Comparative Studies of Some Physico‐mechanical Properties of Alkali and Diazonium Salts‐Treated Jute Fiber

Abstract

The effect of diazonium salts and alkali on some physico‐mechanical properties, viz, tensile strength, tenacity, elongation at break, moisture regain, shrinkage, loss in weight, etc. of jute fiber has been studied. The tensile strength, tenacity, elongation at break, and moisture regain properties of the treated (dyed) fiber are found lower in comparison with those of raw (control) fiber. However, higher tensile strength and tenacity of the diazonium salts‐treated jute fiber are observed in comparison with those of the alkali‐treated fiber. The nature of the shades developed on jute fiber is also reported.     

腰果酚接枝黄麻纤维不饱和聚酯复合材料的力学性能及界面调控

用甲苯二异氰酸酯与腰果酚(CNSL)合成大分子偶联剂接枝黄麻纤维。以接枝的黄麻纤维为增强体,通用的不饱和聚酯树脂为基体,采用热压方式制备复合材料。比较了纯饱和聚酯树脂、5 %CNSL增韧的不饱和聚酯树脂、25 %碱处理的黄麻纤维不饱和聚酯树脂复合材料和25 %的CNSL接枝黄麻纤维不饱和聚酯树脂复合材料的拉伸强度和冲击强度。结果表明,CNSL接枝于黄麻纤维上;CNSL的加入能提高材料的韧性,黄麻纤维能提高材料的拉伸强度而不能提高材料韧性;25 %CNSL接枝的黄麻纤维不饱和聚酯树脂能提高材料的拉伸强度和韧性,25 %CNSL接枝的黄麻纤维增强含5 %CNSL的不饱和聚酯复合材料,其冲击强度为12.10 kJ/m^2。     

Studies on jute-reinforced composites,its limitations,and some solutions through chemical modifications of fibers

Jute, unlike other natural fibers, absorbs moisture and its moisture regain property is quite high. Water migration and subsequent degradation of jute-based composites can be a problem. Because jute is hydrophilic and the matrix resins are mostly hydrophobic, wetting of the fibers with resins is poor, for which high resin consumption may occur that would increase the cost of composites. To reduce the moisture regain property of jute fiber, it is essential to pretreat the jute fiber so that the moisture absorption is reduced and the wettability of the resin is improved. Jute fiber in the form of nonwoven jute has been pretreated with precondensate like phenol formaldehyde, melamine formaldehyde, cashew nut shell liquid-formaldehyde, and polymerized cashew nut shell liquid. The moisture content of the pretreated nonwoven jute has been determined by conventional methods and by a differential scanning calorimetric technique. Treatment of jute with precondensate causes the reduction of water regain property in jute. Pretreated nonwoven jute has been impregnated with phenol formaldehyde resin, and the composite board has been prepared therefrom. The jute composite board has been tested for bending strength, tensile strength, thickness swelling, and water absorption. Thermal analyses, such as differential scanning calorimetry and thermogravimetry, have also been conducted on jute and pretreated jute fibers. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1093–1100, 1998     

Degradation Studies of Thermoplastics Composites of Jute Fiber–Reinforced LDPE/Polycaprolactone Blends

This article reports the fabrication, properties, and degradation studies of jute fiber–reinforced thermoplastic polymers. One of the non-traditional outlets of jute fiber is in the area of fiber-reinforced composites. However, the major drawback associated with the application of jute fiber for this purpose is its high moisture regain. To impart hydrophobicity to the fibers and to concomitantly increase interfacial bond strength, which is a critical factor for obtaining better mechanical properties of composites, jute fibers were treated with benzoylchloride, Y-glycidoxytrimethoxysilane, and neo-alkoxy-tri(N-ethylenediamino)ethyltitanate. Such a treatment resulted in an increase in the diameter and denier of the treated fibers, and deterioration in the mechanical properties was observed. SEM studies revealed an increase in surface roughness after titanate and alkali treatment, which in turn increases interfacial bond strength. A series of low-density polyethylene (LDPE) blends with 5–20% (w/w) of poly(e-caprolactone) (PCL) and with/without treated and untreated jute fibers were prepared by using a single-screw extruder. LDPE modified by blending with PCL (80:20, wt/wt) was used as a thermoplastic matrix. Composites were fabricated by using 1-cm-long jute fibers; the weight fraction of unmodified fibers, silane-treated fibers, and titanate-treated fibers was varied from 0.05 to 0.13. An increase in weight fraction of fibers resulted in an increase in tensile strength and modulus and decrease in elongation at break. Thin sheets and dumbbells were used for enzymatic degradation tests. The degradation of the material was monitored by weight change and loss of mechanical properties. The enzymatic degradation in the presence of Pseudomonas cepacia lipase gave appreciable weight loss in PCL and blended materials.     

