共查询到20条相似文献，搜索用时 46 毫秒
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摘要：分别将质量分数为10%,15%和20%的端羟基聚硅氧烷(PDMS-OH)通过机械共混的方法改性酚醛树脂(PF),进而采用化学发泡的方法制备PF/PDMS-OH泡沫复合材料。采用旋转式流变仪表征共混体系的稳态及动态流变性能,研究黏弹性对树脂发泡过程的影响。傅立叶变换红外光谱表征PDMS-OH与树脂在固化过程中的化学反应。扫描电镜表征不同共混体系下泡孔的结构与形态。结果表明,加入15% PDMS-OH的共混体系具有最利于发泡成型的黏弹性,且可与PF形成化学交联作用,对PF泡沫的泡孔形态影响显著。同时红外表征显示,PDMS-OH与PF在固化过程中发生化学交联,这种互穿交联网状结构为PF及泡沫提供了更多稳定的柔性链段。 相似文献
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白炭黑填充剂对硅橡胶性能的影响 总被引：1，自引：0，他引：1
研究了白炭黑对硅橡胶CKTB—Б性能的影响。在胶料中,气相白炭黑的最佳用量为30～40质量份。在使用气相白炭黑的同时加入定量的钛白粉,可提高硫化胶的强度和弹性。 相似文献
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制备3种硅烷偶联剂（Si69,Si75,NXT）原位改性白炭黑/溶聚丁苯橡胶（SSBR）复合材料,研究硅烷偶联剂对白炭黑/SSBR复合材料流变性能和力学性能的影响。结果表明：硅烷偶联剂NXT在降低善白炭黑填料网络化程度方面比偶联剂Si69和Si75的效果更明显;硅烷偶联剂NXT改性白炭黑/SSBR复合材料（混炼胶和硫化胶）的剪切储能模量较低,Payne效应较弱,加工性能较好,损耗因子和活化能较小,拉伸储能模量对温度依赖性较弱,硬度、拉伸强度和拉断伸长率相当,撕裂强度较大,白炭黑分散性优异,白炭黑与橡胶之间的相互作用较强。 相似文献
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将用偶联剂处理后的新型白炭黑添加到硅橡胶中，可提高硫化胶的性能；当用量为５０份时，可使拉伸强度达１０ＭＰａ以上，撕裂强度达３０ｋＮ／ｍ左右。分析了硫化剂种类及用量对硫化胶性能的影响情况，用新型白炭黑和硫化剂最佳配方量，可使硫化胶在混炼中不产生脱辊、粘辊现象，缩短了混炼时间。 相似文献
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气相法白炭黑补强加成型RTV硅橡胶的研究 总被引：3，自引：0，他引：3
采用气相法白炭黑作补强剂填充加成型RTV硅橡胶,研究了白炭黑含量对硅橡胶黏度、力学性能、介电性能以及硫化时间的影响,并通过SEM考察了白炭黑在硅橡胶中的分散效果.结果表明,白炭黑能显著地增强硅橡胶的力学性能,当白炭黑用量为5%时,硅橡胶的拉伸强度提高了近4倍,其综合力学性能达到最佳,同时能使硅橡胶具有更低的介电常数,且介电损耗变化不大. 相似文献
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采用偶氮二甲酰胺（AC）做为发泡剂，直接通过挤出过程制备聚乳酸（PLA）泡沫塑料，通过显微镜照片、HAKKE流变仪观察和研究了工艺条件对其泡孔结构的影响。结果表明，发泡剂与成核剂的增加能降低发泡PLA的表观密度，增加其泡孔密度。流变试验表明纯PLA与发泡PLA熔体在低剪切速率下都呈现剪切变稀现象，发泡后PLA熔体的黏度会下降10％～30％。发泡剂含量在4％以下时，泡孔直径随发泡剂含量增加而减小；发泡剂含量增加到5％及以上时，PLA熔体强度过小，泡孔会过于密集而导致塌陷和串泡。成核剂的加入能够明显降低PLA熔体强度，异相成核使得泡孔直径较均相成核大，但前者泡孔密度较后者小。 相似文献
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研究了氮化硼微观结构(团聚体和片状微观结构)和用量对硅橡胶复合材料导热性能、力学性能、基体中分散形态结构的影响.结果 表明,随着氮化硼用量的增加,硅橡胶复合材料的拉伸强度和导热系数提高;当硅橡胶复合材料填料用量相同时,氮化硼团聚体比片状氮化硼的导热系数高,但拉伸强度低;当球状结构的氮化硼团聚体用量为100份时,硅橡胶复... 相似文献
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早在上世纪六十年代，单组分室温硫化硅橡胶（以下简称RTV-1）就作为一种多功能和用途广泛的高性能密封剂广泛应用于家用及工业上。RTV-1作为一种可以在室温条件下利用湿气固化的单组分体系，它具有一系列的优异性能：良好的流变性和固化性能，极好的自粘性和透明性，优异的耐高低温性、耐候性、耐臭氧和耐化学物质等性能。这些优异的性能主要与RTV-1体系中的三个因素有关：有机硅聚合物、交联体系和补强填料，而气相法白炭黑是最有效最通用的补强填料。 相似文献
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Jiann‐Wen Huang Yung Chang Hung Ya‐Lan Wen Chiun‐Chia Kang Mou‐Yung Yeh 《应用聚合物科学杂志》2009,112(3):1688-1694
Polylactide (PLA)/silica composite films were prepared by two methods: blending nanoscale colloidal silica sol and sol–gel. The nano and microscale silica particles, respectively, were well dispersed in PLA when observed using scanning electron microscopy and transmission electron microscope. The mechanical and thermal stability of composite films were measured before and after hydrolysis by Instron and thermogravimetric analysis. The fillers increase tensile strength, Young's modulus, thermal stability, and hydrolysis resistance with increasing silica content. The nanoscale particles exhibit better effects than the microscale ones. The activation energy, Ea, of thermal decomposition is also simulated by the Kissinger and Ozawa equation. The results also show that the thermal stability is increased by the incorporation of silica particles and is lowered by hydrolysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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A fluorinated polyimide (PI), synthesized from 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride and 4,4′‐diaminodiphenyl ether, was used as matrix for the preparation of PI/silica hybrids. The inorganic phase