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采用自行研制的新型旋转挤出装置,通过芯棒与口模同时反向旋转挤出制备聚乙烯(PE)管.结果表明,在口模与芯棒反向旋转挤出过程中,管道内外壁除受到轴向应力作用外,还受到芯棒和口模旋转所施加的环向应力,其合力方向不再是沿管道轴向而是与其有一定的角度.因此,分子链的取向方向和以此链为初级成核点形成的串晶偏离轴向,增强了管道抵抗裂纹增长的能力.将内外壁双冷技术引入旋转挤出过程,可抑制分子链的弛豫,促进此种串晶的形成,提高PE管的耐慢速裂纹增长性能.与传统挤出的PE管裂纹引发时间27h相比,芯棒与口模反向旋转挤出的PE管裂纹引发时间达82 h,增幅204%.
A new type of rotary extrusion device developed by ourselves was used to make polyethylene (PE) tube by reverse rotation extrusion simultaneously with the mandrel and the die.The results showed that during the reverse rotation extrusion of die and mandrel, In addition to the axial stress, but also by the mandrel and die rotation exerted by the hoop stress, the combined direction of force is no longer along the pipe axis but with a certain degree of angle.Therefore, the orientation of the molecular chain and to This chain is the core of the formation of primary nucleation point deviate from the axial direction, enhanced the ability of the pipeline to resist crack growth.Will the external cooling technology is introduced into the rotary extrusion process, the molecular chain can inhibit the relaxation and promote the string Forming and improving the slow crack growth resistance of PE pipe.Compared with the traditional PE pipe crack initiation time of 27h, the crack initiation time of PE pipe with mandrel and die reverse rotation reached 82 h, an increase of 204% .