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对四个聚甲基丙烯酸甲酯级分用混合级分法分别进行淋洗柱分级和沉降速度法测定分子量分布的研究,以混合级分的分子量累积分布是否与单一级分累积分布的加和符合,作为分子量分布曲线绝对评价的判据.淋洗柱分级采用苯-甲醇体系,超速离心沉降在丙酮-乙醇体系的θ-温度附近测定.实验结果说明,混合级分的淋洗柱分级曲线与加和曲线比较,显得分子量分布偏窄,分子量小的部分低估,分子量大的部分高估;而用沉降速度法所得混合级分的分子量分布曲线则与加和曲线相符,因此可以用后法所得分子量分布曲线作为评价淋洗柱分级曲线的依据.可以认为淋洗柱分级曲线基本上真实反映试样的分子量分布,但是如用通常方法画出累积分布曲线,则使分布偏窄,对试样中高分子量尾端大大低估.因此如何用分级法分成较少的级分,而对分级数据作出更合理的处理,值得作进一步的研究. 相似文献
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验证了逆转法在场流分级这种单相色谱中的可行性。用逆转法消除样品的多分散性对塔板高度的贡献,以便研究在热场流分级柱槽中其它实验条件的影响。测定了几种聚苯乙烯样品的分子量分布。 相似文献
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PSt-TMI合成及其共聚动力学研究 总被引:4,自引:0,他引:4
以BP0为引发剂,甲苯为溶剂,采用溶液聚合法合成了低3-异丙烯基一α,α’-二甲基苄基-异氰酸酯(TMI)含量的PSt-TMI共聚物(wTMI-O.03~O.11),确定了FTIR方法测定共聚物中TMI含量的方法,并对反应动力学与共聚物组成进行了研究。结果表明:总体反应速率与单体浓度成正比,与引发剂浓度O.5次方成正比,80℃下反应时还存在热引发,终止方式为双基终止;反应总体活化能随单体配比中TMI分率增大而升高。引发剂浓度增大则产物分子量减小,分子量分布不变。随反应转化率提高分子量分布指数增大、产物中TMI含量略有下降。GPC串联紫外分析表明,产物中高分子量部分TMI含量高于低分子量部分中TMI含量。 相似文献
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对顺丁橡胶浓溶液作了较为深入的研究,主要讨论了分子量分布和支化因子与顺丁橡胶浓溶液流动行为的关系。用倒沉淀分级的方法进行了大量分级,得到分子量分布较窄的试样;对这些试样用GPC-自动粘度计联用的方法测定了分子量、分子量分布和支化因子,同时用同轴圆筒式粘度计及落球方法测定了这些试样的浓溶液粘度。 相似文献
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聚碳酸酯(简称PC)是一种综合性能优良的热塑性工程塑料。可用酯交换法或光气法生产。本文用裂解色谱(简称PGC)分析了PC在600℃时热降解产物,用PGC法测定了不同来源PC样品的分子量,其结果与粘度法测定的一致。每次分析时间约30min。微量水份对定量精度有影响。从末端基团降解碎片可以鉴别PC聚合工艺中所用的分子量调节剂。 1.PC样品经沉淀分级法获得的级分,用粘度法测定其分子量,分别为:1.25×10~4;1.79×10~4;2.57×10~4;3.56×10~4。 相似文献
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In this study, the synthesis, characterization, and properties of a short oil length chain–stopped(rapid) alkyd resin is investigated. Gum rosin modified alkyd resin (RA-GR) was prepared using soybean oil, phthalic anhydride, glycerin and gum rosin acid. An alkyd modified with benzoic acid (RA-BA) was also prepared for comparison. FTIR analyses and GPC measurements of the alkyds were used for characterization. Other properties such as the viscosity, acid value, and solid content of the final resins were determined. Separately, the synthesized resins were used in paint formulations without any changes in other parameters such as filler, airdrying agents, solvents, etc. Paints were applied to metal and glass surfaces and the effect of gum rosin was investigated by looking at touch and hard drying times, adhesion to metals and gloss changes. Compared to the benzoic acid modified resin (RA-BA), gum rosin modified resin (RA-GR) exhibited remarkable positive effects on the paint with a better adhesion to the metals, and short drying times without any loses in the glosses. 相似文献
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The fatty acid composition of tobacco seed oil revealed that the oil is rich in unsaturated fatty acids, having linoleic acid (71.63%), oleic acid (13.46%) and palmitic acid (8.72%) as the most abundant unsaturated and saturated fatty acids respectively. So the tobacco oil was characterized as semi-drying type on the basis of fatty acid composition. The synthesis of alkyd resin was carried out by alcoholysis or monoglyceride process using an alkali refined tobacco seed oil, pentaerythritol, cis-1,2,3,6-tetrahydrophthalic anhydride along with lithium hydroxide as catalyst. The alkyd resin so prepared was found to be bright and of low color with high gloss. The drying and hardness properties and adhesion of the tobacco seed oil derived alkyd resin were also found a bit superior to those of other alkyd resins of the same oil length. In addition, the water and acid resistance of the said alkyd was also found comparable to the other alkyds. 相似文献
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Vilas D. Athawale 《Journal of Dispersion Science and Technology》2013,34(7):1014-1022
