Preparation And Properties Of Polylactic Acid/Elastomer Particle Composites

Polylactic acid(PLA)comes from biomass resources and has good machinability and biodegradability.It is widely used in medicine,agriculture,packaging and other fields.The waste PLA can be completely degraded into carbon dioxide and water,which will not pollute the environment,so it can replace most petroleum based products.However,PLA lacks good toughness,slow crystallization rate and long degradation cycle,which limits its application range.Modification is needed to improve the toughness,crystallization and degradation of the material.In this paper,PLA composites with high toughness were prepared by toughening PLA with vulcanized natural rubber particle(VNR)/paraffin oil composite powder system,VNR/ palm oil composite powder system and vulcanized polyester particle(CBEP).The mechanical properties,crystallization properties and degradation properties of PLA composites were studied.The main work is as follows:1.Preparation of PLA / VNR / paraffin oil and PLA / VNR / palm oil ternary composites.According to the solid content quality meter of vulcanized natural rubber,the vulcanized natural rubber latex and paraffin oil were mixed evenly according to the ratio of 1:1,1:2 and 1:3,and the VNR/ paraffin oil composite powder system was prepared by spray drying.According to the same method,a variety of VNR / palm oil composite powder systems were prepared;Then,the VNR / paraffin oil composite powder system,VNR / palm oil composite powder system and PLA were melt blended to prepare PLA / VNR / paraffin oil ternary composites and PLA / VNR / palm oil ternary composites.2.Study on the performance of PLA/VNR/paraffin oil,PLA/VNR/palm oil ternary composites.VNR/paraffin oil composite powder system and VNR/palm oil composite powder system can significantly improve the toughness of PLA;among them,the elongation at break and notch impact strength of PLA/VNR/paraffin oil ternary composites with 5 phr VNR/paraffin oil(mass ratio of 1:2)added to the composite powder system reached 18.21 times and 2.10 times that of PLA,respectively,the elongation at break and notched impact strength of PLA/VNR/palm oil ternary composites with 5 phr VNR/palm oil(mass ratio of 1:2)added to the composite powder system reached 32.14 times and 2.17 times that of PLA.3.Preparation of PLA/CBEP binary nanocomposites: Five different particle sizes(50nm,100 nm,200nm,500 nm,1000nm)polyester emulsion were prepared by radiation crosslinking and spray drying to prepare five kinds of vulcanized polyester powder particles(CBEP),CBEP and PLA melting and blending,and preparation PLA/CBEP binary nanocomposites.4.Performance study of PLA/CBEP binary nanocomposites.CBEP can significantly improve the toughness of PLA;The elongation at break and notch impact strength of PLA/CBEP binary composites containing 5phr CBEP(particle size 50 nm)reached 75 times and 4.04 times that of pure PLA,respectively.In addition,CBEP can be used as a heterogeneous nucleating agent to increase the crystallization rate of PLA;the half-crystallization time of PLA/CBEP binary nanocomposites containing 5 phr CBEP(particle size of 50 nm)is 31.6% shorter than that of PLA.CBEP has good compatibility with PLA and can be used as a heterogeneous nucleating agent to accelerate the crystallization of PLA,forming a larger number of crystals with smaller size.The mass loss rate of PLA/CBEP binary nanocomposites containing 5 phr CBEP(particle size of 50 nm)reached 6.56 times and 4.23 times that of pure PLA under neutral and natural soil environmental conditions,respectively.CBEP is hydrophilic,to a certain extent increases the degradation rate of polylactic acid,in the degradation environment ester group is most vulnerable to attack and decomposition,further increasing the decomposition rate.