Virgin Polyamide Research Articles

Mechanical recycling of polyamide 6 and polypropylene for automotive applications

AbstractThis study investigates the mechanical recycling of polyamide 6 (PA6) from discarded fishing nets and polypropylene (PP) from automotive battery scraps and household waste for automotive applications. The mechanical properties of both materials were evaluated through tensile, impact, and thermal testing, revealing that recycled PA6 (r‐PA6) and recycled PP (r‐PP) can achieve mechanical performance similar to virgin materials. Recycled PA6 was reinforced with 30% glass fiber (GF), significantly enhancing its tensile strength from 70 to 170 MPa, comparable with virgin PA6's (76 MPa). Furthermore, the tensile modulus of r‐PA6 increased from 7720 to 8500 MPa. Recycled PP was compounded with thermoplastic elastomers (TPE) and fillers, such as calcium carbonate (CaCO₃) and talc, improving its impact strength from 5 to 18 KJ/m2 and improving thermal stability, with a heat deflection temperature (HDT) reaching 95°C. The optimized formulations for r‐PP, particularly from automotive battery scrap, achieved a melt flow index (MFI) of 12–16 g/10 min, preventing molding defects. This study highlights the importance of controlled thermal treatments, appropriate additive use, and accurate processing conditions in producing high‐quality recycled polymer compounds.Highlights Recycled PA6 reinforced with 30% GF achieves a tensile strength of 170 MPa. Thermal treatment increases the tensile modulus of r‐PA6 to 8500 MPa, similar to virgin PA6. Incorporating TPE improves the impact strength of r‐PP to 18 KJ/m2. Calcium carbonate and talc enhance the thermal stability of r‐PP to 95°C. The melt flow index of r‐PP optimized to 12–16 g/10 min for better moldability.

Interaction of Pb(II) with microplastic-sediment complexes: Critical effect of surfactant

In this study, the impact of surfactants on the adsorption behavior of Pb(II) onto microplastics-sediment (MPs-S) complexes was investigated. Firstly, virgin polyamide (VPA) and polyethylene (VPE) were placed in Xiangjiang River sediment for six months to conduct in-situ aging. The results indicated that the biofilm-developed polyamide (BPA) and polyethylene (BPE) formed new oxygen-containing functional groups and different biofilm species. Furthermore, the adsorption capacity of Pb(II) in sediment (S) and MPs-S complexes was in the following order: S > BPA-S > VPE-S > VPA-S > BPE-S. The addition of sodium dodecyl benzenesulfonate (SDBS) promoted the adsorption of Pb(II), and the adsorption amount of Pb(II) increased with the higher concentration of SDBS, while adding cetyltrimethylammonium bromide (CTAB) showed the opposite result. The adsorption process of MPs-S complexes to Pb(II) was dominated by chemical adsorption, and the interaction between MPs-S complexes and Pb(II) was multilayer adsorption involving physical and chemical adsorption when the surfactants were added. Besides, the pH exerts a significant effect on Pb(II) adsorption in different MPs-S complexes, and the highest adsorption amount occurred at pH 6. Noteworthy, CTAB promoted the adsorption ability of Pb(II) when the exogenous FA was added. The binding characteristic of sediment endogenous DOM components and Pb(II) was influenced by the addition of MPs and surfactants. Finally, it confirmed that adsorption mechanisms mainly involve electrostatic and hydrophobic interaction. This study provides a new perspective to explore the environmental behaviors of Pb(II) by MPs and sediments with the addition of surfactants, which was conducive to evaluating the ecological risks of MPs and heavy metals in aquatic environments.