Zum Verhalten von Jute- und Flachsfaser-Epoxidharz-Verbunden mit alkalibehandelten Fasern bei Feuchteexposition

Investigations on the influence of exposure to water on the physical properties of untreated and alkali-treated jute and flax fibers and their composites with an epoxy resin were carried out. The moisture uptake led to a strong anisotropic swelling which was more significant for the alkali treated fibers. In general, jute fibers lost roughly 30% of their tenacity after this water exposure, while the tenacity of flax fibers remained unaffected. Due to this, the tensile strength of jute-epoxy composites decreases with increasing water content, while the strength of comparable flax-epoxy composites increases slightly. The dynamic strength of the composites was improved by the use of alkali-treated fibers, the loss of this characteristic value after a 49-days water storage was influenced by the type of fiber and their treatment.     

X-COOL凉爽纤维及其纱线的基本性能

通过对X-COOL凉爽纤维的微观形态结构、单纱强力以及纱线条干均匀度、捻度、回潮率和含水率、耐酸碱等性能的测试发现:X-COOL凉爽纤维纵向为有凹槽的圆柱状,横截面为X形;XCOOL凉爽纱线的断裂伸长较大,单纱断裂强力超过250 c N;捻度较低;回潮率和含水率均较低;耐酸不耐碱,尤其不耐强碱。     

挤出-注塑制备黄麻增强PLA复合材料及其性能

通过挤出共混、造粒、注射成型的方式制备了黄麻纤维填充聚乳酸(PLA)复合材料,研究了复合材料的力学性能以及黄麻与PLA之间的微观界面形貌。结果表明:黄麻的加入,并没有很好地改善黄麻/PLA复合材料的拉伸强度和弯曲强度;碱处理后的黄麻与PLA之间的界面性能有所改善;碱处理黄麻的加入,改善了黄麻/PLA复合材料的断裂伸长率与冲击韧性。     

Composites based on jute fibers and phenolic matrices: Properties of fibers and composites

Composites based on phenolic matrices and both untreated and alkali and ionized air–treated jute fibers were prepared. Different fiber lengths and fiber content were used to reinforce the phenolic matrices. The jute fibers were characterized with respect to lignin, holocellulose, ash, and humidity contents and also to the crystallinity index. The mechanical properties of fibers were investigated by means of tensile analysis and the morphology by SEM. The untreated and treated jute fiber–reinforced composites were characterized as to water absorption. The mechanical property and morphological aspects of the composites were evaluated by impact strength and photomicrographs obtained from SEM. Among the jute fiber treatments considered in the present work, the treatment with a solution of 5% NaOH presented the best results because: (1) the fiber presented a higher tensile strength, and a larger percentage of elongation at break; (2) the composite reinforced with this fiber presented the highest impact strength results when this was the unique treatment (20% of fiber), as well as when it was combined with ionized air (30% of fiber); and (3) the composite that presented the lowest water uptake was that reinforced with this fiber. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1077–1085, 2004     

一步法制备聚乙醇酸纤维的工艺及其性能研究

以聚乙醇酸(PGA)为原料,采用熔融纺丝-拉伸-卷绕一步法工艺制备PGA纤维,研究了工艺路线对纤维结构的影响,重点讨论了拉伸倍数对纤维的结构、力学性能、回弹性能及亲水抗静电性能的影响。结果表明:采用熔融纺丝-拉伸-卷绕一步法工艺,可以较好地实现PGA纤维的热拉伸,纤维与纤维之间不易黏结,纤维结构的稳定性得到改善;随着拉伸倍数的提高,PGA纤维的声速值及结晶度增加,断裂强度提高,断裂伸长率减小,总弹性形变增加,回潮率和体积比电阻变化不大;拉伸倍数从2.8提高到3.0,PGA纤维的断裂强度从2.5 cN/dtex提高至4.1 cN/dtex,断裂伸长率从26.60%降至20.40%,总弹性形变从41.24%增加至51.69%,回潮率从1.14%增加至1.26%,体积比电阻从1.53×10⁹Ω·cm降至1.02×10⁹Ω·cm。     

A Comparative Study on the Mechanical Properties of Jute and Sisal Fiber Reinforced Polymer Composites

The aim of the present study is to investigate and compare the mechanical properties of raw jute and sisal fiber reinforced epoxy composites with sodium hydroxide treated jute and sisal fiber reinforced epoxy composites. This is followed by comparisons of the sodium hydroxide treated jute and sisal fiber reinforced composites. The jute and sisal fibers were treated with 20% sodium hydroxide for 2 h and then incorporated into the epoxy matrix by a molding technique to form the composites. Similar techniques have been adopted for the fabrication of raw jute and sisal fiber reinforced epoxy composites. The raw jute and sisal fiber reinforced epoxy composites and the sodium hydroxide treated jute and sisal fiber reinforced epoxy composites were characterized by FTIR. The mechanical properties (tensile and flexural strength), water absorption and morphological changes were investigated for the composite samples. It was found that the sodium hydroxide treated jute and sisal fiber reinforced epoxy composites exhibited better mechanical properties than the raw jute and raw sisal fiber reinforced composites. When comparing the sodium hydroxide treated jute and sisal fiber reinforced epoxy composites, the sodium hydroxide treated jute fiber reinforced composites exhibited better mechanical properties than the latter.     

