共查询到17条相似文献,搜索用时 140 毫秒
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多级磨盘式强剪切分散混炼器作用下PP/nano-CaCO3体系性能的研究 总被引:1,自引:0,他引:1
为了改善填充和共混体系的混炼和分散效果,自行研制了一套高性能混炼设备(多级磨盘式强剪切分散混炼器),并利用此设备研究了PP/nano-CaCO3体系的稳态流变性、动态流变性和分散性的变化及其影响因素。实验结果表明,未加抗氧剂时,随着混炼器转速的提高,填充体系的MFR增加;nano-CaCO3的加入整体上改善了体系的流变性。当nano-CaCO3的质量分数为4%时,MFR出现最大值。加入抗氧剂之后,PP填充体系中不再有自由基引发的降解反应发生,混炼器转速的提高使填充体系的MFR增加的幅度很小;混炼器的作用导致填充体系的动态贮能模量、损耗模量和复数黏度都下降;经混炼器作用后的填充体系中纳米碳酸钙粒子的分散状态明显优于未经混炼器作用的体系。 相似文献
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采用自制新型混炼器对聚丙烯(PP)与高摩尔质量聚乙烯(HMWPE)进行共混,研究了混炼器转速和HMWPE用量对PP/HMWPE力学性能的影响,并对共混物的结构进行了表征。研究表明,在混炼器作用下,HMWPE与PP共混可提高PP的冲击性能,提高量可达33.7%;但HMWPE的含量太高时,反而会降低共混物的性能;混炼器对拉伸性能的影响较小。共混体系的结构都是海-岛结构,两组分各自在自己的本体中结晶,形不成共晶结构,但两者会相互干涉。混炼器的作用是提高共混物中分散相的分散程度和减小分散相的尺寸。 相似文献
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HDPE/mLLDPE混炼后的性能与结构 总被引:1,自引:0,他引:1
高密度聚乙烯/茂金属线性低密度聚乙烯(HDPE/mLLDPE)40/60共混物经混炼器混炼后的冲击强度比未经混炼器混炼的HDPE增加了96.2%,比未经混炼器混炼的mLLDPE增加了27.0%,其拉伸强度比未经混炼器的mLLDPE增加了49.1%。这表明在混炼器的强剪切分散作用下,HDPE,mLLDPE共混对HDPE和mLLDPE有显著的增韧作用。其微观结构测试表明,mLLDPE与HDPE形成了共晶结构,HDPE含量高的HDPE/mLLDPE共混体系试样内部的晶粒尺寸更为均一。 相似文献
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自行设计一种多级磨盘式强剪切分散混炼器,并研究其强剪切作用对纳米CaCO3填充环氧树脂(EP)体系分散行为及各项力学性能的影响。结果表明,在新型混炼器强烈的剪切作用下,EP高分子产生了新的断链和新的自由基,使纳米CaCO3的分散性能得到很大提高。因此,当复合材料被拉伸时,在传力过程中使复合材料的延伸能力得到提高。纳米CaCO3良好的分散性对于物理交联和交联网络结构的紧固起着关键的作用,使复合材料表现出更高的冲击性能。因此,新式混炼器使EP/CaCO3复合材料的力学性能和分散性能得到很大的改善。 相似文献
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双转子连续混炼机结构与混炼原理 总被引:10,自引:0,他引:10
双转子连续混炼机,是一种新型橡塑连续混炼机械。本文介绍了该机器的主要结构,分析了其工作原理和影响剪切速率、剪应力大小的因素,提出最大剪应力出现在转子混炼段螺校的顶部,其大小与转子的结构、操作条件有关,适当降低转子混炼段螺棱宽度和转子与机筒的间隙,提高转子转速,可以有效地增强转子对物料的剪切作用。 相似文献
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运用有限元分析软件Polyflow对不同结构和不同螺杆转速下的修正Maddock混炼元件流场进行三维非等温数值模拟,得到了流场的压力、速度、温度和剪切速率的分布;利用粒子示踪法(PTA)对不同结构和不同螺杆转速的修正Maddock混炼元件流场内聚合物熔体所经历的混合过程进行模拟,并对结果进行了统计学分析;通过比较平均解聚功等参数对不同结构和不同螺杆转速下修正Maddock混炼元件的分散混合效果进行分析研究,并借助实验进行验证。结果表明,等腰反向型修正Maddock混炼元件对聚合物熔体的剪切作用和分散混合性能最好;适当提高螺杆转速可以有效地促进物料的分散混合。 相似文献
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研究了当半补强炉黑(SRF)用量为0~90质量份时,炭黑填充型粉末氯丁橡胶[P(CR/SRF)]和块状氯丁橡胶(CR/SRF)在密炼机混炼过程中的流变特性,讨论了SRF用量、混炼温度和混炼转速对二者混炼流变性能的影响。结果表明,与CR/SRF相比,P(CR/SRF)的混炼转矩对混炼时间、SRF用量的敏感程度为CR/SRF的65%~70%;P(CR/SRF)的表观剪切黏度对转子转速的敏感程度略低于CR/SRF;随着混炼温度的提高,二者的表观剪切黏度对转子转速的敏感性均有所降低。当SRF用量大于50质量份时,P(CR/SRF)混炼能约为CR/SRF的65%~93%,P(CR/SRF)在较高SRF用量时,具有明显的混炼能耗低的优势;P(CR/SRF)混炼温升对SRF用量不敏感。 相似文献
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Polypropylene–maleic anhydride (PP–MA) graft copolymers were produced from isotactic homopolymer polypropylene (molecular weight > 150,000) utilizing the technique of solid phase graft copolymerization. A high degree of graft (about 8–10%) was achieved on 150 mesh (U.S. Standard Sieve) samples using this process. This free-radical-initiated, catalyst-aided grafting process was effective at low temperatures (100–120°C), atmospheric pressure, and low residence times (60 min). The powder was mixed in a low shear, fixed speed, continuous mixer where the ingredients were added in stages to effect the reaction. The interfacial agent was used to etch the polymer to provide sites for the reaction. The powder was removed from the reactor on completion of the reaction. This process can be further applied to graft other reactive monomers on polypropylene (PP). 相似文献
