3-Pentadecylphenol (PDP) as a Novel Compatibilizer for Simultaneous Toughened and Reinforced PA10,12 Composites

The utilization of polyamide 10,12 (PA10,12) composites in various industries has been limited constrained by their inherent low toughness, making it a challenge to achieve a balance between toughness and structural integrity through conventional elastomer addition strategies. Herein, we introduce a straightforward method for the concurrent toughening and reinforcement of PA10,12 composites. This is accomplished by blending polyolefin elastomer (POE) and 3-pentadecylphenol (PDP) with the PA10,12 matrix. The incorporation of 5 wt% PDP effectively blurred the PA10,12/POE interface due to PDP's role as a compatibilizer. This phenomenon is attributed to the formation of intermolecular hydrogen bonds, as evidenced by Fourier Transform Infrared Spectroscopy (FTIR) analysis. Further investigation, using differential scanning calorimetry (DSC), elucidated the crystallization thermodynamics and kinetics of the resulting binary PA10,12/POE and ternary PA10,12/POE/PDP composites. Notably, the crystallization temperature (Tc) was observed to decrease from 163.1 °C in the binary composite to 161.5 °C upon the addition of PDP. Increasing the PDP content to 10% led to a further reduction in Tc to 159.5 °C due to PDP's capacity to slow down crystallization. Consequently, the ternary composite of PA10,12/POE/PDP (92/3/5 wt%) demonstrated a synergistic improvement in mechanical properties, with an elongation at break of 579% and a notch impact strength of 61.54 kJ/m2. This represents an approximately eightfold increase over the impact strength of unmodified PA10,12. Therefore, our work provides the potential of PDP as a compatibilizer to develop nylon composites with enhanced stiffness and toughness.

Molecular dynamics simulation of the 3-15alkyphenol compatibilizer in highly toughened and robust polyamide 10,12/MWCNT composites

Highly toughened and stiff polyamide 10,12 (PA10,12) composites present a promising alternative to metal products for high-impact environments. However, it is challenging to toughen PA10,12 composites without compromising their robustness. Herein, we report a facile and scalable route to simultaneously develop reinforced and toughened PA10,12 composites via compounding PA10,12, carbon nanotubes (CNTs) and 3-15alkyphenol (PDP). The PDP acted as a compatibilizer to well-disperse MWCNTs since they tended to be adsorbed onto the CNT surface, which was revealed by molecular dynamics simulation. According to the simulation statistics, the vertical PDP conformations (to the CNT surface) were predominant in the ternary composites with ∼78.7% probability. Moreover, the hydrogen bonds (H-bonds) between the PDP and the PA matrix were confirmed using FTIR. A crystallization kinetics study also revealed that the crystallization temperature increased from 166.7 °C for the neat PA10,12 to 168.7 °C for the ternary PA/PDP/CNT composites containing 1.5 wt% CNTs, while the crystallization half-time increased from 0.58 s for the neat PA10,12 to 1.2 s for the ternary composites. It was also found that the notched impact strength of the ternary composites reached 75.2 kJ m-2, which was 970% higher than that of the neat PA10,12 without compromising their tensile strength of 50.5 MPa much. This work provides a new insight into PDP as a compatibilizer to develop simultaneously stiff and toughened nylon composites.

Mechanism Study of the Polymerization of Polyamide 56: Reaction Kinetics and Process Parameters

Polyamide 56 (PA56) has gained significant attention in the academic field due to its remarkable mechanical and thermal properties as a highly efficient and versatile biobased material. Its superior moisture absorption property also makes it a unique advantage in the realm of fiber textiles. However, despite extensive investigations on PA56's molecular and aggregate state structure, as well as processing modifications, little attention has been paid to its polymerization mechanism. Herein, the influence of temperature and time on PA56's polycondensation reaction is detailed studied by end-group titration and carbon nuclear magnetic resonance (NMR) techniques. The reaction kinetics equations for the pre-polymerization and vacuum melt-polymerization stages of PA56 are established, and possible side reactions during the polycondensation process are analyzed. By optimizing the reaction process based on kinetic characteristics, PA56 resin with superior comprehensive properties (melting temperature of 252.6 °C, degradation temperature of 371.6 °C, and tensile strength of 75 MPa) is obtained. The findings provide theoretical support for the industrial production of high-quality biobased PA56.

Characterization and compatibility of bio-based PA56/PET

The properties and compatibility of bio-based PA56 and polyethylene terephthalate (PET) polymers were studied in detail. The experimental results showed that when compared with PET, bio-based PA56 had better moisture absorption, softness, and dyeing characteristics. By calculating and analyzing the macromolecular structures of bio-based PA56 and PET, the difference in solubility was obtained as 4.18 Cal0.5·cm1.5·mol−1. Thermodynamic analysis showed that the measured change in mixing enthalpy far exceeds the range of the compatible system when the proportion of bio-based PA56 exceeded 15%. When the content of bio-based PA56 in PET exceeded 20%, the glass transition temperature of the blends with different proportions all had double peaks and the eutectic phenomenon was not observed. Scanning electron microscopy was used to observe the cross-section morphology of bio-based PA56/PET blends before and after etching. We found that the interface between the two phases was clear and a “sea-island” dispersed structure was formed. The results of the analysis indicated that the compatibility of the bio-based PA56 and PET was not good.

Catalytic Production of Functional Monomers from Lysine and Their Application in High-Valued Polymers

Lysine is a key raw material in the chemical industry owing to its sustainability, mature fermentation process and unique chemical structure, besides being an important nutritional supplement. Multiple commodities can be produced from lysine, which thus inspired various catalytic strategies for the production of these lysine-based chemicals and their downstream applications in functional polymer production. In this review, we present a fundamental and comprehensive study on the catalytic production process of several important lysine-based chemicals and their application in highly valued polymers. Specifically, we first focus on the synthesis process and some of the current industrial production methods of lysine-based chemicals, including ε-caprolactam, α-amino-ε-caprolactam and its derivatives, cadaverine, lysinol and pipecolic acid. Second, the applications and prospects of these lysine-based monomers in functional polymers are discussed such as derived poly (lysine), nylon-56, nylon-6 and its derivatives, which are all of growing interest in pharmaceuticals, human health, textile processes, fire control and electronic manufacturing. We finally conclude with the prospects of the development of both the design and synthesis of new lysine derivatives and the expansion of the as-synthesized lysine-based monomers in potential fields.