Nanocomposites of recycled and of virgin polyamide 6.6 with cellulose nanofibers

The inherent properties of cellulose nanofibers (CNFs) make them an interesting and sustainable choice for reinforcing polymeric matrices intended for the automotive, electronic, construction, and packaging sectors. Effective recycling and reuse of polyamide 6.6 significantly reduce the environmental impact of automotive components throughout its entire life cycle. Nanocomposites of recycled polyamide 6.6 and CNF and of virgin polyamide 6.6 and CNF were processed through dissolution in a formic acid/water mixture followed by melt extrusion and injection molding. The results show that pure recycled polyamide exhibited a thermal degradation onset temperature 10 °C lower and a 9 % lower crystallinity compared to pure virgin polyamide. The method used for processing the nanocomposites resulted in homogeneous dispersion and good anchoring of CNF in both polymer matrices. The processing method and the presence of CNF reduce the thermal stability by up to 15 °C for recycled polyamide nanocomposites and up to 26 °C for virgin polyamide nanocomposites. The processing method did not significantly impair the elastic modulus and tensile strength of both recycled and virgin polyamides, showing a 3 % and 1 % reduction in tensile strength for recycled and virgin polyamides, respectively. The incorporation of 1 wt% and 2 wt% of CNF in virgin polyamide showed an increase in the elastic modulus of 16 % and 5 %, respectively, and a reduction in ductility. In summary, this work offers an alternative processing pathway for nanocomposites of recycled or virgin polyamide 6.6 with CNF; however, some improvements are still necessary to achieve the reinforcing effect of CNF on the mechanical strength of the matrices.

Determination of the flexural properties of additively manufactured polyamide 12 components with antimicrobial titanium dioxide additives

AbstractAntibacterial properties of components are increasingly becoming an important challenge in material development especially in polymer technology. A well‐known additive with which an antibacterial effect can be achieved is the metal oxide titanium dioxide. The aim of this research work was to investigate possible influences on the flexural properties of additively manufactured components resulting from the addition of titanium dioxide as an antimicrobial additive. Compounds with 5 %, 10 % and 15 % titanium dioxide and polyamide 12 as matrix material were produced. Three‐point bending test specimens were fabricated out of these compounds, anaylsed and the results were compared with specimens made of virgin polyamide 12. The investigations show a general loss in ductility compared to the virgin polyamide 12. A comparison of the different titanium dioxide contents shows no clear change in the flexural stress at conventional bending. The flexural strain at break seems to decrease for higher titanium dioxide contents.

Designing Prepregnation and Fused Filament Fabrication Parameters for Recycled PP- and PA-Based Continuous Carbon Fiber Composites.

Continuous carbon fiber (cCF)-based 3D-printed polymer composites are known for their excellent flexural properties; however, the optimization of the overall process is still desired, depending on the material types involved. Here, the improved manufacturing of cCF-based composites is reported, considering virgin polyamide (PA) and postindustrial waste polypropylene (PP), and the parameters affecting the material properties are evaluated. Firstly, the prepregnation technique was optimized to manufacture cCF polymer filaments with various fiber-to-polymer ratios. Secondly, the fused filament fabrication (FFF) technique was optimized. It was observed that the layer height needs to be sufficiently low for proper interlayer adhesion. The influence of the printing temperature is more complicated, with filaments characterized by a lower fiber-to-polymer ratio requiring a higher nozzle diameter and higher temperatures for efficient printing; and for lower diameters, the best flexural properties are observed for parts printed at lower temperatures, maintaining a high interspace distance. Plasma treatment of the cCF was also explored, as was annealing of the produced parts to enhance the flexural properties, the latter being specifically interesting for the PP-based composite due to a lower wetting caused by a higher viscosity, despite supportive interfacial interactions. Eventually, overall guidelines were formulated for the successful production of cCF-based composites.

