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991.
992.
UV-curable hyperbranched polyurethane(UV-HBPU) containing carboxyl groups was synthesized from isophorone diisocyanate(IPDI), diethanolamine(DEOA), polyethylene glycol(PEG-400), hydroxyethyl acrylate(HEA), and 2,2-bis(hydroxymethyl) propionic acid(DMPA). The UV-HBPU was used as a negative-type photoresist for a printed circuit board(PCB). Fourier-transform infrared spectroscopy(FTIR) and proton nuclear magnetic resonance(1HNMR) spectroscopy of UV-HBPUs indicated that the synthesis was successful. Differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA) showed that the thermal stability of the UV-HBPUs decreased as the HEA content increased. The polymer exhibited excellent photoresist properties, and the resolution of circuits based on this negative-type photoresist reached 10 μm. 相似文献
993.
宋远明 《武汉理工大学学报(材料科学英文版)》2014,29(1):93-96
Circulating fluidized bed combustion (CFBC) ash can be used as supplementary cementitious material for concrete production for its high pozzolanic activity. We investigated the effect of curing conditions on the hydration and performance of CFBC ash-Portland cement system (30: 70, by mass) including hydration products, paste microstructure, linear expansion ratio, chemically combined water content and compressive strength. The results show that tobermorite rather than ettringite is generated under the condition of autoclaved curing. The expansion and mortar strength of the system cured in water is higher than those cured in air at a given age, and the strength and bulk volume may retract under the condition of air curing. In addition, autoclaved curing facilitates the increase of strength gain at early curing ages (the increase rate lowers down in the following ages) and the improvement of system volume stability. It is suggested that sufficient water is necessary for the curing of CFBC ash cementitious system, and autoclaved curing may be considered where volume stability is a primary concern. 相似文献
994.
Enhanced healing of full-thickness diabetic wounds using bioactive glass and Yunnan baiyao ointments
In order to accelerate the chronic wounds healing, we investigated the healing effects of bioactive glass and Yuunan baiyao ointments in streptozotocin-induced diabetic rats. The ointments were prepared by mixing 45S5 bioactive glass powder (16% weight) with Vaseline and different weight percentages of Yurman baiyao. Full-thickness defect wounds were created on the back of 130 SD rats and were randomly divided into 8 groups. The wound healing rates were calculated at 4, 7, 10, 14 and 21 days after surgery. The samples were harvested for further observations. Considering the wound closure rate, group 6 (with 5% Yuunan baiyao) has better wound healing performance than other diabetic groups. The lower inflammatory response was observed by gross observation and confirmed by the results of H&E staining and TEM observation. Besides, the proliferation of fibroblasts, the formation of granulation tissue, as well as the vascularization, were improved in group 6 compared to other diabetic groups. All results suggest that bioactive glass and Yunnan baiyao ointments can accelerate the recovery of diabetes-impaired skin wounds, and comparing to other diabetic groups, group 6 (with 5% Yunnan baiyao) has better healing effect. 相似文献
995.
建立了热固性树脂基复合材料固化过程温度和热应力场分析的数学模型,采用有限元方法,进行了三维非稳态数值求解。通过与已有实验结果的比较,验证了数学模型和计算方法的正确性。获得了3234/T300层合板固化过程中内部温度及热应力分布,分析了保温时间、升温速率、铺层设计等对温度、内部热应力的影响。数值计算结果表明:预固化时间越长,层合板内温度梯度越小,热应力峰值越低;升温速率越大,层合板内温度梯度越大,热应力峰值越大;采用对称铺层可降低层合板内部温度梯度和热应力。 相似文献
996.
在Co-Gd二元系合金体系的热力学优化评估的基础之上,应用CALPHAD ( CALculation of PHAse Diagram)技术,研究此二元非晶合金的玻璃形成能力。本文分析了700 K、800 K时Co-Gd合金中各元素含量对非晶形成能力的影响,预测了非晶形成的最优成分,计算过冷液相中的结晶相形成驱动力。通过与部分实验和非晶共晶点准则的比较可见,本文所做的热力学分析对此二元合金的非晶制备具有一定的理论指导意义。 相似文献
997.