Alkyd resins were synthesized from different ratios of sardine fish oil and soybean oil. Three alkyd resin samples were styrenated. The styrenated alkyd resins and alkyd resins were subsequently converted into the polyurethane dispersions. The physicochemical properties, such as iodine value, saponification value, and specific gravity were determined. Infrared spectroscopy and nuclear magnetic resonance techniques were used for structural elucidation of newly synthesized resins. The coating properties, such as adhesion, flexibility, scratch hardness, pencil hardness, impact, solvent, and chemical resistance were evaluated. Thermogravimetric analysis was used to investigate the thermal stability of alkyd resin and polyurethane dispersions. Cost effective volatile organic components (VOC) compliant coatings for various applications can be synthesized successfully by partly replacing soybean oil with commercially available, inexpensive sardine fish oil. 相似文献
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Fatty acid-based alkyd resins prepared with different amounts of glycerol and pentaerythritol were characterized. Sacha inchi oil and linseed oil (comparative purposes) were used as fatty acids’ sources. FT-IR and 1H NMR spectroscopy were done for alkyd structural verification. Alkyd resins were evaluated through physico-chemical (colour, density, viscosity) and thermal characterization. Film coating performance (drying, hardness, chemical resistance) was also studied. The oxidative crosslinking time tendency was corroborated by the quartz crystal microbalance (QCM) technique. Alkyd resins obtained with fatty acids from sacha inchi and linseed oils had similar properties. Results indicated that lighter resins can be obtained from sacha inchi oil, whereas pentaerythritol increases viscosity and thermal stability, and retards drying time of fatty-acid based alkyd resins. 相似文献
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Ge Cheng Barnaby W. Greenland Chris Lampard Neal Williams Malkit S. Bahra Wayne Hayes 《Journal of polymer science. Part A, Polymer chemistry》2013,51(18):3964-3974
Novel acid‐terminated hyperbranched polymers (HBPs) containing adipic acid and oxazoline monomers derived from oleic and linoleic acid have been synthesized via a bulk polymerization procedure. Branching was achieved as a consequence of an acid‐catalyzed opening of the oxazoline ring to produce a trifunctional monomer in situ which delivered branching levels of >45% as determined by 1H and 13C NMR spectroscopy. The HBPs were soluble in common solvents, such as CHCl3, acetone, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide and were further functionalized by addition of citronellol to afford white‐spirit soluble materials that could be used in coating formulations. During end group modification, a reduction in branching levels of the HBPs (down to 12–24%) was observed, predominantly on account of oxazoline ring reformation and trans‐esterification processes under the reaction conditions used. In comparison to commercial alkyd resin paint coatings, formulations of the citronellol‐functionalized hyperbranched materials blended with a commercial alkyd resin exhibited dramatic decreases of the blend viscosity when the HBP content was increased. The curing characteristics of the HBP/alkyd blend formulations were studied by dynamic mechanical analysis which revealed that the new coatings cured more quickly and produced tougher materials than otherwise identical coatings prepared from only the commercial alkyd resins. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3964–3974 相似文献
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酚醛树脂分子量及分布的表征方法有很多,如蒸气压渗透法(VPO)、气相色谱、高压液相色谱和凝胶渗透色谱等,但由于酚醛树脂存在众多异构体,这些方法均有一定限制性.场解吸质谱(FD-MS)方法的特点是只给出样品固有组分的分子峰,不产生碎片离子峰,用于酚醛树脂的表征,可以直接得出树脂所有固有组分的分子离子峰值,及树脂不同缩合度组分的相对含量,非常适用于组份繁多的酚醛树脂的的分子量及分布表征研究.以苯酚、甲酚及甲醛等原料分别制备了Resole型苯酚-甲醛树脂、Novolac型苯酚-甲醛树脂、Novolac型甲酚树脂及混酚-甲醛树脂,利用FD-MS对制备的几种不同类型酚醛树脂的分子量及分布进行了研究.结果表明,通过FD-MS谱图分析还可以得到树脂缩聚程度、原料种类、树脂特性等信息,对于鉴别及剖析各种类型酚醛树脂方便有效. 相似文献