Microplastics enhance the adsorption capacity of zinc oxide nanoparticles: Interactive mechanisms and influence factors

Microplastics (MPs) are of particular concern due to their ubiquitous occurrence and propensity to interact and concentrate various waterborne contaminants from aqueous surroundings. Studies on the interaction and joint toxicity of MPs on engineered nanoparticles (ENPs) are exhaustive, but limited research on the effect of MPs on the properties of ENPs in multi-solute systems. Here, the effect of MPs on adsorption ability of ENPs to antibiotics was investigated for the first time. The results demonstrated that MPs enhanced the adsorption affinity of ENPs to antibiotics and MPs before and after aging showed different effects on ENPs. Aged polyamide prevented aggregation of ZnONPs by introducing negative charges, whereas virgin polyamide affected ZnONPs with the help of electrostatic attraction. FT-IR and XPS analyses were used to probe the physicochemical interactions between ENPs and MPs. The results showed no chemical interaction and electrostatic interaction was the dominant force between them. Furthermore, the adsorption rate of antibiotics positively correlated with pH and humic acid but exhibited a negative correlation with ionic strength. Our study highlights that ENPs are highly capable of accumulating and transporting antibiotics in the presence of MPs, which could result in a widespread distribution of antibiotics and an expansion of their environmental risks and toxic effects on biota. It also improves our understanding of the mutual interaction of various co-existing contaminants in aqueous environments.

Waste Management after the Injection Process by Manufacturing Polyamide Products Based on Regranulate

The aim of the work was to assess the possibility of utilizing the waste generated in the injection molding process for the production of new products based on polyamide 6 reinforced with glass fiber. The manufactured samples were prepared with the addition of 5, 10, 15, and 100 wt.% regrind from the runner system. The impact strength, tensile strength, and hardness of injection products were obtained directly and were assessed after conditioning in distilled water for 24 h. Moreover, the structure of the tested materials was assessed using the FTIR method and their thermal properties using the DSC method. The results of the tests confirm that the addition of regrind up to 15 wt.% to virgin polyamide does not adversely affect its impact strength, tensile strength, and hardness. The water-conditioned materials showed higher values of impact strength but lower values of tensile strength and Young’s modulus at a higher elongation at break. The obtained results are important due to the assumptions of the circular economy and the minimization of the amount of waste and material losses during the injection process.

Characterisation of the mechanical properties of polyamide 12 powder when using titanium dioxide as antimicrobial additive

AbstractAntimicrobial properties of plastic components are an important part of polymer engineering. One commonly used additive with an antibacterial effect is titanium dioxide. The aim of this study is to investigate the influences on the mechanical properties resulting from the addition of titanium dioxide as an antimicrobial additive and the processing of the compounds with selective laser sintering. Compounds with 5 %, 10 % and 15 % titanium dioxide and polyamide 12 as matrix material are fabricated. Tensile test specimen are produced from the compounds, examined and the results compared with virgin polyamide 12. The investigations show a general loss in the ultimate tensile strength compared to the virgin polyamide 12. Comparing the different titanium dioxide contents with each other, an increasing tensile strength with increasing titanium dioxide content of the compound can be examined. A decreasing elongation at break and thus a decreasing ductility can also be observed. Furthermore, the results of the tensile test show a stiffening effect, i. e. an increase in the elastic modulus due to the addition of titanium dioxide.

Increase in temperature increases ingestion and toxicity of polyamide microplastics in Nile tilapia

Microplastics (MP) pollution and global warming are worldwide concerns, creating various physiological problems for aquatic organisms. This study was carried out to know the effects of different temperature (30, 33 and 36 °C) on ingestion of MP along with the physiological consequences in Nile tilapia (Oreochromis niloticus) exposed to virgin polyamide (PA) (10 mg/L water; 500 μm to 4 mm in size) for 15 days. A significant difference was found in PA ingestion of the fish treated with different temperature. Fish from 36 °C temperature groups ingested highest amount of PA (136 ± 24.40 item/fish) during the exposure period. The hemoglobin (Hb) and red blood cell (RBC) decreased significantly in the highest temperature (36 °C) without PA exposure. At the same time, Hb increased, but RBC significantly reduced in all the temperature conditions with PA exposure. The number of white blood cell (WBC) and glucose level increased significantly in the highest temperature (36 °C) without PA exposure. In contrast, WBC increased and glucose decreased significantly in all the temperature conditions with PA exposure. Frequencies of various nuclear and cellular abnormalities of erythrocytes increased significantly in the fish exposed to all temperature with PA exposure, though severity increased with temperature. Similarly, histological damage of gills (hyperplasia, epithelial necrosis, deformed pillar system, epithelial lifting, telangiectasia) and intestine (epithelium breakage, enterocyte vacuolization and shortening of villi) was found to be mild to severe by the accumulation of PA, increased severity with increase of temperature. This study confirms that global warming as a consequence of climate change might influence MP ingestion hampering physiological state of fish.

