Crystalline Modification And Recycling Of The Recycled Polypropylene Packing Film

As one of the five general plastic material with chemical stability,none toxicity,good processability and low cost,polypropylene?PP?is now widely used in many fields,such as food packaging,electronic appliance,construction and buildings etc.When being used as the packaging material,it exhibits high sealing fixation,good resistances to moisture and/or dirt.However,packaging films are normally disposable and hundreds of thousands of tons of abandoned PP packaging material is therefore produced annually in the world,which cause serious problems,including the‘white pollution'and waste of resources.Currently,some problems exist in the recycling of these materials.For instance,after the recycling and reuse of the packaging materials,many properties of them deteriorate,especially in their toughness and heat resistance.Therefore,it is necessary to overcome such problems by the modification of the recycled PP?rec PP?packaging film.Although the recycled PP can be toughened and modified by various elastomers,this method will not only increase the cost,but also weaken the heat resistance of the material.However,when it was modified by rigid component to improve its heat resistance,its toughness will be usually decreased.If recPP is modified by?-nucleating agent?and making?-crystal the main crystal form in the material?,the resulted?-recPP will perform good toughness and heat resistance simultaneously.This will solve the problems aforementioned above.The main problem urgently to be solved in the polymer composite industry in this field is that adding other additives into?-recPP will interfere with the?-nucleation.Therefore,three aspects of the research were implemented in this work:?1??-recPP composite modified by nonmetallic powder of waste printed circuit board?waste PCB powder?;?2??-recPP composite modified by environment-friendly flame retardant of ammonium polyphosphate?APP?;?3?the development of the electric special material based on?-recPP composites.The results of the study are as follows:1.The structure and property of recPP recycled from the household appliance factory in Vietnam were studied.The results indicated that the raw material of recPP was block-copolymerized polypropylene and the ash content was 4.39wt%.After granulitization,recPP showed favorable mechanical properties,which meant that the recPP was a good raw materials to produce the modified PP with good performance.2.recPP was modified by three different kinds of?-nucleating agents?TMB-5,NPG and CaPA?,and the results indicated that TMB-5 had the best?-crystal induction effect among all the?-nucleating agents used.When recPP was modified by?-nucleating agents and waste PCB powder to prepare?-rec PP composite,waste PCB powder?which mainly consisted of glass fiber and epoxy resin?displayed negative effect on the?-crystal induction of TMB-5,but positive effect on the?-crystal induction of calcium pimelate?CaPA?on the contrary.Their mechanism were studied and discussed.Comprehensive comparison,?-rec PP composite containing CaPA and waste PCB powder showed better toughness and rigidity.3.The nucleation mechanism,mechanical property and flame resistance of recPP composites modified by APP and different?-nucleating agents?TMB-5,NAB-82 and JYX-602B?were studied.The results indicated that only APP and TMB-5 had synergistic effect in recPP,making relative content of?-crystal?K_??higher in the material.The corresponding mechanism of nucleation could be as follows:the crystallization period of recPP was longer than pure PP,and APP would further slow the crystallization rate of rec PP.As a result,?-crystal of APP/TMB-5/recPP composite had more time to form in the range of 100¹41°C,leading into the preferentially growth of?-crystal.Besides,APP/TMB-5/recPP composite showed high flame resistance of V-2 and better toughness,flexural modulus and elongation at break.These results provided important basis on the development of flame-retarded?-PP material.4.In order to fabricate electric special material as the intelligent electric kettle base,the anti-aging,toughening,reinforcing,compatibilizing,nucleation and flame-retardant modification on recPP were carried out through adding various additives.The results indicated that the optimum formula for the modification of recPP composite was 28.7wt%recPP,0.3wt%antioxidant 1010,10wt%SEBS,10wt%SEBS-g-MAH,5wt%PP-g-MAH,25wt%glass fiber,5wt%CaSO₄ whisker,12wt%decabrominated dipheny ethane?TDE?,4wt%Sb₂O₃ and 0.3wt%TMB-5.This modified rec PP composite performed high toughness and rigidity,ageing resistance and flame retardance of V-0.Moreover,the optimized model of the electric kettle base was designed and printed by the rapid prototyping 3D printing technology,and the final products with good properties based on the optimized model were fabricated successfully by the injection molding process finally.This study provided a complete set of valuable recycling recPP technology,which confirmed that the high value-added recPP could have huge potential application in the field of intelligent electronic appliances.