies, and wastes, and should be considered the first option for any production process. Then, it must be determined if the waste can be reused in the same or similar applications with or without modifications or transformations. Although several studies have been published on reusing polyamides, especially fibers and membranes, they are not complete in representing the whole range of possible applications. Even nowadays, there are still not enough applications developed to reuse all the generated waste, so another option must be investigated, which is recycling [8,11]. More and more methods are being implemented into production to improve process efficiency and reduce material losses and energy consumption [12]. Due to its efficiency and high accuracy, injection molding technology is widely used for products manufactured from fiber-reinforced thermoplastic materials such as glass fiber (GF) polyamide-based composites [13]. Fernandez et al. described the hybrid injection molding (HM) technique, including polymeric mold cores and cavities obtained from additive manufacturing (AM), and both were placed in an overall metal housing for the final polymeric part production [12]. Vidakis et al. developed a method for recycling polyamide fiber by extrusion melting in multiple recycling cycles and assessed its impact on the mechanical and thermal properties of samples produced by the Fused Filament Fabrication (FFF) method [14]. Mondragon et al. successfully described the thermomechanical recycling of polyamide 6 from fishing net waste [15].
The recycling of plastics can be defined as the process of recovering scrap or used plastics and reprocessing them into valuable goods. Various recycling methods have been proposed depending on how the material is transformed and the origin of the material to be reprocessed [11,16]. Closed-loop recycling is performed on waste produced with a known history. It can be divided based on transformation methods: chemical, biological, physical, mechanical, and thermal recycling [11,17]. Mechanical recycling, also known as secondary recycling, transforms post-production waste via mechanical methods such as extruding, pulverizing, or grinding [18]. These methods of low processing cost generate less residue and require less energy. Although there is a higher risk of contamination, most importantly, these methods are known to degrade the molecular structure of polymers due to oxidation, or chain scission, every time they are reprocessed [11,19]. However, in the case of post-consumer waste based on biocomposites, composting becomes a method of managing these materials [20]. Our previous work assessed the possibility of using grinding from process waste to manufactured products [18]. However, the results did not fully characterize waste material as a source of sustainable secondary raw materials. Therefore, the novelty of this work was the complete rheological characterization of polymer mixtures containing waste material, as well as the assessment of the influence of the type of conditioning (long-term conditioning realized by water immersion and use of a climatic chamber) and UV aging on the properties of the produced samples. In outdoor applications, polymer parts undergo degradation, which depends on the environment (especially sunlight intensity, temperature, and humidity). UV degradation occurs due to the combined action of photolysis and oxidation reactions [21]. Hence, the characterization of the impact of the aquatic environment and UV aging for parts made from recycled materials is an important issue.
This study aimed to assess the possibility of using post-production waste to produce finished polyamide products. Samples containing 5, 10, and 15% by weight of regrind from post-production waste were manufactured using the injection method. The rheological properties and mass flow rate of polymer mixtures were determined. Moreover, the samples were conditioned in the following conditions: 24 h and 14 days in distilled water, in a climatic chamber, and aged in a UV–light chamber. Then, the impact strength, tensile strength, and heat deflection temperature of HDT were assessed.

2. Materials and Methods

2.1. Materials and Sample Preparation

The commercial polyamide 6 (PA6)–based composite with injection molding purposes was selected for testing; it was of a grade with 50% glass fiber and heat stabilized under the trade name Promyde B300 P2 G50 (Nurel, Zaragoza, Spain).
The post-production waste comes from cold runner systems that remained after the injection process was grounded using a low-speed granulator, Rapid Power Tech 150, (Rapid Granulator, Bredaryd, Sweden) with a 4 mm sieve. The arrangement of knives used to maintain a constant distance between the sieve and the housing allows for obtaining grinding with properties similar to those of the original raw material. The regrind obtained during the process was used to manufacture new products. Examples of various types of post-production residues in the form of cold runner injection molding systems and polyamide products are shown in Figure 1. The original polyamide pellets and grinding from cold runner systems are shown in Figure 2.
The samples were formed using an Engel Victory 50 (Engel Austria GmbH, Schwertberg, Austria) injection molding machine with a molding temperature of 260 °C, mold temperature of 40 °C, injection pressure of 67.5 MPa, holding pressure of 42.0 MPa, and holding/cooling time of 6/15 s.
Samples containing 0, 5, 10, 15, and 100% of regrind were produced and described as PA, 5PA, 10PA, 15PA, and rPA. The samples were conditioned for 24 h and 14 days in distilled water and in a BINDER constant climate chamber (70 °C, 62% RH) until the constant mass was obtained. Figure 3 shows the increase in mass of samples conditioned in water. After 14 days, the sample mass increased on average by 2%. Moreover, the samples were aged in a TestAn Xentest 2200 xenon light (TestAn, Gdańsk, Poland) accelerated aging chamber for 168 h (7 days) under 0.55 W/m2 irradiance at 340 nm UV light intensity.

