【作者】 周拥仔；

【导师】 龙春光； 雷正保；

【作者基本信息】 长沙理工大学 ， 载运工具运用工程， 2007， 硕士

【摘要】 研制新型高分子汽车防撞护栏材料,尤其是冲击性能高,弯曲弹性模量足够、价廉、环保和不需维修等特点的护栏材料是目前研究者们追求的目标。本论文在介绍了国内外高分子防撞护栏的发展历程和发展现状、存在的缺点以及防撞机理之后,对新型高分子防撞护栏的研制进行了较为详细的研究和分析:先后通过挤出和注塑成型工艺对聚氯乙烯(PVC)复合材料、PVC/ABS复合材料以及ABS复合材料进行预备实验,通过比较确定汽车防撞护栏材料体系;利用Moldflow软件分析材料注塑成型所用模具的结构设计合理性,以保证在使用Moldflow软件模拟材料注塑成型时的精确性,并且自定义材料数据库;利用正交试验设计和挤出—注塑成型方法制备了纳米CaCO3/钛酸钾晶须(PTW)/丁腈橡胶(P83)/ABS复合材料,并以缺口冲击强度和弯曲弹性模量为主要指标,分别通过极差和方差分析得出了最佳配方;利用扫描电镜(SEM)对最终制得的防撞护栏材料的缺口冲击断面进行防撞机理探讨。结果表明:PVC复合材料和PVC/ABS复合材料的挤出成型容易,但是注塑成型比较困难,成型参数控制不好材料极易发生碳化,性能较差,而纳米CaCO3/PTW/P83/ABS复合材料流动性好,成型加工性能也较优异,适合作为汽车防撞护栏的材料;模具的浇口位置设计较为合理,但模具的型腔厚度设计不太合理,正因如此,Moldflow软件模拟材料注塑成型所得到的优化工艺结果,只具有实验指导作用;纳米CaCO3/PTW/P83/ABS复合材料的最佳制备方案为:PTW的含量(质量百分比,下同)为10%左右,P83的含量为10%左右,纳米CaCO3的含量为2.5%左右,PTW的表面处理方法为钛酸酯偶联剂(NDZ-201)处理,按最佳配方制得的复合材料的冲击强度、弯曲弹性模量、弯曲强度和拉伸强度分别比纯ABS提高了39.8%、176%、79.3%和20.1%,在主要性能上能满足行业标准要求;防撞护栏材料的防撞机理表现为韧窝的出现以及其表面的小韧窝,冲击过程中撕裂比较严重,韧窝较深,起伏较大,这是由于材料受到冲击时橡胶颗粒内及表面产生空穴,伴之以空穴之间聚合物链的伸展和剪切而导致基体的塑性形变,使得材料具有更好的吸能能力。更多还原

【Abstract】 It is the researchers’target to seek for preparing a new kind of macromolecule vehicle crashworthy-guardrail material, especially with properties of a high impact strength,an enough bend Young’s modulus, a low price, no pollution and no servicing, etc. After the development course and progress, existent shortcoming and crashworthy mechanism were introduced in and outside domestic’s macromolecule crashworthy-guardrail, the preparation of the new macromolecule crashworthy-guardrail has been studied and analyzed detailedly in this paper.The vehicle crashworthy-guardrail material system has been determined by comparing, the results of the preliminary experiments of the PVC composite,PVC/ABS composite and ABS composite which have been manufactured by the extruder and injection molding machine successively; To check the accuracy in simulating the injection molding by Moldflow software, the rationality of structure design of the mould that will be used in injection molding have been analyzed by Moldflow,and the material data has been self-defined;NanoCaCO3/PTW/P83/ABS composite was prepared by the orthogonal experiment design and extrusion—injection molding, and the best batch formula was obtained by range and variance analysis according to the main index- notch impact strength and bend Young’s modulus; Finally, the crashworthy mechanism has been analyzed by SEM in notch impact cross-section of the final prepared crashworthy-guardrail material.The results show that the PVC composite and PVC/ABS composite can be easily extruded, but not be easily injected in the preliminary experiment,and the composite can be easily charried and a bad property would be showed if the molding parameter cannot be controlled well.However, the NanoCaCO3/PTW/P83/ABS composite has a good liquidity and a excellent processability, it is suitable for a automobile crashworthy-guardrail material usage; the design of gate position of mould is relatively rational, but the cavity thickness is irrational, just so, the optimize technics results of composite injection molding that gained by Moldflow simulation just as a guidance during the experiment. The best preparation program of NanoCaCO3/ PTW/P83/ABS composite is that the mass percent of PTW is about 10%,P83 , about 10%, NanoCaCO3 , about 2.5% and NDZ-201 is suilable for the surface treatment of PTW.After being re-prepared, the notch impact strength, bend Young’s modulus, flexural strength and tensile strength of the composite are increased by 39.8%,176%,79.3% and 20.1% separately increaser than the pure ABS resin, and its main properties can be satisfied with the industry standard. The crashworthy mechanism of the crashworthy-guardrail composite shows that the cavities are generated and lots of small cavities created in its surface; Serious tearing, deep cavities and biggish fluctuation are main features in the notch impact cross-section, which reasons are that cavities are generated on the surface and inside the rubber particle, then the stretch and shear phenomena are raised among the cavities of polymer chains when composite was impacted, so that the plastic deformation of matrix is raised, which make the composite has better crashworthiness.更多还原