was obtained in situ by a sol–gel route with tetraethoxysilane as precursor. Both micron‐ and nano‐scale hybrids were obtained depending on the interfacial interaction between the organic and inorganic phases. To promote such interaction a compatibilizing agent was synthesized, in the form of an alkoxisilane‐terminated oligoimide. Both the PI and the coupling agent were characterized by FTIR and Raman spectroscopies and by GPC measurements. The effect of the coupling agent on the morphology of the hybrids and on the size of the silica particles was investigated by scanning electron microscopy. The viscoelastic, mechanical, and thermal properties of hybrid composites were studied. It was shown that by adding appropriate amounts of the compatibilizer it was possible to control the morphology and to obtain homogeneous nanostructured systems. A general improvement of the mechanical performances and of the thermal stability was demonstrated, together with an increase of Tg, which was found more pronounced for the nanocomposites than for the microcomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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Yuejing Tong Hangzhong Liu Aicheng Chen Huaimin Guan Junhua Kong Songlin Liu Chaobin He 《应用聚合物科学杂志》2018,135(35)
In this study, high‐temperature vulcanized silicone rubbers (HTV‐SRs) using fumed silica (FSi), precipitated silica (PSi), and modified precipitated silica (MPSi) as reinforcing fillers were prepared. The effect of morphology and surface chemistry of the silica on the thermal and mechanical properties of the resultant silicone rubbers was investigated using curing rheometer, scanning electron microscopy, mechanical test, and dynamic mechanical analysis. The thermo‐oxidative stability and solvent resistance of the vulcanized silicone rubbers were further evaluated via heat ageing test, extraction, and swelling experiments. It is shown that the mechanical properties (tensile modulus and tensile strength) of the as‐prepared HTV‐SRs are in the order of FSi > PSi > MPSi, which could be attributed to the molecular interaction between the filler and the matrix. FSi has the highest surface area, which enhances the hydrogen bonding interaction between the filler and the silicone matrix; while MPSi, in which part of Si? OH groups have been consumed during modification, shows the weakest interaction among the three. The filler–matrix interaction could also explain the lowest swelling and sol fraction in FSi‐filled HTV‐SR, and the low viscosity and good processibility of PSi‐ and MPSi‐filled HTV‐SR. Furthermore, it is also shown that the MPSi‐filled HTV‐SR exhibits the highest retention of mechanical properties after thermal aging at 250 °C for 24 h, which could be attributed to the lowest acidity of the fillers. The possible mechanism for acid catalyzed hydrolytic chain scission and intramolecular chain backbiting has been proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46646. 相似文献
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An experimental study of the rheological behavior of ethylene–octene copolymer vulcanizates in extrusion containing blowing agent has been carried out. The cell morphology development has been studied through a scanning electron microscope. Rheological properties of unfilled and precipitated silica‐filled systems with variations of blowing agent, extrusion temperature, and shear rate have been studied by using a Monsanto processibility tester (MPT). The total extrusion pressure (PT), apparent shear stress (τwa), apparent viscosity (ηa), and die swell (%) of the unfilled and silica‐filled compounds have been determined by using MPT. The effect of blowing agent (ADC) on the rheological properties of the vulcanizates has also been investigated. There is a reduction of stress and viscosity with blowing agent loading. It was observed that the incorporation of a blowing agent led to decreased shear thinning behavior resulting in an increase in power law index. The viscosity reduction factor (VRF) of unfilled vulcanizates is found to be dependent on the concentration of the blowing agent, shear rate, and temperature, whereas VRF of silica‐filled vulcanizates is found to be dependent on shear rate, temperature, and blowing agent concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1132–1138, 2003 相似文献
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The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) with aromatic diamines having aryl–ether, aryl–ether–carbonyl, and aryl–ether–sulfone linkages was studied using differential scanning calorimetry (DSC). Aromatic diaminessuch as 1,3-bis(aminophenoxy)benzene (R), 1,4-bis(aminophenoxy)benzene (H),2,2′-bis[4-(4-aminophenoxy)phenyl]propane (B), 4,4′-bis(4-aminophenoxy)benzo-phenone (P), and bis[4-(4-aminophenoxy)phenyl]sulfone (S) were synthesized and characterized in the laboratory. Curing of DGEBA was done using both stoichiometric and nonstoichiometric amounts of diamines and the reaction was monitored using DSC. The reactivity of the diamines depended on the structure. The presence of electron withdrawing groups, even though significantly apart from the reaction site, reduced the nucleophilicity. No significant change was observed in the activation energy for curing, which was around 56 ± 2 kJ/mol. The glass transition temperature of the epoxy network depended on the structure and was higher when diamines P and S were used in comparison to diamines R, H, and B. The cured resins were stable up to 300°C, and maximum char yield (i.e., 32% at 600°C) was obtained in DGEBA cured with diamine P. The room temperature mechanical properties only changed marginally with the structure of the diamines. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1759–1766, 1998 相似文献
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This paper reports on how the blend ratio and morphology influence the mechanical, thermal, thermomechanical, and rheological properties of poly(propylene) (PP)/low density polyethylene (LDPE) blends. The blend morphology is composed of the major matrix phase and the minor phase, with subinclusions of the major matrix existing within the minor phase. Blends containing low amounts (<20 wt%) of either phase exhibit partial miscibility but the phases are immiscible at higher contents. Partial miscibility of the blends is revealed by scanning electron microscopy studies showing fibril‐like structures and confirmed by rheology. The tensile modulus of the blends decreases with increasing amounts of LDPE, but low LDPE contents exhibit positive deviation from the mixing rule of mixture due to partial compatibility. The crystallinity of PP is affected less than that of LDPE in the blends. Thermomechanical and rheological properties of neat polymers are significantly influenced by blending. The blend ratio and morphology influence impact strength and elongation at break, and the result demonstrates that the 80/20 PP/LDPE blend offers a balance among the mechanical and material properties that are essential for flexible packaging applications.
