无卤阻燃丙烯腈共聚物的制备及性能

Preparation and Properties of Halogen-free Fire Retardant Acrylonitrile Copolymer

以K2S2O8-NaHSO3氧化还原体系为引发剂,采用水相沉淀自由基聚合法合成丙烯腈(AN)-醋酸乙烯酯(VAc)无规共聚物[P(AN-co-VAc)],然后在KOH水溶液中进行P(AN-co-VAc)中VAc单元的选择性水解,再与磷酸和尿素进行磷酰化反应,制备无卤阻燃丙烯腈共聚物.用核磁共振氢谱(1H NMR)、傅里叶变换红外光谱(FTIR)、差示扫描量热(DSC)和热重分析(TGA)对聚合物结构及热性能进行表征,用凝胶渗透色谱(GPC)测定了P(AN-co-VAc)的分子量及其分布,并利用FTIR和扫描电子显微镜(SEM)对无卤阻燃丙烯腈共聚物的炭残渣进行分析.结果表明,VAc与AN发生共聚反应,制得了P(AN-co-VAc),随着KOH水溶液pH值的增大,P(AN-co-VAc)中VAc单元迅速水解;DSC分析结果表明,随着共聚物中VAc单元含量的增大,共聚物的环化放热分解峰值温度(T p)增大,当VAc单元的质量分数为25%时,T p最大值高达328℃,而阻燃丙烯腈共聚物的T p高达340℃;TGA分析结果表明,阻燃共聚物在800℃时的炭残渣量高达55%以上,远高于P(AN-co-VAc)的41%,具有良好的成炭性;炭残渣的FTIR及SEM结果表明,阻燃丙烯腈共聚物的阻燃属于凝聚相阻燃.

Acrylonitrile （AN） -vinyl acetate （VAc） copolymer [ P （AN-co-VAc） ] was synthesized via aqueous phase precipitated radical copolymerization of AN and VAc using K2 $20s-NaHSO3 as initiator. The VAc unit of P（AN-co-VAc） was selectively hydrolyzed with KOH aqueous under different pH values. The halogen-free fire retardant AN copolymer was prepared by the phosphorylation reaction among phosphoric acid, urea and the hydrolyzed P（AN-co-VAc）. The structure of AN copolymer was characterized by nuclear magnetic resonance hydrogen spectrum（1H NMR）, Fourier transform infrared spectroscope （FTIR）, and the thermal property of them was studied by differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）. The num- ber-average molecular weight （ M, ） and polydisperisity index （PDI） of the obtained P （AN-co-VAc） were de- termined by gel permeation chromatography （GPC）. The char residue of the halogen-free fire retardant AN co- polymer was analyzed by FTIR and SEM. The results show that AN is really copolymerized with VAc and P（AN-co-VAc） can be synthesized successfully. VAc unit is quickly hydrolyzed with the increase of pH. DSC indicates that with the increase of mass fraction of VAc in P（ AN-co-VAc）, the temperature of cyclic exother- mic peak（Tp） improves, and Tp reaches to 328 ~C with the mass fraction of VAc being 25%, while Tp of fire retardant AN copolymer can be 340 ~C. TGA demonstrates that the char residue of fire retardant AN copolymer at 800 ~C is 55%, which is higher than that of P（AN-co-VAc） being 41%, it fully proves that fire retardant AN copolymer has good char forming capability. The fire retardant mechanism of fire retardant AN copolymer belongs to condensed phase flame retardant mechanism.