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新型生物材料多聚羟基烷酸的开发与应用 总被引:4,自引:0,他引:4
综述了新型生物材料多聚羟基烷酸开发研究的历史与现状,重点介绍了多聚羟基烷酸生产和应用中取得的成果与存在的问题,并展望了这一新材料的发展趋势与应用前景。 相似文献
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简要介绍了聚羟基烷酸酯(PHAs)的结构、理化性质及其作为载体进行载药微球制备的主要技术(溶剂挥发法、喷雾干燥法、超临界流体法、纳米沉淀法、冷压法),并探讨了聚羟基烷酸酯缓释微球的体外释药机理,展望了今后的研究方向. 相似文献
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聚乙烯亚胺-松香改性聚羟基酸酯类超分散剂的研发 总被引:1,自引:0,他引:1
以松香和12-羟基月桂酸为原料合成溶剂化部分。12-羟基月桂酸在160℃-180℃时用二甲苯为溶剂,在催化剂和氮气保护下反应18小时,生成N=6聚羟基酸酯链。树脂酸与聚羟基酸酯的酯化反应温度为200℃~205℃,氧化二丁基锡作催化剂生成松香改性溶剂化链;再与高分支聚乙烯亚胺(分子量1200)反应合成标题化合物。此分散剂应用于高固体颜料浓缩物(颜料含量40%-60%)在有机溶剂中的分散取得了很好的效果。 相似文献
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目前,国内外工业上脂肪酸的分离主要有分馏法、尿素法、乳化法、溶剂法和现行的压榨法等方法。分馏法目前还只能把碘价相当于商品二级硬脂酸的原料分离成为商品一级和三级硬脂酸。尿素法和农业化肥争原料。乳化法尚只能适应于含不饱和脂肪酸成分多,碘价高的原料,多用于精油酸的生产。我们试验、使用乳化法从碘价30左右的皮油酸(饱和酸主要为十六烷酸)分离出碘价6~10的饱和酸。现商品硬脂酸中十六烷酸与十八烷酸的比例是55:45,因此,把上述分离的饱和酸再与极度氢化油分解的脂肪酸配比后,最好的产品碘价只能达到4左右,且不稳定和得率不高,故乳化法还不能生产商品一级硬脂酸。 相似文献
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这种纤维的组织为:以芳香二羧酸和烷撑二醇作为主要成份,另含有摩尔分数为0.5%-1.5%(基于酸组分)R1O(P:O)(OR2)(OR3(式中R1R2R3=C1-5的烷基)和5%-15%(基于酸组分)Cn≤10的脂肪羟基酸,其特性黏度为0.45-0.80,用沸水将纤维处理60min,特性黏度的保护率(R)≤90%,显示最大损耗角正切值的温度(tmax)为60-90℃,例如:将量比为1:2的H3PO4和ε-己内(I) 的 混合物进行酯化制得磷酸酯,再将磷酸酯与PET齐聚物,对苯二甲酸和乙二醇进行缩聚,制得共聚物(Ⅱ),Ⅱ含有摩尔分数为1.0%和H3PO4结构单元和8%的Ⅰ结构单元,特性黏度(以质量比为1:1的苯酚-四氯乙烷的混合物为溶剂,在20℃下测得)为0.59,然后,将II在270℃下熔融纺丝,拉伸,在190℃下热定型,制得强度4.2c/dtex,tmax为68.3℃和R为86.5%的纤维。将这种纤维的针织品用3%(基于纤维)雷索林半GRF溶液在沸水温度下染色60min,其得色量L值为17.0,抗起球额定值(JIS L-1076-1978-A)为5。 相似文献
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以二苯基二氯硅烷和对苯二酚为原料,采用熔融缩聚反应合成了有机硅预聚物,FT—IR证明了其化学结构,研究表明高温、高真空、长时间的反应有利于预聚物分子量的增长;同时利用N—(4—羟基苯基)马来酰亚胺与有机硅预聚物溶液缩合,采用乙酸乙酯为溶剂,吡啶为缚酸剂,制备了马来酰亚胺封端有机硅齐聚物,利用FT—IR,^1HNMR和DSC对其结构进行了表征,利用端基滴定法测定了齐聚物的分子量。 相似文献
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Carol A. Parish Martel Zeldin Jennifer Pratt 《Journal of Inorganic and Organometallic Polymers》2002,12(1-2):31-47
The conformational flexibility of hybrid organo-disiloxane oligomers, which have enzyme-like properties as synthetic acyltransferases and contain aminopyridine groups in various states of protonation, was investigated. Six molecules were studied using the Low Mode:Monte Carlo conformational search method with the MM2* force field and the Generalized Born/Surface Area continuum solvent model for water. An ensemble of low energy structures was generated and used to investigate the dependence of molecular shape and flexibility on protonation. The results, as measured by the number of unique conformations, the end-to-end or longest intramolecular distance and the radius of gyration of the conformational point cloud, indicate that the number of protonated pyridines plays a significant role in the overall molecular shape; i.e., molecules with multiple pyridinium ions are, on average, significantly larger, less flexible and more extended than molecules without charge. 相似文献
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D. J. Bullock J. D. Cosgrove B. C. Head T. J. Lewis E. J. Marshall D. Wason B. M. Watson 《Propellants, Explosives, Pyrotechnics》1980,5(5):125-128
