Hybrid chipboard panels based on sugarcane bagasse, urea formaldehyde and melamine formaldehyde resin

The expansion of Brazilian agricultural production was very important in the last decade. A number of waste residues were produced showing an enormous potential for industrial crops and products. Sugarcane bagasse is the most important one and it has been investigated for chipboard panel's preparation. In this sense, this work aims to develop, characterize and compare chipboard panels made with sugarcane bagasse with urea formaldehyde (UF) and melamine formaldehyde (MF) resins. Panels were obtained with a mixture of sugarcane bagasse and particles, like pine or eucalyptus, with and without paraffin in the formulation. Nine different types of panels have been made, all with 9% in resin mix, under a pressing cycle of 4.0 MPa cm², and temperature of 160 °C. Under physical tests, the panels complied with the American Standard CS 236-66 for trading chipboards of medium density and, in most cases the results obtained were lower than the ones raised in the literature. Under mechanical tests, that same standard was not complied with and, in most cases the results were close to or higher than those obtained in the literature.     

超高效液相色谱———液相荧光法测定果蔬中壬基酚聚氧乙烯醚及其降解产物

建立了热带水果中环境激素壬基酚聚氧乙烯醚及其降解产物壬基酚的超高效液相色谱测定方法。以乙酸乙酯为提取溶剂,高速匀浆后,滤液以炭黑石墨氨基柱净化浓缩,以 C18 色谱柱进行分离,经液相色谱荧光法测定,结果表明：样品中壬基酚聚氧乙烯醚及壬基酚在0.2～50 μg/mL 范围内线性良好,其方法检出限分别为2、1.6 μg/kg, 回收率NP 在 91％～104％之间,NPEO在75％～83％之间。该方法快速灵敏,准确度高,符合残留检测要求。     

牡丹组培褐变与总酚含量及相关酶活性的关系

以3个褐变程度不同的牡丹品种（‘乌龙捧盛’、‘太平红’、‘凤丹白’）为材料,分析了试管苗在增殖过程中总酚含量、苯丙氨酸解氨酶（PAL）、多酚氧化酶（PPO）和过氧化物酶（POD）活性的动态变化。结果表明:总酚含量及PPO、POD 、PAL 活性与牡丹试管苗增殖过程中的褐变密切相关。褐变越严重的品种,总酚含量和POD活性越低,PPO活性越高,PAL活性与牡丹的褐变程度未能表现出类似的规律。     

活性炭和植物吸收对室内空气甲醛净化的影响

城市住宅的室内空气污染十分严重,甲醛已经成为中国目前室内空气中的首要污染物。本实验以绿萝、常春藤与活性炭为研究对象,采用密闭箱法进行了净化甲醛能力的研究。实验结果表明,绿萝、常春藤与活性炭均对室内甲醛有良好的净化作用,24 h后的甲醛净化能力大小依次为：常春藤＋活性炭（甲醛去除率38.27%）＞常春藤（34.31%）＞绿萝＋活性炭（32.20%）＞绿萝（5.61%）＞活性炭（3.73%）;10天后的净化效果排序为：常春藤＋活性炭（69.91%）＞绿萝＋活性炭（64.28%）＞常春藤（60.44%）＞活性炭（57.50%）＞绿萝（24.99%）。植物与活性炭联合作用对甲醛净化效果比单一用植物或活性炭效果好,而且长期作用比短期作用效果好。     

竹砧板中甲醛释放量测定方法及限量值的确定

以市场上购买的不同产地的碳化与未碳化竹砧板为材料,通过水浸提法和40 L干燥器法检测其游离甲醛的含量和甲醛释放量,并采用40 L干燥器法抽样检测不同产地样品的甲醛释放量。结果表明:国家标准GB 18580—2001中甲醛释放量指标采用40 L干燥器法检测,限量值定为≤1.5 mg/L是较为科学合理的。     

用异氰酸酯胶生产中密度纤维板的尝试

以异氰酸酯为胶黏剂,进行了2种原料的中密度纤维板(MDF)生产试验,分析其生产工艺的特点,并根据我国国标及日本相关标准,对板材的性能与甲醛释放量等指标进行检测。结果表明:用异氰酸酯制造的MDF,其各项指标均优于UF胶的MDF,是一种应用前景广阔的环保板材。     