Thermo‐mechanical recycling of climbing ropes: A case study on a closed loop process for PA6

AbstractGlobal warming has increasingly drastic consequences, especially in the Alps but also in the rest of the world. To reduce greenhouse gases, widespread recycling of plastic waste is becoming an essential necessity. This research investigates a possible recycling process for old climbing ropes made out of polyamide 6. Old climbing ropes were collected and processed with a twin screw extruder to fabricate recycled granulate. Investigating different shredding techniques showed that pretreatment with liquid nitrogen or water and liquid nitrogen are proven to be insufficient. A good shredding was achieved using a shredding‐granulator. Tensile test specimens had been fabricated out of the recycled granulate using an injection moulding process. The tensile tests showed a sufficient material quality and higher tensile strength than the virgin polyamide 6 used for the comparison. Tensile strength and Young's modulus increased, whereas the elongation at break decreased. A previous cleaning of the old ropes showed slightly better material properties of the recycled granulate.

The fate and risk of microplastic and antibiotic sulfamethoxazole coexisting in the environment.

With huge amount of plastic entering to the environment, microplastic pollution has become a great concern. Microplastic behavior in the environment is important to evaluate its harm to ecosystem and human beings. It has been found that microplastic can be used as a carrier to adsorb and enrich heavy metals or organic pollutants in water or soil. With the development of industry and medicine, antibiotics are improperly used in many countries and most of them end up in wastewater. This study investigates the adsorption behavior of sulfamethoxazole (SMX) antibiotic onto virgin and aged polyamide 6 (PA6) microplastics. The maximum adsorption amount was 0.089mg SMX/g PA6 at 25°C and pH 7 with initial SMX concentration of 2mg/L. Results reveal that the adsorption was mainly due to the chemical bounding. The impact of pH, salinity, and humic acid on the adsorption have been studied, and it was found that the pH has significant impact on the adsorption. At pH 5, the adsorption amount was 0.27mg/g which is two times higher than that at pH 7. The SMX adsorbed on PA6 tends to be more likely desorbed in reservoir water than in ultrapure water. For instance, the desorption amount of SMX from virgin PA6 was 0.15mg/L in reservoir water but 0.10mg/L in ultrapure water. The study indicates that microplastics have great threat to environment.

Pore size regulation of polyamide composite membrane via a sol-gel process confined within the selective layer