Study on Mechanical and Dielectric Properties of Jute Fiber Reinforced Low-Density Polyethylene (LDPE) Composites

Abstract

Jute fiber (Hessian cloth) reinforced low-density polyethylene (LDPE) composites were prepared by heat press molding techniques. The mechanical properties such as tensile strength (TS), bending strength (BS), and elongation at break of the composites were studied. The enhancement of TS (33%) and BS (50%) were obtained as a result of reinforcment jute fabrics in LDPE. In order to improve the mechanical properties and adhesion between jute and LDPE, hessian cloth were each treated with 2-hydroxyl ethyl methacrylate (HEMA). The HEMA-treated jute composite showed higher tensile and bending strength compared to untreated jute composite and LDPE. Dielectric properties like dielectric constant and loss tangent (tan δ) of jute, LDPE and composites were studied. Ferro to paraelectric phase transition occurred in both treated and untreated jute composites containing more than 20% jute. Water uptake behaviors of the composite were monitored and HEMA-treated composite showed lower water absorption behavior. The adhesion nature of jute and LDPE also characterized by scanning electronic microscopy (SEM), better adhesion was observed between HEMA-treated jute and LDPE over untreated ones.     

充气式微型保鲜冷库纤维保温材料的筛选与评价

纤维材料将是充气式微型保鲜冷库的最佳保温材料之一,其导热系数、回弹力、密度、纤维细度、弯曲度、吸湿率等指标的评价,是库体保温层厚度定量与排列组合的理论基础。研究结果表明:导热系数、回潮率、密度、表面光滑度是影响纤维保温性能的关键因素;涤纶(120 g/m2)的导热系数为0.031 5 W/m·K,回潮率为0.18%,拉伸强度为0.35 MPa,断裂伸长率为127.48%,自熄性好,是一种很好的充气式微型保鲜冷库保温材料。     

Effect of alkali and ultraviolet (UV) radiation pretreatment on physical and mechanical properties of 1,6‐hexanediol diacrylate–grafted jute yarn by UV radiation

To improve the physicomechanical properties of jute yarn, grafting with 1,6‐hexanediol diacrylate (HDDA) monomer was performed by a UV radiation technique. A series of HDDA solutions of various concentrations in methanol were prepared. A small quantity of photoinitiator (Darocur‐1664) was also added to HDDA solutions. To optimize the conditions for grafting, the effects of monomer concentration, soaking time, and radiation doses were studied by varying the number of soaking times along with variation of monomer concentrations and UV radiation intensities. The extent of polymer loading and the mechanical properties like tensile strength (TS), elongation at break (Eb), and tensile modulus of both treated and untreated jute were investigated. The highest tensile strength, polymer loading, and modulus were achieved with 5% HDDA concentration, 5 min soaking time, and the 4th pass of UV radiation. This set of conditions was selected as optimum and produced enhanced tensile strength (67%), modulus (108%), and polymer loading (11%) over those of virgin fiber. To further improve the mechanical properties the jute yarns were pretreated with alkali (5% NaOH) solution and after that the alkali‐treated yarn were treated under UV radiation of various intensities. The pretreated samples were grafted with optimized monomer concentration (5% HDDA). Increased properties of alkali + UV‐pretreated and grafted samples such as polymer loading (12%), tensile strength (103%), elongation at break (46%), and modulus (114%) were achieved over those of virgin jute yarn. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 18–24, 2004     

Structure and physical properties of grafted jute fiber

Jute fiber was grafted by acrylonitrile and methylmethacrylate monomers in raw and bleached condition. It was also noted that optimum grafting takes place after about 4 h of grafting. It was also noted that in bleached jute fiber, the grafting percentage is higher at all stages of grafting but the tenacity value at the highest add-on is practically the same as that of raw fiber with much less add-on. The crystalline orientation of the grafted jute fiber was correlated with the fiber tenacity. The moisture regain (%) of the fiber after grafting showed a decreasing trend with an increase in grafting percentage. No structural change of the fiber occurred due to grafting. © 1995 John Wiley & Sons, Inc.     

