Recent advances in the use of star polymers in coatings

The synthesis of methacrylate stars by an arm-first process using ethylene glycol dimethacrylate as the core-forming material is described. The level of free arm is an indicator for the extent of termination during the preparation. Using 0.2% (mole basis) of catalyst on initiator instead of higher concentration is helpful. Modifiers for the anion catalyst used in group transfer polymerization (GTP) can be used to reduce termination. Clarity of the two-phase blends with polyester polyol and isocyanate crosslinking agent depended on star composition, hydroxyl-number (OH#) and star level. Recently, benzyl methacrylate has been introduced into this technology to give improved film hardness and clarity with cycloaliphatic polyester coreactants. This permits use of 25–30% star to give fast dry and improved hardness/flexibility balance while also allowing the application at less than 3.5 Ib/gallon of solvent.     

Polyurethane networks from polyols obtained by hydroformylation of soybean oil

BACKGROUND: Vegetable oil‐based polyols are a new class of renewable materials. The structure of oil‐based polyols is very different from that of petrochemical polyols, and it is closely related to the structure of oils. The objective of this work was to analyze the structural heterogeneity of soy‐based polyols and its effect on the properties of polyols and polyurethanes. RESULTS: A series of polyols with a range of hydroxyl numbers were prepared by hydroformylation and partial esterification of hydroxyls with formic acid. Polyols were reacted with diphenylmethane diisocyanate to obtain polyurethanes of different crosslinking density. Gelation was simulated using the Monte Carlo method with a calculated distribution of functionalities for each polyol. CONCLUSIONS: Most polyols are powerful crosslinkers since weight average functionality varied from 5 to 2.5 resulting in gel points from 53 to 83% conversion. Heterogeneity of polyols had a negative effect on mechanical properties of rubbery polyurethanes and this should be taken in account when designing polyols for flexible applications. This effect was not pronounced in glassy polyurethanes. Copyright © 2007 Society of Chemical Industry     

磷腈类催化剂研究进展

介绍了几种磷腈类的开环聚合催化剂,详细描述了无机磷腈盐、有机磷腈盐及氧化磷腈的制备路线,并介绍了这几种催化剂各自的特点。用其合成出的聚合物可克服目前KOH催化聚合物相对分子质量较小、分布宽、不饱和度高等缺点。与双金属氰(DMC)催化剂相比,它具有能使用小分子做起始剂、可直接用环氧乙烷封端以获得伯羟基、聚醚分子的头-尾(H-T)选择率高等优点。     

聚合醇钻井液体系的研究与应用

大斜度定向井钻井施工过程中,使用常规水基钻井液体系钻井,常常出现因井斜角大而引起的高摩阻,给钻柱旋转及起下钻操作带来困难。对聚合醇钻井液体系进行了试验研究,结果表明,钻井液流变性及滤失量变化很小,抗老化性能提高,抗温达到 12 0℃,降摩阻率达 5 0%。现场应用表明,润滑性好,钻井液中粘土的水化膨胀被抑制,具有较强的抑制防塌作用;岩心渗透率提高 2 0%,达到 87.3%,对油气层有较好的保护作用。结合在文3 3- 196井的现场应用,提出这种新型钻井液体系特别适用于大斜度定向井、复杂井和探井。     

影响聚醚型异氰酸酯预聚体储存稳定性的因素

采用聚醚多元醇和甲苯二异氰酸酯合成了聚醚型异氰酸酯预聚体.通过调整反应物的最佳配比,选择适当的酸性阻聚剂合成了性能良好、储存稳定的预聚体,同时对影响预聚体储存稳定性的因素进行了讨论.     

建筑用聚异氰脲酸酯泡沫的研制

以聚醚多元醇,聚酯多元醇,多异氰酸酯PAPI,复合催化剂,发泡剂HCFC－141b等为原料,制备了用于建筑隔热板材的组合聚醚主性聚异氰脲酸酯（PIR）泡沫,该组合聚醚具有较好的贮存稳定性,泡沫制品的密度约38kg/m^3,压缩强度约222kPa ,拉伸强度约256kPa,导热系约0.019W/(m.K),阻燃性能符合GB8624 B2级,尺寸稳定性良,产品性能与国外同类产品相当,讨论了催化剂等因素对泡沫性能的影响,该产品主要用于建筑用夹心板材。     

供热管道保温用的全水发泡聚氨酯泡沫

采用氨基酚类起始剂 ,合成出一种含苯环的聚醚 ,并通过选择适当的辅助聚醚多元醇、泡沫稳定剂、催化剂等原料 ,调配出一种全水发泡硬质聚氨酯泡沫塑料配方体系。所制得的泡沫塑料其密度约为 5 8kg/m3 ,压缩强度 0 .2 5 9MPa ,导热系数 0 .0 2 85W / (m·K) ,在 130℃ 96h线性收缩率为0 .82 % ,重量损失率为 0 .6%。它可应用在城市集中供热管道的保温上     

低碳糖及其相应多元糖醇的折光分析法研究

用折光分析法测定水溶液中五碳糖(木糖、阿拉伯糖)、五碳糖醇(木糖醇、阿拉伯糖醇)、六碳糖(葡萄糖)、六碳糖醇(山梨醇、甘露醇、半乳糖醇)的含量,做了方法回收率实验和相对于各物种常规分析方法的对照实验.得出30℃时上述糖和糖醇水溶液的重量百分浓度(m/V)与溶液折光率的定量关系式为w%=(n-1.3330)/0.0014.实验结果与常规分析法结果可很好吻合,回收率达99%～101%.方法简便、快速、准确.用于木糖醇结晶母液中糖和糖醇总量测定,结果满意.     

Effect of nucleating agents on synthesis of CoNi alloy particles via polyol process

CoNi alloy particles were synthesized via the polyol process using nucleating agents such as copper (II) acetylacetonate and K₂PtCl₄. The phase, morphology, mean size, and magnetic properties were evaluated using X-ray diffractometry, field emission scanning electron microscopy, and a vibrating samples magnetometer. At [Cu]/[Co+Ni]=1×10⁻⁶, the size of the CoNi alloy particles was approximately 320 nm. When the nucleation molar ratio [Pt]/[Co+Ni] was 8×10⁻⁵, the size decreased to 95 nm. This indicates that K₂PtCl₄ is a more effective nucleating agent for controlling the size of CoNi nanoparticles at the tens to hundreds of nanometers scale. The magnetic properties showed that the CoNi alloy particles are typical soft magnetic materials. The coercivity of CoNi alloy particles prepared by using K₂PtCl₄ as a nucleating agent was higher than of particles prepared by using copper (II) acetylacetonate.     

纤维素催化氢解制取多元醇的研究进展

化石资源日益减少和使用化石资源带来的气候与环境问题促使人们将目光转向可再生的生物质资源。由生物质资源制备高附加值的化学品已成为国内外的研究热点。通过催化氢解将纤维素转化为多元醇化学品是一种可行的手段。本文总结了由纤维素氢解制备多元醇的最新研究进展,重点介绍了纤维素转化为山梨醇/甘露醇、异山梨醇和小分子多元醇（丙二醇和乙二醇）的催化剂体系以及可能的转化途径。最后分析了该领域存在的问题和今后的研究趋势。