热塑挤出制备无机阻燃聚乙烯醇泡沫材料及其影响因素的研究

Preparation of Inorganic Flame Retardant Poly(vinyl alcohol) Foam Through Thermal Processing and Investigation of Its Influencing Factors

以水为增塑剂兼物理发泡剂,氢氧化铝(ATH)为无机阻燃剂兼异相成核剂,通过热塑挤出方法制备了无机阻燃聚乙烯醇/氢氧化铝(PVAL/ATH)复合泡沫材料,采用扫描电子显微镜(SEM)等研究了水和ATH含量、口模温度、螺杆转速、交联剂对复合泡沫材料泡孔结构的影响。结果表明,适当的口模温度和螺杆转速是实现体系中水的可控、连续、稳定发泡的关键因素,适量添加的阻燃剂能够起到良好异相成核剂的作用,在最佳工艺条件下,当PVAL/ATH/水为100/80/30,口模温度为125℃,螺杆转速为30 r/min时,制备得到综合性能优异的无机阻燃PVAL/ATH泡沫材料,泡沫材料的表观密度为0.32 g/cm3,膨胀倍率为10.0,泡孔密度约为1.6×105个/cm3。此外,引入硼酸作为交联剂,有效提高了熔体强度并改善了泡孔结构,交联后泡沫材料的拉伸强度和断裂伸长率分别提高到6.3 MPa和59.2%。

Poly(vinyl alcohol)/aluminum hydroxide(PVAL/ATH)foams were prepared through thermal extrusion foaming by using water as both plasticizer and physical blowing agent,using ATH as both flame retardant and heterogeneous nucleation agent.The influences of water and ATH contents,die temperature,screw rotation speed and crosslinking agent on the cell structure of PVAL/ATH foams were investigated.The results show that proper ATH content,die temperature and screw speed are very important in the realization of the controlled,continual and stable melt-extrusion foaming.The addition of appropriate ATH particles act as the effective heterogeneous nucleation sites during the foaming process.PVAL/ATH foam with excellent comprehensive properties is produced under optimal processing conditions.When the ratio of PVAL to water is100∶30,die temperature is125℃and screw speed is30r/min,the foam density is0.32g/cm3and the expansion ratio is10.0,the cell density is about1.6×105/cm3.Besides,the addition of crosslinking agent effectively enhances the melt strength and improves the cellular structure.The tensile strength and elongation at the break of the crosslinked foam are increased to6.3MPa and59.2%,respectively,compared to that of non-crosslinked sample.