Synthesis And Properties Of Emulsion Copolymerization Of Vinylidene Chloride And Acrylate

Polyvinylidene chloride?PVDC?is a well-known material that has excellent barrier properties against oxygen,water vapor and other gases.PVDC also has high toughness,good heat shrink ability,excellent chemical stability and sealing properties.At present,polyvinylidene chloride can be widely used in food,medicine,military and other fields.However,due to its poor thermal stability,it is difficult to process,so it is often necessary to introduce other monomers for copolymerization to improve its performance.Different comonomers will give different properties to PVDC.In this paper,acrylate is used as comonomer,sodium dodecyl sulfate?SDS?and OP-10 are emulsifiers,potassium persulfate?KPS?and sodium bisulfite.?NaHSO₃?is a redox initiator,sodium carbonate?Na₂CO₃?is a pH buffering agent,and a series of vinylidene chloride-acrylate copolymer emulsion and film are prepared by emulsion polymerization,and the content of vinylidene chloride and acrylate are changed.The composition and the introduction of functional monomers were modified,and the properties of the prepared copolymers were studied.The specific research contents are divided into the following aspects:?1?As the content of emulsifier increases,the particle size and surface tension of the copolymer emulsion decrease,the zeta potential value increases,and the stability of the emulsion becomes better.Through the study of the proportion of emulsifier,it is concluded that SDS:OP-10=3:1,when the content is 3%,the performance of the emulsion is better.?2?Introducing MA,MMA,BA,EHA,AN comonomers into the copolymerization system,and examining the properties of the emulsion,it can be concluded that the particle size and surface tension of the copolymer emulsion of VDC-MA are small,Zeta The potential value is larger,the stability of the emulsion is better,and the introduction of different comonomers plays a role in lowering the melting point of the polymer,improving the processability of the copolymer.The performance of the copolymer film is found to be VDC-MA copolymerization.The crystallinity of the material is higher,the film is denser,the water absorption rate is lower,the contact angle is larger,and the water resistance is better.The introduction of different monomers has played a role in improving the mechanical properties of the copolymer,and the soft monomer BA has a better effect.?3?By changing the ratio of VDC to MA,it is found that as the VDC content increases,the particle size and surface tension of the emulsion become smaller,the Zeta potential value becomes larger,and the emulsion is more stable.Among them,VDC90%,MA10%emulsion is the most stable,VDC When the content is increased,the crystallinity of the copolymer becomes higher,the film is denser,the water absorption rate becomes lower,the contact angle becomes larger,and the water resistance is better,but the texture of the film becomes brittle and the mechanical properties are deteriorated,so the VDC content should not be too high.When the VDC content is 90%and MA10%,the properties of the copolymer are good.?4?Introducing functional monomers AA,AN and vinyltriethoxysilane?VTEO?into the VDC-MA copolymerization system,respectively,it was found that as the AA content increases,the surface tension of the emulsion decreases,and the melting point of the copolymer decreases.The toughness of the film is enhanced,and the film forming property of the emulsion is improved.The proper amount of AA can enhance the stability of the emulsion and improve the processability and mechanical properties of the copolymer.A certain amount of AN can reduce the surface tension of the emulsion,the melting point of the copolymer,improve the processability,and enhance the ductility of the film.The addition of AN improves the film forming properties of the copolymer,making PVDC toughness is improved.By introducing the functional monomer VTEO into the VDC-MA,VDC-BA copolymerization system,it was found that the introduction of silicone reduced the surface tension of the emulsion,the water absorption of the film was reduced,the hydrophobic property was enhanced,and the film became more Densification improves the water resistance of the copolymer,lowers the melting point of the copolymer,and improves its processability.?5?Through oxygen permeability test,the oxygen permeability of the copolymer film decreases with the increase of VDC content,and the barrier property of PVDC is enhanced.The introduction of BA,AA and AN makes the oxygen permeability of the film have It is elevated,but it also maintains its basic barrier properties.The introduction of the functional monomer VTEO reduces the oxygen transmission rate of the film and enhances the barrier properties of the copolymer.The PVDC emulsion with good barrier properties is coated on the surface of the starch lunch box,so that the emulsion forms a dense,smooth and good barrier film on the surface of the lunch box,so that it has good waterproof and anti-proof.The oil properties can also make the food not easy to adhere to the surface,play an aesthetic role,and exhibit good application characteristics.