聚乳酸/液态聚异丁烯共混物的研究

Study of Polylactic Acid/Liquid Polyisobutene Blends

为了改善聚乳酸(PLA)材料的脆性,且不影响其可降解性,选择了低分子量液态聚异丁烯(LPIB)和PLA进行共混改性,研究了LPIB用量对PLA/LPIB共混物性能的影响。结果表明,LPIB可提高PLA的韧性,但降低了其拉伸强度,当LPIB质量分数为12%时,共混物的缺口冲击强度达到最高,为5.3 k J/m2,比纯PLA提高了近一倍;LPIB在PLA中起到异相成核的作用,可提高其结晶度。采用扫描电子显微镜观察了共混物的微观形态,发现PLA与LPIB两相是分离的。为提高两者的相容性,采用缩水甘油酯(GMA)接枝LPIB(LPIB-g-GMA)作为增容剂,并研究了其用量对PLA/LPIB/LPIB-g-GMA共混物性能的影响。结果表明,LPIB-g-GMA对PLA/LPIB共混物有一定的增容作用,可使其相界面变得模糊,相容性有明显提高;当PLA,LPIB与LPIB-g-GMA的质量比为88/2/10时,PLA/LPIB/LPIB-g-GMA共混物的缺口冲击强度和拉伸强度达到最大,与未加LPIB-g-GMA的共混物相比,分别提高了20.7%和13.8%;少量LPIB-g-GMA的加入会提高PLA/LPIB/LPIB-g-GMA共混物的结晶度,但其用量过高时,会降低共混物的结晶度。

In order to improve the brittleness of PLA and don＇t affect its biodegradability, liquid polyiosbutene （LPIB） was used as a toughness agent for being blended with PLA. The effects of LPIB content on the properties of PLA / LPIB blends were investigated. The results show that LPIB can improve the britlleness of PLA, the notched impact strength of the blend with 12% LPIB is the best, reaching to 5.3 kJ / m2, nearly twice as much as pure PLA. LPIB acts as a heterogeneous nucleating agent and can improve the crystallization of PLA. Scanning electron microscopy indicates that two phases （PLA and LPIB） are separated. To improve the compatibility between PLA and LPIB, the glycidyl methacrylate grafted LPIB （LPIB-g-GMA） was used as compatilizer, and the effects of LPIB-g-GMA content on the performance of the PLA/LPIB/LPIB-g-GMA blends were investigated. The results show that LPIB-g-GMA can improve the compatibility between PLA and LPIB, make the interface between PLA and LPIB become vague, which indicates that the compatibility is improved. When the mass ratio of the PLA/LPIB/LPIB-g-GMA is 88 / 2 / 10, the notched impact strength and tensile strength of PLA/LPIB/LPIB-g-GMA blends can reach maximum, which increases by 20.7% and 13.8% respectively comparing with the PLA/LPIB blend. A little of LPIB-g-GMA can improve the crystallinity of the PLA/ LPIB / LPIB-g-GMA blend, but too much LPIB-g-GMA has an adverse result.