共查询到17条相似文献,搜索用时 71 毫秒
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新型工艺胶乳法氯化天然橡胶(CNR)产品在干燥过程中会有HCl脱出,其脱出量对CNR的制备、性能等有一定的影响。采用电导法可连续测定CNR在干燥历程中脱HCl量及速率,这是研究CNR在低温下热降解行为的有效方法。用改进工艺的"胶乳法"制备出湿的CNR,并在一定温度下通入氮气进行干燥,在此历程中会发生脱氯化氢反应,其反应过程可分为诱导期、恒速期和低速期。文中使用Friedman法分析该过程在恒速期、低速期的反应动力学参数,其脱氯化氢反应分别为0级反应、1级反应,活化能分别为26.65,36.79 kJ/mol。在80℃以下对产品进行加热(或干燥),虽有少量HCl脱出,但并不会对产品质量造成影响。所以干燥温度应以低于80℃为宜。 相似文献
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天然胶乳氯化反应动力学研究 总被引:5,自引:0,他引:5
新型的“胶乳法”工艺制备氯化天然橡胶,相对于传统的“溶液法”具有污染少、工艺简单、投资小、成本低等突出优点,是氯化天然橡胶的发展方向。对胶乳法的氯化反应历程进行研究,对完善胶乳法工艺具有重要意义,因而采用化学分析方法及SPSS回归分析方法,对胶乳法工艺制备氯化天然橡胶的氯化反应动力学进行了研究。研究结果表明:对现行工艺条件下胶乳法氯化反应,可采用经验式y=18.8350Inx 62.8390(R^2=0.9897,P=0.0000)预测氯化反应程度,即根据氯化时间(x),计算氯含量(y);利用方程式Y=0.0605e^4.3179X(R^2=0.9982,P=0.0000)可由实际测得的氯含量(X),计算出相应的氯化反应转化率(Y);本氯化反应的表现反应级数为:n=0.3。 相似文献
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新型的低浓度"胶乳法"工艺制备氯化天然橡胶,相对于传统的"溶液法"具有污染少、工艺简单、投资小、成本低等突出优点,是氯化天然橡胶的发展方向。文章对其氯化反应历程进行研究,采用化学分析方法、origin8.0回归分析方法和MATLAB科学计算平台,对该方法制备氯化天然橡胶的氯化反应动力学进行了研究。研究结果表明:对现行工艺下低浓度胶乳法的氯化反应,可采用经验式预测不同相对反应时间的含氯量。根据氯含量随相对时间的变化规律,可以把反应过程分为两个阶段:高速期和低速期。在CNR氯化反应的第二阶段,反应温度的升高有利于氯含量提高,但温度过高,能量耗费过大,加上要考虑到反应的宏观动力学等因素,CNR氯化的第二阶段反应温度以343.15~353.15K为宜。通过使用Matlab语言求算化求出氯化反应的反应级数,其第一阶段表观反应级数为3.2871,第二阶段表观反应级数平均值为:n=0.6254,表观活化能为6.493 kJ/mol。 相似文献
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介绍了采用浅床层固定床反应器,在近似工业条件下对AKZO公司开发的FPC-2LD催化剂进行了氧气法乙烯氧氯化制二氯乙烷的本征动力学研究,用多元线性回归数学模型对实验数据进行计算,建立了该催化剂的主反应动力学方程式。 相似文献
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Ying Cai Si‐Dong Li Cheng‐Peng Li Pu‐Wang Li Chen Wang Ming‐Zhe Lv Kui Xu 《应用聚合物科学杂志》2007,106(2):743-748
The thermal degradations of chlorinated natural rubbers from latex (CNR‐L) and from solution (CNR‐S) under nitrogen atmosphere were studied with thermogravimetric analysis (TGA). The thermal degradations of CNR‐L and CNR‐S are one‐step reaction. The shapes of the thermogravimetric and derivative thermogravimetric curves are similar. The degradation temperatures of CNR‐L and CNR‐S increase linearly with the increment of heating rates. The heating rate hardly affects the thermal degradation rates of CNR‐L and CNR‐S at the various degradation stages. The thermal degradations of CNR‐S and CNR‐L are dehydrochlonation reactions. The reaction activation energy (E) of CNR, at the first stage, is around 100 kJ/mol. After that, E remains relatively steady (80–140 kJ/mol). At the last stage, E rises rapidly (130–270 kJ/mol). The variation tendency of frequency factor (A) is similar to that of E. As the initial degradation temperature T0 of CNR‐L is 10.9°C lower than that of CNR‐S, the thermal stability of CNR‐S is better than that of CNR‐L, which may be caused by the difference of molecular structure between CNR‐L and CNR‐S, as FTIR results indicate that there are more ? OH, ? C?O and ? COO? groups in the CNR‐L molecular chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