Membrane with pores of homogeneous size distribution is vital to high fraction efficiency of nanofiltration process. In this study, a novel approach of space-confined sol-gel was put forward to regulate the size and distribution of the pores of interfacially synthesized polyamide composite membrane for enhanced fraction efficiency. Tetraethyl orthosilicate (TEOS) was introduced into the porous polyamide network of the selective layer and employed to in situ generate a new silica network through space-confined hydrolysis and condensation. Membrane property including pore size distribution and separation performance was tuned by regulating the content of TEOS and systematically characterized by ATR-FTIR, XPS, SEM, AFM and cross-flow permeation test. The sol-gel of TEOS molecules confined within the selective layer was found to form a new polyamide-silica based separation layer with decreased pore size and homogenized pore size distribution. The mean size in diameter and geometric standard deviation of size distribution of the pores of the virgin polyamide based membrane were about 0.64 nm and 1.32, while those of the desired polyamide-silica based membrane obtained with a TEOS content of 3.0 v/v% were 0.59 nm and 1.26, respectively. The glucose rejection increased significantly from 58.0% of virgin polyamide membrane to 81.5% of the desired polyamide-silica based membrane. Permeation tests with concentrated mixed solution also revealed that, the desired polyamide-silica based membrane possessed better efficiency in the removal of sodium sulfate from the concentrated brine compared to the commercial membrane NF270, showing an average Na2SO4 rejection above 98.3%, a water flux around 120.0 l/m2 h, and nearly no NaCl rejection to a concentrated brine containing 200.0 g/L NaCl and 10.0 g/L Na2SO4 under 30.0 bar and 40.0 °C.

Polyamide microplastic exposure elicits rapid, strong and genome-wide evolutionary response in the freshwater non-biting midge Chironomus riparius

Susceptibility to hazardous materials and contamination is largely determined by genetic make-up and evolutionary history of affected organisms. Yet evolutionary adaptation and microevolutionary processes triggered by contaminants are rarely considered in ecotoxicology. Using an evolve and resequencing approach, we investigated genome-wide responses of the midge C. riparius exposed to virgin polyamide microplastics (0–180 μm size range, at concentration 1 g kg−1) during seven consecutive generations. The results were integrated to a parallel life-cycle experiment ran under the same exposure conditions. Emergence, life-cycle trait, showed first a substantial reduction in larval survival, followed by a rapid recovery within three generations. On the genomic level, we observed substantial selectively driven allele frequency changes (mean 0.566 ± 0.0879) within seven generations, associated with a mean selection coefficient of 0.322, indicating very strong selection pressure. Putative selection targets were mainly connected to oxidative stress in the microplastics exposed C. riparius population. This is the first multigenerational study on chironomids to provide evidence that upon exposure to polyamide microplastic there are changes on the genomic level, providing basis to rapid adaptation of aquatic organisms to microplastics.

Ground tire rubber/polyamide 6 thermoplastic elastomers produced by dry blending and compression molding

This study investigates the addition of ground tire rubber (GTR) into virgin polyamide 6 (PA6) to produce thermoplastic elastomer (TPE) blends. In particular, a wide range of GTR concentration (0–100% wt.) was possible by using a simple dry blending technique of the materials in a powder form followed by compression molding. The molded samples were characterized in terms of morphological (scanning electron microscopy), physical (density and hardness) and mechanical (tension, flexion and impact) properties. The results showed a decrease in tensile and flexural moduli and strengths with GTR due to its elastomeric nature. However, significant increases were observed on the tensile elongation at break (up to 167%) and impact strength (up to 131%) compared to the neat PA6 matrix. Based on the results obtained, an optimum GTR content around 75% wt. was observed which represents a balance between high recycled rubber content and a sufficient amount of matrix to recover all the particles. These results represent a first step showing that a simple processing method can be used to produce low cost PA6/GTR compounds with a wide range of physical and mechanical properties.

Evaluation of the potential toxicity of UV-weathered virgin polyamide microplastics to non-biting midge Chironomus riparius

