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991.
992.
Nicholas Yafrate Jason DeJong Don DeGroot Mark Randolph 《Canadian Metallurgical Quarterly》2009,135(9):1179-1189
The undrained remolded shear strength of soft clays is of importance in geosystem design, particularly for offshore structures. Common methods to estimate remolded shear strength, such as correlations with cone penetration data, direct measurement with an in situ field vane shear device, and laboratory measurements, produce varied results and can be particularly costly and time consuming. Full-flow penetrometers (T-bar and Ball) provide an alternative rapid method to estimate remolded shear strength and soil sensitivity through remolding soil by repeated cycling of the penetrometer up and down over a given depth interval. The cyclic penetration resistance degradation curve inherently contains information regarding remolded strength and sensitivity. The objective of this paper is to assess the ability of full-flow penetrometers to predict remolded strength and soil sensitivity, and to develop a suite of predictive correlations in which these properties can be estimated in the absence of complementary laboratory or in situ test data. To accomplish this, full-flow penetration profiles and cyclic tests were performed at five well characterized soft clay sites, which together represent the broad range of soils in which the penetrometers will be often used. A previously developed model for the reduction in penetration resistance with cycling is modified to predict the entire degradation curve, including the remolded penetration resistance using only measurements obtained during initial penetrometer penetration and extraction. Using field vane shear strength as the reference measurement, correlations are developed to predict soil sensitivity and remolded shear strength based solely on full-flow penetrometer data, which is particularly useful in site investigation programs where site specific data are not yet available or are sparse. Finally, the usefulness of these relationships is demonstrated by implementing them for two additional soft clay sites. 相似文献
993.
Various straight-chain unsaturated fatty acids from C14 to C24 were evaluated for their ovipositional repellency against gravid females of the southern house mosquitoCulex quinquefasciatus Say, and the relationship between the structures of the fatty acids and their ovipositional repellency was determined. A double bond withZ configuration was prerequisite for an unsaturated fatty acid to be highly repellent;E isomers were less active or even inactive. No relationship was found between the repellency and the number of double bonds in the unsaturated fatty acids. In C18 monounsaturated fatty acids, (Z)-9 acid was more active than (Z)-11 and (Z)-6 acids, indicating that a double bond at the 9 position rendered an acid highly repellent. Among (Z)-9-alkenoic acids of different chain lengths, the most repellent was C18 acid which was also more active than (Z)-11-C20, (Z)-13-C22, and (Z)-15-C24 acids. Oleic[(Z)-9-octadecenoic]acid, which met all these criteria, was the most ovipositionally repellent among the unsaturated fatty acids tested.Diptera: Culicidae. 相似文献
994.
In this paper, three bio-based unsaturated polyesters were synthesized from itaconic acid and different diols which could be derived from renewable resources. Their chemical structures were confirmed by FT-IR, 1H NMR and acid value as well as hydroxyl value. Waterborne UV curable networks based on these polyesters were manufactured and their mechanical properties, thermal stability and coating properties including pencil hardness, flexibility, adhesion, water resistance and solvent resistance were investigated. Results showed that the UV-cured polyester coatings exhibited high hardness, good water resistance and solvent resistance. The coatings reported in this paper combined the merits of bio-based materials, UV-curing process and water distribution. 相似文献
995.
996.
氢氧化铝含量对聚酯/玻璃纤维复合材料阻燃性能和力学性能的影响 总被引:1,自引:0,他引:1
通过熔融混炼和模压成型工艺,制备含氢氧化铝(ATH)的干式不饱和聚酯/玻璃纤维(UP/GF)共混复合材料。采用氧指数法(LOI)和垂直燃烧法(UL94)表征UP/GF复合材料的阻燃性能,采用DMA研究UP/GF复合材料的动态力学性能,采用静态力学方法研究UP/GF复合材料的冲击和弯曲性能。结果表明:UP复合材料中,ATH的含量在25%时,既能够满足V—0级阻燃级别,氧指数值为28.7%,且材料的冲击和弯曲强度分别为5.66kJ/m2和58.72MPa,同时也有较好的动态力学性能。 相似文献
997.
孔晋峰;杜瑞奎;刘亚青 《中国塑料》2009,23(4):41-43
本文研究了超临界二氧化碳对不饱和聚酯树脂固化反应的影响。结果表明超临界二氧化碳能够使不饱和聚酯树脂体系的固体时间有明显的缩短,达到原来固体时间的53.8%。随着超临界二氧化碳的加入,双键反应率有明显降低,但是双键反应率并没有随着压力的升高继续减小。 相似文献
998.
This research examined the remedial effect of Ca on H- and Al- depression of willow (Salix viminalis L. 78183) growth. A greenhouse experiment was conducted with willow cuttings for 3 and 30 days in two ammonium nutrient solutions, one at pH value of 5.0 and another at 3.8. Nutrient solutions at pH 5.0 were: no Ca additive (NS); 2.75 mol m-3 Ca(H2PO4)2 (NSCaP); 2.75 mol m- 3 CaCl2 (NSCaCl2). Nutrient solutions at pH 3.8 (NSA) were: no Ca additive (NSA), 2.75 mol m-3 CaCl2 (NSACaCl2), 2.75 mol m-3 Ca(H2PO4)2 (NSACaP); 0, 0.26, 0.78, and 1.56 mol m-3 of Al (Al0, Al1, Al2, Al3) were added to each NSA treatment. Tree growth was best with NSCaCl2 over 3 days, but equal the other treatments at 30 days. Over 3 days, the NSACaCl2 treatment (pH 3.8; Al0) resulted in greater growth than occurred in NSA and NSACaP, but the responses of plant parts were different. Root growth (weight and length) in the presence of increasing Al was reduced in the NSA treatments but improved with the addition of CaCl2 and Ca(H2PO4). Total tree growth for 30 days was lowest in NSA, but highest in NSACaCl2Al0 and NSACaPAl0. Calcium in either Cl or PO4 form increased willow growth by partially reducing the depressive effects of H and Al, and increasing plant nutrient concentrations. Leaf weight, root length, and tissue dry weight, hydration, and several other parameters measured were significantly associated with solution calcium-aluminum balance (CAB) (CAB = Log Ca/Al, molar concentrations). The use of the term calcium-aluminum balance might be useful in predicting tree performance under acid conditions. 相似文献
999.
松香改性不饱和聚酯树脂的合成研究 总被引:11,自引:0,他引:11
松香与丙烯酸加成反应后代替邻苯二甲酸酐合成不饱和聚酯树脂具有放热温度低,收缩变型小的优点,有利于玻璃钢产品的加工成型设计。 相似文献
1000.
崔益华 《玻璃钢/复合材料》1999,(5):30-31
通过添加不同含量的低轮廓添加剂,运和比重法测定了S-602树脂的固化收缩率,分析了LPA对S-602树脂工艺性能和力学性能的影响。 相似文献