A Study On The Structure And Properties Of Ozonized Styrene Elastomer And Toughenging PA6 With Ozonized Styrene Elastomer

The effects of ozone treatment on the structure and properties of styreneelastomer (SBS,SEBS and SEEPS) were studied in this thesis. Based on theseresults, the mechanism of color degradation caused by ozonization was furtheranalysed, moreover, two different type of SEBS was chosen to be ozonized andtoughening PA6, the PA6/SEBS blend with high toughness was prepared. Theexperimental results show that:1. Through ozonization, some oxygen-containing groups (mainly carboxylgroups) are introduced onto the molecular chains of Styrene Block Copolymer(SBC). The surface energy of SBC is thus improved. Ozonization causes thedegradation of SBC, the molecular weight is decreased and its distribution becomeswider. Prolonging ozonization time of SBC, thetensile strength at 100% and300% elongation is decreased. Compared with linear SEEPS4044 and SEBS503,linear SBS791 is easier to be oxidized. Compared with star SEBS602, the linearSEBSS03 is easier to be oxidized.2. With the increase of ozonization time, the yellowness index of SBC increases.With the improving of thermal treating temperature, the yellowness index of SBC and ozonized SBC both increases. Compared with SBC, the increasing amplitudeof yellowness index of ozonized SBC is more obvious, which indicates that the colorof ozonized SBC is easier to degrade. The structure of SBC and the content ofcarboxyl group have more effects on the color degradation. The color degradationof ozonized SBC is mainly attributed to the formation of vinylphenylketone, styrenederivant andα,β-unsaturated carboxyl during ozonization process.3. The interfacial interaction of PA6 and ozonized SEBS is improved. Theozonized SEBS is dispersed evenly in PA6 matrix and the size of ozonized SEBSparticle is decreased. Compared with PA6/ozonized SEBS602 blend, the size ofdispersed phase in PA6/ozonized SEBS503 blend is smaller.4. With the increase of ozonized SEBS (O₃-SEBS) content, the PA6/O₃-SEBSblend transfer from brittleness to toughness. Compared with PA6/SEBSS03(80/20)blend, when the SEBS is ozonized for 90 minutes, the impact strength ofPA6/O₃-SEBS503 (80/20) is increased from 21.47 kJ/m² to 68.66 kJ/m². The yieldstrength of PA6/SEBS blend is lower than that of PA6. With the increase ofO₃-SEBS content,the yield strength of PA6/O₃-SEBS blend decreases and theelongation at break increases. The ozonization time of SEBS has little effect on theyield strength of PA6/O₃-SEBS blend. However, the elongation at break ofPA6/O₃-SEBS blend is improved while prolonging ozonization time of SEBS.5. With the increase of shear rate, the shear viscosity of PA6/SEBS blenddecreases and displays the behavior of shear thinning. Compared with PA6/SEBSblend, the shear viscosity and shear stress of PA6/O₃-SEBS blend are increased.