FRW阻燃胶合板的DMA分析

目前世界范围内木材资源短缺的情况日益加剧,发展人造板工业已成为世界各国解决木材资源严重不足的重要途径.其中,胶合板作为室内装饰的主要材料,其产量和需求量都在急剧增长.我国胶合板产量从1980年的33.00万m3增长到2004年的2 098.62万m3,呈现大幅度增长的趋势(张文标等,2000).但由于普通胶合板具有易燃性,在许多领域的应用上受到限制.因为一旦发生火灾,不仅造成重大的经济损失,而且往往会发生人员伤亡.1950-2003年全国共发生火灾4 177 730起,直接经济损失2 434.525 1亿元,因火灾死亡174 855人,受伤329 352人.     

Hygrothermal effect of bamboo by dynamic mechanical analysis

Dynamic properties of bamboo, Phyllostachys pubescens, with moisture content (MC) ranging from −130 to 130°C, were studied by dynamic mechanical analysis (DMA). The results showed that the hygrothermal effect on dynamic mechanical properties was negative. The storage modulus decreases with increasing temperature and MC, and glass transition temperature decreases with increasing MC. The glass transition temperature and tan delta of bamboo were 30.5°C, 0.02 and 10.61°C, 0.04, when MC was 10% and 34%, respectively. __________ Translated from Journal of Nanjing Forestry University (Natural Sciences Edition), 2006, 30(1): 65–68 [译自: 南京林业大学学报(自然科学版), 2006, 30(1): 65–68]     

利用动态热机械分析仪对低毒脲醛树脂性能的研究

利用动态热机械分析(DMA)对不同固化体系下3种低毒UF树脂固化物的力学性能进行了研究。试验结果表明:不同固化体系下3种低毒UF树脂固化物的力学性能不同。对于UF-1,使用氯化铵为固化剂,树脂交联固化程度要高于其他两种固化体系,固化物储存模量最高。对于UF-2来说,在3种固化体系下,固化物的储存模量之间相差不是很大。对于UF-3,在第2种固化体系条件下,固化物的储存模量最大,损耗角正切最小。因此在实际应用过程中,针对不同的低毒UF树脂胶黏剂需要选择与之相匹配的固化体系,才能达到最佳的固化效果和胶接强度。     

The development and comparison of bio-thermoset plastics from epoxidized plant oils

This study investigates the development of thermoset plastics from plant-based oils (e.g., linseed, soybean, cottonseed, oilseed radish, and peanut oils) using an optimal process of solvent-free epoxidation. The epoxidation of plant oils can be accomplished economically by reacting the double bonds of fatty-acids with hydrogen peroxide. During the solvent-free process catalyzed by the ion-exchange resin, we observed that the influence of several variables was important: the molar ratio of hydrogen peroxide to unsaturation, acetic acid to unsaturation, and temperature. The epoxidation of plant oils was determined from the liquid mixture and the composite matrix by thermal and spectroscopic analyses. Compounds with a higher double-bond (iodine) value showed higher oxirane oxygen percent and selectivity, and a higher hydroxyl value because of a greater possibility of attack by solutions causing side reactions. Lower iodine values indicated fewer epoxy groups and selectivity, and a lower hydroxyl value. Benzyl pyrazinium hexafluoroantimonate (BPH) yielded good thermal curing properties; as little as 1% added to the plastics produced light-weight composites. Epoxidized linseed oil promises the highest modulus and impact resistance due to the largest number of double bonds to contribute more epoxy groups and the large proportion of linolenic acids to produce epoxy groups rapidly.     

Study on Technology of Black Silkies Chicken Semen Freezing by DMA Pellet

The aim was to explore the effects of different kinds of dilution and thawing devices on the N,N-dimethylformamide (DMA) pellet frozen semen of Black Silkies. Firstly,the motility and fertility of the frozen semen thawed by different dilutions were compared;Then,the motility of the frozen semen was compared when the pellets were thawed using different tube and different number.Finally,the motility and fertility of the sperm thawed by three kinds of thawing devices (thermostat water bath,hotfunnel and hotplate ) were tested. The results showed that:①There was similar order of the sperm motility and fertility in the different dilution groups (LR > F > B > L),and there was significant difference among those groups (P < 0.05).②The motility was the best when the frozen semen was thawed with large thin-wall glass tube at 60℃.③The best temperature range of the 3 devices was different. The highest motility for thermostat water bath was 50 to 60℃ (0.51 to 0.59),and thermostat hotfunnel was 40 to 45℃ (0.42 to 0.46),while thermostat hotplate was 50 to 55℃ (0.61 to 0.63).There was no significant difference of the motility in the optimum temperature range for each device (P > 0.05).④The fertility of the different devices in their best thawing temperature was 26.91% (55℃,thermostat hotplate),23.08% (60℃, thermostat water bath), 20.93% (40℃, thermostat funnel),respectively,and there was no significant differences among those groups (P > 0.05).Therefore,the efficiency thawing condition for the Black Silkies frozen semen was the LR diluent,DMA cryoprotectant,pellet freezing,thawed in the thermostat hotplate at 54.9℃.     

