Effect of Alkali and Silane Treatments on Mechanical and Interfacial Bonding Strength of Sugar Palm Fibers with Thermoplastic Polyurethane

Sugar palm fibers (SPF) are one of valuable natural fibers which are abundantly available in Malaysia as agricultural biomass. The aim of this study to investigate on the effects of alkali, silane, and combination between alkali (6%) and silane (2%) on physical and mechanical properties of SPF to improve interfacial bonding of SPF with thermoplastic polyurethane (TPU) matrices. Scanning electron microscopy and Fourier transform infrared spectroscopy was used to observe the effectiveness of the alkali and saline treatments in the removal of impurities. Silane treated SPF exhibits better tensile strength than those of alkali, alkali-silane treated and untreated SPF. Droplet test indicates that the interfacial stress strength (IFSS) of alkali and silane treated SPF are enhanced whereas silane treated fibers exhibit highest IFSS. It is assumed that fiber treatments will help to develop high performance SPF reinforced polymer composites for industrial applications.     

Effect of chemical treatments on tensile properties and interfacial shear strength of unsaturated polyester/fan palm fibers

Surface treatment of fan palm fibers (FPFs) was investigated as a means of improving fiber tensile strength (FTS) and interfacial shear strength (IFSS) of unsaturated polyester (UPR)/FPFs samples. The fibers were treated with sodium hydroxide, silane, and a combined sodium hydroxide and silane. FT-IR spectra and SEM observation indicated the removal of hemicellulose and lignin components after chemical treatments. The alkaline treatment of FPF resulted in the highest tensile strength of 816 MPa. The interfacial shear strength of FPF/UPR samples was increased for all treated FPF. The highest IFSS (4.1 MPa) was obtained for the alkaline-treated FPF/UPR sample.     

表面改性对黄麻纤维性能的影响

采用三种不同的化学处理剂,碱、KMnO4和硅烷偶联剂A-151分别对预处理黄麻纤维进行表面改性,测试了它们的基本性能,借助动态接触角分析了黄麻纤维的表面能变化,并通过SEM观察了不同处理后的纤维表面。研究结果表明：经过碱处理和A-151处理后黄麻纤维的回潮率和细度都明显降低;碱处理后,纤维的拉伸强度提高14．64％：黄麻纤维经过不同的表面处理后,纤维的表面能相应降低,微观结构发生改变。     

碱处理对木棉纤维结构及性能的影响

采用质量浓度分别为4、6、8、10、12 g/L的Na OH溶液对木棉纤维进行处理,对比分析了不同质量浓度碱处理对木棉纤维的表面形态、质量损失率、力学性能、浸润性能、热性能以及化学组成等结构及性能的影响。结果表明:碱处理可去除木棉纤维表面的胶质,是纤维素的净化过程;经过适当质量浓度的碱处理,木棉纤维的断裂强力、浸润性能均有所增加,但当碱液质量浓度增加到一定范围时,木棉纤维的断裂强力、浸润性能会出现下降;碱处理对纤维素的热稳定性影响不大。     

聚酰亚胺织物的羧基化表面改性

为提高聚酰亚胺织物的服用性能,采用碱剂对聚酰亚胺织物表面进行羧基化改性处理。借助X 射线光电子能谱、红外光谱、热重、热阻、湿阻等测试手段研究了碱处理后聚酰亚胺织物的性能,并探讨了阳离子染料对其的染色性能。结果表明：碱处理可对聚酰亚胺纤维进行有效的改性;碱处理在聚酰亚胺纤维表面引入大量氧元素,纤维分子中引入了羧基和酰胺酸;改性后聚酰亚胺织物热稳定性保持良好;碱处理后聚酰亚胺织物热阻、湿阻略有下降,极限氧指数可达到37%,阻燃性能优异;聚酰亚胺纤维羧基化改性增加了阳离子染料的亲和力,平衡上染百分率显著提高,染色吸附等温线符合Langmuir 吸附模型。     

Effectiveness of Alkali and Sodium Bicarbonate Treatments on Sugar Palm Fiber: Mechanical,Thermal, and Chemical Investigations

