| Reactive compatibilizers,especially comb copolymers,can significantly improve the compatibility of immiscible polymer blends by decreasing the interfacial tension and enhancing the interfacial adhesion,and thus obtain the material with the excellent mechanical property.However,the comb compatibilizer is generally prepared by solution reaction with complicated steps,and only worked for a specific immiscible polymer system.Therefore,this paper innovatively proposes a simple and efficient compatibilization strategy by melt blending reactive linear copolymers with immiscible polymers with functional groups.Due to the effects of high temperature and shearing,the two polymers could be grafted on to the linear copolymer via chemical reactions,and thus in-situ formed double comb-like copolymers.Due to the strong entanglement between its two side chains and the two phases,the double comb-like copolymers easily stablize at the interface,effectively decrease the interfacial tension,refine the phase size,and thus play an important role in compatibilizing immiscible polymer blends.This paper choose poly(styrene-co-glycidyl methacrylate)(SG)as the main chain,which owns abundant reactive epoxide groups.Moreover,the compatibilizing effects of this method on three immiscible polymer systems with reactive functional groups were studied,mainly in the following three aspects:1)Reactive compatibilization on PC/PLLA blends: Both PLLA and PC own reactive terminal groups like carboxyl and hydroxyl groups,so they can be grafted onto the SG to form the double-grafted copolymers in the melt blending by chemical reactions.It was found that a little amount of compatibilizer can significantly reduce the domain size,enhance the interfacial adhesion,and thus improve the compatibility of immiscible polymer blends.Moreover,different functional groups vary in reactivity with epoxide groups of SG.And numerous comb polymers with different molecular structures were synthesized,which can significantly effect the compatibilization efficiency.It was found that the highly symmetric double comb-like copolymer is more conducive to balancing the interaction between the two phases,easier to stable at the interface of two phases,and thus take an important role in compatibilizing immiscible polymer blends.And LG10%(PLLA/SG=10/1)exhibits the highest compatibilization efficiency in our research.2)Reactive compatibilization on PA6/PBT blends: Both PBT and PA6 exhibits reactivity due to amino and carboxyl groups,so the compatibilization effects of comb copolymers with varied molecular structures on PA6/PBT blends were systematically studied via the same method.However,PA6/PBT immiscible blends exhibits different compatibilizing mechanism due to the different reactivity.PA6 contains two end groups of high reactivity with epoxy groups,easier cross-linking when react with excessive epoxy groups.Therefore,the copolymer AG generated by PA6 and SG pre-grafting has poor compatibilzing efficiency.PBT can not cross-link with SG owing to the very low reactive hydroxyl groups.It was found that all compatibilizers could remarkedly refine the domain size,and the toughness and strength of blends have been improved.3)Reactive compatibilization on PC/LDPE blends: Although LDPE has no reactive functional groups,but acrylic acid can be introduced into the LDPE chain by simple melt grafting method to prepare LDPE-g-AA with carboxyl groups that can react with epoxy groups.Since both PC and LDPE-g-AA have reactive functional groups,LDPE and PC chains could be grafted onto SG main chain in the melt blending,in-situ forming the double comb-like copolymers,easily stabling at the interface,and thus taking a crucial role in the compatibilizing immiscible PC/LDPE blends.The influence of compatibilizer on the compatibilization effect of blends was systematically studied via different processing conditions,and the compatibilization effect of the double comb-like copolymers was proved. |
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