低吸水厚度膨胀率纤维板基材制造工艺技术

针对强化木地板基材吸水厚度膨胀率偏高的问题,重点研究低吸水厚度膨胀率纤维板基材制造工艺技术,探讨胶黏剂适应性、压制工艺对板材性能的影响。结果表明,采用三聚氰胺改性脲醛树脂(MUF)胶黏剂,在热压温度180℃,施胶量14%,石蜡加入量1.5%的工艺条件下,工业化生产密度为0.85 g/cm^3的纤维板基材,吸水厚度膨胀率较标准规定的最大限定值降低46%,生产的强化木地板产品合格,具有优良的环保性能。

低吸水共聚聚酰胺树脂的制备及性能表征

选用4,4′-二氨基二环己基甲烷(PACM)和1,6-己二酸为原材料,首先成盐,然后用制备的PACM-6盐和己内酰胺按质量比进行高温缩聚,制备得到一系列低吸水共聚聚酰胺树脂。核磁共振氢谱和红外光谱测试结果表明PACM成功引入低吸水共聚聚酰胺树脂的分子链中;热性能分析测试结果表明随着PACM-6盐添加量的增加,低吸水共聚聚酰胺树脂的熔点逐渐降低而耐热性能逐步提升;万能试验机和水分测定仪测试结果表明随着共聚组分中PACM-6尼龙盐含量的逐步提升,低吸水共聚聚酰胺树脂的物理力学性能均呈现出逐步递增的变化趋势,另一方面,由于大量脂环结构的引入,可显著降低聚酰胺树脂分子主链上酰胺基的含量,从而使低吸水共聚聚酰胺树脂表现出低吸水率的特性。

低吸水率PA6材料的制备

通过双螺杆挤出机熔融共混制备低吸水率聚酰胺(PA)6材料,研究增韧剂、低吸水助剂及其复配对PA6材料的吸水率、力学性能的影响.结果表明,增韧剂聚烯烃弹性体接枝马来酸酐(POE-g-MAH)能在一定程度上降低PA6材料的吸水率,缺点是添加量大、降低PA6材料的刚性.添加质量分数10%的增韧剂,PA6材料的吸水率下降16%;低吸水助剂能明显降低PA6材料的吸水率,添加量越高,吸水率越低,但导致PA6材料的力学性能下降;当添加3%低吸水助剂,PA6材料的吸水率下降了22%,拉伸强度下降了11.2%,缺口冲击强度下降了35.4%;增韧剂与低吸水助剂的复配使用降低PA6材料的吸水率,同时具有添加量少和对力学性能影响小等优点;添加2%增韧剂和2%低吸水助剂制备的低吸水率PA6材料的吸水率下降了31%左右,拉伸强度略有下降,缺口冲击强度略有增大.

低吸水率特性轻质高强陶粒配制混凝土的应用研究

本文以高岭土尾矿-煤矸石-粉煤灰烧制的低吸水特性陶粒为骨料,研究不同预湿时间对配制不同强度等级混凝土的坍落度、1h坍落度损失、压力泌水及28d抗压强度的影响。研究表明未经预湿处理的低吸水性陶粒仍会对混凝土产生不利影响,而经过3h预湿浸泡处理的陶粒能配制出各项性能符合要求的高性能陶粒混凝土。

低吸水率PA66材料的制备

通过双螺杆挤出机熔融共混制备低吸水率PA66材料,研究增韧剂、低吸水助剂及其复配对PA66材料的吸水率、力学性能的影响。结果表明:PA66材料的吸水率与增韧剂(POE-g-MAH类)添加量成反比,随着添加量的增加能一定程度降低吸水率,但会对PA66的刚性造成降低,且添加量大。低吸水助剂能明显降低了PA66材料的吸水率,随着材料中低吸水助剂的增加,材料吸水率会相应降低,且低吸水助剂的添加量与材料力学性能成反比。通过相关研究发现在PA66材料中按比例添加增韧剂与低吸水助剂会在保证材料力学性能的前提下使材料的吸水率降低,且添加量比单独使用增韧剂(POE-g-MAH类)及低吸水助剂时少。

发动机护板用PA6管夹料开发与应用

采用双螺杆挤出机制备了耐高低温、高流动、低吸水的尼龙6(PA6)管夹料,研究了增韧剂含量、成核剂母粒含量和增韧剂种类对管夹料性能的影响。结果表明,随着增韧剂含量的增加,管夹料的断裂伸长率和缺口冲击强度逐渐增加,熔体流动速率和平衡吸水率逐渐降低;当增韧剂的质量分数达到4%时,管夹料出现脆-韧转变;当增韧剂质量分数达到6%时,管夹料的综合力学性能最优,管夹样件耐高低温不变形;当成核剂母粒质量分数为10%时,管夹料的拉伸强度、弯曲强度、弯曲弹性模量分别提高了25.45%,51.43%和25%,而23℃和–40℃缺口冲击强度分别降低了18.18%和33.33%,管夹料有较低的平衡吸水率,管夹样件耐高低温不变形;使用低温增韧剂N413,管夹料在低温下有更好的表现,管夹样件耐高低温不变形。当成核剂母粒E5073/低温增韧剂N413质量比为10/6时,PA6管夹料的综合力学性能最优,吸水率较低,管夹样件耐高低温不变形。

