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21.
采用实验室小型RIM机制备了一组不同芳香二胺扩链的嵌段聚氨酯-脲(PUU)弹性体,借助于IR、DSC、DMTA、SEM以及拉伸试验等测试手段对其结构与性能进行了研究.通过比较由MDA、DETDA以及CAMDA三种不同活性和结构的芳香二胺扩链剂与二异氰酸酯反应形成的硬链段对RIMPUU弹性体的结构与性能的影响,表明:MDA基RIMPUU中软、硬链段微区界面作用指数很小,微相分离程度却很大,其性能最差;DETDA基RIMPUU弹性体有理想的界面作用指数,以及适当的微相分离程度,其性能位于三者之中最佳.DMTA研究证实在一定的温度范围内DETDA基RIMPUU的模量稳定性最好. 相似文献
22.
一种西佛碱侧链型液晶高分子的合成及表征 总被引:2,自引:0,他引:2
一种西佛碱侧链型液晶高分子的合成及表征邹友思,林国良,姚青青,戴李宗,潘容华(厦门大学化学系厦门361005)关键词联苯,西佛碱,侧链型,液晶高分子,基团转移聚合Finkellnann等提出的柔性基去偶合概念’]已在侧链型液晶高分子的研究中得到了证实... 相似文献
23.
René Grouls Wim van de Laar Henk M. J. Goldschmidt Frits G. van Merode 《Accreditation and quality assurance》2004,10(1-2):41-46
Many medical professionals are involved in patient care processes. For pharmaceutical care this results in many information transfer moments. To provide optimal care, communication and information the transfer should be conducted in a timely manner, fully transparent, complete and relevant. The TRANSFORM project is directed towards the development of a reference information model of the pharmaceutical care chain with the aim to improve the availability (time, place, completeness) and access of pharmaceutical information regarding patients, thereby resulting in continuity and quality of pharmaceutical care, reduction in medical errors and improvement in patient safety through the design of a safer healthcare system. TRANSFORM leads to improved insight into the processes and data transfer points in the pharmaceutical chain of care. Focussed on laboratory medicine and pharmacy, the implementation of the integration of laboratory test and pharmacy information may result in major improvements in drug therapy monitoring and guidance (i.e. drug impact monitoring). Because of the overwhelming amount of data generated by this integration of drugs, drug effects and laboratory test results, an online decision support system is warranted.Presented at the 9th Conference on Quality in the Spotlight, 18–19 March 2004, Antwerp, Belgium.The following paper may appear at first sight not to be specifically within the realm of ACQUAL. It has been accepted for publication anyway as it is about reliable handling of data, incl. measurement results, which lead to important decisions (in this case related to a patient). The reliability of handling (a large amount of) measurement results towards a basis for important decisions, is a very important feature of the use of such results.Paul De Bièvre, Editor in Chief 相似文献
24.
通过DSC、X-射线衍射、红外光谱及拉伸试验研究了HDPE与LLDPE、HDPE与LDPE之间的晶相相容性.结果表明,链结构相近的HDPE和LLDPE的晶相相容性好,能形成共晶;而链结构差异较大的HDPE和LDPE的晶相相容性较差,倾向于分别结晶,但有部分链段被对方的晶区夹持.不论是支化度大的LDPE链段插入以HDPE为主的晶区,还是支化度小的HDPE链段插入以LDPE为主的晶区,都可破坏晶区的规整性.共晶的形成使共混物的熔点、结晶度、晶粒体积等低于两组份的线性加和,而力学性能,尤其是断裂伸长率,则显著提高,呈协同效应. 相似文献
25.
A new family of hydrophobically modified polyacrylamides was synthesized via copolymerization of acrylamide (AM) and anionic surface-active monomer of acrylamide-type, sodium 2-acrylamido-tetradecane sulfonate (NaAMC14S), in aqueous solution. In the copolymerization, by varying various factors, such as the feed ratio of NaAMC14S to AM and the amount of added electrolyte NaCl and initiator, we prepared copolymers NaAMC14S/AM with different block structures. The relationship between structures and hydrophobic association properties of copolymer chains was studied by using fluorescence probe and viscosimetry. Effects of the content and length of the hydrophobic blocks and the total molecular weight on hydrophobic association of the copolymers in pure water and in brine solution were examined, respectively. The results show that in pure water, hydrophobic association of the copolymers was enhanced as the content and length of the hydrophobic block increase. On the other hands, for a given content and length of the hydrophobic block, the hydrophobic association of the copolymers was enhanced as the total molecular weight increases. For all the copolymers studied, the apparent viscosity of their solutions in pure water has a limited value, but the apparent viscosities of the copolymer brine solutions are much higher than that of their corresponding water solutions, and show strong positive salinity sensitivity. Similarly, the hydrophobic association of the copolymer in brine solutions was enhanced as the content and length of the hydrophobic block increase. 相似文献
26.
