Synthesis Of High-barrier Polyvinylidene Chloride Emulsion And Its Performance Study

In recent years,As the country increases its efforts on environmental protection,green and environmentally friendly packaging materials are receiving more and more attention.Polyvinylidene chloride(PVDC)is an environmentally friendly material,due to its structure contains symmetric chlorine atoms,had good barrier properties,can resist water vapor,oxygen,salt,corrosive gases,was widely used in packaging materials,flame retardant fibers,anti-corrosion coatings,and other fields.However,PVDC emulsions still have poor film formation,short shelf life of goods,poor adhesion,barrier properties that do not meet the applicable standards,and other problems,therefore,the development of the comprehensive performance of PVDC emulsions become particularly important,In this thesis,the basic formulation for synthesizing highly stable polyvinylidene chloride emulsion was discussed,the emulsion was modified and the emulsion and film properties were investigated,and the synthesized emulsion was used as a finishing solution to modify the waterproofing and finishing of all-starch biodegradable lunch boxes.Vinyl chloride(VDC),methyl acrylate(MA)as monomer,using KPS/SHS as the initiating system,SDS/OP-10 emulsification system,polymerization temperature of 62℃,to obtain a series of excellent performance of PVDC emulsion;using DAS/SSS composite emulsifier,emulsion stability of up to 12 months or more.A series of multi-poly PVDC emulsions were synthesized with different soft and hard segments as copolymer monomers,and it was found that the maximum particle size of PVBMM was 390.1 nm,and the minimum particle size of PVEM was 179.5 nm.T_gmoved to lower temperatures as the side chain of acrylate became more flexible.The water absorption of the copolymer adhesive films were all below 2%;PVEMM had the best barrier performance of 9.21 cm3/(m~2·24h).The adhesion of the latex films increased with the growth of the acrylate side chains.The adhesion of methacrylate monomer in the same side chain was poorer compared to that of acrylate monomer.With VDC-MA as the core,VDC-BA as the shell and VTMO as the modified cross-linking agent,a hard core and soft shell were constructed to synthesize PVMBV emulsions with different VTMO contents.It is found that with the increase of VTMO content,the crystallinity of the film slightly decreases;the water absorption increases;the contact angle increases;the adhesion improves;the yield strength of the film increases and then decreases,and the toughness improves;the thermal stability improves;the T_gof PVMBV shifts to lower temperature,and the Tanδmax gradually increases;the XPS test results show that due to the lower surface energy of Si,it leads to its migration to the surface of the film and improves the surface properties of the film.The surface properties of the film were improved.The oxygen transmission rate of the emulsion film was 5.68 cm~3/(m~2·24h)when VTMO was introduced at 1%,and the barrier performance of the film was improved effectively.A series of PVDC emulsions were synthesized to coat all-starch biodegradable tableware,and their performance was examined and found to have excellent barrier properties.The coated tableware can guarantee no leakage under boiling water,vegetable oil and rice vinegar for 24 hours and meet the application standard.