Adsorption of dimethyl trisulfide from aqueous solution on a low-cost adsorbent:thermally activated pinecone

Thermally activated pinecone(TAP) was used for the adsorption of dimethyl trisulfide(DMTS)from aqueous solutions,which was proved to be the main odorous in algae-caused black bloom.The effects of adsorbent dosage,adsorbate concentration and contact time on DMTS biosorption were studied.The TAP produced at 600℃ exhibited a relatively high surface area(519.69 m^2/g) and excellent adsorption capacity.The results show that the adsorption of DMTS was initially fast and that the equilibrium time was6 h.Higher initial DMTS concentrations led to lower removal percentages but higher adsorption capacity.The removal percentage of DMTS increased and the adsorption capacity of TAP decreased with an increase in adsorbent dosage.The adsorption process conforms well to a pseudo-second-order kinetics model.The adsorption of DMTS is more appropriately described by the Freundlich isotherm(R^2=0.996 1) than by the Langmuir isotherm(R^2=0.916 9).The results demonstrate that TAP could be an attractive low-cost adsorbent for removing DMTS from water.

Removal of Cu^2＋ Ions from Aqueous Solutions by Adsorption on Libyan Soil

Heavy metals are well recognized as potential health hazards as they can neither be degraded nor biologically detoxified. This experimental study aims to investigate the possible use of Libyan local soil, Ashkida soil, mined in the Southern Province of Libya as a low cost adsorbent to remove copper ions from aqueous solutions. In this work, the effects of various parameters such as adsorbent dosage, initial concentration of copper, agitation rate, contact time and solution pH level on the adsorption efficiency are investigated through batch experiments at room temperature. The results indicate that the optimum conditions for copper removal from aqueous solutions are 60 minutes contact time, 10 g/L adsorbent dose and 500 rpm agitation rate at natural pH value. The results are fitted to Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherms. A satisfactory agreement between the experimental data and the model-predicted values is expressed by the correlation coefficient, r^2, and the total mean error, E%. Freundlich model offers the best representation of adsorption process revealing a monolayer adsorption capacity, qmax, of 27.03 mg/g. A comparison of kinetic models applied to the adsorption of copper ions on the adsorbent is evaluated by simple first order, pseudo first order and pseudo second order kinetic models. Kinetic parameters, rate constant, equilibrium sorption capacities and related correlation coefficients for each kinetic model are determined revealing that the pseudo second order kinetic model is in a better correlation with the experimental data in comparison with the other isotherms.

Effects of waterborne Fe(Ⅱ) on juvenile turbot Scophthalmus maximus:analysis of respiratory rate,hematology and gill histology

The concentration of Fe（II） is high in some groundwater supplies used in turbot culture, and the toxicity of waterborne Fe（II） is unknown. We investigated the stress responses of juvenile turbot, Scophthalmus maximus, exposed to Fe（II） of different concentrations （0.01, 0.05, 0.1, 0.5, 1, and 2 mg/L） for 1, 7, 14, and 28 d, under the same ambient conditions of other parameters. Changes in respiratory rate, hematological parameters, and gill structure were determined. The results show that waterborne Fe（II） did not cause severe hematological perturbation to turbot. A low-medium Fe（II） concentration （lower than 0.1 mg/L） could boost the respiratory rate, and caused no or very limited damage to fish. A high Fe（II） concentration （0.1 mg/L or higher）, however, caused gill damage, such as vacuoles in branchial lamellae, epithelial necrosis, and hypertrophy of epithelial cells, and even death after extended exposure time. Therefore, excess waterborne Fe（II） and long-term exposure to Fe（II） could be responsible for poor growth and high mortality of turbot in culture. The concentration of waterborne Fe（II） in turbot culture should be kept below 0.1 mg/L.

Influence of CaO-based expansive agent,superabsorbent polymers and curing temperature on pore structure evolution of early-age cement paste

Cracks easily generate in concrete at early age owing to the shrinkage deformation.CaO-based expansion agent(CEA)and superabsorbent polymers(SAP)have been extensively used for the mitigation of concrete shrinkage.The macroscopic properties of concrete are highly determined by the microstructure.In this study,the influence of CEA and SAP addition on the pore structure evolution of cement paste under different curing temperatures was evaluated via low-field nuclear magnetic resonance spectroscopy.Test results indicated that,in cement paste,a higher CEA content led to a higher porosity and a larger most probable pore diameter(MPPD).Meanwhile,SAP addition increased the porosity and MPPD of CEA cement paste at early age but decreased them after 7 d,and a higher SAP content always brought a higher porosity and MPPD.Furthermore,the addition of SAP led to a lower porosity and MPPD of CEA cement paste than that of plain cement paste after 14 d.Moreover,the porosity and MPPD of CEA cement paste decreased first and subsequently increased as the curing temperature raised.