The relevance of the environmental hazard evaluation of virgin plastics particles is problematic, as plastics almost never occur in a virgin state after being discarded into the environment. However, the producers or importers must evaluate the environmental effect of their products as they are produced. Many plastic types e.g., polyamide, polyethylene are already under pre-registration, according to the database of the European Chemicals Agency (ECHA), in order to restrict the placing on the market of polymers (as defined by Article 3(5) of EU's REACH regulation (Registration, Evaluation, Authorization & Restriction of Chemicals), as a substance or in a mixture (ECHA, 2019). However, the hazard of microplastics could not be evaluated without relevant data on its (eco)toxic effects. In this work, the long-term toxicity of virgin polyamide microplastic (PA-MP) (size from 0 to 180 μm) and UV-weathered virgin PA-MP was investigated in the controlled life cycle experiments conducted in accordance with the OECD guidelines for testing of chemicals using Chironomus riparius (OECD test 218). In addition, a three-generation test was conducted to understand the trans-generational toxicity potential of virgin PA-MP. After UV irradiation (26 d) the buoyancy and color of the particles was changed and the share of smaller particles (of a few micrometer size range) increased. The exposure of C. riparius larvae to UV-weathered PA-MP (1000 mg kg−1) during their life cycle (28 d), negatively affected their development and subsequent emergence as adults. However, the exposure to virgin PA-MP throughout the life cycle and also over three consecutive generations did not significantly reduced the number of emerged adults. From the point of view of environmental hazard, the virgin polyamide plastics have probably no long-term hazard to chironomids. While it may not be relevant as environmental pollutant in the strict sense, UV-weathering may turn it hazardous.

Toughening mechanism of long chain branched polyamide 6

Polyamide 6 (PA6) materials with different degrees of long chain branching (LCB) were prepared via extrusion through varying the addition of chain extender. The LCB degree was quantitatively determined by using a rheological method based on macromolecular dynamic models. The topological structures of long-chain branching and crosslinked network were effectively distinguished through rheological percolation analysis so that modified PA6 with ultra-high LCB level was obtained. The XRD analysis indicated that LCB modification favored the generation of the γ-form, and the γ-form content of LCB-PA6 increased with increasing degree of LCB, which could provide a reasonable explanation for the high Izod impact strength of ultra-high LCB-PA6. Another reason for the great enhancement of impact toughness was the strong interfacial interaction between LCB molecules and virgin PA6 matrix. A large number of fibrillar ligaments and cavities during crack propagation were observed in the SEM analysis.

Enhancement of Mechanical Properties of PA6 Blending with Talcum for Fused Deposition Modeling

AbstractThe objective of this work is to fabricate polyamide 6 (PA6) composite filament with enhanced mechanical properties and low cost for fused deposition modeling (FDM). The composite filaments are obtained by compounding PA6 and talcum fillers and then single screw extruding. Virgin PA6 and commercial e‐PA6 are set as controls. First, the rheological behaviors and thermal properties of PA6/talc, PA6, and e‐PA6 pellet materials are investigated, including viscosity, melting temperature, crystallinity, and decomposition temperature, which are important parameters for fabricating filament feedstocks. The results show that 10 wt% addition of talcum content accelerates the increase of the viscosity among the processing temperature. Accordingly, virgin PA6 and PA6/talc5 with good flowability are produced and subsequently evaluated by tensile and flexural tests. It is notable that the introduction of talcum increases the diameter constant and shape stability of PA6‐based filament. Also, it is found that both PA6 and Pa6/talc5 filaments exhibit superior tensile properties to the commercial e‐PA6 counterparts. Especially, PA6/talc5 filaments achieve the maximum tensile yield strength of 67.1 MPa and modulus of 3.10 GPa. Finally, auxetic lattice parts are successfully printed via FDM using lab‐made PA6, PA6/talc5, and commercial e‐PA6 filaments, and PA6/talc5 exhibits remarkable loading and energy absorption capability.

Ingestion and effects of virgin polyamide microplastics on Chironomus riparius adult larvae and adult zebrafish Danio rerio

