Biodegradable and resilient poly (propylene carbonate) based foam from high pressure CO2 foaming

Poly(propylene carbonate) (PPC) is a biodegradable polymer incorporating over 40 wt% CO2 in the main chain. High-foaming ratio while resilient biodegradable PPC foam is quite difficult to prepare since PPC is a brittle aliphatic polycarbonate, and blending with other biodegradable plastics like poly(butylene adipate-co-terephthalate) (PBAT) faces the challenge of compatibility. Here, Joncryl ADR-4368 chain extender was successfully used as compatibilizer between PPC and PBAT. Even 1 wt% ADR-4368 in PPC/PBAT blend (29/70 in weight ratio) showed remarkable effect, where the tensile strength of the resulting blend showed Ca. 100% increase from 14.2 MPa to 28.9 MPa with the elongation at break increased from 491% to 1026%. Meanwhile, the complex viscosity at 150 °C and angular frequency of 10−1 rad/s increased 4.1 times from 308 Pa s to 1273 Pa s. As a bonus of PPC which is a CO2-philic polymer capable of absorbing 23.1 wt% CO2, uniform and resilient biodegradable foam was prepared under high CO2 pressure foaming, whose cell size was Ca. 15 μm with foam density of 0.083 g/cm3. It should be noted that the foam ratio increased from 3 to 15 with only 1 wt% ADR-4368 added.