True-spiral angles in diploid and tetraploid native cotton fibers grown at different locations

In this article, data on true-spiral angles in respect to the same 12 cotton varieties grown at different agroclimatic locations and in different crop years in India are presented and discussed. It has been concluded that the values of true-spiral angles are different for different varieties but within a variety remain practically invariant irrespective of the location and environmental conditions of growth. The parameter therefore appears to be genetic in origin. It is believed that this information can be suitably exploited by progressive cotton breeders for evolving high-strength cottons, keeping in view the demand of the modern cotton processing technologies. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 303–310, 1998     

工程塑料与通用塑料注塑工艺的差异

注塑企业最常犯的错误是采用类似聚丙烯的加工方法来注塑各种工程塑料.聚丙烯具有很好的剪切流变特性,不介意通过细小的潜伏式浇口或针式浇口喷注成型.它对熔体和模具的温度也不挑剔.快速填充、低温模具都能很好的实现注射成型.     

Damage mechanism and residual strength at different impact locations for composite bonding scarf repairs

Composite scarf repair has been widely applied as a high efficiency choice for force transferring in aircraft structure repair. The damage tolerance and resistance to low velocity impact are significant for structure design especially for primary load-bearing structures. Some literature studied impact damage and resistance for scarf topology repairs or joints. However, it is not clear that which location in bonded area is the most sensitive to the impact load. The impact location effect on impact damage mechanisms and capacity of tension after impact (TAI) are studied in this paper. Central point in bonded zone has the strongest influence on impact damage. The scarf adhesive film fractured from the feather tip of the back side and oriented to the weakest material. The load capacities of tension after impact at different locations coincide with the adhesive damage area ratio. The finite element model based on CZM (Cohesive Zone Model) is built. And the simulation results validate that central location has the most sensitive characteristic to impact damage and TAI capacity.     

Weatherability of rigid vinyl siding

Vinyl siding is described as a product in the early maturity stage of business development. The competitive position of rigid vinyl siding vis-a-vis other products is discussed. Total weathering exposures from point sources not usually thought of are reviewed. Methods of control for weathering caused changes as well as resistance evaluation are covered. The impact on the industry of the voluntary product standard PS55-72 is mentioned.     

核磁共振技术在HDPE耐候性研究中的应用

本文介绍了核磁共振的基本原理及特点，用＾１３Ｃ ＮＭＲ谱分析法对ＨＤＰＥ老化机理，晶态变化进行了分析。     

炭黑填充导电涂层耐候性研究

采用环氧树脂E-51为基体材料制备导电涂层材料,通过改变炭黑添加量、固化时间、固化温度、固化剂当量、稀释剂含量,考查其电阻率的变化来表征其耐低温、耐湿热以及耐老化性能。研究结果表明,当炭黑含量21%,稀释剂含量20%,固化剂当量0.8,固化温度80℃,固化时间4 h时,导电涂层材料具有最佳的耐老化性能。这种方法制备的导电涂层材料的耐老化与耐低温性能较好,电阻率稳定,并且通过添加柔性稀释剂可大幅提高材料的耐湿热性能。     

钛白粉耐候性的快速表征

用175℃恒温下的浓硫酸溶解经过无机包覆的钛白粉,以过氧化氢比色法进行定量分析,建立了快速表征钛白粉耐候性的方法。标准样品选择光谱纯二氧化钛,对测量条件、曲线配制、影响因素进行了试验和探讨。该方法精密度较高,相对标准偏差（n=8）均在1%以下。     

The effect of chemical exposure on the EMI shielding of conductive plastics

The electrical properties of a number of filled plastics were examined after subjecting the materials to exposure to isopropyl alcohol, a 25°C detergent/water solution, an 80°C detergent/water solution, and at various chemical plant sites. Compositions which contained metal fillers maintained their conductivity only when a high temperature thermally stable polymer was used as the polymer matrix, while compositions which are made conductive through a carbon filler network maintained their conductivity under most of the exposure conditions examined even when low temperature polymers were used as matrices.     

