A Study On The Preparation And Properties Of Transparent & Toughened PVC

The effects of interfacial compatibility and morphology on the mechanical properties and transparency of PVC/SBS, PVC/SBS/MBS and PVC/SBS-SiO₂/MBS blends were studied in this thesis. The experimental results show that:1) With the increase of SBS content, the impact strength of PVC/SBS blend is improved. While the SBS content is 8 phr, the impact of PVC/SBS₇₉₁, PVC/SBS₈₀₁ blend reach a maximum value of 24.59 kJ/m² and 19.13 kJ/m² respectively. While SBS content is 10 phr, the impact strength of NBS₇₉₂, SBS₈₀₂ blend with PVC show a maximum value of 22.55 kJ/m² and 19.22kJ/m² respectively. At the same SBS content, the impact strength of linear-SBS/PVC blend is higher than. that of starSBS/PVC blend. With the increase of SBS content, the tensile strength of PVC/SBS blend decreases. For the PVC/SBS blend having more PB section, the tensile strength decrease faster. With the increase of SBS content, the elongation at break of star-SBS/PVC blend shows a maximum value, while that of linear-SBS/PVC blend changes little. The transparency of PVC/SBS blend decreases. Compared with SBS (PS/PB=3/7)/PVC blend, the transparency of SBS (PS/PB=4/6)/PVC blend is higher.2) The impact strength of PVC/SBS/MBS blend is higher than summation of that of PVC/SBS and PVC/MBS blend, the synergistic effect is very obvious. With the increase of MBS content in PVC matrix,, the impact Strength of PVC/SBS/MBS is improved greatly. When the MBS content is about 4～5 phr, the impact strength of PVC/SBS792/MBS blend shows a maximum value of 84.16 kJ/m², and that of PVC/SBS₈₀₂/MBS blend reaches a maximum value of 136.11 kJ/m² while MBS content is about 2～3 phr. Due to the improvement of interracial compatibility between PVC and SBS through the addition of MBS in the blend, SBS is dispersed evenly in PVC matrix, and the size of SBS is decreased, the transparency is thus improved a little.3) With the increase of SiO₂ content, the tensile strength at 100% and 300% elongation of SBS/SiO₂ blend, increase, and reach a maximum value while SiO₂ content is 40%. With the increase of SiO₂ content, the elongation at break change little. The nano SiO₂ is easy to agglomerate in the SBS matrix, which make the tensile strength of SBS/nano SiO₂ blend decrease.4) For the PVC/SBS-SiO₂/MBS blend, SiO₂ particles are coated by SBS and form the core-shell strcture. The core-shell particles have a good compatibility with PVC matrix. With the addition of 3μm SiO₂, the impact strength of the blend is improved obviously. When the content of 3μm SiO₂ is 4 phr, the impact Strength of PVC/SBS₇₉₂/MBS blend is increased from 84.16 kJ/m² to148.29 kJ/m². The addition of SiO₂ causes the transparency of the PVC/SBS₇₉₂/MBS blend decrease to some extent. The transparency of PVC/SBS₇₉₂/MBS blend containing 40 nm SiO₂ is higher than that of blend containing SiO₂ of large particle size. The larger the particle size of SiO₂ in the blend, the faster the transparency of the blend decreases.