Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) microcellular foams using a melt memory effect as bubble nucleation sites

Abstract Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBH) foams were prepared by a foam injection molding (FIM) process using nitrogen (N 2 ) as physical blowing agent. PHBH is marine degradable polymer known for its heat treatment weakness. Gel permeation chromatography and rheological measurements showed that the molecular weight was reduced when processed at temperature higher than 160°C; however, it had prominent melt memory of crystallization lower 170°C. The effect increased provided crystal nucleation sites, which became bubble sites in foaming process. Microcellular foams, whose cell size smaller 30 μm density 3 × 10 8 cells cm −3 , while suppressing thermal decomposition tuning injected polymer's (melting temperature) core‐back timing. mechanical properties resulting evaluated, indicating high ductility microcellular obtained melting 150°C.