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1.
用SEM和TEM对甲基丙烯酸锌(ZDMA)粒子及其填充的丁腈橡胶(NBR)混炼胶和硫化胶进行了观察,结果发现,在溶解效应和剪切效应的共同作用下,大多数ZDMA粒子在其NBR混炼胶中的尺寸由混入前的几十微米缩小到10μm以下;进而由过氧化物引发进行原位自聚合并参与交联反应,大部分粒子尺寸继续缩小,并生成20~30nm的聚甲基丙烯酸锌粒子。最终的复合材料中含有大量的纳米粒子和少量残余的微米粒子,可称为纳米-微米混杂复合材料,研究了4种丙烯酸金属盐增强NBR的力学性能,结果表明它们的综合力学性能均高于用炭黑N 220增强的橡胶,具有较高的拉伸强度、100%定伸应力和撕裂强度。  相似文献   

2.
采用甲基丙烯酸锌(ZDMA)增强NBR硫化胶,并对其微观结构、力学性能及ZDMA用量对体系Mullins效应的"放大器效应"进行了研究。结果表明,ZDMA在NBR中分散较为均匀;ZDMA增强NBR硫化胶的强度明显提高;在单轴循环压缩过程中存在明显的Mullins效应,在同一压缩应变下,最大压缩应力第1次加载-卸载循环中达到最大值,自第2次循环压缩时发生不同程度下降;增加ZDMA用量及增大压缩应变,Mullins效应增强。  相似文献   

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丁腈橡胶/硼酸酯偶联剂改性纳米碳酸钙复合材料的性能   总被引:2,自引:0,他引:2  
用硼酸酯偶联剂对纳米碳酸钙进行表面改性,研究了丁腈橡胶(NBR)硼/酸酯偶联剂改性纳米碳酸钙复合材料的性能。结果表明,使用硼酸酯偶联剂改性纳米碳酸钙填充NBR能提高硫化胶的物理机械性能,当硼酸酯偶联剂用量为4份、改性纳米碳酸钙用量为75份时,硫化胶的综合性能最好;与未改性纳米碳酸钙填充NBR相比,硼酸酯偶联剂改性纳米碳酸钙填充的NBR混炼胶和硫化胶的弹性模量较小,Payne效应减弱,而损耗因子却较大;用硼酸酯偶联剂改性纳米碳酸钙填充NBR,化学交联质量分数提高,无机粒子与橡胶基体之间的化学结合作用增强。  相似文献   

4.
采用正交试验法.研究了炭黑、纳米粘土和甲基丙烯酸锌3种补强剂并用对丁腈橡胶(NBR)综合性能的影响。优选了补强剂的并用配比,当炭黑/纳米粘土/甲基丙烯酸锌的质量比为1/0.7/0.3时,NBR的综合性能较好。进一步研究了炭黑/纳米粘土/甲基丙烯酸锌补强剂并用对NBR硫化胶的协同补强效应。NBR硫化胶补强性的提高,一方面需要粒子与大分子之间有较强的结合力,另一方面也需要粒子表面上的分子产生滑移。  相似文献   

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利用扫描电子显微镜(SEM)和透视电子显微镜(TEM)研究了甲基丙烯酸锌增强多种弹性体(包括BR,SBR,EPDM,NBR,EPM,POE和HNBR)的微观相态结构。发现混炼胶在混炼工艺中所具有的粘度是决定ZDMA粒子在混炼胶中分散状态的主要因素,对于高粘度胶料,如EPDM和NBR体系,在混炼中ZDMA颗粒的尺寸显著减小,部分甚至达到了纳米级,而对于低粘度胶料,如POE体系,ZDMA的尺寸特征在混炼工艺中基本不变。由于ZDMA在橡胶中的原位聚合反应历程与其分散尺寸密切相关,所以这种ZDMA在混炼胶料中初分散状态的不同必然会对其硫化化胶料的最终相态和性能产生重大的影响。  相似文献   

