回用苇浆性能的变化规律及其机理

本文研究了漂白硫酸盐苇浆的末端分全浆和筛分后的纤维级分在回用中各项物理、化学性能、纤维形态以及成纸性能的变化规律及其机理。结果表明全浆与纤维级分的纸页紧度、抗张和耐破强度、耐折度均随回用下降，且第一体回用后下降程度最大，耐折度先上升后下降，纤维柔软度、润胀度和聚成精含量在回用中下降是这些纸张强度性能下降的主要原因，纤维级分成纸紧度与抗张、耐破强度分别成直线关系。     

苇浆回用性能的研究

本文研究了漂白硫酸盐苇浆在反复回用过程中物理化学性能的变化规律。试验表明，随着回用次数增加，聚戊糖含量、保水值、纸页紧度、抗张与耐破强度、耐折度逐渐降低，且对原浆打浆有较大的下降趋势；平均聚会度、相对结晶指数与散射系数具有增加的总趋势；纤维平均长度由于细小级分流失有所增加；零距裂断长变化较小。打过浆与未打浆苇浆在回用过程中抗张指数与紧度均成对数直线关系，其斜率分别为2．481和2.09。     

杨木APMP浆重复使用性能初探

研究了杨木APMP浆的循环回用次数及打浆对不透明度和强度的影响。通过研究发现,APMP浆随着纤维回用次数的增加,不透明度逐渐增大,而抗张强度略有增加。随着打浆度的增加,不透明度逐渐下降,抗张强度先增后减。     

淀粉在高得率浆表面凝胶化增强的研究CSCD

使用原淀粉增强漂白阔叶木化学热磨机械浆成纸强度,通过糊化淀粉形成凝胶提高纤维表面的淀粉保留率以及纤维之间结合的方式改善纸张强度,并用单因素实验评估淀粉用量、交联剂用量、糊化浓度、挤压作用对纸张强度的影响情况并探究最佳工艺条件,结果表明,当淀粉用量为15%、交联剂用量为2%、糊化浓度为15%,并配有机械挤压作用时,原淀粉对化机浆的增强效果最明显,和原纤维相比,经淀粉处理后化机浆成纸抗张指数、耐破指数、淀粉保留率都均有较大提升,但耐折度没有明显变化。     

纤维回用对纸浆液体吸收性能的影响

探讨了纤维回用对纸浆液体吸收性能的影响。结果显示 ,漂白硫酸盐针叶木浆和漂白硫酸盐阔叶木浆纤维回用后其浆张的液体吸收表观动态接触角变化规律极为相似 ,第一次回用对表观动态接触角变化和液体吸收时间的影响最大 ,回用两次后趋向稳定。纤维回用对化学热磨机械浆液体吸收性能的影响较小 ,即使经过五次回用 ,其表观动态接触角和液体吸收时间的变化也较小。由此推出的液体吸收模型可表述为 ,浆张的吸液过程大致可分为快速吸收和慢速吸收两个阶段 ,快速吸收阶段由渗透过程控制 ,慢速吸收阶段由扩散过程控制     

机械处理方法对竹浆性能的影响

利用双螺杆挤压搓揉机搓揉结合KRK高浓磨浆机磨浆的组合机械处理方法对蒸煮物料成浆方式进行了研究,探讨了搓揉-磨浆组合成浆方式对竹浆纤维形态及物理性能的影响.结果表明,在实验条件下,由这种组合成浆方式获得的竹浆纤维长度最长可达1.786m m,抄成的纸张的最大裂断长为5.70 km.撕裂指数和耐破指数分别为11.7 mN...     

GMA改性水溶性PVA纤维的制备及其增强作用

通过悬浮接枝共聚法以甲基丙烯酸缩水甘油酯(GMA)为功能化单体,制备了一种具有反应活性的聚乙烯醇(PVA)纤维。研究了纸张中改性PVA纤维的质量分数和干燥温度对纸张耐折度、抗张强度以及湿强度的影响。结果表明,当纸张中改性PVA纤维的质量分数为9%,纸张干燥温度为110℃时,纸张获得较佳强度,耐折度为72次,干拉力为70.4 N,湿拉力为15.6 N。热重分析(TGA)表明,GMA在纤维表面发生了接枝共聚反应。原子力显微镜(AFM)照片显示,改性PVA纤维形成了表面乳突结构,有助于形成疏水表面。纸张的扫描电镜(SEM)照片显示,添加改性PVA纤维的纸张,其耐折测试断裂面纤维的长度较短,且纸张表面PVA纤维的溶解程度显著下降。     

