| Seeking for biobased polymer materials having the physical properties comparable that of engineering plastics is becoming more and more important for human beings in the 21st century.The main goal is to replace"fossil carbon"with"renewable carbon",and overall strategy is to mitigate climate change by reducing the environmental impact of products throughout their life cycles.Based on the quantity of commodity,the most successful and promising example of the bioplastics is poly（lactic acid）（PLA）.PLA has been proved to have excellent properties such as high modulus,strength and optical clarity.However,PLA is intrinsically brittle,sensitive to notches and has low impact and tear resistance,which greatly limite its application in many fields.Toughening modification of PLA is the key and hot research topic in PLA research field.Graft polymers are effective compatibilizers for the immiscible components in binary blends.Considering the wide availablility,low cost,and excellent properties of polyolefins,graft copolymers based on PLA and polyolefins are highly desirable compatibilizers or toughening agent for PLA and various polyolefin containing blends to achieve high performance materials with wide application prospect.In this work,polypropylene（PP）graft PLA copolymer ionomer with different PLA branch length and graft density were synthesized via a reactive isotactic PP reactive intermediate.Based on the results of physical characterizations,these newly designed graft copolymers were used to toughen PLA via solvent blending.The graft copolymers can be dispersed as nanoscaled particles in the PLA matrix.Singnificant enhancement in toughness of PLA was achieved for the blend without obvious sacrificing of stiffness and optical clarity,resulting in greater than 20-fold increase in the tensile toughness over the neat PLA.The toughening mechanism was proposed:the nanoscale dispersing of copolymeric ionomer played a key role in concurrent cavitation,crazing,and shearing yielding of matrix. |
PDF Full Text Request