Tailoring PA6 Properties with In-Situ Generated Nanofibrils

Abstract

This thesis investigates the enhancement of polyamide 6 (PA6) properties through the incorporation of in-situ generated nanofibrils, focusing on mechanical performance, flame retardancy, and hydrophobicity. The research is divided into three main sections, each addressing a distinct challenge associated with PA6-based composites and proposing innovative solutions using in-situ nanofibrillation techniques.The first section explores the improvement of impact performance in PA6 composites by integrating polyphenylene sulfide (PPS) nanofibrils. The resulting composites exhibit an 85% increase in impact strength compared to neat PA6 without sacrificing its tensile properties. This enhancement is attributed to the formation of transcrystalline structures and smaller crystal sizes within the fibril network, which contribute to improved stress distribution and overall mechanical properties. The second section focuses on developing flame-retardant PA6 composites by incorporating a combination of PPS nanofibrils and ammonium sulfamate (AS). The resulting composite, containing 15 wt% PPS and 1 wt% AS, achieves a UL 94-V0 rating and a limiting oxygen index (LOI) of 33.8%. Rheological, micro-combustion calorimetry and char residue analyses indicate that the entangled PPS fibril network effectively suppresses flame propagation and dripping, leading to a 17% reduction in peak heat release rate (PHRR). This synergistic effect between PPS and AS demonstrates a promising approach to enhancing the flame-retardant performance of PA6 composites. The final section presents a unique method for fabricating hydrophobic PA6-based nonwoven mats. By utilizing a ternary blend system of polypropylene (PP), PA6, and polyvinylidene fluoride (PVDF) with in-situ fibrillation, the study achieves a micro-nano hierarchical structure that significantly enhances hydrophobicity. The optimized mats exhibit an impressive oil-water separation efficiency of up to 97.4%, demonstrating their potential for applications in industries requiring water repellency and efficient oil-water separation. Overall, this research provides comprehensive insights into the material design and enhancement of PA6 composites, addressing specific performance challenges such as impact resistance, flame retardancy, and hydrophobicity. The findings contribute to a deeper understanding of process-structure-property relationships in advanced composite materials, offering practical solutions for broadening the application scope of PA6 in engineering and environmental sectors.