共查询到17条相似文献,搜索用时 203 毫秒
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在胶原蛋白(Col)与聚乙烯醇(PVA)共混纺丝原液中,加入丁烷四羧酸(BTCA)作为交联剂,经湿法纺丝得到初生纤维,经热拉伸和热定型、缩醛化处理得到Col/PVA复合纤维;分析了Col/PVA复合纤维的结构和性能。结果表明:BTCA可以使纤维内部形成交联结构,提升纤维内部Col的稳定性,红外光谱分析表明,BTCA与PVA上的羟基反应生成了酯键;经扫描电子显微镜观察发现BTCA交联处理后复合纤维内部致密,孔洞和缺陷少;差示扫描量热法分析表明BTCA的交联作用会抑制纤维内PVA的结晶,使结晶度有所下降;BTCA添加质量分数为3%的复合纤维的断裂强度、断裂伸长率、Col保留率分别为4.94 cN/dtex,12.56%,91.09%,水中软化点为106℃,具有优良的综合性能。 相似文献
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在一定比例的环氧树脂(EP)和线型酚醛树脂(PN)固化剂中加入丁酮溶解好的促进剂,制备了EP/PN体系。研究了不同促进剂对于EP/PN体系的固化反应动力学的影响。研究结果表明,2-乙基-4-甲基咪唑(2E4MZ)和三苯基膦(TPP)均可加速EP/PN体系的固化。使用外推法确定两体系的凝胶温度、固化温度和后处理温度等特征温度,发现2E4MZ促进的固化体系其凝胶温度较低,而固化温度和后处理温度略高。同时利用Kissinger方程和Ozawa方程计算出2E4MZ促进体系的平均表观活化能为74.92 kJ/mol,TPP促进体系的平均表观活化能为78.59 kJ/mol。 相似文献
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将聚乙二醇(PEG)与聚乙烯醇(PVA)溶液混合,加入丁烷四羧酸(BTCA)作为交联剂配制纺丝原液,采用干法纺丝制得BTCA改性PEG/PVA相变储能纤维;研究了BTCA含量、热处理条件对交联程度的影响,并对纤维的结构、形态、储能性能及力学性能进行了分析。结果表明:在热处理温度为180℃,热处理时间为12 min时,纤维可达到良好的交联效果,纤维的交联程度随BTCA含量的增加呈上升趋势,BTCA质量分数为3%时达到平衡;改性纤维中PEG以独立微相区形式存在,而经热处理后可保留在交联网络中;热处理后的改性纤维力学性能随BTCA含量增加而提高,储能性能也增加且稳定;当BTCA质量分数为6%时,热处理后的纤维断裂强度达3.49 cN/dtex,再经沸水处理后纤维相变焓值可达23.01 J/g,PEG保留率达80%。 相似文献
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采用TG-DTG技术研究了2-巯基吡啶镉(Ⅱ)、汞(Ⅱ)配合物在氮气气氛中的热分解机理及非等温动力学。采用积分法(Coats-Refern方程,HM方程,MKN方程)和微分法(Achar方程)对非等温动力学数据进行了分析,得到了配合物第一步热分解反应的机理函数、动力学参数和热分解动力学方程。结果表明:其热分解过程属F2(化学反应)机理控制,非等温热分解的动力学方程为dα/dT=A/β.e-E/RT(1-α)2,其中镉(Ⅱ)配合物的表观活化能E=86.35 kJ/mol,指前因子A=4.72×107s-1;汞(Ⅱ)配合物的表观活化能E=189.67 kJ/mol,指前因子A=3.79×1018s-1。 相似文献
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柔性UPR树脂/粉煤灰非等温固化动力学 总被引:1,自引:0,他引:1
用差示扫描量热法(DSC)研究了柔性不饱和聚酯树脂/粉煤灰体系的非等温固化过程,利用T-β外推法确定了体系的固化工艺温度:凝胶温度257.625K、固化温度374.275K、后处理温度406.565K。用Flynn-Wall-Ozawa法和Friedman-Reich-Levi法获得了柔性UPR固化反应表观活化能为Ea=83.94kJ·mol-1。由ASTME698-79标准方法求得指前因子,lnA=25.27;结合Crane方程分析知,复合体系的固化反应接近于一级反应。最终建立了复合体系固化反应动力学方程为ln(ddαt)=25.27-10096.22T+ln(1-α)0.9126。 相似文献
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研究了盐酸四环素的降解动力学模型。通过不同的升温速率(β=5、10、20、25K/min)下进行热重量分析得到降解数据,并根据无模型动力学方法,得到降解活化能E及其与反应转化率α之间的关系(在转化范围0<α<0.3内,E的平均值为200kJ/mol;当α>0.3时,E值随着α变化而变化)。 相似文献
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以聚乙二醇(PEG)为相变物质,聚乙烯醇(PVA)为纤维基体,加入少量丁烷四羧酸(BTCA)作为交联剂,采用干法纺丝制备相变储能纤维,利用原位交联法在纤维拉伸热定形过程中使BTCA与PVA、PEG发生交联,将PEG接枝在PVA上。研究了BTCA、PEG合适的添加量以及最佳热定形温度对PEG保留率的影响,并通过差示扫描量热法、扫描电镜对纤维的热性能和形貌进行了分析。结果表明:当PEG添加量为30%(占PVA质量的百分数)、BTCA添加量为5%(占PVA质量的百分数)时,纤维充分交联,200℃下热处理10 min所得纤维PEG的保留率98%;制得的纤维的相变热焓可达34 J/g,拉伸强度可达3.26 cN/dtex;在升降温循环400次后仍具有良好的储能性。 相似文献
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ABSTRACT: Electrospun nanofibrous hydrogel membranes have been gaining significant importance due to the combination of unique physical properties of nanofibers and biocompatibility of hydrogels. Thus, they are considered as potential candidates for medical textile applications. This study deals with electrospinning of poly(vinyl alcohol) (PVA) hydrogel nanofibrous membranes. The chemical crosslinking of PVA with proportionate quantities of 1,2,3,4 butanetetracarboxylic acid (BTCA) was undertaken to form hydrogel structures. Cross‐linked membranes were characterized by scanning electron microscopy, FT‐IR and thermogravimetric analysis, water swelling, and durability tests. FT‐IR analysis demonstrated the formation of ester linkages between PVA and BTCA and thermogravimetric analysis showed that crosslinking improved the thermal stability of the nanofibrous structure. Furthermore, the results indicated that crosslinking with BTCA improved water stability of PVA membranes and the nanofibrous structure was preserved after water treatment. It is envisaged that use of BTCA as a cross‐linker to form hydrogel nanofibers could be a practical and a promising method for medical textile applications, especially for wound dressings given its nontoxicity and immiscibility with polymer solutions. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
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The crosslinking reaction of poly(vinyl alcohol) (PVA) by esterification using poly(acrylic acid) (PAA) as a crosslinking reagent was investigated to obtain highly insoluble PVA materials. Blend films of PVA and PAA (PVA/PAA = 8/2) were prepared to examine the effect of degree of neutralization (DN) in PAA and heat‐treatment conditions on the degree of crosslinking reaction. The degree of crosslinking reaction varied significantly when the DN of PAA changed. The optimum DN for the crosslinking reaction was in the range of 5 to 10 mol %. In the case of unneutralized PAA, the degree of crosslinking reaction was at most 15 mol % by heat treatment for 20 min at 200°C. Applying partially neutralized PAA (DN = 10 mol %) raised the degree to about 40 mol % under the same heat‐treatment conditions. FTIR analysis revealed that the hydroxyl group of PVA in the film blended with unneutralized PAA was degraded to a greater degree than that with partially neutralized PAA as a result of heat treatment. It was found that heat treatment at a low pH condition enhances the degradation of the hydroxyl group of PVA, resulting in a decrease of the number of crosslinking sites by esterification. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2420–2427, 2003 相似文献
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苯氨基甲酸甲酯热解制备苯基异氰酸酯的非等温动力学 总被引:1,自引:0,他引:1
采用热分析与红外联用技术对苯氨基甲酸甲酯(MPC)热解历程进行分析,结果表明,苯氨基甲酸甲酯的热解过程是一步生成苯基异氰酸酯同时释放出甲醇气体. 进一步对该热解反应进行了非等温动力学研究,对MPC的热解数据采用Flynn-Wall-Ozawa法计算得到反应活化能. 采用5种方法考察反应动力学参数,结果表明,MPC热解机理为相边界反应模型,机理函数为G(a)=a1/3,热解反应活化能E=20.52 kJ/mol,指前因子lgA=2.23,动力学方程为a1/3= 169.82exp[20.52′103/(8.314T)]t. 相似文献
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This study investigates the effect of 1,2,3,4-butane tetracarboxylic acid (BTCA) crosslinking treatment on the electrical properties of poly-p-phenylene terephthalate (PPTA)/cellulose insulation paper to prepare a novel composite insulation paper with low dielectric constant and good electrical performance. Three-layer PPTA/cellulose composite paper crosslinked by BTCA under various conditions, composite paper without crosslinking, directly mixed composite