【作者】 钟序光；

【导师】 周国发；

【作者基本信息】 南昌大学 ， 化工过程机械， 2006， 硕士

【摘要】 气辅共注成型是一种先进聚合物成型工艺，融合了共注成型和气辅成型的优点，是一种生产高性能、低成本制品的环境友好成型技术，最有希望解决未来重大工程材料问题。然而迄今为止，国内外有关气辅共注成型研究报道却相当罕见。基于气辅共注成型技术的先进性与研究匮乏这一突出矛盾，本文对气辅共注成型工艺进行了数值模拟研究和实验研究，主要取得如下成果： 1．针对气辅共注成型工艺聚合物熔体充模流动特点，基于流体动力学、聚合物流交学理论，经合理假设，建立了描述气辅共注成型聚合物熔体充模流动过程的全三维瞬态等温粘弹性理论模型。 2．基于Mini-Element法、罚函数法、Galerkin法、EVSS／SU法等混合有限元稳态离散技术，建立了求解气辅共注成型熔体充模流动过程全三维粘弹性理论模型的稳态有限元数值离散模型。并采用时间依赖的Lagrange移动界面技术，成功实现了气泡界面的追踪、重构和更新。基于该研究的数值模拟程序，实现了气辅共注成型中气体在粘弹性聚合物熔体内穿透的动力学行为的有限元数值模拟，并建立了气泡在粘弹性聚合物熔体内穿透过程中的速度场、压力场和应力场等变量的分布规律。 3．通过对气体在粘弹性聚合物熔体内穿透的动力学行为全三维的数值模拟，研究了松弛时间和熔体粘度对聚合物熔体残留在圆管壁面的剩余壁厚的影响规律，研究发现，在低剪切速率下，熔体的剩余壁厚分数随松弛时间增大而增大，但在较大剪切速率下，松弛时间对剩余壁厚分数的影响趋势刚好相反。这一结论与Yijie Wang等人对气泡在非牛顿流体中穿透实验研究的结论吻合。剩余壁厚分数随着聚合物熔体粘度增大而增加。 4．通过气辅共注成型的实验研究，研究了熔体温度、气体压力、气体填充量和延迟时间等工艺参数对气辅共注成型的影响规律。在此基础上，基于理论分析，揭示了工艺参数对气辅共注成型的影响机理。更多还原

【Abstract】 Gas-assisted co-injection molding (shortened as GACIM) is an advanced polymer molding technique. This technique has the advantages of both co-injection molding technique and gas-assisted injection molding technique, and it is the environmental friendly molding technique by which high performance, low cost goods are produced. So the technique is regarded as one of the most advanced polymer molding techniques by which the future important problems of engineering material will be resolved. Up to the present, few of researches on GACIM technique have been reported at home and abroad. Based on the inconsistency between the advance and research shortage of GACIM, the numerical and experimental researches on GACIM are implemented in this paper, which yield the following main achievements:To the flowing characteristics of GACIM and on the basis of polymer rheology and fluid dynamics, reasonable assumptions were put forward, and 3D unsteady isothermal viscoelastic theoretical model is established to describe the GACIM polymer melt filling process.Based on the of the mixed finite element stable discrete techniques of Mini-Element method, penalty function method, Galerkin method and DEVSS/SU method etc., stable finite element numerical models is established for 3D GACIM viscoelastic polymer melt filling process. And By means of time dependent moving Lagrange interface technique, the tracing, regenerating and update of gas moving front interface were implemented successfully. Based on the numerical simulation code of the research, the numerical simulations of gas penetration during viscoelastic polymer melt were implemented. the distributed rules of variable fields for velocity, pressure and stress of gas penetration during viscoelastic polymer were given.By means of 3D numerical simulations of gas penetration during viscoelastic polymer melt, the influencing rules of relaxation time and polymer melt viscosity on coating layer thickness of the polymer left on the wall were studied. The fractional coverage was found to be strong dependent of shear rate and polymer melt viscosity. At low shear rate region, relaxation time increased, the fractional coverage increased. But at high shear rate, increasing of relaxation time resulted in a reverse trend of fractional coverage. It was in accordance with Yijie Wang’s work in which experiments on gas penetration during non-Newtonian fluids was conducted. Moreover, polymer melt viscosity increased, fractional coverage increased.By means of experiments of GACIM, the influencing rules of process parameters such as polymer melt temperature, gas pressure, gas filling volume and delay time etc. on GACIM were studied. The influencing mechanisms were disclosured by theoretical analysis.更多还原