Preparation Of Silane Coupling Agent Grafted Polypropylene And Degradation Inhibition Research

In recent years,the market demand for lithium-ion batteries has continued to expand, and the performance requirements for its components have become more stringent.When PP is used as the inner layer material of the aluminum-plastic composite film for the flexible packaging of lithium-ion batteries,its performance need to be improved.PP grafted with silane coupling agent and then hydrolyzed and crosslinked can effectively improve the solvent resistance of the inner film,but PP will inevitably degrade when peroxide is used to initiate the grafting reaction.In this paper,the researches on promoting PP grafting of 3-(methacryloxy)propyltrimethoxysilane(KH570)and inhibiting degradation are carried out.The main contents are as follows:1)Solution grafting.N-Phenylmaleimide(N-PMI)and 2-hydroxypropyl methacrylate(2-HPMA),which have greater conjugation effect than KH570 and polar effect different from KH570,are selected as co-agents.When the dosage of dicumyl peroxide(DCP)is 0.8%,KH570,N-PMI,2-HPMA are added respectively,and it is founded that 2-HPMA has little effect on PP degradation.As the molar ratio of KH570/co-agent changed,the grafting rate of KH570 in the N-PMI system is higher;when the molar ratio of KH570/2-HPMA is 7/4,the overall effect of promoting grafting and inhibiting degradation is better.When the amounts of KH570/co-agent increased,2-HPMA has less effect on the viscosity average molecular weight([M]_?)of PP,while N-PMI is beneficial to the grafting of KH570.When N-PMI is used as the co-agent(the feeds of KH570 is 3%),the KH570 grafting rate of PP reached 0.83%,and the[M]_?of the reaction product is 86910,which is slightly lower than the[M]_?of PP.The enthalpy ratio(?/?')of the melting DSC main peak of the reaction product and the shoulder peak in the high temperature zone is10.56,which is slightly lower than the?/?'value of PP.When 2-HPMA is used as the co-agent(the KH570 dosage is 3%),the KH570 grafting rate is 0.65%,the[M]_?of the reaction product is 93472,and the?/?'value is 11.46.The infrared test showed that KH570 is grafted onto PP,and the co-agents N-PMI and2-HPMA also participated in the grafting reaction.The XRD test showed that the crystal morphology of the product remained unchanged.2)Melt grafting.The molar ratio of KH570/co-agent is fixed at 7/4.As the amount of KH570/co-agent increased,the reduction trend of[M]_?of PP gradually decreased,the melt flow rate of the reaction product gradually decreased,and the grafting rate of KH570 gradually increased;when 2-HPMA is selected as co-agent,the effect of inhibiting PP degradation is overall better than that of N-PMI,and when N-PMI is selected as co-agent,the effect of promoting KH570 grafting is overall better than2-HPMA.When N-PMI is used as the co-agent(KH570 feeds is 3%),the KH570grafting rate of PP reached 0.79%,and the flexural strength of the product after hydrolysis and crosslinking is increased by 7.21%and the tensile strength by 18.63%compared with the raw material.In addition,Trimethylolpropane trimethacrylate(TMPTMA)and Isopentaerythritol tetraacrylate(PET4A)are introduced to investigate the effect of multifunctional monomers on KH570 grafting and PP degradation.The addition of multifunctional monomers is not good for the grafting of KH570,but it can effectively inhibit the degradation of PP.PET4A is overall better than TMPTMA in inhibiting PP degradation.When 2-HPMA is selected as the co-agent,the products after hydrolysis and crosslinking are tested for resistance to ethylene carbonate.After solvent immersion,the mass change rate of the sample is lower than that of the raw material,and the tensile strength and bending strength of the sample are higher than that of the raw material.The sample has better solvent resistance.