不同竹龄毛竹增强相的动态热机械研究

利用动态热机械分析仪检测不同竹龄的毛竹,实验证明:在常温条件下,毛竹竹青的刚性随毛竹竹龄的增加而增加,当毛竹到了一定竹龄后,其竹青的刚性渐渐趋于稳定。一般5~6年生的成熟毛竹的竹青部分的常温存储模量位于10¹⁰Pa(10GPa)数量级以上,一般能满足做为风力发电叶片复合材料中增强相材料的使用。因此,最佳的风力发电叶片复合材料增强相材料是5~6年生的成熟毛竹。     

Effects of storage on the physico-chemical properties of corn tortillas prepared with glycerol and salt

Corn tortillas have a short shelf life due to increased firmness and microbial spoilage. Commercial corn tortillas use carboxymethyl cellulose (CMC) to delay staling; however this gum is expensive when compared to the rest of the tortilla ingredients. Glycerol has been added to bread and wheat tortillas to increase pliability and salt has been shown to mask the flavor of glycerol in corn tortillas. The possibility to reduce staling in corn tortillas by adding glycerol/salt as an alternative to CMC was investigated by monitoring changes in physico-chemical properties during 2 weeks of storage at 25 °C. Molecular and macroscopic changes were followed using thermal and mechanical analysis. During storage an increase in amylopectin recrystallization was observed in all samples. The “freezable” water content of all tortillas decreased over the first 3–5 days of storage with an increase after 7 days, while moisture content and water activity remained constant. Glycerol/salt tortillas exhibited a sharper transition region in the DMA temperature scan suggesting a more homogenous sample. CMC tortillas were significantly stiffer than glycerol tortillas after 14 days of storage. Glycerol/salt combinations may offer at least a partial replacement for CMC since it helped control the stiffness, water homogeneity and distribution during storage.     

ω-3脂肪酸在改善禽蛋营养质量方面的研究进展

本文概述了ω-3脂肪酸的化学结构及其特性。着重对富含ω-3脂肪酸的禽蛋产品开发的研究背景、进展、意义、优势及其存在的问题进行了分析,并提出了解决问题的看法。     

以杉木积成材为芯板的新型细木工板的动态热机械分析

为了探索以杉木积成材为芯板的新型细木工板的动态热机械性能,利用动态热机械分析技术对新型细木工板进行了研究,结果表明:以杉木积成材为芯板的新型细木工板的储能模量(E′),随着试验温度的升高而迅速下降;损耗模量(E″)和损耗角正切(tan d),却随着试验温度的升高而迅速上升;其使用环境温度不能高于88℃。     

马来麻竹生物质风电叶片的制造与评价

针对目前玻璃钢风电叶片存在的不可再生利用的问题,利用动态热机械分析仪(DMA)检测1～4 a竹龄的马来麻竹竹青试件的常温存储模量值,用于作为最佳的风电叶片复合材料的增强相使用,再按不同竹龄将马来麻竹竹青制成竹青层积材,利用INSTRON 5582万能力学试验机对马来麻竹竹青层积材分别进行检测。实验证明:随着马来麻竹竹龄的增加,马来麻竹竹青试件的常温存储模量值也相应的增加,也就是说,在常温条件下,马来麻竹竹青的刚性随马来麻竹竹龄的增加而增加,但是马来麻竹到了一定竹龄后,其竹青的刚性渐渐趋于稳定。一般3 a生的成熟马来麻竹的竹青部分的常温存储模量位于1010Pa(10 GPa)数量级以上,一般能满足作为风力发电叶片复合材料中增强相材料的使用。由3 a生的成熟马来麻竹竹青制成的竹青层积材复合材料,其物理力学性能均达到或超过目前国外风电叶片在用的常规木材/环氧层积材。