ACETYLATED PLANT-FIBER-REINFORCED POLYESTER COMPOSITES: A STUDY OF MECHANICAL,HYGROTHERMAL, AND AGING CHARACTERISTICS

The potential of acetylation of plant fibers to improve the properties of composites was studied. The chemical modification of oil palm empty fruit bunch (EFB), coconut fiber (Coir), oil palm frond (OPF), jute, and flax using noncatalyzed acetic anhydride were investigated. Proof of acetylation was indicated by the increase in weight percent gain (WPG). Acetylation at a reaction temperature of 120°C had resulted in the reduction in the tensile properties (stress, modulus, and elongation at break) of EFB and Coir composites. However, at 100°C, the acetylated samples exhibited improved properties. The mechanical properties of acetylated EFB- and Coir-fiber-reinforced polyester composites was evaluated at different fiber loadings. The tensile strength and modulus were improved, but elongation at break was slightly reduced upon acetylation, particularly at high fiber loading. Impact properties were moderately increased for those composites with fiber loadings up to 45%. Acetylation exhibited a low moisture absorption, comparable with glass-fiber composites. Acetylated EFB and Coir composites showed superior retention of tensile and impact properties after aging in water up to 12 months.     

Effect of hydrogen peroxide bleaching onto sulfonated jute fiber

Bleaching of raw and sulfonated jute fiber with hydrogen peroxide were carried out in an aqueous medium. To obtain the optimum condition for bleaching, the effects of hydrogen peroxide concentration, temperature, time, pH, and fiber–liquor ration were studied. Bleaching affected the whiteness and tenacity, and the optimum whiteness index (76) and tenacity (13.7 g/tex) for the bleached sulfonated jute fiber were obtained with 2.1% hydrogen peroxide at pH 11, temperature 95°C, treatment time 110 min, and fiber–liquor ratio 1 : 7. The photo‐oxidative degradation of bleached sulfonated jute fiber was characterized by UV light exposure and compared with that of bleached raw jute fiber. It has been observed that the photo‐oxidative degradation as well as loss in tenacity and yellowness of the bleached sulfonated jute fiber was 63 and 40% lower than that of bleached raw jute fiber. Bleached sulfonated jute fiber had excellent impact on color fastness with reactive dyes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3603–3607, 2006     

磁性纤维及其纱线的基本性能

通过对磁性纤维的微观形态结构、单丝力学性能及其混纺纱的断裂强力、回潮率和含水率、耐热性和耐酸碱性等性能的测试发现:磁性纤维表面分布着不规则的磁粉微粒;磁性纤维的断裂伸长率较大;磁性纤维湿纺纱的单纱断裂强力接近300 cN,其延伸性较好,回潮率和含水率均较低,耐干热性良好,耐湿热性较差,耐酸不耐碱,尤其不耐强碱。     

Sorption behavior and crystallinity of jute fiber at higher alkali treatments

Moisture regain of jute fiber was studied at different alkali concentrations and temperatures. It was found that the moisture regain increased up to 4.5N alkali treatment and then leveled off. Variation in swelling temperature had no significant effect on moisture regain. Amorphous fraction calculated from Valentine's equation using sorption ratio was compared with infrared crystallinity. The accessibility was increased with decreasing crystallinity in alkali-treated jute fiber, where as in cyanoethylated jute fiber it increased with increasing the degree of cyanoethylation.     

脂肪族水性聚氨酯胶膜的合成和性能研究

用傅里叶变换红外光谱以及凝胶渗透色谱对异氟尔酮二异氰酸酯（IPDI）型脂肪族水性聚氨酯胶膜进行了结构表征及分子量分布测试。在此基础上，详细研究了影响胶膜拉强度，断裂伸长率，24h吸水率等性能的关键因素。结果表明：用IPDI为原料合成的脂肪族中性聚氨酯胶膜的耐光性比用甲苯二异氰酸酯为原料合成的芳香族水性聚氨酯胶膜强；异氰酯基/羟基（NCO/OH，摩尔比）对胶膜的拉伸强度和断裂伸长率有显著影响。NCO/OH增大，胶膜的拉伸强度也增大；NCO/OH越大，胶膜越硬，断裂伸长率越小，亲水基团含量越大，胶膜24h吸水率也越大，胶膜的耐水性越低。     

A Comparative Study on the Mechanical,Degradation and Interfacial Properties of Jute/LLDPE and Jute/Natural Rubber Composites

Jute fabric (hessian cloth) reinforced low-density polyethylene (LLDPE) composites (40 wt%) and solid natural rubber-(NR) based composites (40 wt%) were fabricated by compression molding. Tensile strength (TS), tensile modulus (TM) and percentage elongation at break (Eb) of jute/LLDPE composites were found to be 29, 680 MPa and 20%, and for jute/NR-based composites were also found to be 15, 122 MPa and 94%, respectively. Interfacial shear strength (IFSS) of the jute/LLDPE and jute/NR systems was investigated by using the single fiber fragmentation test (SFFT). Scanning electron microscopy (SEM) and aqueous degradation tests were also performed.