纤维素酶对马尾松热磨机械浆改性的研究

用商品纤维素酶处理马尾松热磨机械浆 (TMP) ,在一定酶活剂量作用下 ,能使纸浆的打浆度明显降低 ,而手抄纸的强度几乎不受影响 ;通过扫描电镜 (SEM)观察纸浆表面纤维形态的变化 ,发现纤维表面的细小纤维被清除。     

化学气相沉积PPy/UHMWPE纤维的研究

采用化学气相沉积制备了聚吡咯/超高相对分子质量聚乙烯(PPy/UHMWPE)纤维,测试了不同氧化剂浓度、不同沉积时间和温度下PPy/UHMWPE纤维的表面剪切强度,用扫描电镜、动态热机械分析仪、傅立叶变换红外光谱仪分析了PPy/UHMWPE纤维的表面形态、热机械性能和复合材料官能团的变化。结果表明:PPy均匀分布在UHMWPE纤维表面,UHMWPE纤维与PPy之间无化学键作用而是分子间作用力;随着氧化剂三氯化铁浓度的增加和吡咯沉积时间的延长,PPy/UHMWPE纤维表面剪切强度先增大后减小;随着处理温度的升高,PPy/UHMWPE纤维表面剪切强度先增大,当处理温度超过85℃时,其剪切强度则减小。     

三维间隔连体织物酚醛泡沫复合材料性能研究

制备了三维间隔连体织物酚醛泡沫复合材料。研究发现,随着密度增加,泡沫孔的刚性提高,纤维增强效应增加,材料的压缩强度近似呈现指数增长;随着三维间隔连体织物高度的增加,复合材料的压缩强度呈现下降趋势。酚醛树脂经聚酰胺树脂增韧后,韧性提高,泡沫伴随纤维错动、屈曲的可能性增加,复合材料的压缩强度有所降低。泡沫与纱线之间的协同增强效应使得材料在灼烧后保持良好的几何形状,复合材料的耐灼烧性能及隔热性能良好,经过最高热面温度1200℃的石英灯静热测试后,1200 s时背面温度为151.1℃。     

Effects of Chemical Treatments on Ultra-High-Yield Pulping. VI. The Relative Effect of Lignin Oxidation and Sulfonation

The chemical properties and performance of aspen percarbonate (P) and sulfite (S) chemimechanical pulp (CMP) fibers are very comparable. The PCMP, when compared with SCMP of the same yield, has a slightly higher tear index, same beatability and light scattering coefficient, but a lower tensile index and brightness. The strength properties of these fibers are closely related to the total acidic group content resulting from lignin oxidation (carboxyls) and sulfonation (sulfonate).     

Production and characterization of high strength,thin-layered,pulp fiberboard using soy protein adhesives

Making thin-layered fiberboard and recycling the fiberboard materials are two major approaches to save quantities of wood fiber in fiberboard manufacture, which offer both environmental and economic benefits to the society and industry. The objective of this research was to develop high-strength, thin-layered pulp fiberboards (TLPBs) using sodium dodecyl sulfate (SDS)-modified soy protein adhesives for packaging applications. SDS-modified soy protein adhesives demonstrated significantly higher bonding strength than did unmodified soy protein adhesive. Results showed that the TLPB with SDS-modified soy flour adhesive (0.05?g/cm² area density and 0.6?mm of thickness) had stronger tensile strength, similar burst index, and similar or better water soaking properties in comparison to commercial solid fiberboard (1.24?g/cm² area density and 1.7?mm thickness).     

Effect of Xylanase and Dosage on the Refining Properties of Unbleached Softwood Kraft Pulp

Abstract

Two xylanase preparations were compared at different doses for their abilities to enhance the refining properties of a never-dried, unbleached kraft pulp derived from radiata pine. These enzymes varied in their ability to solubilise xylan from pulp, and the selective removal of pulp xylan did not reduce intrinsic fibre strength. At low levels of xylan solubilisation, there were increases in sheet densification after PFI refining without change in tensile and tear strength at a given sheet density, indicating lower pulp refining requirements. At high levels of xylan solubilisation, the level of sheet densification was greater but there was a small decrease in tensile strength at a given sheet density and an increase in tear strength. One of the xylanases yielded a selective increase in tear strength at a given tensile strength.     