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A solid-state chemical reaction occurs when a solvent cast film of a blend of masticated natural rubber and chlorinated natural rubber is heated in the presence of air at 150°C. The thermal behavior of solvent cast films of chlorinated natural rubber, masticated natural rubber, and a 1 : 1 w/w blend (2% w/v in xylene) of these two polymers has been studied using differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, and nuclear magnetic spectroscopy. The results suggest that carbonyl groups are incorporated into the blend on heating and that the vinyl functionality of the isoprene units is modified during this apparent oxidation. Heating for 2 h at 150°C results in a material that no longer contains the rubber-like cis-1,4-polyisoprene units. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1379–1384, 1997 相似文献
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以压缩永久变形为寿命分析研究对象,研究了常用工况下老化时间对黏弹性阻尼硅橡胶的储能模量、损耗模量及损耗因子的影响,同时采用热空气加速老化试验方法探究了黏弹性阻尼硅橡胶在不同温度(348,363,378,393 K)下压缩永久变形性能保持系数随老化时间的变化规律,并通过对两种老化动力学模型进行研究分析和修正获得了黏弹性阻尼硅橡胶的老化反应速率,此外,还对不同老化动力学模型下老化反应速率对Arrhenius模型的非线性行为进行了分段研究,推测了黏弹性阻尼硅橡胶的储存寿命。结果表明,在室温(298 K)下两种老化动力学模型在储存寿命为10.0 a时的压缩永久变形性能保持系数均为0.60;当选择压缩永久变形性能保持系数为0.50作为失效判据时,黏弹性阻尼硅橡胶的储存寿命分别为20.0 a和19.2 a,使用两种模型所得黏弹性阻尼硅橡胶的储存寿命误差仅为4%。 相似文献
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G. R. Van Atta D. F. Houston W. C. Dietrich 《Journal of the American Oil Chemists' Society》1947,24(5):149-155
Summary Dichlorinated palmitic acid was catalytically dehydrochlorinated rapidly and nearly completely in the vapor phase at low pressures
and at temperatures of 220–315°C. Polymerization of the liquid desaturated material is catalyzed by strong acids. This was
prevented from occurring in the recovered products, which were clear and pale in color, by maintaining the pressure of hydrogen
chloride liberated in the reaction at less than 2 mm. However, some nonvolatile polymers were formed in the process and deposited
on the surface of the solid catalyst, thus lowering its activity and shortening its period of usefulness.
The desaturated products of the process contained about 20 per cent of γ-lactones and some conjugated unsaturation.
Presented at 20th annual fall meeting, American Oil Chemists' Society, Oct. 30–Nov. 1, 1946, Chicago, Ill.
One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S.
Department of Agriculture. 相似文献
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High‐resolution pyrolysis gas chromatography‐mass spectrometry (HRPyGC‐MS) and Fourier transform infrared spectrometry (FTIR) were used to study the structures of the chlorinated natural rubbers (CNR) prepared by two different processes. The results indicate that the fine structures of CNR prepared from “latex” and “solution” processes are different, whereas their basic structures are similar. The molecule of CNR from the “latex” process contains a few carboxyl and carbonyl groups. The rings on CNR molecular chains should be hexatomic rings. The optimum pyrolytic temperature for CNR is 445°C, with an available range from 386 to 590°C. The characteristic pyrolytic products are cyclohexane homologues. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 199–204, 2003 相似文献