The use of wood pulp and radiation‐modified starch in wastewater treatment

Radiation‐induced graft copolymerization of maize starch/acrylic acid has been performed. Also, natural byproduct wood pulp was used after chemical treatment for the removal of metal ions from the investigated wastewater. The surface and structure morphology of the wood pulp and starch/acrylic acid were investigated by scanning electron microscopy and infrared spectroscopy. The physical parameters, such as swelling, gel percentage, and grafting efficiency (%) of starch/acrylic acid copolymer, were studied. The factors affecting the abilities of the prepared materials for removing heavy metal ions and dyes from aqueous solutions were studied. It was found that the maximum metal uptake is in the following sequence: Fe³⁺ > Cr³⁺ > Pb²⁺ > Cd²⁺. The adsorption capacity of such investigated metal ions increases with the increase of pH values. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

不同筛分设备对化学浆细小纤维质量性能的影响

对漂白针叶木浆进行了纤维筛分分级制取细小纤维试样,对比探讨了DDJ和SWECO圆形振动筛两种细小纤维筛分的特性,并且与标准纤维进行配抄,研究了不同细小纤维添加量对纸张性能的影响.实验结果表明:SWECO细小纤维收益率明显高于DDJ细小纤维;DDJ细小纤维具有较高的表面电荷,而SWECO细小纤维具有较高的粘度、比沉降容积;与DDJ细小纤维相比,SWECO细小纤维更能减少纸张的松厚度和透气度,增强纸张的强度.     

聚碳酸酯基聚氨酯/芳纶纤维复合材料的制备与性能

以聚碳酸酯二元醇为软段,利用预聚体法制备了系列聚碳酸酯基聚氨酯/芳纶浆粕纤维(Aramid pulp)复合材料,研究了芳纶浆粕纤维对聚碳酸酯基聚氨酯弹性体(PUE)力学性能的影响。采用扫描电镜、X射线衍射、差示扫描量热分析、热重分析、红外光谱及电子拉伸机等测试仪器对聚氨酯复合材料的结构与性能进行了表征和分析。结果表明,芳纶浆粕纤维能有效实现对聚氨酯弹性体的增强作用,其中对撕裂强度的增强尤为突出。当芳纶浆粕纤维用量为0.5%时,复合材料的撕裂强度由106 k N/m提高到120 k N/m,表现出最好的力学性能;芳纶浆粕纤维在聚氨酯中分散均匀,提高了复合材料的热稳定性。     

一种纸浆模塑蜂窝板材缓冲性能的研究

目的 为了解决因技术水平制约,纸蜂窝材料芯纸构型单一、单层厚度受限等瓶颈问题,开发一种通用型缓冲结构板材。方法 以纸浆模塑为原材料,以六棱柱结构为例,设计并加工出一种通过正反插方式组合而成的蜂窝板材,并采用有限元方法进行仿真,得到关键结构参数和相关最优参数组合。结果 正反插结构的纸浆模塑板材具有较好的耦合效应,承载能力相较于单层板材大幅提高;结合极限载荷、比吸能等评价指标对板材性能进行定量分析,初始压缩载荷最大可达到73.7kN,满足托盘等重型包装器具的承载需求。通过极差和方差分析可知,各结构参数对板材承载性能和缓冲性能的影响程度,研究表明单元壁厚、中截面边长对该板材承载性能和缓冲性能影响显著。结论 正反插结构解决了现有纸蜂窝材料高度、厚度受限,构型单一等瓶颈问题,提高了纸浆模塑蜂窝板材的承载性能和缓冲性能,可以满足重载要求。与之相关的其他正多边形锥形薄壁管单元亦可以使用同样的正反插设计理念和研究方法。     

落叶松锯材抗弯强度尺寸效应

以兴安落叶松锯材为研究对象,研究了不同目测等级下锯材尺寸与其抗弯强度之间的关系。试验选取1961根6.5、9.0和14.0cm 3种宽度尺寸的目测等级锯材,每个宽度尺寸分为高、低目测等级组,按照每组试件宽度18倍的测试跨度测试锯材的抗弯强度。利用斜率法和形状参数法确定高、低目测等级组抗弯强度5%分位值的长度与宽度的组合尺寸效应。研究结果表明,斜率法获得高、低目测等级组试件抗弯强度5%分位值的组合尺寸效应分别为0.19和0.23。     

