High‐temperature copolyamides obtained by the efficient transamidation of crystalline–crystalline polyamide blends

High‐performance thermoplastic composites based on semiaromatic polyamides are prime candidates for metal replacement in lightweight structural applications. However, the low ductility and toughness of semiaromatic polyamides remain major obstacles to their wider industrial application. In this study, we showed that novel random copolymers were formed by the unexpectedly efficient transamidation during the melt compounding of semicrystalline semiaromatic and aliphatic polyamides. Thus, homogeneous materials with a single glass transition and a high degree of crystalline order were obtained from blends of the semiaromatic poly(hexamethylene terephthalamide‐co‐isophthalamide) (PA6TI) with poly(hexamethylene adipamide) (PA66) or poly(hexamethylene sebacoamide) (PA610). By contrast, phase segregation and a less efficient transamidation was observed for cocompounded PA6TI and polylaurolactam (PA12). We attributed this to differences in the hydrogen‐bonding patterns of the two polyamides. This study opened the way for the preparation of novel high‐performance thermoplastic polyamides and composites through simple melt compounding. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44349.     

Polyester networks based upon epoxidized and maleinated natural oils

Novel families of flexible, semiflexible and rigid crosslinked polyesters were prepared from modified natural oils such as soybean, rape-seed and linseed oil. Maleinated oils were used as anhydride-functional curing agents of epoxy resins such as bisphenol-A-diglycidylether and epoxidized natural oils. A new class of unsaturated polyester resins was based upon maleic anhydride, epoxidized natural oils and styrene. The resulting thermosetting polyesters were reinforced with natural fibers such as hemp and flax fibers. The influence of molecular architectures, curing conditions and formulations on thermal, mechanical and morphological properties were investigated.