Abstract

Yodthong Baimark* and Onanong Cheerarot

DOI : http://dx.doi.org/10.13005/ojc/310204

The influences of chain extension and blending temperature on the thermal properties of poly(L-lactide) (PLL) were investigated. Joncryl^® ADR 4368, a styrene-acrylic multifunctional oligomeric agent, was used as a chain extender. Differential scanning calorimetry and thermogravimetry were used to determine the thermal transition properties and thermal stability of the chain extended PLL, respectively. The chain extension reaction occurred at a blending temperature of 190 °C better than at 170 °C. The molecular weights of the chain extended PLLs increased and melt flow indices decreased when the Joncryl^® ADR 4368 ratio was increased. The addition of Joncryl^® ADR 4368 had an effect on the glass transition temperature, crystallizing temperature and crystallinity of the PLL for the blending temperature of 190 °C. The chain extended PLLs with branched structures showed lower thermal stability than the linear PLLs. The content of branched PLLs increased with the Joncryl^® ADR 4368 ratio and blending temperature. The chain extension reaction was complete when 2% Joncryl^® ADR 4368 and a blending temperature of 190 °C were used. The results indicated that the chain extension improved the PLL’s melt strength and it has an effect on the thermal stability of the PLLs.

Biodegradable polymer; Polylactide; Chain extender; Melt flow index; Thermal stability

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