【作者】 陈长森；

【导师】 申开智；

【作者基本信息】 四川大学 ， 高分子材料加工工程， 2005， 硕士

【摘要】 物理场直接作用于熔融聚合物的“聚合物动态成型技术”,已成为聚合物成型加工领域行之有效的强化成型加工过程的新方法之一。目前,有关聚合物动态成型的理论与实验研究已成为高分子材料成型加工工程、高分子物理以及高分子化学等学科领域中的一个热点。本论文中设计出一套液压振动装置,其频率在1～100Hz范围内可调,振幅在0～70mm内可调。采用此振动源,在挤出机头内部引入振动场,成功地实现了HDPE在振动场中挤出成型时的自增强。详细研究了在各种条件下不同频率和振幅的振动对HDPE挤出成型时流变行为的影响。并采用对比研究的手法,研究加入少量高分子量聚乙烯后,振动使HDPE挤出成型制品发生的深刻变化。力学性能测试揭示振动对HDPE宏观性能的改变,进而采用现代分析测试手段对它们的微观结构进行了表征。研究结果表明: 1.机械振动可以显著降低HDPE挤出成型时的表观粘度,研究中最大降低为52.7%。频率和振幅对表观粘度都有影响,在频率较低时,随频率的增加,表观粘度急剧下降,但频率进一步增加时,表观粘度反而有所回升,回升趋势比较平缓。回升后的表观粘度仍然低于未振动时的表观粘度。而振幅则是较大时表观粘度降低更明显。 2.不同的温度、剪切速率、结晶条件下,振动对HDPE表观粘度的影响不一样。温度较低、剪切速率较低、结晶度小,结晶相对不完善的情况下,振动对其表观粘度的影响更大。 3.将机械振动引入HDPE6100M的挤出过程可以提高HDPE的纵横向拉伸强度,但提高幅度不大,最大分别为11.9%和6.9%;向6100M中加入4%高分子量更多还原

【Abstract】 The Polymer Dynamic Shaping Technologies which the physics field acts on the polymer melt directly; have already become one of the effectual new methods to strengthen the shaping course of the polymer processing. At present, investigation on the theory and experiment of the polymer dynamic shaping has already become a hot point in polymer processing engineering, high polymer physics and high polymer chemistry, etc.This work designed a set of hydraulic vibration device. Its frequency is adjustable within the range of 100Hz; the amplitude is adjustable from 0mm to 7mm. Using this vibration source, the high density polyethylene was successfully extruded with vibration-assisted extrusion which the vibration field was applied to the inner of the die. The influence of the frequency and amplitude to the apparent viscosity of HDPE was researched under various conditions during the vibration- assisted extrusion.During the study great changes of the HDPE extrudate were found experimentally by comparing the mechanical properties of HDPE products made by vibration-assisted extrusion with those made through optimized conventional extrusion .At the same time high molecular weight PE was blended to enhance this influence. The resins utilized during the studywere 6100M and DMDY1158. Then the microscopic structures and the morphologies of the products were investigated through modern analysis and test methods. The result of the study shows:1. Mechanical vibration may greatly reduce the apparent viscosity of HDPE when it is extruded . During the research, the biggest reduction of the apparent viscosity was 52.7%. The frequency and amplitude can influence the apparent viscosity. When frequency is low, with the increase of frequency, apparent viscosity drops rapidly, but when frequency increases further, the apparent viscosity goes up on the contrary, but the rise trend is milder. When using larger amplitude, the apparent viscosity reduces more obviously.2. The impact on HDPE’ s apparent viscosity of vibration is different under different temperature, shearing rate or crystallization condition. It is greater when having a lower temperature or shearing rate, or having a lower crystallization degree or the crystals having more defects.3. The longitudinal and transverse tensile strength of 6100M products improved 11.9% and 6.9% respectively when made by vibration-assisted extrusion. After adding 4% of the high molecular weight PE DMDY1158 to 6100M, the influence that the vibration brought was much more remarkable. The maximum longitudinal tensile strength improved 27.9%, and the maximum transverse tensile strength improved 32. 9%.4. The DSC analyses result indicates, vibration raised the crystallinity degree of 6100M sample, while the melting point was reduced; to 6100M/1158 system, vibration raised its crystallinity degree greatly, and narrowed the melting dimension, but there was no obvious change with the melting point.5. SEM was used to study the crystal morphology of the samples made by vibration-assisted extrusion. Found that the vibration made the lamellar crystal of the pure 6100M and 6100M/1158 system obviouslyorientated, and the orientation direction kept the same with the vibration direction or had a certain slope.6. The wide angle X ray diffraction test result shows: The micocrystallite size of 6100M sample was diminished, and the perfection degree of the crystal was reduced, but its crystal and molecular chain appeared to be orientated; To the 6100M/1158 sample, vibration made the crystal become more perfect, and also diminished the micocrystallite size, at the same time the orientations of its crystal and molecular chain were obvious. Using WAXD to study the conformational structure, it indicated that the vibration had little impact on the cell parameter of 6100M or 6100M/1158.更多还原