Interfacial adhesion in jute‐polyolefin composites

The interfacial adhesion between four different forms of jute fibers (sliver, bleached, mercerized and untreated) and polyolefinic matrices (LDPE and PP) was studied, as a critical factor affecting the mechanical behavior of these composites. The fiber‐matrix adhesion was estimated by means of the critical fiber length (l_c) and the stress transfer ability parameter (τ); such parameters were obtained by Single Fiber Composite (SFC) tests. Tests were carried out to evaluate the mean tensile strength of the fibers, the mean critical fiber lengths and the stress transfer ability parameter for every fiber‐matrix combination, according to Weibull's statistical method. Thermal‐mechanical characterization of the fibers was also carried out to evaluate the resistance to processing conditions. A limited degradation of strength was observed, which, however, does not preclude the use of jute fibers as reinforcing means in polyolefin based composites. It was found that the adhesion was better in PP‐jute composites than in LDPE‐jute composites. In both cases the results showed that the sliver jute and the untreated jute had better adhesion to both matrices than had the bleached and the mercerized fibers. With both matrices the interface adhesion was in the order: mercerized < bleached < untreated = sliver.     

Comparative Studies of Mechanical and Interfacial Properties Between Jute Fiber/PVC and E-Glass Fiber/PVC Composites

Composites (50 wt% fiber) of jute fiber reinforced polyvinyl chloride (PVC) matrix and E-glass fiber reinforced PVC matrix were prepared by compression molding. Mechanical properties such as tensile strength (TS), tensile modulus (TM), bending strength (BS), bending modulus (BM) and impact strength (IS) of both types of composites was evaluated and compared. Values of TS, TM, BS, BM and IS of jute fiber/PVC composites were found to be 45 MPa, 802 MPa, 46 MPa, 850 MPa and 24 kJ/m², respectively. It was observed that TS, TM, BS, BM and IS of E-glass fiber/PVC composites were found to increase by 44, 80, 47, 92 and 37.5%, respectively. Thermal properties of the composites were also carried out, which revealed that thermal stability of E-glass fiber/PVC system was higher. The interfacial adhesion between the fibers (jute and E-glass) and matrix was studied by means of critical fiber length and interfacial shear strength that were measured by single fiber fragmentation test. Fracture sides after flexural testing of both types of the composites were investigated by Scanning Electron Microscopy.     

Fabrication and Mechanical Characterization of Jute Fabrics: Reinforced Polyvinyl Chloride/Polypropylene Hybrid Composites

Jute fabrics such as reinforced polyvinyl chloride (PVC), polypropylene (PP), and a mixture of PVC and PP matrices-based composites (50 wt% fiber) were prepared by compression molding. Tensile strength (TS), bending strength (BS), tensile modulus (TM), and vbending modulus (BM) of jute fabrics' reinforced PVC composite (50 wt% fiber) were found to be 45 MPa, 52 MPa, 0.8 GPa, and 1.1 GPa, respectively. The effect of incorporation of PP on the mechanical properties of jute fabrics' reinforced PVC composites was studied. It was found that the mixture of 60% PP and 40% PVC matrices based composite showed the best performance. TS, BS, TM, and BM for this composite were found to be 65 MPa, 70 MPa, 1.42 GPa, and 1.8 GPa, respectively. Degradation tests of the composites for up to six months were performed in a soil medium. Thermo-mechanical properties of the composites were also studied.     

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。     

Effect of alkaline treatment on physical,mechanical, and thermal characteristics of jute filler reinforced epoxy composites

With burgeoning environmental concerns worldwide, using natural fibers/fillers to produce composites rather than conventional fibers is on the rise. The current work focuses on the physical and thermomechanical characteristics of alkaline-treated jute filler-based epoxy composites. The composites have been prepared with different weight fraction of jute fillers (0%, 2.5%, 5%, 7.5%, 10%, and 12.5%) using hand layup process. The X-ray diffraction and Fourier transform infrared spectroscopy analysis observed that the alkali treatment of jute fillers improved the crystallinity and molecular structure, enhancing the interfacial and molecular bond between fillers and matrix. The mechanical characterizations of developed composites analyzed that the inclusion of treated jute fillers strengthened the tensile and flexural properties. The 5% filler-based composites have demonstrated maximum tensile strength (54.06 MPa) and modulus (3.12 GPa) with maximum flexural strength (67.55 MPa) and modulus (3.90 GPa). The viscoelastic characteristics of composites revealed that the 7.5% filler-based composite has the highest storage modulus (3.75 GPa), loss modulus (0.496 GPa), and glass transition temperature (91°C) due to greater interfacial interactions of molecules. The weight loss and degradation of composites analyzed with thermogravimetric analysis, and observed better thermal stability with treated jute fillers. The morphological analysis at fracture surfaces analyzed the brittle catastrophic failure of composites. Therefore, the finding produced better specific strength and stiffness with greater thermal stability for electronics equipment, packaging, and transportation.     