paper, and conventional Kraft paper are prepared. The morphology and surface chemical composition of the paper samples are characterized. Dielectric, mechanical, and thermal properties are investigated. Results show that the BTCA concentration of 0.2 mol L−1 with a 180°C curing temperature is the relatively superior crosslinking condition to prepare a novel composite with low dielectric constant and good comprehensive performance. The dielectric constant and loss of the novel composite paper decrease to 3.21 and 0.392 at 50 Hz. The tensile strength of the BTCA crosslinked three-layer PPTA/cellulose composite paper (thickness: 130 μm) has reached 10.01 kN m−1, increased by 41.6% than the directly mixed composite paper. The novel BTCA crosslinked composite paper also shows improved thermal stability. The BTCA crosslinking proves to be a promising method to improve the dielectric properties and electrical performance of the PPTA/cellulose composite paper. 相似文献
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Morphology and mechanical properties of pullulan/poly(vinyl alcohol) blends crosslinked with glyoxal
Naozumi Teramoto Masahiko Saitoh Johta Kuroiwa Mitsuhiro Shibata Ryutoku Yosomiya 《应用聚合物科学杂志》2001,82(9):2273-2280
We prepared pullulan/poly(vinyl alcohol) (PVA) blend films by casting the polymer solution in dimethyl sulfoxide. Their morphology and mechanical properties were investigated. Scanning electron micrographs revealed that the pullulan was immiscible with PVA over the entire composition range. The tensile strength and modulus of the blend films were lower than those predicted by the upper bound composite equation. To improve the mechanical properties, we investigated the reaction of the 40/60 blend with glyoxal. The infrared spectral change and the increase in the glass‐transition temperature (corresponding to the PVA component) accompanying the reaction indicated that crosslinking with glyoxal had proceeded. The crosslinked films were homogeneous and had higher tensile strengths and moduli than the simple blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2273–2280, 2001 相似文献
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Thermoplastic starch (TPS)/poly(vinyl alcohol) (PVA) blend films were modified by crosslinking through soaking the films in glutaraldehyde aqueous solution and then heating in an oven. The effects of the concentration of the glutaraldehyde aqueous solution, soaking time, reaction temperature, and time on the crosslinking reaction were investigated. The moisture absorption and mechanical properties of the films were measured to characterize the influence of the crosslinking modification. It was found that the crosslinking modification significantly reduced the moisture sensitivity of the TPS/PVA blend films and increased the tensile strength and Young's modulus but decreased the elongation at break of the TPS/PVA blend films. The described method could be used for posttreating TPS/PVA‐based products to optimize their properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献