2.2. Methods

The filler particle size analysis was performed based on microscopic images obtained from the Opta-Tech MB200s (Opta_Tech, Warszawa, Poland) digital optical microscope connected with the Meiji Techno HD2600T camera (591 Division St., Campbell, CA, USA). The observations were made using 40× magnification. The presented results of particle size determination were made for at least 500 measurements.
The rheological behavior of polyamide composites containing various amounts of recycled fraction was analyzed using an Anton Paar MCR 301 (Anton Paar, Graz, Austria) oscillatory rheometer equipped with 25 mm diameter parallel plates and a 1 mm gap. The measurements were conducted at 275 °C. Preliminary tests were performed using the strain sweep mode to ensure later experiments were located in the linear viscoelastic (LVE) region. Angular frequency sweeps were performed at 0.05% strain in the LVE region, in the 0.15 to 500 rad/s range.
Melt mass flow rate (MFR) was measured for the investigated mixtures of polyamide with regrind using a Dynisco 4004 (Dynisco, Franklin, MA, USA) melt flow indexer according to ISO 1133 (load 5.00 kg, temperature 275 °C) [22].
The impact strength of the rectangular notched samples of 80 × 10 × 4 mm was assessed by the Charpy method according to ISO 179 standard [23], at room temperature with a span of 62 mm. In addition, during the test, the peak load was measured as the maximum force (Fmax). Zwick/Roell HIT 25P (Zwick, Ulm, Germany) impact strength apparatus with 5 J hammer was used.
The tensile test was carried out on a Zwick/Roell Z010 (Zwick, Germany) universal testing machine following the ISO 527 standard [24] at a crosshead speed of 10 mm/min.
The heat deflection temperature (HDT) was assessed using the HDT testing machine RV300C (Testlab, Warszawa, Poland) in an oil bath with the ISO 75 standard [25], load 1.8 MPa, and a heating rate of 120 °C/h.
The thermal stability was measured by the thermogravimetric method (TGA) from 30 to 900 °C at a heating rate of 10 °C/min under nitrogen atmospheres using a TG 209 F1 Netzsch apparatus (Netzsch-Gerätebau GmbH, Selb, Germany). Approximately 10 mg samples were placed in ceramic pans. The T5% and T10% decomposition temperature was determined as 5% and 10% weight loss temperature, respectively. The residual mass (ΔW%) was determined at about 900 °C. The maximum temperature of thermal degradation and rate was also determined based on derivative thermogravimetric curves (DTG).

3. Results

3.1. Fiber Length Distribution

Figure 4 shows the results of measurements of the length distribution of glass fibers in the composite. The analysis was performed for samples packed at a temperature of 700 °C for 3 h in an oxidizing atmosphere. Based on the results obtained, it can be clearly stated that the additional processing cycle increased the share of shorter fibers. In the case of the extruded samples, the dominant fiber length range was 50–75 μm, while after processing, it was 25–50 μm. The share of fractions with a length not exceeding 25 μm also increased with an additional processing cycle.