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利用扫描电子显微镜(SEM)和透视电子显微镜(TEM)研究了甲基丙烯酸锌增强多种弹性体(包括BR,SBR,EPDM,NBR,EPM,POE和HNBR)的微观相态结构。发现在各体系的硫化胶料中均存在两类基本分散结构:纳米分散结构和微米分散结构。其中纳米增强结构是在胶料过氧化物交联过程中由ZDMA原位聚合生成的;而微米结构就是残余的ZDMA颗粒。这两种结构的尺寸及相对含量因不同的复合体系而不同。对于BR和SBR体系,其微米分散结构较其他体系更多,且纳米分散结构的尺寸相对略小。而在EPDM,NBR,EPM,POE,HNBR中,微米分散结构较少,且纳米分散结构的尺寸相对较大。还研究了ZDMA颗粒的原生尺寸对硫化胶料的相态结构的影响,发现在POE体系,较大的ZDMA原生尺寸将造成其硫化胶料中微米分散结构的大量增多;而EPDM,EPM,NBR,HNBR胶料的相态则对ZDMA原生尺寸的变化不敏感。硫化胶料的微观相态的差异必将对其物理机械性能产生直接的影响。  相似文献   

7.
原位生成PNaMAA/NBR纳米复合材料的研究   总被引:2,自引:0,他引:2       下载免费PDF全文
焦海全  赵素合  苑伟 《橡胶工业》2004,51(7):389-393
采用原位生成法制备聚甲基丙烯酸钠(PNaMAA)/NBR纳米复合材料,研究混炼工艺、硫化剂DCP用量、丙烯酸(MAA)与氢氧化钠的摩尔比和甲基丙烯酸钠(NaMAA)的理论生成量对复合材料物理性能的影响。结果表明,采用先快速加酸后分次加碱的混炼工艺,DCP用量为1.5份,MAA与氢氧化钠的摩尔比为1.5∶1,NaMAA的理论生成量为30份,混炼胶在160℃×t90条件下硫化,可获得物理性能优异的PNaMAA/NBR纳米复合材料。  相似文献   

8.
碳酸钙/聚丙烯复合材料的力学性能对比研究   总被引:2,自引:0,他引:2  
研究了无机刚性材料纳米或微米碳酸钙对聚丙烯(PP)的填充改性以及利用钛酸酯偶联剂对纳米碳酸钙进行表面处理后,对于碳酸钙/聚丙烯复合材料体系的力学性能的影响.结果表明,纳米碳酸钙/聚丙烯复合材料的力学性能明显优于微米碳酸钙/聚丙烯复合材料的力学性能;钛酸酯偶联剂改性处理纳米碳酸钙粒子后,其复合体系的冲击强度和断裂伸长率有明显的提高.  相似文献   

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采用乳液法和机械共混法制备有机蒙脱土(OMMT)/NR/NBR复合材料,并对其微观结构、物理性能、动态力学性能和耐油性能进行研究.结果表明:大多数OMMT片层以纳米尺寸均匀分散在NR基体中;随着OMMT用量的增大,OMMT/NR/NBR复合材料物理性能和耐油性能提高;与NR /NBR并用胶相比,OMMT/NR/NBR纳米复合材料具有更低的滚动阻力.  相似文献   

10.
论文研究了单甲基丙烯酸锌(HZMMA)、HZMMA和炭黑混合物、炭黑增强丁腈(NBR)橡胶及氢化丁腈(HNBR)复合材料的热氧老化行为。实验结果表明:单甲基丙烯酸锌(HZMMA)对丁腈(NBR)橡胶及氢化丁腈(HNBR)均表现出良好的增强作用,丁腈橡胶复合材料的使用温度上限不能超过150℃。氢化丁腈橡胶复合材料在130℃下老化时,由于物理交联点和化学交联点的共同作用,橡胶复合材料老化1周的拉伸强度和100%定伸强度均出现极值点,随着老化时间的进一步延长,材料的力学性能逐渐下降。材料的断裂伸长率随着老化时间的延长,呈单调递减趋势。老化温度越高,HZMMA的耐热氧老化效果愈加显著。HZMMA、HZMMA和炭黑混合物、炭黑等增强的HNBR橡胶复合材料的耐热氧老化能力的顺序为HZMMAHZMMA/炭黑混合物炭黑。  相似文献   

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Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.  相似文献   

13.
In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.  相似文献   

14.
Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.  相似文献   

15.
A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by 1H MAS NMR. For direct comparison purposes, an SiO2 coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N2 absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.  相似文献   

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Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.  相似文献   

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