ABSTRACT

Sugar palm fiber (SPF) as one of the attractive natural fibers to reinforce matrix is gaining attention. This is largely due to its similar properties when compared with other established natural fibers. The aim of this study is to investigate the effectiveness of sodium bicarbonate as a treatment chemical for SPF in comparison with established alkaline treatment. Both treated and untreated fibers were characterized and it was found that the treated fiber shows an increase in crystallinity, thermal stability, and surface’s roughness when compared with the untreated. Among the two different treatments, SPF treated with alkali has an initial decomposition temperature of 255.47°C, while sodium bicarbonate treated and untreated fibers have 250.19°C and 246.76°C, respectively. In both cases, the thermal stability of the fiber was improved. Also, as revealed by the X-ray diffraction (XRD) analysis, the crystallinity index of SPF treated with alkali and sodium bicarbonate increased by 18.43% and 13.60%, respectively, when compared with untreated fiber. In conclusion, the investigation proved that treatment with the sodium bicarbonate has a significant effect on the physicochemical properties of SPF and the chemical could be an alternative chemical for treating other cellulose fibers.     

碱处理对木棉纤维形态结构及靛蓝染色性能的影响

通过常温和高温碱处理对木棉纤维进行表面处理,测试了纤维的失重率及吸湿率。研究了常温碱处理和高温碱处理对木棉纤维表面形态、化学结构、结晶度及靛蓝上染率的影响。结果表明,碱处理后的木棉纤维重量下降、吸湿率降低;当碱液浓度为1~15g/L,90℃碱处理后的木棉纤维的上染率较30℃碱处理后的纤维的上染率低;高温处理后的木棉纤维表面出现明显的沟痕;碱处理后木棉纤维中的羰基特征峰强度降低,结晶度随碱液浓度增加整体降低。     

Isora Fibre

Abstract

‘Isora’ is a bast fibre separated from the bark of Helicteres isora plant by retting process. Chemical constituents, morphology and physical properties of these fibres have been studied. Density and microscopic methods are used to determine the cross-sectional area and diameter of fibre bundles. Surface modification by alkali and silane treatment was tried. Tensile properties of the treated and untreated fibres were determined by density method. Average tensile strength of the fibre decreased and density increased to some extent on treatment with alkali and silane. The thermal characteristics, crystallinty index, reactivity, and surface morphology of the untreated and treated fibres have been studied by TGA, DSC, DTA, WAXRD, FTIR and SEM. SEM studies showed that fibre surface becomes rough on modification. Thermal analysis showed that chemical modification improves the thermal stability of the fibre. The strength of the fibre was theoretically calculated.     

碱处理对Lyocell纤维热性能的影响

采用保持原长方式在不同碱浓度下处理Lyocell纤维(Newcell和Tencell纤维)，探讨碱处理对Lyocell纤维热稳定性的影响。DSC和TGA结果表明，碱处理Newcell纤维与未处理：Newcell纤维相比，热分解峰顶温度提高了11℃，重量变化速率最大温度提高了10～11℃：碱处理Tencel纤维与未处理Tencell纤维相比，热分解峰顶温度提高了11～17℃，重量变化速率最大温度提高了10～17℃。Lyocell纤维经一定浓度的碱处理后，增加了纤维的晶粒尺寸，消除或减少了纤维原有晶体的缺陷，从而提高了纤维的热分解稳定性。     

Mechanical Characterization and Water Ageing Behavior Studies of Grewia Serrulata Bast Fiber Reinforced Thermoset Composites

Natural fiber-reinforced polyester composites were prepared using bast fibers as the reinforcement which were extracted from Grewia serrulata trees. Chemical treatments such as alkali pretreatment followed by permanganate treatment, acetylation and silane treatment were exclusively applied to modify the fiber surface. Hand lay-up technique with compression molding was adapted for the fabrication of axially oriented fiber reinforced composites. Tensile, flexural and impact strength properties of the specimens prepared were evaluated following the standard procedures. The SEM images of the fractured surfaces shows improvement in compatibility between the chemically treated fibers and the matrix. It was found that the tensile and flexural strengths of chemically treated fiber-reinforced polyester composites have significantly improved when compared to untreated fiber-reinforced polyester specimens. The properties of 1200 hrs water aged specimens were found deteriorated considerably due to diffusion of water into the composite material system. The chemical treatment of fibers prior to fabrication of composites improves the resistance to water absorption tendencies.     