固化淤泥土压缩性试验研究 总被引:1,自引:0,他引:1
淤泥由于含水率高强度低,无法直接作为工程用土。对淤泥进行固化处理,可以实现废弃淤泥的资源化利用。选择常州市武进区废弃淤泥作为研究对象,利用42.5普通硅酸盐水泥作为固化添加剂,通过固化淤泥的单向压缩试验,探讨4种水泥参量变化条件下共24个试样的压缩变化机理,描述水泥添加量对压缩模量的影响,分析其影响规律。通过试验对比分析,可知:同一含水率下,淤泥随着水泥参量的增加,试样压缩性减小;各试样在压缩试验过程中,其压缩变形规律基本一致,荷载达到200kPa时,其压缩性趋于稳定;随着固结压力的不断增加,沉降变形量逐渐减缓,最后趋于收敛;随着水泥参量的增加,同一应力条件下,试样稳定需要的时间缩短;淤泥固化效果在水泥参量接近50%时较优,超过此数值,强度虽提高,固化工作经济效益降低。 相似文献
998.
Xiao-qing Niu Ji-chun Chen 《北京科技大学学报(英文版)》2014,(10):1028-1032
The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100℃ causes anhydrite to disintegrate into smaller crystals, accompanied by a slight in- crease in d-spacing. Without calcination and modification, the solidification time and curing time of anhydrite are 15 and 77 h, respectively. After the treatment, however, the solidification time and curing time are shortened significantly to 9.5 and 14 rain, respectively. The com- pressive and flexural strengths of hydration products made from the treated anhydrite reach 10.2 and 2.0 MPa, respectively. The much shorter solidification and curing time make it possible to use anhydrite as a building and construction material. 相似文献
999.
Low-temperature sintering and properties of LTCC (low temperature co-fired ceramics) materials based on CaO-BaO-Al2O3-B2O3-SiO2 glass and various fillers such as Al2O3, silica glass, christobalite, AlN, ZrO2, MgO-SiO2, TiO2 were investigated. The results show that densification, crystallization, microstructures and dielectric properties of the composites are found to strongly depend on the type of filler. The densification process of glass/ceramic composites with various fillers is mainly from 600 ℃ to 925 ℃, and the initial compacting temperature of samples is 600 ℃. The initial rapid densification of samples starts at its glass softening temperature. LTCC compositions containing Al2O3, silica glass, AlN and MgO-SiO2 fillers start to have the crystallization peaks at 890, 903, 869 and 844 ℃, respectively. The crystallization peaks are believed as correlated to the crystallization of CaAl2SiO8, β-SiO2, Ca2Al2SiO7 and β-SiO2. The composite ceramic with Al2O3, silica glass and TiO2 ceramic have a better dense structure and better smooth fracture surface. Sample for Al2O3 has the lowest dielectric loss tanδ value of 0.00091, whereas the sample for MgO.SiO, has the highest dielectric loss tanδ value of 0.02576. The sample for TiO2 has the highest dielectric constant value of 14.46, whereas the sample for AIN has the lowest dielectric constant value of 4.61. 相似文献
1000.
利用顺序互穿法制备了聚甲基丙烯酸甲酯(PMMA)/环氧(EP)互穿网络聚合物(IPNs)。通过差示扫描量热法(DSC)研究了PMMA/EP IPNs的固化反应动力学,用红外光谱法进一步确定了固化反应条件。结果发现,PMMA的加入会延缓EP的固化,固化表观活化能由EP的53.2kJ/mol上升到PMMA/EP IPNs的61.5kJ/mol;在固化工艺条件为45℃/18h+85℃/3h+130℃/3h时,PMMA/EP IPNs体系固化反应完全,能够满足固化工艺要求。 相似文献