Preparation And Performance Study Of PVC Hydrophilic Modified Film

PVC is a resin material with abundant raw materials,low price and non-toxic side effects.It has many excellent properties such as acid and alkali resistance,electrical insulation,anti-microbial,abrasion resistance,etc.It is widely used in construction materials,artificial leather,pipes,wires and cables,films and foams,etc.Due to the restricted synergistic movement of the internal chain segments of PVC,the free volume is small,resulting in poor moisture permeability of the PVC film,making the disposable PVC gloves made of PVC a raw material with poor comfort and a stuffy feel.To solve the above problems,this paper uses polyvinyl alcohol（PVA 1788）,ethylene vinyl acetate copolymer containing 25%and 40%of vinyl acetate（VA）to blend and modify PVC,scrape it into a film,set and dry it in 10 minutes at 200℃,cool it to 190℃,5 min gel plasticizing,a series of PVC blend films were obtained.Three foaming agents,AC,DIAD,and Na HCO₃,were investigated for the foaming effect of films with good comprehensive performance,in order to make the films softer.The water contact angle measuring instrument,moisture permeability testing instrument,universal material testing machine,and thermogravimetric analyzer（TG）system were used to study the moisture permeability,mechanical properties,and thermal properties of the blend film.The results showed that:（1）PVA and PVC are partially compatible systems that utilize the degree of phase separation between the two components to adjust the membrane structure and improve its hydrophilicity,thereby improving the performance of the membrane.After the addition of PVA,the hydrophilic groups increased,and there was a difference in wettability between the inner and outer sides of the membrane.The water vapor transmittance（WVT）increased to 521.55 g/m²·24h,which was 219.5%higher than the 284.10 g/m²·24h of PVC film,improving the moisture absorption of PVC film.When the PVA content is 5%,the tensile properties of the film are good,and the thermal stability of the blended film increases with the increase of PVA content.（2）When EVA and PVC were blended and modified,it was found that the viscosity of PVC/EVA blend emulsion with 25%VA increased sharply when the temperature was lower than 40℃,which was not conducive to film formation.EVA with 40%VA content was blended with PVC emulsion in different proportions to make films.And an anionic/non ionic surfactant composed of sodium dodecyl sulfate（SDS）and S2 polyoxyethylene stearate（Brij 72）was selected as the emulsifier to synthesize an anionic polyacrylate water repellent with a Zeta potential of-57.97 m V and good stability.Mix 50 g/L polyacrylate water repellent and 40 g/L anionic WPU coating agent onto the inner surface of PVC/EVA blend film,and dry and crosslink at 120℃for 3 minutes.When the proportion of EVA-40is less than 15%,the water contact angle on the inner surface increases to 92.7°～100.8°,and the water contact angle on the outer surface decreases,forming a difference in wettability.When the proportion of EVA-40 is 5%,the 4-hour moisture permeability of PVC/EVA-40 film is 0.219 g,and the WVT is 464.31 g/m²·24h,which is 184.4%higher than that of PVC film.This indicates that the addition of EVA-40 improves the hydrophilicity of PVC film.Using a universal material testing machine and a thermogravimetric analyzer（TG）,it was found that the elongation at break of PVC/EVA-40 film increased with the increase of EVA-40 ratio,while the fracture strength gradually decreased.When the EVA-40 ratio was 5%,the fracture strength of the film did not change much,and the thermal stability improved.（3）A study was conducted on the foaming effect of AC,DIAD,and Na HCO₃ on the PVC/EVA-40 film with a 5%ratio of EVA-40 with good comprehensive performance.It was found that when AC was used as the foaming agent and the AC ratio was 5%,the foaming effect was better,the foam cells were uniform without collapse and fracture.The WVT was 536.40 g/m²·24h,and the fracture strength gradually decreased due to the small force area of the foam cells during stretching.This article found through research that PVA blended with PVC improved the moisture permeability and thermal stability of the film;When blending EVA with PVC,no other solvents need to be added.After foaming,the film is soft and has good moisture permeability,which has great application potential in disposable PVC gloves.