Flotation performances of polymorphic pyrrhotite

The floatability of different crystalline structures of pyrrhotite (monoclinic and hexagonal) was studied. It is shown that the floatability of monoclinic and hexagonal has obvious difference, and that the flotation recovery of monoclinic pyrrhotite is larger than that of hexagonal pyrrhotite using different collectors. When butyl dithiophosphate is used as the collector, the recovery is larger than that by sodium butyl xanthate and sodium diethyl dithiocarbamate. At the pH values ranging from 6 to 9, monoclinic pyrrhotite can be floated well, and the flotation recovery is higher than 90%. Monoclinic and hexagonal pyrrhotites are more easily activated by Cu²⁺ in acidic conditions than in alkaline conditions. But Cu²⁺ cannot activate hexagonal pyrrhotite using sodium diethyldithiocarbamate as the collector. By the measurement of contact angle, it is indicated that monoclinic and hexagonal pyrrhotites float well and are easily activated by Cu²⁺ when dithiophosphate is used as the collector. Using sodium diethyl dithiocarbamate as a collector, the relationship between potential and pH range for pyrrhotite flotation is established. At pH 5, the optimal potential range for flotation of monoclinic pyrrhotite is about 125–580 mV (vs SHE), with the maximum flotation occurring at about 350 mV (vs SHE); the optimal potential range for flotation of hexagonal pyrrhotite is 200–580 mV (vs SHE), with the maximum flotation occurring at about 300 mV (vs SHE).     

离心式纸浆泵内部流动的数值模拟

为研究小流量工况下离心式纸浆泵内部流动特性,采用Mixture多相流模型对某一离心式纸浆泵内部流动进行三维不可压两相湍流流动计算,并与清水工况的计算结果进行了比较。对比分析了不同流量工况及介质对泵内流体速度、压力和体积浓度分布的影响,并预测了水力性能。结果显示:纸浆泵叶轮流道内速度变化不均,存在大面积回流;相同介质时,流量越小叶轮流道内部流动越不稳定;相同工况下,清水介质下的流动较两相流时更为稳定;两相流时泵的扬程及效率整体都低于清水介质;纸浆分布局部不均,叶片表面进口处叶根和叶顶部位浓度较大,易造成局部磨损,降低叶轮寿命。     

Effects of Heat Treatment on Dimension Stability of Larch Pallet Decks

The useful life of wooden pallets is lower because of the defects in lumbers. The quality of lumber can be significantly enhanced by heat treatment. In this paper, the larch pallet decks samples were heat-treated under the conditions of different time and temperatures. The quantity of water uptake has reduced 16.8％ under the condition of 250 ℃ for 150 min. The resistance of water absorption efficiency increases 165.34％ under the condition of 175 ℃ for 90 min. The anti-shrink efficiency increases 72.08％ under the condition of 250 ℃ for 90min. The results showed that the dimension stability of larch panels can be improved by heat treatment. The condition of 250 ℃ for 180 min is the best heat treating condition to improve the dimension stability.     

琥珀酸酐改性麦草浆对Cd(Ⅱ)的吸附性能

以二甲苯作溶剂、三乙胺作催化剂,通过琥珀酸酐改性麦草浆(WSP),制备出一种新型吸附剂S-WSP。通过红外光谱对S-WSP进行表征结构分析,该酯化反应在异相催化条件下能够顺利进行。S-WSP的羧酸基团与NaOH溶液作用去质子化可成功获得NaS-WSP。NaS-WSP悬浮在水溶液中吸附Cd2+,最大吸附量可达105.7mg/g,其动力学过程遵循伪二级动力学模型。由于在离子交换过程中竞争质子,该吸附剂的吸附能力会随着pH的下降而降低。