3.2. Rheological Behavior

Figure 5 shows the results of oscillatory rheological measurements showing changes in storage (G′), loss (G″), and complex viscosity (|η*|) as a function of ω. The addition of recycled polymer decreased complex viscosity in the entire considered angular frequency range (Figure 5c). Despite the different geometry of the measurement system and the range of shear rates compared to the flow in a capillary channel, it can be concluded that these results are consistent with the results of the melt flow rate. Regardless of the share of rPA, all materials showed no plateau in the range of low ω values. This effect is a characteristic feature of composites containing a high amount of fillers or nanofillers [26,27]. In this case, the fibrous filler and its fragmented fractions were mechanically hindered, creating a three-dimensional network of physically connected structures in the polymeric bulk. This effect can also be noted in the lack of dependence between changes in storage modulus and angular frequencies below 10−1 rad/s. In the case of composites rPA, a flattening of the G′(ω) curve can be observed at lower ω values. This may be related to the reduced share of long fibers caused by processing and intense shear forces during plastification in the injection molding process. In the case of all series, viscous properties dominate over elastic ones, which is confirmed by the higher values of loss modulus than storage modulus (G″ > G′) in the entire ω range.
MFR allows the evaluation of the flow behavior of the molten thermoplastic under applied stresses. MFR is described as a mass of plastic flowing through a capillary matrix of a specified diameter and length under a specified load and temperature. This indicates the processability of the plastic in terms of how easily it flows in a molten state. Low MFR–characterized thermoplastics are used as extrusion-grade polymers, while higher MFR–value polymeric materials are used for injection molding. It can be seen that the addition of regrind increased the MFR value of the tested materials (Table 1). This effect may be an indirect result of the shortening of the length of the glass fibers due to processing. As reported by Gültürk et al. [28], the increment in the MFR values may result from the reduction in melt viscosity due to the thermomechanical degradation of the polymer matrix during the recycling process and fiber shortening. The processing of polymeric materials filled with short fibers involves the fragmentation of fibers due to the intense shear deformation of high-viscosity systems [29].

3.3. Impact Strength

The impact strength of reinforced polymer materials depends, among other things, on the structure, the share of individual matrix/reinforcement phases, and the dispersion of additional components in the polymer matrix [30]. The influence of fibers on crack propagation in a thermoplastic matrix is to increase the volume in which energy dissipation can occur. Fibers also increase the potential energy-absorbing mechanisms in the system [31]. A noticeable drop in impact strength can be noted for the sample made of 100% regrind. This may be due to the fact that more fractured fibers will have more ends that might introduce a notching effect [32]. Polyamide products are repeatedly exposed to variable humidity and UV radiation throughout their service. PA6 is hygroscopic; moisture diffusion may change its properties [33]. Therefore, assessing changes in the mechanical properties of samples after conditioning in various conditions provides comprehensive information regarding the scope of application of a given product. The average Charpy impact strength and maximum force of tested samples are presented in Table 2 and Table 3. As expected, the amount of energy absorbed by the fractured parts fluctuated in a narrow range. It can be seen that the conditioning environment affects the impact strength of the tested samples, reaching the highest values for samples conditioned in the chamber and the lowest for the UV aging chamber and unconditioned parts (Figure 6). Water acts as a plasticizer for polyamide parts. The higher the amount of absorbed water (until the saturation plateau), the higher the impact strength of the parts.
On the other hand, parts exposed to UV rays were more brittle, resulting in lower braking resistance. The samples made of 100% regrind exhibit significantly lower impact strength than those made of virgin material. It can also be observed that conditioning in water for 24 h increased the maximum force required to destroy the sample.

3.4. Tensile Strength

Data from the tensile strength test of the tested samples are presented in Table 4, Table 5 and Table 6. It can be seen that adding regrind to the virgin material in the range of 5–15% wt. has a minor impact on the mechanical performance of the tested samples. The tensile strength shows a small reduction after increasing the fraction of regrind, which may be related to the reduction in the fiber length in the secondary material [34]. According to the mechanism of stress transfer and strengthening of materials through fibers, it can be assumed that there is a critical length below which the reinforcing effect of the fibers decreases rapidly due to the overwhelming presence of fiber ends, which constitute the weak points of the composite [35]. Therefore, the lowest values of modulus and strength were recorded for the samples made of 100% regrind. As expected, the parts conditioned in the chamber and immersed in water for 14 days become saturated, leading to the lowest tensile strength values. On the other hand, the samples with a lower moisture content (not conditioned) present a 45% higher tensile strength. Aging the parts using UV light has a negligible impact on part performance, as the carbon black used as a colorant acts as a UV stabilizer, protecting the molecule chains from degradation. This effect aligns with the observations of Sahu et al. made for high-density polyethylene modified with carbon black [36].
Water has a plasticizing effect on the polyamide material, reducing its elastic modulus and yield point, thus simultaneously increasing the flexibility and elongation of the material. As a result of conditioning polyamide samples in a humid environment, water molecules come into the polymer and diffuse through the material, moving polymer chains apart and causing swelling [37]. The bonds between the amide groups are stronger than the attraction of water, so water acts as a plasticizer rather than a solvent [37]. Separating polymer chains reduces the polar attraction between the chains and increases chain mobility, translating into lower mechanical properties, such as strength and stiffness. The moisture content of polyamide has a significant impact on both processing and end-use performance [38].

