Study On The Anti-aging Mechanism And Related Properties Of PVC Calendered Film

Polyvinyl chloride(PVC)is a thermoplastic resin polymerized by vinyl chloride monomer under the action of an initiator.Products made of PVC not only have the characteristics of wear resistance,corrosion resistance,good insulation and flame retardancy,but also low price.According to different uses,a variety of molding processes can be used to prepare PVC products.Among them,PVC produced by calendering is generally used to make sheets and films materials,which have very good applications in agricultural films,packaging materials,building materials,and housing materials for home appliances.However,it is easy to chemically interact with ultraviolet rays in the sun,water and oxygen in the air,causing it to undergo different degrees of degradation.The specific manifestation is that the surface color is easy to change and its mechanical properties are reduced.To solve the above problems,the purpose of this paper is to improve the aging resistance of the PVC calendered film.In the paper,the authors used anatase titanium dioxide(Ti O2(A))and hindered amine light stabilizers([6-[(1,1,3,3-tetramethylbutyl)amino]]-1,3,5-triazine-2,4-[(2,2,6,6,-tetramethyl-piperidinyl)imino]-1,6-hexanediene[(2,2,6,6-tetraMethyl-4-piperidinyl)imino],C944),ultraviolet absorber 2-(2ˊ-hydroxy-5ˊ-methylphenyl)benzotriazole(UV-P),modified hydrotalcite(LDH-BP)and the compound of the above-mentioned compounds as anti-aging additives.The accelerated aging experiment was used to study the aging resistance of the PVC calendered film.The colorimeter,tensile tester,impact tester,infrared spectroscopy(FT-IR)and scanning electron microscope(SEM)have been used to characterize its aging resistance.The research results are as follows:(1)Different amounts of Ti O2(A)were added to the rolled PVC film to study its aging resistance.The research results show that with the increase of Ti O2(A)content,the aging resistance of the PVC calendered film gradually improves.After 672 h of accelerated aging,for the color difference value,the PVC calendered film without Ti O2(A)is 37.30,and the PVC/20%Ti O2(A)film is 6.74;For the elongation at break,the PVC calendered film without Ti O2(A)was 11.0%and 3.0%before and after aging,respectively,with a decrease of 72.7%,while the PVC/20%Ti O2(A)film was 16.0%and 13.5%before and after aging,respectively,with a decrease of 15.6%;For the impact strength,the rolled PVC film without Ti O2(A)was33.4 k J/m~2,9.1 k J/m~2 before and after aging,and the decrease rate was 72.8%,the PVC/20%Ti O2(A)film is 16.0 k J/m~2,14.6 k J/m~2 before and after aging,and the decrease is8.8%;For the carbonyl index,the PVC film without Ti O2(A)is 4.70,and the PVC/20%Ti O2(A)film is 3.80.(2)Different parts of hindered amine stabilizer C944 were added to the PVC calendered film to study its aging resistance.The research results show that as the content of C944 increases,the aging resistance of the PVC calendered film increases first and then decreases.After 672 h of accelerated aging,for the color difference value,the PVC calendered film without C944 is37.30,while the PVC/2%C944 film is 0.95;For the elongation at break,the PVC film without C944 was 11.0%and 3.0%before and after aging,and the decrease was 72.7%,while the PVC/2%C944 film was 18.6%and 17.7%before and after the aging,respectively,and the decrease was 4.8%;For the impact strength,the PVC calendered film without C944 was 33.4k J/m~2,9.1 k J/m~2 before and after aging,a decrease of 72.8%,and the PVC/2%C944 film was16.1 k J/m~2 and 15.8 k J/m~2 before and after aging,with a decrease of 1.9%.In addition,the coordinated light stabilization effect of C944 and UV-P on the PVC calendered film was further studied.The research results show that C944 and UV-P have a synergistic light stabilization effect on the PVC calendered film.When the mass ratio of C944 and UV-P is 1:1 and the total mass fraction is 2%,after 672 h of accelerated aging,the surface color difference of PVC/1%C944/1%UV-P is 2.57;The elongation at break was 17.2%and 16.5%before and after aging,with a decrease of 4.1%;The impact strength was 15.8 k J/m~2,15.6 k J/m~2 before and after aging,with a decrease of 1.3%;The carbonyl index was 0.43.(3)Modified hydrotalcite(LDH-BP)was prepared by roasting reduction method,and it was confirmed by infrared spectrometer(FT-IR)and X-ray diffractometer(XRD)that the hydrotalcite contained 2-hydroxy-4-methoxy Benzophenone-5-sulfonic acid(BP).The hydrotalcite before and after the modification was added to the PVC calendered film to study the aging resistance of the PVC calendered film.The research results show that,compared with LDH,LDH-BP has better anti-aging performance for PVC calendered film.After 672 h of aging,as for the color difference value,the PVC calendered film without LDH-BP is 37.30,while the PVC/6%LDH-BP film is 23.08;For the elongation at break,the PVC calendered film without LDH-BP was 11.0%,3.0%before and after aging,and the decrease was 72.7%,while the PVC/6%LDH-BP film was 10.8%,10.3%before and after aging,a decrease of 4.6%;For the impact strength,the PVC calendered film without LDH-BP was 33.4 k J/m~2,9.1 k J/m~2 before and after aging,and the decrease was 72.8%,the PVC/6%LDH-BP film was 27.8 k J/m~2,22.2k J/m~2 before and after aging,and the decrease was 20.1%;For the carbonyl index,the PVC calendered film without LDH-BP was 4.70,the PVC/6%LDH-BP film is 0.12.