材料物性参数对双层微管气体辅助共挤出胀大的影响

Effect of material physical parameters on gas-assisted coextrusion swelling for double-layer microtubule

建立了单腔双层微管的传统微共挤和气辅微共挤流动模型,采用数值模拟技术研究了零剪切黏度(η_(0))、松弛时间(λ)、材料参数ε和ξ等对挤出胀大率的影响规律。结果表明,传统微共挤过程中,挤出胀大率受η_(0)和λ的影响较大,随着外层熔体η_(0)增大,由29.15%增大至43.77%后趋于稳定;挤出胀大率受ε和ξ的影响较小,随着ε和ξ的增大略有减小,胀大率在37%~39%区间变化。而气辅共挤过程中,当η_(0)、λ、ε和ξ变化时,挤出胀大率始终接近零,无明显胀大和变形现象。

In this study,the traditional micro-coextrusion and gas-assisted micro-coextrusion flow models were established for double-layered microtubules.The effects of zero shear viscosity(η_(0)),relaxation time(λ),and material parameters ε and ξ on the die swell rate were investigated by using a numerical simulation technology.The results indicated that the die swell rate was greatly affected by η_(0) andλin the traditional micro-coextrusion process.With an increase in the outer melt viscosity,the die swell rate increased from 29.15% to 43.77% and then tended to be stable.The die swell rate was less affected by ε and ξ,and it decreased slightly with an increase in ε and ξ.The die swell rate varied between 37% and 39%.However,in the gas assisted co-extrusion process,the die swell rate always approached zero when η_(0),λ,ε and ξ changed,and there was no obvious swelling or deformation phenomenon.