CAJ | 학술논문

以L型双层共挤异型材为研究对象，采用Phan-Thien and Tanner(PTT)本构方程，应用Arrhenius方程来描述温度对黏度的影响，通过有限元方法分析了聚丙烯(PP)/聚苯乙烯(PS)熔体在气辅共挤口模内的三维黏弹非等温流动过程，对比分析了不同流率下气辅共挤口模所需的最短气辅段长度，同时分析了口模出口面的剪切速率及第一法向应力差的分布情况。结果表明，气辅共挤并不能完全消除挤出胀大，但能极大限度地降低挤出胀大；通过分析流道内的压力、剪切速率及第一法向应力差分布可以确定一个合适的气辅段长度；随着熔体流率的增加，气辅共挤口模所需的最短气辅段长度也相应地增加，但增速并不明显。
이L형쌍층공제이형재위연구대상，채용Phan-Thien and Tanner(PTT)본구방정，응용Arrhenius방정래묘술온도대점도적영향，통과유한원방법분석료취병희(PP)/취분을희(PS)용체재기보공제구모내적삼유점탄비등온류동과정，대비분석료불동류솔하기보공제구모소수적최단기보단장도，동시분석료구모출구면적전절속솔급제일법향응력차적분포정황。결과표명，기보공제병불능완전소제제출창대，단능겁대한도지강저제출창대；통과분석류도내적압력、전절속솔급제일법향응력차분포가이학정일개합괄적기보단장도；수착용체류솔적증가，기보공제구모소수적최단기보단장도야상응지증가，단증속병불명현。
Taking L-shaped coextrusion proifle as an example,the three-dimensional non-isothermal viscoelastic flow process of polypropylene(PP) and polystyrene(PS) in gas-assisted coextrusion die were investigated by the finite element method,the polymer melts were characterized by Phan-Thien and Tanner(PTT) constitutive equation and the Arrhenius equation was used as temperature-dependent viscosity law. The shortest gas-assisted length needed for the gas assisted die as well as the distribution of pressure,shear rate and the ifrst normal stress difference at die exit were discussed in different flow rate. The results revel that die swell can’t be eliminated absolutely in gas-assisted coextrusion,but it can be reduced vastly. An appropriate gas-assisted length can be obtained after analysing the distribution of pressure,shear rate and the ifrst normal stress difference in the die. The shortest gas-assisted length needed for the die increase as the flow rate increase,but the increasing speed is low.