可发性聚甲基丙烯酰亚胺前驱体珠粒的制备及发泡性能

Preparation and Foaming of Expandable Polymethylacrylimide Precursor Beads

以丙烯腈(AN)和甲基丙烯酸(MAA)为共聚单体、偶氮二异丁腈(AIBN)为引发剂、含有双键的可共聚单体甲基丙烯酸叔丁酯(tBMA)为热分解发泡剂,采用水相悬浮聚合法制备出可发泡的聚甲基丙烯酰亚胺(PMI)前驱体珠粒。讨论了水相悬浮聚合中分散剂种类和用量、搅拌速率、油水比、单体配比、水相阻聚剂等因素对珠粒粒径和分布的影响,并利用傅里叶变换红外光谱、扫描电镜、差示扫描量热法、热失重分析和万能试验机等方法对珠粒发泡前后的结构和性能进行分析测试。结果表明,当油相中AN/MAA为0.3/0.2、可共聚发泡剂tBMA为7%,引发剂偶氮二异丁腈AIBN为0.14%,水相中有机分散剂羟丙基甲基纤维素(HPMC)为单体质量的1.4%并添加适当NaCl、水相阻聚剂和无机分散剂,油水比为1/5,反应温度为60℃、搅拌速率为250~275 r/min,可制备出平均粒径在1~2 mm且分布窄、产率约80%的可发泡的PMI前驱体球形珠粒。含7%发泡剂的可发泡珠粒在230℃的模具中发泡成型为密度150 kg/m3的PMI泡沫,其10%压缩强度为2.15 MPa,热分解起始温度为368.2℃。

Using acrylonitrile(AN)and methacrylic acid(MAA)as co monomer,azodiisobutyronitrile(AIBN)as initiator,and tert-butyl methacrylate methacrylate(tBMA)containing double bonds as thermal decomposition foaming agent,the precursor beads of foamable polymethylacrylimide(PMI)were prepared by aqueous suspension polymerization.The effects of dispersant type and dosage,stirring rate,oil-water ratio,monomer ratio,aqueous polymerization inhibitor and other factors on the particle size and distribution of beads in aqueous suspension polymerization were discussed,and the structure and properties of beads before and after foaming were analyzed by Fourier infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),differential scanning calorimetry(DSC),thermogravimetric test(TGA)and universal testing machine.The results show that when the mole ratio of AN/MAA in oil phase is 0.3/0.2,the copolymerizable foaming agent is 7%,the organic dispersant in water phase is 1.4%of the monomer mass,and appropriate NaCl,aqueous phase polymerization inhibitor and inorganic dispersant are added,the oil-water ratio is 1/5,the reaction temperature is 60℃,and the stirring rate is 250~275 r/min,the foamable PMI precursor spherical beads with an average particle size of 1~2 mm,narrow distribution and about 80%yield can be prepared.The foamable beads containing 7%foaming agent were foamed into PMI foam with a density of 150 kg/m3 in mold at 230℃.The 10%compressive strength is 2.15 MPa,and the initial temperature of thermal decomposition is 368.2℃.