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Poly(propylene carbonate phthalate) (PPC-P) is a chemically modified poly(propylene carbonate) (PPC) biodegradable thermoplastic by introducing phthalic anhydride (PA) as the third monomer into the copolymerization of propylene oxide (PO) and CO2. To enhance the thermal and mechanical properties of PPC-P, a branching agent pyromellitic anhydride (PMDA) was introduced into the terpolymerization of PO, PA and CO2. The resulting copolymers with branched structure, named branched PPC-P, can be obtained using metal-free Lewis pair consisting of triethyl borane (TEB) and bis(triphenylphosphine)iminium chloride (PPNCl) as catalyst. The products obtained were analyzed by NMR spectroscopy and their thermal, mechanical properties and melt processability were evaluated by DSC, TGA, tensile test and melt flow index (MFI) measurement. The obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol−1. It shows an increased glass transition temperature (Tg) higher than 50 °C and an enhanced tensile strength as high as 38.9 MPa. Noteworthily, the MFI value decreases obviously, indicative of an improved melt strength arising from the branched structure and high molecular weight. What is more, the branched PPC-P exhibits reasonable biodegradability, which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics. [ABSTRACT FROM AUTHOR]

Poly(propylene carbonate maleate) (PPCMA) was successfully synthesized from carbon dioxide with propylene oxide and maleic anhydride using supported zinc glutarate as catalyst. The PPCMA can be readily cross-linked using dicumyl peroxide (DCP) as a cross-linking agent. The gel content, thermal performance and mechanical properties of the cross-linked PPCMA were then investigated. The results showed that the gel content increased with increasing DCP content and reaction temperature. The as-prepared PPCMA showed higher glass transition temperature ( Tg) and decomposition temperature compared with uncross-linkable poly(propylene carbonate) (PPC). The introduction of small amount of cross-linkable moiety provides a very effective way to improve the thermal stability and to extend the molecular weight of PPC, consequently extending its application area. [ABSTRACT FROM AUTHOR]