3.5. Heat Deflection Temperature (HDT)

The heat deformation temperature (HDT) determines the resistance of the polymer to changes under a given load at an elevated temperature. The measurement allows for determining the change in material stiffness with increasing temperature and assessing the finished product’s operating temperature range. The HDT average values are presented in Table 7. There is a 5% decrease in the temperature at which the samples deform as the parts saturate with water. Adding up to 15% of the regrind to the virgin material has a negligible influence on the HDT values. The samples produced using 100% regrind exhibit significantly lower temperature values (Figure 7). This effect may be caused by glass fiber shortened during milling and, thus, the lower stiffness and increased mobility of the polymer chains [39].

3.6. Thermogravimetry

Data on the degradation characteristics of polyamide materials, such as the mass loss temperatures of 5% and 10% (T5% and T10%), maximum intensity of thermal degradation temperatures (DTG), and residual mass, are listed in Table 8. The characteristic curves of the TG and DTG are presented in Figure 8. These results confirmed that the addition of waste polyamide does not negatively affect the thermal stability of the materials. The T5% value for all of the tested materials was similar and amounted to an average of 403 °C, and the residual mass was about 48%. High amounts of burnout residue were noticed, which indicates the presence of an inorganic phase. For all of the tested polyamide samples, a single-stage decomposition was observed, which is confirmed by the visible characteristic DTG peak at a temperature of 456 °C (Table 8).

4. Discussion

Plastic recycling can be defined as the process of recovering and valorizing waste or post-consumer plastics and reprocessing them into full-value products. From the point of view of the safety and stability of the industrial production process, primary recycling (closed-loop recycling) is performed on waste of known history. Reprocessed materials have a specific origin because they never left the processing site [11]. Polyamides are thermoplastic materials that melt in the range of 220–250 °C and are most often processed using injection molding and extrusion [40]. The chemical structure of polyamides is composed mainly of amide groups that participate in hydrogen bonds, resulting in reduced interchain mobility, causing high melting points and strength [41]. Due to the wide range of products manufactured for the construction and automotive industries, using polyamide from recycling and post-production waste management brings significant environmental benefits. Many footwear manufacturers also use PA foams, which increases the amount of post-consumer waste [42,43]. Recycling plastics is one of the most effective methods of reducing the negative impact of accumulated post-consumer and post-production waste on the natural environment [28]. The data show that European post-consumer recycled plastic production in 2022 amounted to 7.7 Mt. Conversion into plastic products and parts by European companies amounted to 54 Mt in 2022, including 8% in the automotive, 23% in the building and construction, and 6% in the electrical and electronics industries [7]. In all of these industries, polyamide and its derivatives are widely used; therefore, demonstrating an effective way of managing its post-consumer waste brings many benefits for waste management worldwide. The presented work highlights the benefits of grinding from waste generated during production to manufacture new ready-to-use parts. The influence of the aquatic environment and UV aging on the thermal and mechanical properties was also analyzed.

5. Conclusions

This study presents a method of managing production waste from elements remaining after the injection process of cold-runner systems to produce new products made of polyamide 6 reinforced with glass fiber. Moreover, due to polyamide’s hygroscopic nature, the impact of conditioning on its mechanical properties in various conditions was assessed. Significantly, the addition of grinding up to 15% did not have a considerable effect on the mechanical properties, HDT values, and thermal stability of the tested samples. The addition of regrind also has a slight impact on reducing the melt viscosity and increasing the MFR. These observations allow us to conclude that such recycled material can be successfully used in mass production, which will reduce the waste generated during the injection process. Conditioning the samples in an aqueous environment improves the impact strength of the tested materials, which is of great importance when using them as construction materials. The highest increase in impact strength from 9 kJ/m2 to 12 kJ/m2 was observed for the samples conditioned in the climatic chamber. Water acts as a plasticizer; therefore, while the impact strength of polyamide (cracking resistance) increases, its elastic modulus decreases. Since injection molding using cold channel technology is still used in the industry, managing the waste generated in this way and production in a closed cycle is crucial to reducing material and energy losses.

Author Contributions

Conceptualization, T.O. and D.M.; methodology, T.O.; software, J.A.; validation, M.B. and J.A.; formal analysis, M.B.; investigation, T.O., D.M. and M.B.; resources, J.A.; data curation, T.O.; writing—original draft preparation, T.O. and D.M.; writing—review and editing, T.O. and D.M.; visualization, M.B.; supervision, D.M.; project administration, D.M.; funding acquisition, T.O. All authors have read and agreed to the published version of the manuscript.

