共查询到20条相似文献,搜索用时 156 毫秒
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利用可视化挤出实验对螺杆冷却情况下的单螺杆挤出熔融机理进行了研究。实验表明,挤出过程中固体床始终保持连续而不会出现固体床破碎现象,螺槽表面会出现聚合物的亚稳态相转变行为。通过建立螺杆冷却时熔融理论的数学模型,用数值方法获得了熔融段聚合物流场的数值解,结果表明,理论预测的固体床宽度和机筒压力与实验结果基本吻合。 相似文献
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鉴于聚合物组合的形态结构可使聚合物共混胶的性能测定达到准确无误的程度,为此,挤出机设计需要采用模型,以能计算熔体输送段中挤出机螺杆长度上的估算形态发展。由于观测到的最明显的形态变化出现于熔融段,本文就着重描述了挤出机这一段中的共混胶熔融过程中形态的形成和发展。文中对PP和PA6共混胶的熔融流变性、界面张力、熔融形态进行了描述,并对熔融过程中开始时的固体含量、固体温度平均熔体温度及溶体温度的发展熔融过程的模拟、熔融度、粘度比、单位挤出恒定时的速度影响、挤出机规格影响、螺杆顶部的熔融度、挤出量恒定时螺杆速度的影响、恒速下挤出量的影响、粘度比的影响、微滴分散与聚结等作了较为详尽的计算与讨论。从而为研究熔融过程、形态发展以及为理论模型和形态发展对比提供了数据基础。 相似文献
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啮合同向双螺杆挤出过程聚合物粒料熔融机理研究(一):熔融机理研究现?… 总被引:3,自引:2,他引:1
综合介绍了双螺杆挤出过程熔融机理研究中常用的实验装置并比较了其优缺点;对啮合同的双向螺杆挤出机中聚合物的熔融区域进行了明确定义,探讨了挤出过程中聚合物熔融的可能机理;总结了近年来啮合同向双螺杆挤出过程熔融机理研究所取得的进展,并提出了今后的研究方向。 相似文献
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综述了国内外熔融还原炼铁用耐火材料的研究现状。讨论了熔融还原技术的工艺特,点及其耐火材料的使用条件。分析了目前已基本成熟的COREX工艺的耐火材料的使用现状及存在问题,和铁浴式熔融还原炉用耐火材料的研究现状,存在问题及前景。 相似文献
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在振动诱导单螺杆挤出机中,通过螺杆的轴向振动使聚合物的熔融塑化过程在周期性的振动状态下进行,而经典熔融塑化理论无法描述处于周期性振动状态的熔融塑化过程。通过可视化和剖分料筒实验,观察了振动诱导单螺杆挤出机的熔融过程,深入分析了振动诱导熔融机理,建立了熔融过程动态物理模型,提出了振动场作用下熔融过程的质量平衡方程、动量平衡方程、能量平衡方程及本构方程,并运用复杂的数学方法求得近似解析解,最后得到了熔融速率方程和熔膜厚度方程,从公式中可以看出:熔融速率与熔膜厚度都是与振动参数相关的,且具有时间依赖性,振动场的引入可以加快熔融速率,减少熔膜厚度。理论研究与前面的实验结果符合得很好. 相似文献
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综合介绍了双螺杆挤出过程熔融机理研究中常用的实验装置并比较了其优缺点;对啮合同向双螺杆挤出机中聚合物的熔融区域进行了明确定义,探讨了挤出过程中聚合物熔融的可能机理;总结了近年来啮合同向双螺杆挤出过程熔融机理研究所取得的进展,并提出了今后的研究方向 相似文献
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熔融插层法制备聚合物/纳米蒙脱土的研究进展 总被引:1,自引:0,他引:1
简要介绍了熔融插层法制备聚合物/纳米蒙脱土复合材料的研究进展。结合热力学和动力学的分析,概括了熔融插层法一些理论上的研究进展。总结了目前关于熔融插层法制备聚合物/纳米蒙脱土复合材料及其表征的最新研究成果。 相似文献
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何蓉 《硫磷设计与粉体工程》2006,(6):40-42
针对熔硫系统原料固体硫磺杂物多、槽内易淤积,影响连续生产、开车率低的问题,对原设计不合理部分采取了整改措施,从而减少了停车检修和清理的次数,使熔硫效能有了显著提高。 相似文献
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The Wertheim lattice thermodynamic perturbation theory is used to predict the liquid-liquid and solid-liquid coexistence data for a model polymer solution. The theory predicts bimodal LCST phase behavior and an unusual step with composition in the solid-liquid equilibrium of the solvent.The theoretical solid-liquid equilibrium calculations are used to interpret experimental data obtained for aqueous solutions of poly(vinyl methyl ether) (PVME), which is known to show bimodal LCST phase behavior. An experimental method is proposed, employing Fourier transform infrared (FTIR) spectroscopy to determine the equilibrium melting line of water in the presence of PVME. In addition, the complete melting line of water is obtained by partial integration of the melting endotherm observed using modulated temperature differential scanning calorimetry (MTDSC). Both, the FTIR and MTDSC