速生杨木材的动态润湿性能

润湿性是木质材料科学的一个重要界面特性,它可以表征胶黏剂与木质材料接触时,在木质材料表面上黏附、渗透及铺展的难易程度和效果。根据木质材料的结构与性能特点,建立了描述其表面动态润湿性能的数学模型,在模型中提出了用衰减系数K来评价材料的润湿性能。并运用该模型研究了杨木表面脲醛树脂和酚醛树脂2种胶黏剂的动态润湿性能,用脲醛树脂胶研究同一年轮内早材和晚材的润湿性;与PF相比,UF在杨木表面的润湿性能较好;与晚材相比,早材的润湿性能较好。     

Fortification of sulfited tannin from the bark of Acacia mangium with phenol–formaldehyde for use as plywood adhesive

The Acacia mangium tree contains 10% bark (v/v), of which about 20% are extractives. Extraction of this bark using a combination of water and sulfite medium can produce between 15% and 25% tannin materials (dry weight). In this work, several extraction conditions such as bark size, plantation site, extraction time and extraction medium were studied. The results showed that by using either hot water or a sulfite medium, a reasonable amount of tannin yield can be obtained. Bark size of less than 1-mm mesh size gave relatively high tannin yield irrespectively of the extraction medium used. Using a 600:100:2:0.5 (w/w) ratio of water:bark:sodium sulfite:sodium carbonate, and reacted at 75 °C for 3 h improved the tannin yield by at least 30%. The extracts were reasonably reactive towards formaldehyde as shown by their high Stiasny number; water extract, 60–70% and aqueous sulfite–carbonate extracts, 85–90%. The gluing results showed that the shear strength of the plywood can meet the requirements of the European Standards EN 314-1 and EN 314-2:1993. Incorporation of low molecular weight PF resin (10 parts) and PF (10 parts) improved the shear strength from 0.96 MPa to 1.43 MPa after a 72 h boiling test. This study showed that A. mangium tannin blended with commercial plywood phenol–formaldehyde resin, low molecular weight PF and paraformaldehyde as a cross-linker can be used to bond Kedondong (Canarium spp.) wood veneers suitable for both interior and exterior grade plywood.     

虎尾兰吸收甲醛及其保护酶活性的初步研究

通过对不同甲醛浓度处理的密闭容器中甲醛含量、虎尾兰植株体内甲醛含量及其保护酶活性的测定,探讨虎尾兰吸收空气中甲醛的效果,并分析不同甲醛浓度处理后植株体内甲醛含量与保护酶活性的差异性.结果表明:虎尾兰吸收甲醛量随着甲醛处理浓度的提高而增加,当甲醛处理浓度为0.347 mg·m-3、0.431 mg·m-3、0.543 mg·m-3、0.672 mg·m-3、0.884 mg·m-3,虎尾兰吸收甲醛量分别占容器中甲醛总量的14.98%、20.64%、30.76%、39.43%、45.14%;不同处理虎尾兰植株体内甲醛含量差异不显著,且其含量随着处理时间呈波动性变化态势;各处理的虎尾兰植株体内保护酶(POD、SOD和CAT)活性差异不显著.由此推断,虎尾兰吸收的甲醛没有在植株体内积累,甲醛处理对虎尾兰植株影响不显著.     

甘薯叶中清除自由基活性物质的提取·保存与定性分析(英文)

[Objective] The research aimed to provide reference for the application of extracts from sweet potato leaves in anti-aging cosmetics. [Method] The extraction and storage conditions for free radicals scavenging substances from sweet potato leaves were optimized by orthogonal test and the bioactive components in extracts were investigated by correlation analysis. [Result] Sweet potato leaves contain the bioactive substances scavenging DPPH free radical and hydroxyl free radical. Extracting solvent species is the most important factor that influencing extraction yield. The optimal extraction and storage conditions are as following: water as solvent,pH 8.0 of extracting liquid,storage at 25 ℃. There is a good positive linear relationship between the content of total phenols in sweet potato leaves and corresponding scavenging rates against both the DPPH free radical and hydroxyl free radical. For the content of total flavones in sweet potato leaves,just a correlation with scavenging rate against hydroxyl free radical shown in test. [Conclusion] The phenols in extracts could effectively scavenge both the DPPH free radical and hydroxyl free radical,whereas the flavones in extracts can only function on the hydroxyl free radical.