New copolyamides based on adipic acid, aliphatic diamines and amino acids: Synthesis, characterization and biodegradability, 5

Novel series of biodegradable copolyamides were synthesized via melt copolymerization. The statistical copolymides were produced by reaction of the salt of adipic acid (AA) and bis( para ‐aminocyclohexyl)methane (PACM) or isophoronediamine (IPD)/α‐amino acids at 250°C. Elemental analyses, density, viscosity, differential thermal analysis (DTA) and gelpermeation chromatography (GPC) measurements and FT‐IR spectroscopy were employed for the characterization of these copolyamides. The semicrystalline (AA/PACM/α‐amino acids) or amorphous (AA/IPD/α‐amino acids) nature of these copolyamides was shown with DTA and wide angle X‐ray diffraction patterns. Several methods were used in order to investigate and assess their biodegradability such as alkaline hydrolysis (10% w/v NaOH, 80°C), burial in soil (microbial and bacterial attack) and enzymatic hydrolysis (α‐trypsin and α‐chymotrypsin). The degradation of the copolyamides was evaluated with the aid of GPC and DTA measurements and correlated to the α‐amino acid content. These copolyamides could eventually find applications in the field of food packaging and agriculture (disposable plastics) and medicine (sutures).