Study On The Compatibility Of Modified PVC Calendered Film Substrate

PVC/titanium dioxide calendered film has the advantages of high mechanical strength,strong weather resistance,high whiteness,etc.,it is widely used in the packaging of daily necessities packaging,automotive films,furniture films and other fields.However,the surface of titanium dioxide is weak in hydrophobicity,has poor compatibility with PVC,and is prone to agglomeration,which seriously affects the performance and appearance of PVC calendered films,and the high production cost makes the production and application of PVC/titanium dioxide calendered films extremely restrictive.However,the surface of titanium dioxide is weak in hydrophobicity,and has poor compatibility with PVC.It is easy to agglomerate,which seriously affects the performance and appearance of PVC calendered film,and its production cost is high,the production and application of PVC/titanium dioxide calendered film are greatly restricted.In this paper,starting from improving the compatibility of titanium dioxide and PVC matrix and reducing the production cost of PVC calendered film,we choose to use coupling agent to modify titanium dioxide to enhance the compatibility of titanium dioxide and PVC resin matrix,and choose to use low cost precipitated barium sulfate partially replaces titanium dioxide.This article selected 3-triethoxysilyl-1-Propanamine（KH-550）,3-glycidoxypropyltrime-thoxysilane（KH-560）,3-（trimethoxysilyl）-1-propano methacrylate（KH-570）,stearic acid（SA）,titanate（NDZ）five different coupling agents to treat titanium dioxide and barium sulfate with wet modification process,and compare the modification effect of the modifier by analyzing the contact angle,infrared spectrum,and grafting rate of the modified product;prepare PVC composites by melt blending method,explore the effects of titanium dioxide addition,barium sulfate addition,and the type of coupling agent used on the mechanical properties of PVC composites,and analyze the cross-sectional morphology of PVC/modified filler composite material by scanning electron microscope;the modified titanium dioxide and modified barium sulfate with the best modification effect are used to prepare compound fillers to study the mechanical properties of different mixing ratios on PVC composites and the influence of apparent morphology.When using five different coupling agents to modify titanium dioxide,it was found that titanate modification had the best effect.The contact angle of titanium dioxide powder after modification with titanate reached 139.1°,and the graft ratio reached 3.13 wt%Infrared spectrum shows infrared absorption peaks of methyl and methylene near 2900 cm^-1.When the addition amount of titanium dioxide is 20 phr,the PVC/modified titanium dioxide composite material shows better tensile properties and impact properties,and the composite mechanical properties of PVC composites with titanate modified titanium dioxide are the best.Its tensile strength,tear strength and impact strength reached 29.9 MPa,165N/mm,3.67 kJ/m²,which was 9.52%,12.24%,23.99%higher than that of PVC/titanium dioxide composites with the same amount of unmodified titanium dioxide.Scanning electron microscopy（SEM）shows that the modified titanium dioxide has less agglomeration on the fractured cross-section of the PVC/titanium dioxide composite,and the cross-section is uniform and dense.When using different coupling agents to modify barium sulfate,it was found that stearic acid is the best modifier for barium sulfate.The contact angle of stearic acid modified barium sulfate powder was 134.5°,the grafting rate was 2.97 wt%,infrared the spectrum shows a carbonyl vibration peak at 1700 cm^-1.When the amount of barium sulfate added is20 phr,compared with the PVC composite material filled with unmodified barium sulfate,,PVC/modified barium sulfate composites exhibit better tensile properties and impact properties,and the comprehensive mechanics of PVC composites with stearic acid modified barium sulfate best performance,its tensile strength,tear strength and impact strength reach28.7 MPa,151 N/mm,4.25 kJ/m²,compared with PVC/barium sulfate composite materials with the same amount of unmodified barium sulfate,it has increased 13.39%,11.85%,24.63%.SEM shows that the stearic acid-modified barium sulfate is more evenly dispersed in the PVC matrix,and the agglomeration phenomenon is somewhat reduced.The total amount of fixed titanate-modified titanium dioxide and stearic acid-modified barium sulfate is 20 phr.By changing the mixing ratio of the two,the effect on the mechanical properties and apparent morphology of PVC composites was explored.The results show that when the compound filler is added in an amount of 20 phr,as the proportion of barium sulfate in the compound filler becomes larger,the tear strength of the PVC composite material decreases and the impact strength and hardness increase;the tensile strength rises first and then decreases,when the ratio of titanium dioxide to barium sulfate is15/5,the tensile strength reaches the maximum;the elongation at break increases first and then decreases,when the ratio of titanium dioxide to barium sulfate is 5/15,the elongation at break reaching the maximum;when the ratio of titanium dioxide and barium sulfate changed from 0/20 to 5/15,the whiteness of PVC composites increased rapidly,and the transparency decreased rapidly,continued to increase the addition ratio of titanium dioxide,the whiteness and transparency of the composites did not change much.