Preparation of stiffer ternary blends of polypropylene/polyamide 6/biodegradable polymers with improved interfacial adhesion

Abstract

Blends of polypropylene (PP), polyamide 6 (PA6), and biodegradable polymers (BPs) such as poly(D,L-lactic acid) (PDLLA), poly(lactic acid-co-ε-caprolactone) (poly[LA-co-ε-CL]) and poly(ε-caprolactone) (PCL) were prepared using a twin-screw mini-extruder. The composition of the blend PP/PA6 was fixed at a mass proportion of 70/30, and the compatibilized blends contain 5 wt% of each BP. The morphology observed through scanning electronic microscopy, the dynamic mechanical thermal properties (DMTA), and the biodegradation test after composting and performing optical microscopy (OM) of the blends were investigated. The blend PP/PA6 compatibilized with polypropylene grafted with maleic anhydride (PPMA) was also obtained and used as a reference. The results showed that the PP/PA6/PPMA revealed a more homogeneous morphology and resulted in higher modulus; nevertheless, the sample obtained with the lower molar mass PDLLA as an alternative for PPMA showed a storage modulus behavior close to the reference material. Poly(LAco-ε-CL) and PCL also showed changes in the morphology of the PA6 dispersed phase. Positive results were observed in the biodegradation test examined by OM for all samples containing BPs. The novelty of this work was to employ BPs as compatibilizing agents of the blends comprising PP/PA6, producing ternary blends with superior mechanical properties due to the better dispersion of the phases.

Recycling of polyamides: Processes and conditions

“…The effect of biopolymer (PCL and PLA) addition (as compatibilizing agents) on PA6/PP (30/70) blends was investigated by Amantes et al 37 The specimens (20 mm × 15 mm × 3 mm) were buried in soil at room temperature for up to 140 days with constant compost humidity. Using morphological and mechanical analyses, a slight initial degradation was observed (short time), but limited biodegradation occurred due to the good homogeneity of the ternary blends produced.…”