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丙烯腈/衣康酸在DMSO/H2O中的共聚物结构模拟 总被引:4,自引:0,他引:4
采用丙烯腈(AN)与衣康酸(IA)在DMSO/H2O中共聚,计算了两种反应单体的竞聚率:rAN=0.405,rIA=2.946。采用计算机模拟,进一步研究了聚(丙烯腈 co 衣康酸)共聚物的分子结构与转化率的关系。给定自由基共聚反应的初始条件,还模拟了丙烯腈与衣康酸二元共聚物序列分布。随着转化率不同,共聚物中衣康酸的组成相差较大,反应初期大多数的IA共聚单体参加反应,特别是在少量衣康酸作共聚单体时,随着衣康酸的加入,丙烯腈的平均序列长度快速降低。 相似文献
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丙烯腈-衣康酸铵共聚竞聚率的测定及共聚组成的控制 总被引:1,自引:0,他引:1
研究了丙烯腈-衣康酸铵共聚体系的竞聚率和不同加料方式下聚丙烯腈(PAN)树脂中衣康酸铵含量的变化规律。采用Fineman-Ross法测得丙烯腈(AN)-衣康酸铵(AIA)体系的竞聚率为:AN=1.30,AIA=0.59,该体系属于非理想非恒比共聚。元素分析和热重分析表明,在聚合过程中逐步补加AN,有效地抑制了PAN树脂中AIA平均含量的变化幅度;补加单体法获得的树脂与一次性投料方式下生成的PAN树脂相比,前者的热稳定性较高。γγ 相似文献
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丙烯腈、偏二氯乙烯水相沉淀共聚的研究 总被引:4,自引:1,他引:3
讨论了丙烯腈(AN)、偏=氯乙烯(VDC)水相沉淀共聚合过程中的反应条件、助溶剂及第三单体甲基丙烯磺酸钠等对总单体转化率、共聚体中VDC含量及共聚体相对粘度(ηγ)的影响。结果表明:提高总单体浓度和引发剂用量能显著地提高总单体转化率和共聚体中VDC的含量。但共聚体ηγ随之下降;在相同反应条件下,与甲醇相比,采用乙醇作助溶剂能获得更高的总单体转化率和共聚体中的VDC含量;采用甲基丙烯磺酸钠作第三单体能提高总单体转化率以及共聚体中的VDC含量和ηγ。 相似文献
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用氧化还原引发体系在低温下研究了丙烯腈与丙烯酸乙酯的乳液共聚合。考察了聚合温度、乳化剂浓度和分子量调节剂浓度对聚合的影响 ,结果表明 ,随温度升高 ,乳化剂浓度增大 ,单体转化率和分子量增大 ,乳液更稳定 ;链转移剂十二烷基硫醇浓度增加 ,分子量显著降低 ,转化率有所降低 ,表明十二烷基硫醇在调节分子量的同时也起着缓聚剂的作用。用激光粒径分析仪考察了 2 0℃时聚合过程中乳胶粒子大小的变化 ,发现聚合过程的成核和增长均在胶束中进行的。用凝胶渗透色谱法研究了十二烷基硫醇对聚合物分子量的影响 ,发现聚合时加入分子量调节剂 ,活性链寿命较短并呈单峰分布 :聚合时不加入分子量调节剂 ,活性链寿命较长并呈双峰分布。 DSC结果表明 ,随聚合体系中软单体含量增加 ,共聚物的玻璃化温度降低。 相似文献
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对氯乙烯5甲基丙烯酸-2-羟乙酯(VC-HEMA)乳液共聚的稳定性、动力学和组成控制进行了研究。发现:由于反应过程中HEMA主要分配在水相,对乳化剂十二烷基硫酸钠有强烈增溶作用,并存在HEMA水相聚合,使乳液聚合稳定性随HEMA/H2O比增大而降低。随投料单体中HEMA含量增加,共聚速率和聚合转化率降低。得到了VC-HEMA共聚竞聚率为rVC=0.0123,rHEMA=18.53,乳液共聚表观竞聚率r'VC=0.341,r'HEMA=4.29。VC-HEMA间歇乳液共聚得到的共聚物组成极不均匀,采用多步添加HEMA的半连续乳液共聚,合成了组成较均匀、HEMA质量分数在10%以下的共聚物。 相似文献
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乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。 相似文献
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The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1‐h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and β‐1,4‐glucoside linkage or hydrogen bonds. Breakage of the β‐1,4‐glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3526–3531, 2003 相似文献
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我厂3号回转窑(Φ4m×60m)生产线在1996年年底由SP窑(产量912t/d)改为NSP窑(产量1320t/d),预分解系统为四级旋风预热器带离线式分解炉 相似文献
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Conclusions It is significant that the purification on a single passage of viscose through porous ceramic corresponds to the result of a two-stage filtration of it in industrial filter-presses with standard fillings.Kiev Combine. Kiev Technological Institute of Light Industry. Translated from Khimicheskie Volokna, No. 3, pp. 20–22, May–June, 1969. 相似文献
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A refined nonlinear value of the main parameter of a material, i.e., the elongation modulus versus the instant temperature value, was suggested for introduction into the computational algorithm of tempering stresses. 相似文献