Funding

The research was carried out as part of the Implementation Doctorate Program of the Ministry of Education and Science in Poland, Agreement No. DWD/7/0114/2023.

Data Availability Statement

Data are contained within the article.

Acknowledgments

The authors would like to thank NB Polska Sp. z o. o. for your cooperation.

Conflicts of Interest

The authors declare no conflicts of interest.

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Processes 12 01304 g001
Figure 1. Examples of (a) waste from cold runner injection molding systems and (b) polyamide products.
Figure 1. Examples of (a) waste from cold runner injection molding systems and (b) polyamide products.
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Figure 2. (a) The original polyamide pellets and (b) the grinding from cold runner systems.
Figure 2. (a) The original polyamide pellets and (b) the grinding from cold runner systems.
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Figure 3. Influence of water conditioning time on the weight of the molded samples.
Figure 3. Influence of water conditioning time on the weight of the molded samples.
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Figure 4. Fiber length distribution in composite before (PA) and after (rPA) recycling.
Figure 4. Fiber length distribution in composite before (PA) and after (rPA) recycling.
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Figure 5. Oscillatory rheological measurements results: storage (a), loss (b), and complex modulus (c) vs. angular frequency.
Figure 5. Oscillatory rheological measurements results: storage (a), loss (b), and complex modulus (c) vs. angular frequency.
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Figure 6. The impact strength (ak) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Figure 6. The impact strength (ak) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
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Figure 7. Heat deflection temperature (HDT) of the tested samples.
Figure 7. Heat deflection temperature (HDT) of the tested samples.
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Figure 8. TG and DTG curves of investigated materials.
Figure 8. TG and DTG curves of investigated materials.
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Table 1. The mass flow rate (MFR) of the investigated materials.
Table 1. The mass flow rate (MFR) of the investigated materials.
NameMFR
(g/10 min)
PA47.8 ± 1.0
5PA53.6 ± 0.4
10PA65.4 ± 0.5
15PA66.2 ± 1.0
rPA91.7 ± 3.5
Table 2. The impact strength (ak) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Table 2. The impact strength (ak) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Namencw24hw14dChUV
ak [kJ/m2]ak [kJ/m2]ak [kJ/m2]ak [kJ/m2]ak [kJ/m2]
PA9.1 ± 0.59.2 ± 0.211.4 ± 0.212.6 ± 0.78.6 ± 0.8
5PA9.5 ± 0.49.8 ± 0.210.8 ± 0.312.1 ± 0.68.1 ± 0.4
10PA9.0 ± 0.49.7 ± 0.812.0 ± 0.712.7 ± 0.67.9 ± 0.5
15PA9.2 ± 0.410.2 ± 0.911.5 ± 0.712.0 ± 0.68.4 ± 0.7
rPA8.4 ± 0.89.6 ± 0.79.8 ± 0.511.4 ± 0.78.2 ± 0.6
Table 3. The maximum force (Fmax) recorded during impact strength tests of samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Table 3. The maximum force (Fmax) recorded during impact strength tests of samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Namencw24hw14dChUV
Fmax [N]Fmax [N]Fmax [N]Fmax [N]Fmax [N]
PA562.5 ± 23.5637.5 ± 60.1475.3 ± 15.8470.9 ± 14.2515.3 ± 24.6
5PA560.9 ± 12.1622.5 ± 34.2474.1 ± 15.2484.6 ± 14.5477.8 ± 15.2
10PA529.4 ± 27.5 500.6 ± 25.1496.2 ± 10.1524.1 ± 12.5468.6 ± 26.1
15PA507.9 ± 33.5522.9± 11.9537.2 ± 21.8480.8 ± 15.5503.3 ± 40.2
rPA525.1 ± 55.7465.61 ± 13.8535.6 ± 51.8448.6± 9.2427.7 ± 14.3