Effect of Thermal Aging and Chemical Treatment on Tensile Properties of Coir Fiber

Effect of thermal aging and chemical treatment on the physical properties of coir fiber was investigated. Coir fibers were treated with sodium hydroxide and glutaraldehyde for 2 h. The influence of alkali and aldehyde treatment on tensile strength and elongation at break was studied in detail. Enhancement in tensile strength of coir fiber was observed up to five days of aging at 50°C and further decreased. Thermal cross linking of cellulose present in the fiber may be the reason for the increase in tensile strength and thermal degradation due to the chain scission of cellulose reduced the tensile strength. Sodium-hydroxide-treated samples showed an increase in tensile strength and reduction in elongation at break. The removal of impurities such as waxy and fatty acid residues from the coir fiber by reacting with strong base solution improved the strength of fiber. Cross linking of cellulose with glutaraldehyde in the fiber reduced the elasticity and enhances the strength of the material. Scanning electron microscopy was employed to analyze the change in surface morphology upon chemical treatment. Improvement in the tensile strength suggests that NaOH and glutaraldehyde can be effectively used to modify coir fiber with excellent physical properties.     

环境湿度对常压等离子体处理拒水纤维效果的影响

针对常压等离子体处理过程中水分存在的问题,在空气相对湿度分别为5％、65％和95％时,对超高模量聚乙烯进行常压等离子体处理,测定处理前后纤维的静态接触角以及纤维与树脂间的层间剪切强度,采用原子力显微镜和X射线光电子能谱探测纤维表面的变化.结果表明,处理后纤维表面粗糙度、含氧基团和纤维与树脂间的层间剪切强度增加,静态接触...     

纸浆纤维的改性及其研究进展

介绍了近十几年纸浆纤维改性的研究进展,除对纸浆纤维的常规化学改性和酶改性的研究进展进行了总结外,着重介绍了几种纤维改性的新方法:浸渍处理、多层膜技术、空间基化纤维(spacered fiber)等.这些方法中,硅烷浸渍处理和多层膜技术都是首次用于纸浆纤维的改性,取得了比较理想的效果.浸渍处理中的填糖法对降低纸张的成本有重要的意义,机械预处理对提高二次纤维的强度性质特别有效.最后展望了纸浆纤维改性的发展趋势和应用前景.     

黄麻纤维毡的表面处理及其增强复合材料的力学性能

用3种不同的化学处理剂,碱、KMnO4和A-151硅烷偶联剂分别对黄麻纤维针刺毡表面进行处理,采用真空辅助树脂传递模塑法制备黄麻纤维毡增强乙烯基酯树脂复合材料。借助动态接触角分析了黄麻纤维的表面能变化,并通过SEM观察了纤维表面和复合材料的拉伸断裂面。研究结果表明:经表面处理后,黄麻纤维表面能有所降低,纤维表面的微观结构发生变化,纤维与树脂的界面相容性得到改善,综合力学性能提高。经A-151硅烷偶联剂处理后,复合材料的力学性能提高最为显著,拉伸强度和弯曲强度分别提高了51.38%和77.46%。     

天然的保暖纤维——木棉纤维

纤维的超细化和织物的轻量化正是目前保暖材料行业的发展趋势。木棉是迄今为止中空率最大、密度最小的天然纤维，其独特的中空结构使纤维的比表面积增大，因而同时具有优异的导湿功能，是一种理想的保暖纤维。     

Henequen纤维/PHBV树脂可生物降解复合材料界面粘结性能的研究

本文通过对Henequen纤维表面形态进行改性 ,探讨了提高Henequen纤维与聚羟基丁酸 /戊酸酯 (PH BV)树脂复合材料界面剪切强度的方法。采用氢氧化钠溶液处理纤维和稀PHBV溶液预浸纤维 ,增加纤维的表面积和湿润性以增强纤维与基质间的物理化学作用。Henequen纤维 /PHBV复合材料界面剪切强度的大小用微粘结法 (microbond)测试 ,结果表明纤维经碱处理后再预浸处理可使界面剪切强度从未处理情况下的 5 .0 5MPa提高到 9.5 5MPa,增加了 89%。     

