Employing a novel bioelastomer to toughen polylactide

Biodegradable, biocompatible polylactide (PLA) synthesized from renewable resources has attracted extensive interests over the past decades and holds great potential to replace many petroleum-derived plastics. With no loss of biodegradability and biocompatibility, we highly toughened PLA using a novel bioelastomer (BE)–synthesized from biomass diols and diacids. Although PLA and BE are immiscible, BE particles of ∼1 μm in diameter are uniformly dispersed in the matrix, and this indicates some compatibility between PLA and BE. BE significantly increased the cold crystallization ability of PLA, which was valuable for practical processing and performance. SEM micrographs of fracture surface showed a brittle-to-ductile transition owing to addition of BE. At 11.5 vol%, notched Izod impact strength improved from 2.4 to 10.3 kJ/m2, 330% increment; the increase is superior to previous toughening effect by using petroleum-based tougheners

Biorenewable blends of polyamide-11 and polylactide

Polyamide-11(PA11) is melt blended with polylactide (PLA) using 0.00 to 0.10 wt% titanium isopropoxide catalyst to investigate potential compatibilizing reactions. Blend properties are characterized by differential scanning calorimetry (DSC), thermogravimetric analysis, dynamic mechanical thermal analysis, and tensile and impact testing. DSC shows two separate glass transition temperatures indicating only partial miscibility. Base etching to remove PLA domains followed by field emission scanning electron microscopy confirms the two phase nature of the blends. Storage and tensile moduli of the blends increase monotonically with increasing PLA content. Interchange reactions during reactive mixing were investigated by 13 degrees C-NMR spectroscopy but the analysis shows little evidence of interchange reactions. This is true irrespective of catalyst level and mixing time over the temperature range from 185 degrees C to 225 degrees C. At the upper end of the temperature range investigated, significant degradation is observed. The combined results indicate that degradation reactions dominate over compatibilizing interchain transreactions. (C) 2013 Society of Plastics Engineer