27.
Khalid Ibrahim Katariina Yliheikkilä Barbro Löfgren Markku Leskelä Jukka Seppälä 《European Polymer Journal》2004,40(6):1095-1104
Four tetradentate nitrogen ligands, viz. dichloro{[N,N′-diphenyl-N,N′-di(quinoline-2-methyl)]-1,2-ethylene diamine} (1), {[N,N′-dioctyl-N,N′-di(quinoline-2-methyl)]-1,2-ethylene diamine} (2), {[N,N′-dibenzyl-N,N′-di(quinoline-2-methyl)]-1,2-ethylene diamine} (3), and (1R,2R)-(−)-N,N′-di(quinoline-2-methyl) di-iminocyclohexane (4), were investigated as novel complexing ligands in iron-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate where ethyl-2-bromoisobutyrate was the initiator in o-xylene at 90 °C. With ligands 1 and 2 the experimental molecular weights increased gradually with monomer conversion. High to moderate conversions (87%, 43%) were obtained in relatively short times (90 min for 1 and 30 min for 2), which indicates an efficient catalyst system, but after these times a dramatic increase in viscosity of the polymerization medium led to loss of control. It is noteworthy that polymerization proceeded in a controlled manner with ligand 1, which has two rather bulky substituents on the N-atom. Such bulky ligands did not work for a copper-based system, where they led to excessive terminations or other side reactions. When the bulkiness of the substituents was significantly increased, as in ligand 3, a decrease in polymerization rate and loss of control occurred. Ligand 4 was less efficient than the other ligands, probably because the ethylene bridge was replaced by cyclohexane bridge. 相似文献
28.
G. Sivalingam R. Karthik Giridhar Madras 《Journal of Analytical and Applied Pyrolysis》2003,70(2):631-647
The thermal degradation/modification dynamics of poly(-caprolactone) (PCL) was investigated in a thermogravimetric analyzer under non-isothermal and isothermal conditions. The time evolution of the molecular weight distribution during degradation was studied using gel permeation chromatography. Experimental molecular weight evolution and weight loss profile were modeled using continuous distribution kinetics. The degradation exhibited distinctly different behavior under non-isothermal and isothermal heating. Under non-isothermal heating, the mass of the polymer remained constant at initial stages with rapid degradation at longer times. The Friedman and Chang methods of analysis showed a 3-fold change (from 18 to 55–62 kcal mol−1) in the activation energy from low temperatures to high temperatures during degradation. This suggested the governing mechanism changes during degradation and was explained using two parallel mechanisms (random chain scission and specific chain end scission) without invoking the sequential reaction mechanisms. Under isothermal heating, the polymer degraded by pure unzipping of specific products from the chain end. 相似文献
29.
The ionic transport process in polymer electrolytes (such as polyethylene oxide) wassimulated numerically on a two dimensional square lattice where charge carriers areaccommodated by the lattice sites connected randomly with available bonds to represent theamorphous chain configuration. Following the dynamic bond percolation theory(DBPT),the chainmotion contribution to the ionic conduction was incorporated via periodical renewal of the randombond configuration. To check and extend the prediction made by DBPT employing global abruptbond renewal,spatial correlation of the bond reassignment was introduced to the system by: 1)regional bond renewal and 2) organized bond motion. It is found that the difference between thediffusivities simulated involving regional bond renewal and those of DBPT becomes negligiblewhen the bond renewal rate approaches the carrier hopping rate. 相似文献
30.
直链醇链长对层状液晶结构与稳定性的影响 总被引:8,自引:4,他引:8
作为助表面活性剂,直链醇在层状溶致液晶的制备中是非常重要的。本文以层状液晶的相行为和小角度X射线衍射测量,研究了直链醇链长对层状液晶结构与稳定的影响。 相似文献