自由基引发剂过氧化二异丙苯对聚乳酸性能的影响

Effects of Free Radical Initiator Diisopropylbenzene Peroxide on Properties of Polylactic Acid

以过氧化二异丙苯(DCP)为自由基引发剂,采用熔融共混法制备了聚乳酸(PLA)/DCP共混物,研究了自由基引发剂DCP对PLA凝胶含量、结晶性能、流变性能和力学性能的影响。通过力学测试及动态流变实验,结合Han图和Cole-Cole图反映出DCP改性后的PLA具有交联和支化结构,这种交联和支化结构的形成改善了PLA的拉伸强度,显著提高PLA的复数黏度、储能模量和损耗模量;改性后的PLA具有更长的松弛时间,弹性响应更加明显,熔体强度得到提升。当DCP质量分数低于0.3%时,只有少量的凝胶产生,这种交联和支化结构能促进晶核的形成,起到了异相成核作用,有效改善PLA的结晶速率和结晶度。

Poly(lactic acid)(PLA)/diisopropylphenyl peroxide(DCP)blends were prepared by melt blending method using DCP as a free radical initiator,and the effects of the free radical initiator DCP on the gel content,crystalline properties,rheological properties and mechanical properties of PLA were investigated.The mechanical tests and dynamic rheological experiments,combined with Han and Cole-Cole plots,reflect that the DCP-modified PLA has cross-linking and branched structures,and the formation of such cross-linking and branched structures improves the tensile strength of PLA,while significantly increases the complex viscosity,energy storage modulus and loss modulus of PLA.The modified PLA has a longer relaxation time and a more pronounced elastic response,which effectively improves the melt strength of PLA.When the mass fraction of DCP is lower than 0.3%,only a small amount of gel is produced,and the formation of this cross-linking and branched structure can promote the formation of crystalline nuclei,which plays the role of heterogeneous nucleation,effectively improves the rate of crystallization of PLA and increases the degree of crystallinity.