Secondary microplastics (MP) produced by fragmentation of plastic in the environment or as a result of human activities can easily be taken up by organisms. The harmful effects of MP depend on e.g., the type, dimensions, sorption capacity and concentration of MP. In this study the ingestion of virgin irregularly-shaped polyamide microplastics (PA-MP; up to180 μm) by two different species was evaluated: 3rd - 4th instar larvae of midge Chironomus riparius and adult fish Danio rerio. More specifically, in the case of C. riparius larvae their feeding strategy, i.e. the ability to differentiate between food and non-food material (PA-MP) and the impact of pseudo-satiation by PA-MP on larval growth, development and emergence was evaluated. Two feeding regimes (with and without food supply) and two PA-MP concentrations (100 mg kg−1 and 1000 mg kg−1) were applied. Fish were exposed to two PA-MP concentrations (30 and 330 mg L−1) for 48 h followed by 48 h of depuration. The fish were fed during both periods. Both, chironomid larvae and adult zebrafish actively ingested PA-MP. Remarkably more PA-MP was ingested when larvae were not fed during the exposure to PA-MP. In the case of fish, the ingested particles were effectively evacuated from the gastrointestinal tract. Even the highest PA-MP concentrations did not cause obvious harmful effects to either species. The obtained data are informative for risk evaluation of PA-MP as polyamide is registered in the database of the European Chemicals Agency (ECHA) in the framework of the EU’s REACH (Registration, Evaluation, Authorization & Restriction of Chemicals) regulation.

Indoor Air Concentration from Selective Laser Sintering 3D Printer using Virgin Polyamide Nylon (PA12) Powder: A Pilot Study

Environmental emission from additive manufacturing (AM) have attracted much attention recently. The capability in fabricating complex part make AM famous in developing prototype and product in various industries especially in aerospace, medical, automotive, and manufacturing industries. However, the study on emission and exposure mainly focusses on the desktop type such as fused deposition modelling. This study investigates the emission and indoor concentration from powder bed fusion of selective laser sintering (SLS) technologies. Prior to the investigation, virgin PA12 undergone characterization in terms of morphology, size and thermal analysis. Calibration block using virgin polyamide nylon (PA12) are selected to be printed in this study. Parameters such particulate matter size 2.5 µm (PM 2.5), total volatile organic compound (TVOC), carbon dioxide (CO2), formaldehyde, temperature and relative humidity (RH) are set to be monitored through real time sampling of 8 hours based on Industry Code of Practice on Indoor Air Quality 2010 by Department Occupational Safety and Health (DOSH) Malaysia. Four phases of printing process involve are background data, preprinting, during printing and post printing. Based on the study it was found that PM 2.5 and CO2 exceed the acceptable limit recommended by DOSH Malaysia during preparation of powder (preprinting) at 1218 ppm and 1070 µg/m3 respectively. Meanwhile TVOC concentration was influence by the sintered powder temperature and recorded at 0.5 ppm. Temperature, relative humidity and formaldehyde were maintained throughout the SLS process. Mitigation strategies using mechanical ventilation and personal protective equipment (PPE) are recommended to be used to reduce potential of occupational hazard to the operators.

Isothermal Crystallization Kinetics Study of Fully Aliphatic PA6 Copolyamides: Effect of Novel Long-Chain Polyamide Salt as a Comonomer.

N1, N6-bis (4-aminobutyl) adipamide (BABA) diamine and sebacic acid (SA), also called BABA/SA polyamide salt, were used in a typical melt polymerization processes of polyamide 6 (PA6) to form a series of PA6-BABA/SA copolyamides. The effects of BABA/SA on the isothermal crystallization kinetics of PA6-BABA/SA were studied for the first time. An isothermal crystallization analysis demonstrates that the PA6-BABA/SA matrix provided a higher crystallization rate and shorter half-crystallization time than virgin PA6 did. The degree of crystallization of the PA6-BABA/SA30 matrix was also the lowest among all of the samples considered herein. This result is attributed to the high nucleation efficacy of a small amount of BABA/SA in the crystallization of PA6. Values of the Avrami exponent (n) from 1.84 to 3.91 were observed for all of the polyamide samples, suggesting that the crystallization was involved via a two- to three-dimensional growth mechanism. These findings deepen our understanding of the structure–property relationship of PA6-BABA/SA copolyamides, favoring their practical application.