In the poor solvent acetone/ethanol the viscosity of a 3% solution of 12.6% N pyro nitrocellulose is found to be related to the geometric mean of the number average and weight average molecular weights. The fractional increase in the viscosity of such a solution on the addition of lead ß-resorcylate is a function only of number average molecular weight. Once calibration has been made against osmotic pressure measurements and intrinsic viscosity, both number and weight average may be measured rapidly with an accuracy which is no less than that of the osmotic pressure and intrinsic viscosity measurements themselves. 相似文献
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为进一步理解有机溶剂对木质素的提取率以及结构的影响,系统地研究了6种有机醇溶剂(甲醇、乙醇、正丙醇、乙二醇、1,3-丙二醇和1,4-丁二醇)在提取过程中溶剂极性等特性对木质素收率的影响;同时采用SEM(扫描电镜)、GPC(凝胶渗透色谱仪)、NMR等方法进一步探讨了不同醇溶剂对木质素形貌、分子量与官能团等的影响。结果表明,在所研究的6种有机醇溶剂中,极性、碳链长度与羟基数目对木质素收率、形貌、分子量、官能团等具有显著的影响;羟基数相同时,碳链越长、极性越弱,木质素的收率越高,重均分子量相对越大;一元醇溶剂体系提取的木质素中C、H元素的含量随着碳链长度的增长而降低,而二元醇体系中提取的木质素中C、H元素的含量呈相反的变化趋势;同等碳数的有机醇溶剂随羟基数增多,木质素的收率降低,重均分子量也相应减小。 相似文献
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William A. Dark Robert J. Limpert Jordan D. Carter 《Polymer Engineering and Science》1975,15(12):831-833
It is now possible to do molecular weight distribution of polymeric material almost as fast as you can put them in solution. μSYRAGEL® has opened a new era in the determination of molecular weight distribution of polymers. With operational efficiencies of 800 plates/min., one can obtain a molecular weight distribution in 15 mins. Combining three of the newest advances in liquid chromatography—solvent delivery, septumless injection, and μSYRAGEL—now makes it possible to use molecular weight distribution as a quality control tool in polymerization and fabrication. The reproducibility of the molecular weight distribution is now good enough that overlays can be done from the raw data. The chromatograms can be used right off the recorder. The reproducibility of the weight average and number average molecular weight is 2–3 percent. 相似文献
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A correlation was developed for predicting limiting mutual diffusion coefficients of gaseous and liquid solutes in normal alkane solvents with carbon numbers ranging from 7 to 28 at temperatures to 570 K. The functional form of the correlation is based on the rough hard sphere theory. The parameters needed in the correlation are the molecular weights and hard sphere diameters of the solute and solvent molecules and molar volume of the solvent. The data used in the development of the correlation included 143 measurements with solute/solvent molecular mass ratios ranging from 0.005 to 2.26 and size ratios ranging from 0.3 to 1.3. The average absolute error in predictions was only 6.3%. When the correlation was used to predict literature values for binary n-alkane systems, the average absolute error was 16.7%. 相似文献
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对一种褐煤的直接液化加氢前、后溶剂油进行了1H核磁共振波谱、元素组成和分子量等性质的分析和平均结构参数的计算,研究了加氢前、后溶剂油分子的平均结构。结果显示:加氢处理前、后溶剂油的平均分子式为C17H23S0.004N0.09O0.12和C16H24S0.003N0.03O0.03,加氢前溶剂平均分子的芳碳率fa为0.46,平均分子结构含有2~3个环,其中芳香环为1~2个,环烷环为1个。经过加氢处理后溶剂油分子的平均结构发生较大的变化,溶剂平均分子芳碳率fa为0.37,平均分子结构中含有2个环,其中芳香环1个,环烷环1个,经加氢处理后,溶剂具备了较好的供氢性能。 相似文献
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药物研制过程存在着大量的液–液均相有机反应,合适的反应溶剂能够大幅提高此类反应的反应速率与选择性,从而提高合成效率,提升药物质量。以2,4-二氯-5-硝基嘧啶与对氨基苯腈的芳香亲核反应(SNAr)为研究对象,采用计算机辅助分子设计(computer-aided molecular design, CAMD)的方法进行反应溶剂设计。首先使用量子力学(quantum mechanics, QM)计算的方法获得少量溶剂中的反应速率常数并通过反应动力学模型与溶剂性质关联,然后构建同时考虑选择性和反应速率常数的混合整数非线性规划(mixed-integer nonlinear programming, MINLP)的多目标优化模型,最后采用分解式算法对模型优化求解,实现制药反应溶剂设计的目标。 相似文献