阻燃PVA-g-AN的制备、表征及性能

以K₂S₂O₈-NaHSO₃氧化还原体系为引发剂, 将丙烯腈(AN)接枝到聚乙烯醇(PVA)上, 得到聚乙烯醇接枝丙烯腈聚合物(PVA-g-AN), 将其与磷酸-尿素反应制备阻燃聚乙烯醇接枝丙烯腈聚合物(FR-PVA-g-AN). 利用傅里叶变换红外光谱(FTIR)、 X射线能谱(XPS)和X射线衍射(XRD)对其结构进行表征, 并用热重分析(TGA)对其热性能进行研究. 结果表明, 当引发剂用量占反应物总质量的1%, n(K₂S₂O₈):n(NaHSO₃)=5:1, m(丙烯腈):m(聚乙烯醇)=3.5:1, 70 ℃反应4 h时, 接枝率可达190%; 在m(磷酸):m(尿素)=5:1, 85 ℃条件下处理接枝产物PVA-g-AN 4 h时, 获得阻燃性能良好的FR-PVA-g-AN, 700 ℃马弗炉热处理后, 残炭量达到63%. TGA结果显示, FR-PVA-g-AN的热降解过程较PVA减慢, 且800 ℃后残炭量由PVA的3.12%增加到54.3%, 说明FR-PVA-g-AN具有优异的热稳定性和成炭性.

Preparation, Characterization and Property of FR-PVA-g-AN

Flame retardant polyvinyl alcohol(PVA) grafted with acrylonitrile(AN)(FR-PVA-g-AN) was prepared via grafting copolymerization of AN onto PVA (PVA-g-AN) using K2S2O8-NaHSO3 as initiator followed by the chemical modification reaction with phosphoric acid and urea. The structure of FR-PVA-g-AN was characterized by Fourier transform infared spectroscope(FTIR), X-ray photoelectron spectroscopy(XPS) and X-ray diffraction(XRD), and the thermal property was studied by thermogravimetric analysis(TGA). The results show that the grafting percent reaches 190% under the condition of the mass fraction of initiator being 1% of the total reactant, the molar ratio of K2S2O8 to NaHSO3 being 5:1, the mass ratio of AN to PVA being 3.5:1, and reaction temperature being 70 ℃, and the reaction time of 4 h. The FR-PVA-g-AN with excellent fire retardancy can be obtained with the mass ratio of phosphoric acid to urea being 5:1 and reaction temperature of 85 ℃ for 4 h. There is about 63% char residue left after FR-PVA-g-AN was treated at 700 ℃ with muffle. The TGA curves indicate that the thermo-oxidative degradation of FR-PVA-g-AN is slower than that of PVA, and the char residue of FR-PVA-g-AN increases to 54.3% at 800 ℃, while the char residue of PVA is only 3.12%, which fully proves that FR-PVA-g-AN has better thermal stability and char forming capability.