Table 4. The tensile strength (δm) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Table 4. The tensile strength (δm) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Namencw24hw14dChUV
δm [MPa]δm [MPa]δm [MPa]δm [MPa]δm [MPa]
PA193.3 ± 2.9177.4 ± 2.2135.6 ± 2.6133.2 ± 5.5189.7 ± 0.9
5PA189.0 ± 1.0178.4 ± 1.1137.4 ± 1.5132.0 ± 2.6173.7 ± 6.7
10PA190.5 ± 0.6176.8 ± 1.3136.4 ± 1.5129.6 ± 4.9183.2 ± 1.7
15PA187.6 ± 2.1173.6 ± 1.1136.2 ± 0.8130.6 ± 1.7181.2 ± 1.7
rPA171.0 ± 1.0161.0 ± 2.0124.3 ± 0.6120.7 ± 1.0166.2 ± 1.5
Table 5. The Young’s modulus (Et) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Table 5. The Young’s modulus (Et) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Namencw24hw14dChUV
Et [Mpa]Et [Mpa]Et [Mpa]Et [Mpa]Et [Mpa]
PA9447 ± 3555662 ± 684576 ± 2897500 ± 24810,225 ± 126
5PA7540 ± 2705514 ± 2563488 ± 5067467 ± 1529463 ± 226
10PA5535 ± 1295404 ± 983157 ± 4967060 ± 1077823 ± 240
15PA4363 ± 1215412 ± 1533654 ± 9856728 ± 2083970 ± 204
rPA3285 ± 1205260 ± 2363157 ± 3726048 ± 3692225 ± 757
Table 6. The elongation at break (Et) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Table 6. The elongation at break (Et) of the samples: not conditioned (nc), conditioned in the chamber (Ch), conditioned in the water for 24 h (w24h), for 14 days (w14d), and in the UV aging chamber (UV).
Namencw24hw14dChUV
εm [%]εm [%]εm [%]εm [%]εm [%]
PA6.2 ± 0.19.1 ± 0.35.7 ± 0.36.4 ± 0.95.8 ± 0.1
5PA6.1 ± 0.19.4 ± 0.35.9 ± 0.36.9 ± 0.15.1 ± 0.4
10PA6.1 ± 0.19.1 ± 0.35.8 ± 0.36.8 ± 0.45.2 ± 0.1
15PA6.0 ± 0.49.3 ± 0.26.2 ± 0.27.1 ± 0.35.2 ± 0.1
rPA6.1 ± 0.19.1 ± 0.26.1 ± 0.37.3 ± 0.35.6 ± 0.1
Table 7. Heat deflection temperature (HDT) of the tested samples.
Table 7. Heat deflection temperature (HDT) of the tested samples.
Heat Deflection Temperature [°C]
NameNot ConditionedConditioned
in the Chamber		Conditioned
in the Water 24 h		Conditioned
in the Water 14 d		UV Aging Chamber
PA209.1 ± 0.2199.7 ± 0.4202.9 ± 0.8201.9 ± 0.8204.3 ± 0.5
5PA207.0 ± 0.3200.8 ± 0.3204.3 ± 0.6202.3 ± 0.6203.0 ± 0.3
10PA209.6 ± 0.3202.4 ± 0.7205.3 ± 0.7202.3 ± 0.7205.7 ± 0.2
15PA211.5 ± 0.7196.7 ± 0.3208.9 ± 0.3207.9 ± 0.3208.9 ± 0.2
rPA202.9 ± 0.7193.7 ± 0.3199.9 ± 0.8197.9 ± 0.8201.1 ± 0.5
Table 8. TG and DTG data of investigated materials.
Table 8. TG and DTG data of investigated materials.
NameT5% [°C]T10% [°C]Residual Mass [%]DTG
PA402.2423.550.0454.2 °C; −12.9%/min
5PA403.0423.347.1456.7 °C; −13.7%/min
10PA404.3424.148.1456.6 °C; −14.4%/min
15PA405.6425.548.6456.1 °C; −13.6%/min
rPA403.3427.347.2464.2 °C; −13.6%/min
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Olszewski, T.; Matykiewicz, D.; Barczewski, M.; Andrzejewski, J. Efficient Use of Secondary Raw Material from the Production of Polyamide Construction Products. Processes 2024, 12, 1304. https://doi.org/10.3390/pr12071304

AMA Style

Olszewski T, Matykiewicz D, Barczewski M, Andrzejewski J. Efficient Use of Secondary Raw Material from the Production of Polyamide Construction Products. Processes. 2024; 12(7):1304. https://doi.org/10.3390/pr12071304

Chicago/Turabian Style

Olszewski, Tomasz, Danuta Matykiewicz, Mateusz Barczewski, and Jacek Andrzejewski. 2024. "Efficient Use of Secondary Raw Material from the Production of Polyamide Construction Products" Processes 12, no. 7: 1304. https://doi.org/10.3390/pr12071304

APA Style

Olszewski, T., Matykiewicz, D., Barczewski, M., & Andrzejewski, J. (2024). Efficient Use of Secondary Raw Material from the Production of Polyamide Construction Products. Processes, 12(7), 1304. https://doi.org/10.3390/pr12071304

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