Degradation induced by nanostructural evolution of polylactide/clay nanocomposites in the isothermal cold crystallization process
作者：Wu, Defeng，Wu, Liang，Yu, Wei，Xu, Bin，Zhang, Ming
關鍵字：polylactide, clay, nanocomposites, cold crystallization, intercalation, degradation
論文來源：期刊
具體來源：Polymer International
發表時間：2009年
BACKGROUND: The aim of the work presented was to study the nanostructural evolution of clay tactoids during the isothermal
cold crystallization of polylactide/clay nanocomposites (PLACNs). An interesting degradation behavior of the polylactide (PLA)
matrix, however, was observed simultaneously with nanostructural evolution. The possible mechanisms of degradation and
structural evolution are discussed.
RESULTS: The evolution of thenanostructure and thedegradationwere studied online or off line using parallel plate rheometry,Xray
diffraction, transmission electron microscopy, differential scanning calorimetry, nuclear magnetic resonance spectroscopy,
gel permeation chromatography and thermogravimetric analysis. The results showed that the intercalation level of the clay
tactoids further increased during cold crystallization, leading to simultaneous degradation of the PLA matrix, which was further
confirmed by the marked change of small- and large-amplitude oscillatory shear flow behavior of the PLACNs before and after
cold crystallization.
CONCLUSION: The increase of the intercalation level of the tactoids is due to the diffuse in movement of the PLA chain segments
during cold crystallization. In this case, chain-end scission occurs more easily, especially for those PLA chains around the loose
edge and defect site of the tactoids during crystallization, which results in a simultaneous degradation of the PLA matrix. Hence,
both the linear and nonlinear dynamic viscoelastic properties show a remarkable change after cold crystallization.
c 2009 Society of Chemical Industry