原位红外研究SBS接枝前后的热氧化过程

采用原位红外对比研究了热塑性弹性体苯乙烯 -丁二烯 -苯乙烯 (SBS)、马来酸酐接枝 SBS(SBS- g-MAH)、聚丁二烯 (PB)和聚苯乙烯 (PS)的热氧化过程。研究表明 ,接枝产物对双键的保护作用使得 SBS-g- MAH的抗热氧化性比纯 SBS明显提高 ,热氧化速率变慢 ;SBS中 PB段的双键和烯丙位同时氧化 ;PB的热氧老化机理和 SBS一样 ,但 PB的起始热氧化温度比 SBS低 ,热氧化速率比 SBS快 ,说明苯乙烯段有抑制氧气向丁二烯段扩散的作用 ;SBS中 PS段未氧化。研究结果表明材料抗热氧化性能的顺序为 :PS>SBS- g- MAH>SBS>PB

INVESTIGATION OF THERMAL OXIDATION PROCESSES OF SBS AND SBS-g-MAH BY IN-SITU FT-IR ANALYSIS

The thermal oxidation processes of styrene butadiene styrene tri block copolymer (SBS) and maleic anhydride (MAH) grafted with SBS were studied by in situ FT IR analysis in air. Carbonyl and hydroxyl groups were thermal oxidation products in SBS and SBS g MAH. The anti thermal oxidation property of SBS g MAH was better than SBS, because the carbon carbon double bonds of PB block was protected by the grafting of MAH. PB has the same thermal oxidation results as SBS but in a higher oxidizing rate, which indicates that PS block has inhibited the diffusion of oxygen hence inhibited the thermal oxidation of PB block. Just as carbonyl group was not observed in PS, PS block was not oxidized in SBS. The sequence of anti thermal oxidation property was: PS>SBS g MAH>SBS>PB.