高耐候性聚硅氧烷涂料的研制

以高硅含量、高固低黏的改性聚硅氧烷树脂为基础,制备了聚硅氧烷涂料,并用氨基硅烷固化,制得改性聚硅氧烷涂层。考察了氨基硅烷固化剂用量和种类对聚硅氧烷涂层老化失光和变色行为的影响规律。研究结果表明:在改性聚硅氧烷树脂固定不变的情况下,可通过固化剂的种类和用量调节聚硅氧烷涂料的耐老化性。聚硅氧烷涂料具有远优于聚氨酯涂料的耐老化性和耐盐雾性,可作为氟碳面漆的理想替代品。     

聚丙烯材料耐候性能研究进展

综述了聚丙烯材料耐候性能的影响因素,主要包括主链结构、残留催化剂及外部环境中的光、热、氧及水汽等;系统分析了聚丙烯的老化机理,主要有热氧老化和光氧老化,两者都与自由基链式反应有关;最后概括了改善聚丙烯材料耐候性能的方法,主要是添加有机助剂、无机纳米材料和选择合理的加工方式。     

磺化聚苯硫醚砜膜的耐候性

借助X射线衍射(XRD)、傅立叶变换红外光谱(FTIR)、热重(TG)分析及机械拉伸等测试技术研究了磺化聚苯硫醚砜膜的微观结构及耐候稳定性能。结果表明,XRD图谱及FTIR图谱证实了膜的微观结构;根据TG分析计算得到的磺化聚苯硫醚砜膜的磺化度为52%,与给定的磺化度(50%)基本吻合;此外,磺化聚苯硫醚砜膜还表现出了很好的热稳定性及力学稳定性,膜中硫醚键缓慢氧化成砜基可能是热稳定性和力学稳定性得以改善的微观结构原因。     

聚乙烯材料耐候性能研究进展

综述了聚乙烯材料耐候性能的影响因素,包括自身结构因素及外部环境因素;系统分析了聚乙烯的老化机理,主要有热氧老化、光氧老化和环境应力开裂,其中前两者都与自由基链式反应有关;最后概括了改善聚乙烯材料耐候性能的方法,主要为添加抗氧剂、光稳定剂和控制加工工艺。     

增塑剂对脲醛树脂模塑料性能的影响

以尿素、甲醛及木质纤维素等为原料,通过添加聚乙二醇6000、聚乙烯蜡、磷酸三苯酯和对甲苯磺酰胺4种增塑剂,研究其对脲醛树脂模塑料(UF)流动性能、力学性能的影响,并采用动态热机械分析仪(DMA)分析了脲醛树脂模塑料的动态力学性能。研究表明,4种增塑剂均能明显提高脲醛树脂模塑料的流动性能;聚乙二醇6000对脲醛树脂模塑料的流动性能和力学性能增强最为明显,并增强了脲醛树脂模塑料的耐热性能,添加的质量分数为1.0%~3.0%时脲醛树脂模塑料的综合性能最优,弯曲强度为80~86 MPa,冲击强度为1.63~1.75 kJ/m2,流动性能为76~83 mm。     

Protein and oil content of soybeans from different geographic locations

Data on soybean yield, protein content and oil content were provided by three crushing companies. There was a definite trend toward lower protein content in soybeans processed and most likely grown in northern versus southern locations (about 34 to 44 N latitude) in 1986–87 (r=0.77). In 1983–86, protein content was generally lower in soybeans processed in Minnesota than in those processed in Indiana and Illinois. Effects of location on oil content and of year on protein and oil content were less clear. Uniform Soybean Tests data over 11 years and four locations (3 in Minnesota, 1 in Illinois) showed significant effects of year on oil content and of location on yield and oil content, but little effect of either on protein content.     

不同发泡剂的硬质聚氨酯泡沫塑料

综述了硬质聚氨酯泡沫塑料中使用的发泡剂。HFC－245fa、HFC-365mfc和戊烷系列碳氢化合物是目前最具竞争力的发泡剂。     

自行车涂层耐候性检测方法探析

结合自行车涂层特点,采用自然曝晒、荧光灯人工气候老化UVA和UVB 3种检测方法检测涂层耐候性,通过分析检测方法和检测结果的差异,选择便宜、快捷、直观的UVB作为自行车涂层的耐候性检测方法。     

乳胶漆的保色耐候性

从乳液品种、颜料体积浓度（PVC）或颜基比、颜填料品种等方面讨论了外墙乳胶漆保色耐候性的影响因素,重点讨论了彩色颜料的品种及其加入方式对外墙乳胶漆保色耐候性的影响。     

高耐候水性氟碳外墙乳胶涂料的研制

简要介绍了高耐候水性氟碳外墙乳胶涂料研制的技术路线、涂料配方等;讨论了涂料组分的作用及影响;通过涂料的检测与应用,展示了其良好的效果与前景.     

提高钛白粉耐候性的工艺研究

钛白粉化学性质非常稳定,应用广泛,未经表面处理的钛白粉颜料具有光化学活性,易产生失光、黄变、粉化等现象,影响钛白粉在不同介质中的应用性能。因此耐候性成为二氧化钛很重要的应用指标。采用二氧化钛紫外光催化罗丹明降解实验,比较SiO_2、Al_2O_3包膜和硅铝复合包膜的效果。结果表明:硅铝复合包膜的效果优于市场上的产品及单独包覆的钛白粉。