Our group published No. 132 paper in ACS Journal, Ind. Eng. Chem. Res. in Jan. 2014
Preparation
and Characterization of High-Melt-Strength Polylactide with Long-Chain
Branched Structure through γ-Radiation-Induced Chemical Reactions
Hongjun Xu, Huagao Fang,* Jing Bai, Yaqiong Zhang, and Zhigang Wang*
Ind. Eng. Chem. Res. 2014, 53, 1150-1159.
ABSTRACT: An easy procedure was applied to prepare high-melt-strength
polylactide (PLA) that involves γ-radiation-induced free-radical
reactions to introduce a long-chain branched structure onto a linear PLA
precursor with addition of a trifunctional monomer, trimethylolpropane
triacrylate (TMPTA). The results from size-exclusion chromatography
coupled with multiangle laser light scattering (SEC-MALLS) detection
indicate that the resultant long-chain branched PLA (LCB PLA) samples
have an increased molecular mass and an elevated branching degree with
increasing amount of TMPTA incorporated during the irradiation
process. Various rheological plots including viscosity, storage modulus,
loss tangent, Cole?Cole plots, and weighted relaxation spectra were
used to distinguish the improved melt strength for LCB PLA samples. The
effect of LCB structure on elongational rheological properties was
further investigated. The LCB PLA samples exhibited an enhancement of
strainhardening under elongational flow. The enhanced melt strength
substantially improved the foaming performance of the LCB PLA samples.