The use of Isocyanate as a Bonding Agent to Improve the Mechanical Properties of Polyethylene-Wood Fiber Composites

Abstract

Chemithermomechanical pulp (CTMP) of aspen was used as a filler in high density (HDPE) and linear low density (LLDPE) polyethylenes. To improve the bonding between the fiber and polymer, different chemical treatments of the fiber a) treatment with different isocyanates b) coating with maleic anhydride was carried out. Composites with isocyanate treated wood fibers produced higher tensile strength compared to untreated fiber composites. But when compared to diisocyanate, the polyisocyanate treated fibers produced higher gain in strength. HDPE or LLDPE filled with maleic anhydride coated CTMP aspen fibers showed a slight decrease in strength with the increase in filler concentration. Tensile modulus generally increased with filler loading and was not much affected by fiber treatment.     

阳离子改性滑石粉处理OCC纸浆中胶黏物的研究

研究了阳离子改性滑石粉处理废旧瓦楞纸箱(old corrugated containers,OCC)纸浆胶黏物过程的影响因素和作用机理,同时比较了改性前后滑石粉对胶黏物作用效果的差异。结果表明:在一定的滑石粉用量的条件下,适当的纸浆温度和浓度可以促进改性滑石粉的作用效果,当改性滑石粉用量为1.5%,温度80℃,浆浓为20%(wt)时,胶黏物去除率可达到58%;阳离子型助剂能够使滑石粉表面带正电荷,增大滑石粉的比表面积,促进胶黏物吸附改性滑石粉,形成胶黏物―滑石粉微球,有利于胶黏物黏性降低和去除;由OCC手抄片的纸性检测发现:其作用后纸页的紧度、耐破指数、抗张指数和撕裂指数略有下降。     

响应面优化桔梗多糖可食用复合膜的制备

为了拓展桔梗多糖的应用领域及可食膜材料种类的单一性,利用玻璃板流延法制取多糖复合膜,采用响应面分析,研究了复合膜的制备配比,并测定其性能。结果表明:以抗拉强度(TS)为评价指标,复合膜的最佳配比条件为:桔梗多糖含量2.16%、海藻酸钠含量2.66%、甘油含量1.88%,此优化条件下的抗拉强度为7.875MPa;以耐折度(FE)为评价指标,复合膜的最佳配比条件为:桔梗多糖含量2.04%、海藻酸钠含量1.92%、甘油含量1.97%,此优化条件下的抗折度为167双折次。比较后,在多糖、海藻酸钠、甘油含量分别为2.0%、1.8%、2.0%的条件下,TS为7.875MPa、FE为167双折次,综合指标最好。     

The effect of borax‐modified starch on wheat straw‐based paper properties

This study was focused on the improvement of mechanical strength properties of wheat straw‐based paper through modification of wet‐end cationic starch with borax. Borax has been used extensively in many industrial applications for its unique physical and chemical properties. We investigated the strengthening effect of borax‐modified starch (BMS) as wet‐end paper strength additive on the mechanical strength properties especially the tensile strength of wheat straw‐based paper. Hand‐sheets made of typical wheat straw‐based papermaking furnish were investigated. Experimental results showed that BMS substantially increased the strength properties. Tensile index, elongation, tensile energy absorption, and wet tensile index were increased by 17%, 23%, 20%, and 21%, respectively. A short mill trial was also conducted on papermaking machine in which the impact of BMS on wheat straw‐based low grammage paper (<90 gsm) was investigated. The objective of mill trial was to reduce costly virgin softwood pulp content in wheat straw‐based paper recipe. Mill trial results showed similar trends in strength properties as in case of laboratory studies. Virgin softwood pulp was reduced from 30% to 25% in papermaking furnish. Furthermore, no sheet breaks were reported during trial which often happened due to poor strength of paper web. This study strongly suggests that modification of wet‐end cationic starch with borax holds a tremendous potential as wet‐end strength additive. It can provide significantly improved strength properties, reduction in softwood pulp costs, and better papermaking machine performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013