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91.
介绍结晶性塑料在注塑过程中的塑化特点、取向与结晶的关系及其对制品性能的影响,注塑参数对结晶性塑料塑化、取向、结晶的影响。讨论了在实际工作中如何利用这些特性进行注塑机塑化系统、模具的设计并确定注塑工艺,从而得到品质优良的制品。  相似文献   
92.
乙丙橡胶接枝改性技术   总被引:1,自引:0,他引:1  
李金玲  赵孝伟  关颖 《弹性体》2006,16(3):61-64
综述了以苯乙烯、丙烯腈、马来酸酐、甲基丙烯酸缩水甘油酯、甲基丙烯酸甲酯、乙酸乙烯酯及硅烷偶联剂为接枝单体的乙丙橡胶接枝改性技术,包括溶液接枝法、熔融接枝法、直接溶胀接枝法以及近年来最新的电子束辐射接枝和热炼接枝等接枝方法。  相似文献   
93.
Three different polyethylene/polypropylene (PE/PP) blends were microcellular foamed and their crystallinities and melt strengths were investigated. The relationship between crystallinity, melt strength, and cellular structure was studied. Experimental results showed that the three blends had similar variation patterns in respect of crystallinity, melt strength, and cellular structure, and these variation patterns were correlative for each blend. For all blends, the melt strength and PP melting point initially heightened and then lowered, the PP crystallinity first decreased, and then increased as the PE content increased. At PE content of 30%, the melt strength and PP melting point were highest and the PP crystallinity was least. The blend with lower PP crystallinity and higher melt strength had better cellular structure and broader microcellular foaming temperature range. So, three blends had best cellular structure at PE content of 30%. Furthermore, when compared with PE/homopolymer (hPP) blend, the PE/copolymer PP (cPP) blend had higher melt strength, better cellular structure, and wider microcellular foaming temperature range, so it was more suited to be microcellular foamed. Whereas LDPE/cPP blend had the broadest microcellular foaming temperature range because of its highest melt strength within three blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4149–4159, 2007  相似文献   
94.
^60Co—γ辐照改性法制备高熔体强度聚丙烯   总被引:6,自引:2,他引:6  
以多官能度丙烯酸酯类单体为辐照敏化剂,在氮气保护下,通过^60Co-γ射线的引发作用,将普通线怀聚丙烯改性成为具有长支化结构的高熔体强度聚丙烯。研究了辐照敏化剂的官能度数,用量以及辐照的剂量对凝胶含量的影响。通过辐照聚丙烯熔体流动速率和熔体强度的测定,可以得出结论;在氮气氛围中,普通聚丙烯树脂加入1.0%的两官能度辐照敏化剂,采用1kGy剂量的^60Co-γ射线进行辐照,可得到高熔体强度的聚丙烯;增塑剂和抗氧剂的加入,以及聚丙烯辐照前,后的热处理对辐照聚丙烯熔体强度的提高均有不同程度的促进作用。  相似文献   
95.
Nucleation from a supercooled melt of palm oil was studied by optical microscopy and differential scanning calorimetry (DSC). Despite being a multicomponent system, palm oil exhibits a rather simple cooling thermogram with its high- and low-T exotherms exclusively related to the “hard” and “soft” components of the oil. As the “hard” components are being removed, the position of the high-T peak shifts down toward the low-T peak with diminishing peak intensity, while the position of the latter remains virtually unchanged. At 288°K, nucleation in a palm oil melt is instantaneous. Its induction time-temperature curve shows an abrupt discontinuity at 297°K, which demarcates the occurrence of one polymorph from another. Nucleation data fit very well into the Fisher-Turnbull equation. Its larger activation free energy of nucleation is accompanied by lowering of the melting point and an increase in the crystal/melt interfacial free energy as compared to palm stearin. The slow rate of nucleation in palm oil is attributed to intermolecular interaction between its “hard” and “soft” components. Partly presented at the 1989 PORIM International Palm Oil Development Conference, September 5–9, Kuala Lumpur, Malaysia.  相似文献   
96.
介绍了熔体管道设计中管道壁厚选择、熔体流量、熔体管道流动压力降和熔体流速等计算方法和设计要点。  相似文献   
97.
The importance of some relative surface characteristics which determines the strength of adhesive joints: specific surface of substrate , relative contact area β and specific contact area β in the adhesion interaction process were emphasised. Existing and potential methods of experimental evaluation of these characteristics were shortly analysed. The durability of the adhesive joints in water media significantly increases with growth of specific surface * of chemically treated substrate evaluated from the SEM micrographs. Specific surface calculated from the experimental data of hexane adsorption measurements for iron particles (particulate model of steel substrate) is more then ten times greater than respective * values. The relative contact area β of the Al2O3 particles (in wide range of ) with PE melt was in a roundabout way evaluated by experimental determination of the affect of on kinetic of peel strength formation of adhesive joints: Al2O3 filled PE-steel. The speculation was based on the ability of Al2O3 to adsorb low-molecular products of contact oxidation of PE which takes place in the process of formation of adhesive joints and determines their strength. The ability of sorption in its turn is proportional to efficient value of β. The availability of the Al2O3 surface was evaluated.  相似文献   
98.
Two types of SBS/OMMT composites are prepared by melt blending using a twin‐screw extruder. An X‐ray diffractometer indicates that polymer chains have intercalated into the gallery of the clay. It is shown in TEM photos that the thickness of the layer aggregate in the SBS1301 matrix is approximately 200 Å, but in the SBS4402 matrix the size of the filler particle is in micrometers. When SBS1301 is intermingled into SBS4402/OMMT, the particle size is reduced obviously. The tensile strength and elongation at break of the nanocomposite, SBS1301/OMMT, increase with the addition of OMMT; and when addition is 5phr, they achieve maximum. A small content of OMMT (less than 5phr) can prevent the deterioration of the mechanical properties of the SBS1301/MMT. In addition, a small content of SBS4402 (less than 20 wt %) can improve the mechanical properties of the SBS1301/OMMT composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 146–152, 2005  相似文献   
99.
采用熔体插层法制备有机蒙脱土(OMMT)/IIR纳米复合材料。试验结果表明,OMMT/IIR纳米复合材料是插层型纳米复合材料;与无机粘土/IIR微米复合材料及IIR相比,OMMT/HR纳米复合材料具有良好的物理性能,且其物理性能均随OMMT用量的增大而明显提高;与IIR相比,OMMT/HR纳米复合材料具有优异的气密性。  相似文献   
100.
2008年初南方地区抗击雪灾中大量使用融雪剂清除冰雪,进而引发对融雪剂所带来危害的关注,呼吁有关部门高度重视融雪剂对钢筋混凝土路面的腐蚀危害,提出合理除雪和科学使用融雪剂的方法。  相似文献   
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