Modified Bio-based Polymer Blend System With Ionomer Elastomers

Polylactic acid（PLA）and poly（3-hydroxybutyrate-co-3-hydroxyvalerate）（PHBV）,as fully biodegradable polyester materials,both of them can be obtained from renewable resources such as corn,potatoes and other agricultural products.PLA has good mechanical properties,thermoplasticity,high transparency and biocompatibility.As a typical commercial product of polyhydroxyalkanoates（PHAs）produced by bacterial fermentation or other microorganisms,PHBV has good biodegradability,biocompatibility and high crystallization.These attractive performances of PLA and PHBV make them be very promising alternatives for petroleum-based plastics.However,both of them are hard and brittle polymers,the poor toughness and high cost greatly limits their wide applications.Melt blending is an effective and simple method for preparing high performance biobased materials.Recently,as a cost-effective method,blending has attracted intensive attention for modification of PLA or PHBV material.In these blends,poor compatibility between the components in the blend is the key challenge to achieve superior properties.For PLA-elastomer based blends,the transparency of the blend is often sacrificed due to the phase-separation,which greatly hinder its application in packaging area.As for PHBV-based blend,the toughening efficacy is usually very low to meet the requirement of commercial application because of the poor interfacial adhension between the matrix and elastomer.In this thesis,a series of imidazole-substituted chlorinated rubber ionomers（ECO-PF₆,BF₄,TFSI）were facile and efficiently synthesized by using quaterisation reaction of biomass-derived chloroether rubber with imidazole monomer.Through melt blending method,these ionomers were studied as novel modifying agents for the PLA and PHBV materials.In PLA/ionomers blends,inspired by refractive index matching theory,we successfully achieved highly transparent PLA blending system for the first time.The optimum blend showed an high impact strength of>80 k J/m²,an elongation at break of 400%,and high transparency（90%）.These characteristics are of great importance for potential applications such as packaging.For the PHBV-elastomeric ionomer blending system,the ionomers were proved to be an effective toughening agent.The thermal stability,processability and mechanical properties of PHBV are greatly improved with addition a low amount of the ECO-ionomers.The ion content and anions species play a crucial role in improvement the PHBV/ionomer system.The research in this paper provided a new series of functional ionomer for modifying biopolyester like PLA and PHBV,which will greatly expand their application prospect in wide areas.