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R. Scaffaro F.P. La Mantia L. Botta M. Morreale N. Tz. Dintcheva P. Mariani 《Polymer Engineering and Science》2009,49(7):1316-1325
Two samples of high‐density polyethylene with different molecular weight were processed in a batch mixer and the rheological and structural properties were investigated. In particular, the effect of different processing parameters and the eventual presence of different stabilizers were evaluated. Actually, two reactions may occur during processing: branching/crosslinking or chain scission. The results indicate that when the processing conditions promote a scarce mobility of the macromolecular chains (lower temperatures, lower mixing speed, and higher molecular weight), branching is more favored than chain scission. On increasing the mobility of the chain (higher temperature, higher mixing speed, and lower initial molecular weight), branching appears still the predominant reaction, but the chain scission becomes progressively more important. In both cases, no crosslinking occurs. The presence of stabilizers has different effects on the relative extent of branching or chain scission reactions depending on the kind and of the amount of stabilizer and on the processing condition adopted. The correct choice of a stabilizer system will, therefore, depend on the desired final structure. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers 相似文献
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Woranut Kaiyaded Ekachai Wimolmala Wanlop Harnnarongchai Watcharin Sitticharoen Narongrit Sombatsompop 《应用聚合物科学杂志》2012,125(3):2312-2321
This study used a newly developed rotating die system for purposes of reducing entrance pressure drop and sharkskin fracture for molten polypropylene (PP) and wood/polypropylene (WPP) composites in a single-screw extruder. The sharkskin fracture characteristics of the PP and WPP composite surfaces were examined quantitatively via roughness profiles and relaxation time evaluations, and qualitatively through scanning electron microscopy under the effects of wood content, shear rate, die temperature, and die rotation speed. The experimental results suggested that the entrance pressure drop of PP increased with increasing wood content and shear rate. The die entrance pressure drop for WPP composite melt with 30 wt % wood content could be minimized by 20–50% by using a die rotation speed of 70 rpm. The roughness level (sharkskin) and relaxation time were found to increase with increasing wood content, but could be minimized by rotating the die—the die rotating effect being more meaningful for WPP when compared with neat PP extrudate. The rotating die system was found to be an effective technique for minimizing the extrusion load and fracture level of extrudate skins for high-viscosity materials such as the WPP composites used in this work. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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三元乙丙橡胶/聚丙烯动态硫化热塑性弹性体的相态结构 总被引:2,自引:1,他引:1
用扫描电镜研究了三元乙丙橡胶(EPDM)聚/丙烯(PP)动态硫化热塑性弹性体(TPV)相态结构的形成过程,探讨了交联密度、制备工艺、螺杆转速对EPDM/PP TPV相态结构的影响。结果表明,采用以酚醛树脂为硫化剂的动态硫化工艺制备的EPDM/PP TPV,其相态结构实现了由EPDM和PP组成的双连续相到以EPDM为分散相、PP为连续相的转变;当硫化剂用量为7份时,橡胶相硫化速率和交联密度最大;当螺杆转速为180 r/m in时,反应性挤出工艺较之密炼机工艺制备的EPDM/PP TPV的橡胶粒子更细小、分散更均匀。 相似文献