Preparation Of Styrene-acrylonitrile-glycidyl Methacrlate Copolymer And Its Application In Chain Extension And Compatibilzation Modification

Glycidyl methacrylate(GMA)has carbon-carbon double bonds and active epoxy groups that can undergo free radical addition polymerization.The carbon-carbon double bond is copolymerized with styrene(St)and acrylonitrile(AN)to prepare functional styrene-acrylonitrile-glycidyl methacrylate terpolymer(SAG).Both suspension polymerization and solution polymerization can produce SAG.The reaction of epoxy groups with amino groups or carboxyl groups on the molecular structure of the copolymer can extend the chain and increase the viscosity of the modified engineering plastics polyamide 6(PA6).In addition,the chemical structure of SAG is similar to acrylonitrile-butadiene-styrene copolymer(ABS)and can be used for the compatibilization modification of PA6/ABS alloy.In this paper,suspension polymerization of St,AN and GMA monomers is first used to prepare SAG.Control the mass ratio of St.AN and GMA to 71:54:5,and optimize the influence of reaction time,reaction temperature,amount of dispersant and type of dispersant on SAG conversion rate.Suitable reaction conditions are:reaction time is 6 h,reaction temperature is 70?,dispersant is 4wt%calcium hydroxyphosphate.The conversion rate of the obtained SAG is 92.3%,the epoxy value is 0.029 mol/100g,and the epoxy group ret ention rate reaches more than 80%.Fourier transform infrared spectroscopy and differential scanning calorimeter are used to characterize the structure and performance of the product.Suspension polymerization uses water as a medium.Because epoxy groups are hydrolyzed in water,the resulting SAG epoxy value is 0.057 mol/100and the epoxy group ret ention rate is only 16.2%with 37:12:50 of St:AN:GMA mass ratio-In order to obtain a copolymer with a high epoxy group retention rate,solution polymerization is used for three monomers.When the St:AN:GMA mass ratio is 37:12:50,the epoxy value is 0.31 mol/100g,and the epoxy group retention rate is 88.4%.which is significantly higher than that of suspension polymerization products.Using the chain extension of solution polymerization SAG(epoxy value 0.31 mol/100g)and DCP-induced graft modification of PA6,the effects of both dosages on the processing performance,mechanical properties and dynamic rheological properties of PA6 are studied.The results indicate that the combination of the two can effectively improve the balance torque and notch impact strength of PA6.After adding 0.2wt%SAG and 0.2wt%DCP,the balance torque and notched impact strength of PA6 are increased by 53%and 116%respectively,which is similar to 1.0wt%SAG alone;dynamic rheological analysis makes sure that it is the same as 1.0wt%alone.Compared with%SAG,PA6 modified with 1.0wt%SAG and 0.2wt%DCP becomes sensitive to shear rate and glass transition temperature becomes higher.Zero shear viscosity and non-Newtonian index obtained by Cross equation fitting.It indicates that the molecular chain of PA6 in the compounding system is branched,and a possible reaction mechanism is proposed.SAG from suspension polymerization(epoxy value 0.029 mol/100g)is used as compatibilizer for PA6/ABS alloy modification,and the effects of the mass ratio of PA6 and ABS and the amount of SAG added on the mechanical properties and processing properties of PA6/ABS alloy are investigated.Studies have indicated that for PA6/ABS alloy without SAG compatibilizer,when the ABS mass fraction reaches 40%,the PA6/ABS alloy undergoes a brittle-tough transition.At this time,the notched impact strength is 54.4 kJ/m2;adding 5wt%SAG compatibilizer,the brittle-tough transition occurs when the ABS mass fraction is 20%,and the notched impact strength is as high as 73.1 kJ/m2.The mass ratio of PAC to ABS is 80:20,and the addition amount of SAG is 2.5wt%,5.0%,7.5%,and 10.0%.A torque rheological test is performed on the same mass ratios of PA6 and S AG,and the results makes clearly that the balance torque of PA6 increases first and then remains unchanged with the increase of SAG mass score.When the mass ratio of PA6 to SAG is 76:5,the balance torque of PA6 is increased from 4.6 N-m to 5.5 N-m,and the masa fraction of SAG continues to increase,there is no significant change in the balance torque of PA6C which indicates that the reaction between PA6 and SAG readies saturation.Scanning electron micrograph of PA6/ABS alloy cross section after etching demonstrates that when 5wt%SAG is added and the mass ratio of PA6 to ABS is 80-20,the dispersion size of ABS in the obtained alloy is small and the distribution is uniform.