共查询到20条相似文献,搜索用时 46 毫秒
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采用液态丁腈橡胶(LNBR)对水滑石(HT)进行表面包覆改性制备了LNBR/HT,并用其填充聚氯乙烯(PVC)制备了复合材料,采用红外光谱仪(FTIR)简支梁冲击试验机、万能试验机、氧指数测定仪、动态力学分析仪(DMA)、、扫描电子显微镜(SEM)等仪器研究了LNBR对HT的改性方式和改性前后HT含量对复合材料力学性能、阻燃性能、动态力学性能及微观形貌的影响。结果表明,LNBR对HT的改性为物理改性,由于LNBR与PVC基体有良好的相容性,经LNBR改性的HT在PVC基体中的分散性得以改善,其与PVC基体的界面黏结作用增强;PVC/LNBR/HT复合材料较PVC/HT表现出优异的力学性能和阻燃性能;PVC/LNBR/HT复合材料的拉伸强度和缺口冲击强度在LNBR/HT含量分别为5 份和10 份时分别达最大值,为29.8 MPa和17.7 kJ/m2;PVC/LNBR/HT复合材料的极限氧指数在LNBR/HT含量为40 份时达34.6 %;由于LNBR在复合材料体系中充当增容剂和增塑剂的双重作用,PVC/LNBR/HT复合材料的刚性增加,但耐热性出现小幅下降。 相似文献
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探讨氯磺化聚乙烯橡胶(CSM)、氯化聚乙烯橡胶和乙烯-乙酸乙烯酯共聚物作为相容剂对丁腈橡胶(NBR)/三元乙丙橡胶(EPDM)并用胶的相容改性作用,并研究硫化体系对NBR/EPDM/CSM并用胶性能的影响。结果表明:CSM作为相容剂能改善NBR与EPDM的相容性,提高NBR/EPDM并用胶的物理性能;随着促进剂DPTT用量的增大,NBR/EPDM/CSM并用胶的物理性能提高;硫黄硫化体系与过氧化物硫化体系并用的NBR/EPDM/CSM并用胶的物理性能最佳;过氧化物硫化体系单用的NBR/EPDM/CSM并用胶的耐热老化性能最佳。 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
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ZDMA/白炭黑填充HNBR的结构与性能 总被引:4,自引:3,他引:1
以甲基丙烯酸锌(ZDMA)/白炭黑填充氢化丁腈橡胶(HNBR),研究ZDMA/白炭黑并用比、硫化剂DCP用量及硫化时间对HNBR硫化胶结构和性能的影响。结果表明,在填料总量不变的前提下,随着白炭黑用量的增大,ZDMA/白炭黑填充HNBR硫化胶拉伸强度和压缩永久变形先减小后增大,填料分散性下降;随着硫化剂DCP用量的增大,ZDMA/白炭黑填充HNBR硫化胶物理性能和动态性能提高,填料分散性变好。当ZDMA/白炭黑并用比为10/30、硫化剂DCP用量为5~6份、一段硫化条件为160℃×45min、二段硫化条件为150℃×(9~12)h时,ZDMA/白炭黑填充HNBR硫化胶综合性能较好。 相似文献
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采用原位改性的方法制备了硅烷偶联剂Si 75 改性纳米氧化镁/顺丁橡胶复合材料,通过橡胶加工分析仪、扫描电镜等研究了其硫化特性、物理机械性能及动态力学性能。结果表明,当改性剂的用量为填料质量的3%时能有效提高纳米氧化镁/顺丁橡胶胶料的硫化速率和交联程度,且硫化胶的综合物理机械性能最好; 与未改性氧化镁填充的顺丁橡胶相比,改性氧化镁与橡胶之间的相互作用得到了增强,纳米氧化镁在橡胶中的分散性有了较大程度的改善,从而提高了改性纳米氧化镁/顺丁橡胶硫化胶的物理机械性能和损耗因子。 相似文献
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研究炭黑、白炭黑、碳酸钙和陶土对氢化丁腈橡胶(HNBR)/丁腈橡胶(NBR)耐热密封复合材料的硫化特性、物理性能、耐热空气老化性能和耐油性能的影响。结果表明:白炭黑补强并用胶的耐热空气老化性能和耐油性能较好,但压缩永久变形大;陶土和碳酸钙补强并用胶的各项性能均较差;炭黑N220补强并用胶的物理性能较好,压缩永久变形小,更适合作为制备HNBR/NBR耐热密封材料的补强填料;炭黑N220和N330在并用胶中分散均匀,而炭黑N770分散不均匀,粒子聚集体较多。 相似文献
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Silvia Schicker Daniel E. García Igor Gorlov Rolf Janssen Nils Claussen 《Journal of the American Ceramic Society》1999,82(10):2607-2612
Wet milling of Al2 O3 -aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al2 O3 and Fe2 O3 /Al/Al2 O3 powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe2 O3 /Al/Al2 O3 powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al2 O3 powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8. 相似文献
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A new ampholytic homopolypeptide, , which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO4 and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu2+ and Ca2+, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu2+ complex near 240 nm. Dependence of the peak intensity on pH at various q values () indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu2+ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu2+ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu2+-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation. 相似文献
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Sintering kinetics of the system Si3 N4-Y2O3 -Al2 O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si3 N4 were studied with additions of 4 to 17 wt% Y2 O3 and 4 wt% A12 O3 . Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si3 N4 and glass or β '-Si3 N4 , α '-Si3 N4 , and glass. The compositions and amounts of the residual glassy phases are estimated. 相似文献
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Akira Akimoto 《Polymer》1974,15(4):216-218
The polymerization of vinyl chloride has been investigated using an catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed. 相似文献
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Won-Hyuk Lee Yoshihiro Abe Eikichi Inukai 《Journal of the American Ceramic Society》1993,76(4):849-856
Ag2 O-doped superconducting Bi2 Sr2 Ca1 Cu2 O x ceramics were prepared by a melt-quenching–reheating method. It is found that the Ag2 O-doped, as-cast specimens exhibit superconductivity ( T c = around 80 K) by heat treatment at temperatures around 800°C even in an evacuated and sealed silica glass tube, while the undoped specimens do not and vaporize by the corresponding heat treatment. Conversion of the Ag2 O-doped, as-cast specimens into superconducting ceramics when heated in an evacuated vessel is explained in terms of the oxygen donor of Ag2 O in the specimen. This finding enables us to fabricate a desired shape of superconducting Bi2 Sr2 Ca1 Cu2 O x ceramics sealed in metals or glasses. The addition of Ag2 O to Bi2 Sr2 Ca1 Cu2 O x melt, however, had deleterious influences on the superconducting properties ( T c and J c ) of the resultant ceramics when obtained by heat treatment in air. 相似文献
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Mats Carlsson Mats Johnsson Mats Nygren 《Journal of the American Ceramic Society》1999,82(8):1969-1976
Ta0.33 Ti0.33 Nb0.33 C and Ta0.33 Ti0.33 Nb0.33 C x N1− x whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N2 . The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO2 , Ta2 O5 , Nb2 O5 , C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl2 ( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature. 相似文献