Mechanical and flame-retardant properties of biodegradable polylactide composites with hyperbranched silicon-containing polymer

A hyperbranched polymer (HBP-B2) containing siloxane chains was synthesized via bulk polymerization of diepoxide with a primary amine in the presence of monoepoxide. The weight-average molecular weight of the prepared polymers was approximately 9200. Composites of polylactide (PLA) with aluminum trihydroxide (ATH) and the HBP-B2 were prepared via direct melt compounding using a brabender. The test results showed that the LOI could be raised to 34% for the PLA composite with 25wt% ATH and 5% HBP-B2. The surface thermal profile of the composite during UL94 V test was further captured by an infrared camera, which was helpful to understand the flame-retardant properties of the different samples. A V-0 rating could be achieved by adding ATH and HBP-B2 to the PLA matrix. Incorporation of HBP-B2 as a plasticizer could increase the impact strength of a PLA blend or composite. For example, an addition of 10wt% of HBP and 20wt% ATH increased the elongation at break from 5% for neat PLA to 155% for the PLA composite.