挤压膨化对豆渣复配粉中膳食纤维的影响

为提高豆渣利用率,改善其风味和口感,拓宽豆渣在食品领域的应用,本研究以豆渣为主要原料,与低筋粉进行调配后制得复配粉,并对其进行挤压膨化处理。以可溶性膳食纤维含量为指标,采用响应面法优化挤压膨化工艺。通过傅立叶红外光谱和粒度仪对挤压膨化前后复配粉的官能团及粒度进行分析,差示量热扫描对其进行稳定性分析。结果表明,最佳挤压膨化加工参数为物料水分30%、挤压温度180℃、螺杆转速160 r/min。此时复配粉中可溶性膳食纤维含量由3.11%提升至15.47%,挤压膨化后复配粉的持水性由3.45 g/g提升至4.86 g/g,复配粉的持油性由2.27 g/g提升至4.85 g/g;挤压膨化后复配粉中的膳食纤维,红外光谱图具有显著的糖类特征吸收峰;挤压膨化后复配粉中的可溶性膳食纤维粒度减小;挤压膨化后复配粉具有高度的热稳定性。综上,经过挤压膨化改性后豆渣复配粉的理化性质有着明显的提升,本研究为豆渣改性利用提供了理论依据。     

Effect of Process Parameters on Grafting Ratio and Thermal Stability of Lactide-Grafted Sisal Fiber

Polylactide (PLA) was grafted onto sisal fiber (SF) on the basis of the principle of lactide coordinative ring-opening polymerization. The orthogonal test was done to investigate which process parameter affected the grafting ratio mostly. Then the thermal stability of lactide-grafted sisal fiber (SF-g-LA) was studied. Results demonstrated that the lactide was grafted on sisal fiber surface and initiator amount was found to be the most important determinant of the grafting ratio. After grafting copolymerization reaction, the thermal stability of sisal fiber decreased. The increase of grafting ratio does not decreased the thermal stability of SF-g-LA.     

3种提取方式对芹菜可溶性膳食纤维品质特性的影响

以芹菜渣为原料,采用水提、碱提和超声辅助碱提3种方式制备可溶性膳食纤维(Soluble dietary fiber,SDF),通过响应面优化超声提取SDF的制备条件,并对比分析不同提取方式得到SDF的结构和功能特性。结果显示,SDF的最佳提取工艺参数为:超声功率184 W、提取时间30 min、提取温度48 ℃,在此条件下SDF得率为36.86%。功能特性分析结果显示,超声能显著提高SDF的持水性、持油性、溶胀力和葡萄糖吸附与胆固醇结合能力,其中对持油性、溶胀力和胆固醇结合能力分别提高了49.80%、46.59%和54.92%。综上,超声提取的SDF可作为潜在减肥降脂功效成分用于功能性食品加工过程中并能表现出良好的稳定性。研究结果将为以芹菜渣为原料生产可溶性膳食纤维及其应用提供理论依据。     

Optimization for alkali extraction of windmill palm fibril

Optimization conditions for windmill palm fibril extraction from palm surface fiber with NaOH were investigated using response surface methodology. Thus, changes in NaOH and H₂O₂ concentration and temperature occurring in palm surface fiber before and after alkali treatment were studied. A central composite design was employed to build the empirical model. The optimal conditions for weight loss were established as: an NaOH concentration of 1.93%, H₂O₂ concentration of 4.17%, and extraction temperature of 67.08 °C. Under these conditions, a loss rate of 53.14 ± 0.27% was observed. This is in good agreement with the predicted value of 52.99%. Changes after optimum alkali treatment were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, and thermogravimetric measurements. These measurements indicated that the alkali treatment removed most of the hemicellulose and lignin covering the palm surface and increased its crystallinity as well as the initial thermal degradation temperature.