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Cyanate esters are a class of important thermally resistant polymers. To tailor their processability and thermomechanical properties, a series of cyanate ester blends based on a trifunctional novolac cyanate ester (HF‐5), a difunctional bisphenol E cyanate ester (HF‐9), and a reactive catalyst [2,2′‐diallyl bisphenol A (DBA)] were formulated. The effect of the blend composition on the rheology and curing behavior of these cyanate ester blends and the corresponding thermal and mechanical properties of the cured cyanate ester blends was studied. The results showed that HF‐5 contributed to good mechanical property retention at high temperatures because of its trifunctionality, whereas HF‐9 imparted processability by reducing the viscosity and extending the pot life of the formulated cyanate ester blends at the processing temperature. On the basis of the results, an optimal cyanate ester blend suitable for resin transfer molding was determined: the HF‐5/HF‐9/DBA weight ratio of 80 : 15 : 5 exhibited good processability and thermomechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4284–4290, 2006 相似文献
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Epoxy/polysufone (PSF) composites cured with 4,4'-diaminodiphenyl sulfone (DDS) and 4,4'-diaminodiphenyl methane (DDM) were fabricated, and the effect of dual curing reaction of diamines with epoxy on morphology, mechanical, and thermal performance was investigated. DSC results indicated that DDM was more reactive than DDS and the activation energy decreased with the rising of DDM content. Structures with small domain size at the early stage of phase separation were fixed by the fast epoxy-DDM reaction. When the DDM content was elevated to a high level, large dual structures were changed to fine bicontinuous structures, which was favorable to improve the mechanical property. The mechanical performance of epoxy composites was enhanced and the maximum values were achieved when the DDM/DDS ratio was located at 75/25 (PSF/DDS0.25-DDM0.75). The flexural and tensile strength relative to epoxy/DDM system were enhanced more than those relative to epoxy/DDS, while the increase in toughness was the opposite. TGA measurement showed that thermal stability of epoxy/PSF composites was improved because of the restricting effect of continuous PSF domains on thermal motion of epoxy. DMA analysis exhibited two relaxation peaks for PSF/DDS0.25-DDM0.75, which could be attributed to the formation of phase separated morphology and epoxy network with different cross-link density. 相似文献
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In this article, a series of hybrid organic–inorganic coatings based on silica‐epoxy composite resins were prepared with the sol‐gel method by using γ‐aminopropyl triethoxysilane as a coupling agent. Especially, the research emphasized on the factors that influenced on the properties of the prepared hybrid coatings. Firstly, epoxy resin was reacted with γ‐aminopropyl triethoxysilane at a specific feeding molar ratio; subsequently, the asprepared sol–gel precursor was cohydrolyzed with tetraethoxysilane (TEOS) at various contents to afford chemical bondings to form silica networks and give a series of organic–inorganic hybrid coatings. They were loaded and cured on steel panels and characterized for FTIR, TGA, DSC, water contact angles (WCA), pencil hardness, surface & three‐dimensional morphological studies, and potentiodynamic polarization tests. The surfaces of the hybrid coatings showed Sea‐Island or Inverting Sea‐Island morphologies at a certain relative content of two components, which made the coatings possess hydrophobic property. Due to the contribution of organic and inorganic components, the prepared hybrid coatings possess a lot of properties such as pencil hardness, thermotolerance, and corrosion resistance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41010. 相似文献