methods are in good agreement, experimentally confirming the predicted step with composition in the solid-liquid equilibrium. This peculiar concentration dependence of the melting curve of ice provides a new explanation for the inhibited crystallization of water in aqueous PVME solutions, since the actual supercooling (at high polymer concentration) is smaller than it could be anticipated for a conventional course of the melting curve. Hence, the vicinity of the glass transition region in these highly concentrated polymer mixtures leads to a dramatic slowing down of the nucleation rate and thus the subsequent crystallization. Moreover, the atypical shape of the equilibrium melting line also provides a new explanation for the double melting endotherm observed in (MT)DSC experiments, which is conventionally attributed to the melting at different temperatures of bound and free water. 相似文献
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单螺杆挤出机挤出理论研究进展 总被引:2,自引:0,他引:2
潘龙;张玉霞;金志明;薛平 《中国塑料》2009,23(5):12-19
论文回顾了单螺杆挤出机挤出理论发展史,并从固体输送、熔融、熔体输送和混合四个方面详细介绍了近十年来挤出理论的最新研究进展。在指出现有不足的同时,提出了单螺杆挤出机未来的研究方向。 相似文献
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首次建立了单螺杆挤出过程固相多点破碎球形块径向熔融模型,并推导出球形块内部温度分布公式。根据固相加速实验结果,提出固相碎块轴向熔融长度计算公式。利用上述公式,对LDPE和PP进行了计算,此外,分析了三种规则几何体与熔融速度关系,指出了细化碎块实现稳定挤出的途径。 相似文献
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Jinping Qu Guansheng Zeng Yanhong Feng Gang Jin Hezhi He Xianwu Cao 《应用聚合物科学杂志》2006,100(5):3860-3876
A model for investigating the melting process of polymer in a vibration‐induced single‐screw (VISS) extruder is presented. The key feature of this model is as follows: vibration force field is introduced into the overall course of extrusion by the axial vibration of the screw, and the velocity distribution in the polymer melt behaves strongly nonlinear and time‐dependent. To analyze this model, half‐open barrel visible experimental method and low‐density polyethylene material are adopted to investigate the effect of the vibration parameters on the melting process, which goes into further details of study and research on the melting mechanism, and thus, a novel physical melting model is derived. Combining the conservation equations of mass, movement, energy, and constitutive, analytical expressions of the melting rate, the energy consumption, the length of melting section, and the distribution of solid bed are obtained. This model enables the prediction of the processing and design parameters in the VISS extruders from which the optimum conditions for designing VISS extruder and polymer processing are obtained. The theory is supplemented by a calculation sample and experiment, which shows that the introduction of vibration force field can improve the melting capacity and decrease the power consumption of extruder greatly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3860–3876, 2006 相似文献