Abstract
The effects of addition of hyperbranched polyesters (HBPs) and nanoclay on the material properties of both solid and microcellular polylactide (PLA) produced via a conventional and microcellular injection-molding process, respectively, were investigated. The effects of two different types of HBPs (i.e., Boltorn H2004® and Boltorn H20®) at the same loading level (i.e., 12%), and the same type of HBP at different loading levels (i.e., Boltorn H2004® at 6 and 12%), as well as the simultaneous addition of 12% Boltorn H2004® and 2% Cloisite®30B nanoclay (i.e., HBP–nanoclay) on the thermal and mechanical properties (both static and dynamic), and the cell morphology of the microcellular components were noted. The addition of HBPs and/or HBP with nanoclay decreased the average cell size, and increased the cell density. The stress–strain plots of all the solid and microcellular PLA-H2004 blends showed considerable strain softening and cold drawing, indicating a ductile fracture mode. Among the two HBPs, samples with Boltorn H2004® showed higher strain-at-break and specific toughness compared to Boltorn H20®. Moreover, the sample with Boltorn H2004® and nanoclay exhibited the highest strain at-break (626% for solid and 406% for microcellular) and specific toughness (405% for solid and 334% for microcellular). Finally, the specific toughness, strain-at-break, and specific strength of microcellular samples were found to be lower than their solid counterparts.
Keywords
Clay,
injection molding of plastics,
crosslinking,
plastics,
extrusion,
wood-plastic composites,
composite materials,
mechanical properties,
thermoplastic composites,
recycled products,
recycling,
polyesters,
fracture mechanics,
strains,
stresses,
maleic anhydride,
nanocomposites,
nanoclay,
wood-plastic materials,
thermal degradation,
biocomposites,
microcellular injection molding,
strength
Citation
Pilla, Srikanth; Kramschuster, Adam; Lee, Jungjoo; Clemons, Craig; Gong, Shaoqin; Turng, Lih-Sheng. 2010. Microcellular processing of polylactide-hyperbranched polyester-nanoclay composites. Journal of materials science. Vol. 45, no. 10 (May 2010): p. 2732–2746.
