一种阻燃抗静电聚丙烯的流变性能

采用毛细管流变仪和旋转流变仪分别研究了溴系阻燃剂、炭黑填充对聚丙烯熔体高剪切挤出畸变和动态黏弹特性的影响。发现低含量下随填充量的提高，发生挤出畸变的临界剪切速率提高，扩大了加工窗口。动态流变试验表明树脂中添加更多炭黑后剪切变稀时的复数黏度、储能模量和损耗模量都增大，但损耗因子下降。进一步用缠结模型和Cross模型定量分析表明，填料吸附高分子链段而减少其壁面吸附，减轻挤出畸变，进而提高临界剪切速率；粒子分布网络提高了平台模量和缠结密度，缩短了松弛时间，恢复更快而减小挤出胀大比。复合材料中添加3.5%（质量）炭黑后形成逾渗网络，表现为高零切黏度和长松弛时间，发生“类液-类固”转变；同时材料表面电阻下降明显，此时黏弹逾渗点与导电逾渗点基本一致。

Rheological properties of flame retardent and antistatic polypropylene material

The effects of brominated flame retardant and carbon black-filling on the extrusion distortion of PP melt and dynamic rheological properties were investigated by capillary rheometer and rotational rheometer. It was shown that the more filled resin exhibited higher critical shear rate for extrusion distortion corresponding to wider processing window in low filler content range. In dynamic rheometry, the higher filled resins behavior in shear thinning with higher complex viscosity,storage modulus and loss modulus instead of lower loss factor. Quantitative analyses were conducted using entanglement model and Cross model. Filler can absorb polymer chains to reduce wall adsorption dropping distortion and result in higher critical shear rate. Particle filled network increases in the plateau modulus and entanglement density shortening relaxation time for quicker recovering according to smaller extrusion swell ratio. Carbon black more than 3.5%(mass) in composite forms percolation network being characterized by higher zero shear viscosity and longer relaxation time where liquid-solid-like transition occurs. Simultaneously, the surface resistivity decreased obviously. The viscoelastic percolation value consistent with the electrical percolation value approximately.