Characterization and mechanical property of Trinidad coir fibers

Coir fibers were retted in distilled water (DW) and saline water (SW) for up to 12 weeks. Fibers had diameters of 0.16 mm to 0.56 mm, gauge lengths (GL) of 20 mm and 50 mm, and loaded at strain rates of 5, 20, 40, and 60 mm/min. Tensile strength, Young's modulus, and strain at break properties were evaluated and the results statistically analyzed using analysis of variance (ANOVA). For non‐retted fibers, as the gauge length decreased, the tensile and strain at break increased by 14% and 42%, respectively, while the stiffness increased by 33% for larger gauge lengths. As the fiber diameter decreased, the tensile strength increased from 48.45 MPa to 134.41 MPa for 50 mm gauge length fibers. X‐ray diffraction (XRD) was used to calculate the crystallinity index (CI) of the coir fibers. Secondary electron microscopy was used to assess the fiber surface and fractured area. Although the chemical composition was different, the properties of Trinidad coir fibers were in‐line with coir fibers from other parts of the world making them an ideal material of choice for composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43692.     

黄麻纤维增强不饱和聚酯树脂初步研究

以油酸为偶联剂,将氢氧化钠-油酸处理后的黄麻纤维布作为填充材料制备了不饱和聚酯复合材料,并对氢氧化钠处理黄麻纤维的适宜浓度、复合材料的拉伸强度、冲击强度、吸水率进行了研究测试。结果表明:氢氧化钠的适宜浓度为20%,黄麻纤维增强不饱和聚酯树脂的冲击强度及拉伸强度最大值分别为12.75 kJ/m2和33.05 MPa,复合材料的最大吸水率为4.07%。经油酸处理的黄麻纤维可有效提高不饱和聚酯复合材料的性能。     

黄麻纤维增强聚丙烯的力学性能

本文讨论了注塑成型黄麻纤维增强聚丙烯的制备方法和力学性能.将纤维重量含量分别为10%、20%和30%的复合材料进行比较,分析纤维含量对复合材料拉伸、弯曲和冲击性能的影响;将纤维分别切成约3mm、5mm和10mm长制成复合材料进行比较,分析纤维长度对复合材料拉伸、弯曲和冲击性能的影响.掺入黄麻纤维能使聚丙烯的拉伸和弯曲性能提高,但使其冲击强度降低;随纤维含量的增加或纤维长度的增加,复合材料的强度和模量是递增的,而冲击强度是递减的.     

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.     

改性黄麻纤维增强聚氨酯硬泡性能的研究

采用碱处理工艺对黄麻纤维进行了表面改性,提高了纤维对基体树脂的浸润性,改善了纤维与树脂基体的界面粘结。研制了一种新型的黄麻纤维增强硬质聚氨酯结构泡沫材料。测试结果发现,碱处理后纤维表面出现沟槽和裂纹,拔出的单丝纤维表面包覆有聚氨酯基体,纤维与基体结合紧密。压缩性能实验结果表明,添加改性纤维的复合材料,其压缩强度明显提高,当纤维质量分数为3.0%时,复合材料的压缩强度达到最大值(8.01 MPa);纤维质量分数为3.0%、长度为3 mm的短切纤维的增强效果较好;随着纤维含量和长度的增加,复合材料的压缩模量亦随之增大。     

Effect of the atmospheric plasma treatment parameters on jute fabric: The effect on mechanical properties of jute fabric/polyester composites

The effect of atmospheric air plasma treatment of jute fabrics on the mechanical properties of jute fabric reinforced polyester composites was investigated. The jute fabrics were subjected to different plasma powers (60, 90, and 120 W) for the exposure times of 1, 3, and 6 min. The effects of plasma powers and exposure times on interlaminar shear strength, tensile strength, and flexural strength of polyester based composites were evaluated. The greatest ILSS increase was about 171% at plasma power of 120 W and exposure time of 6 min. It is inferred that atmospheric air plasma treatment improves the interfacial adhesion between the jute fiber and polyester. This result was also confirmed by scanning electron microscopy observations of the fractured surfaces of the composites. The greatest tensile strength and flexural strength values were determined at 120 W for 1 min and at 60 W for 3 min, respectively. Moreover, it can be said that atmospheric air plasma treatment of jute fibers at longer exposure times (6 min) made a detrimental effect on tensile and flexural properties of jute‐reinforced polyester composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study of interfaces of high-performance glass fibers and DGEBA-based epoxy resins using single-fiber-composite test

The single-fiber-composite (SFC) technique was used to study the interfacial behavior between two flexible blends of diglycidylether of bisphenol A (DGEBA)-based epoxy and polyglycol epoxide and three glass fibers. Dog-bone-shaped SFC specimens were made and strained to obtain a distribution of fragment lengths. The fibers were tension-tested at two different gauge lengths. The fragment length distributions, the fiber strength data, and a Monte Carlo simulation of a Poisson/Weibull model for fiber strength and flaws were used to obtain the effective interfacial shear strength values. The results show that the interface does not fail. Instead, penny-shaped transverse cracks appear at every fiber break and grow as the specimen is strained. The interfacial shear strength values are many times higher than the yield shear strength values of bulk epoxy obtained from the tension test.     

Effect of coupling agents on the thermal and mechanical properties of polypropylene–jute fabric composites

Composites with different jute fabric contents and polypropylene (PP) were prepared by compression molding. The composite tensile modulus increased as the fiber content increased, although the strain at break decreased due to the restriction imposed on the deformation of the matrix by the rigid fibers. Moreover, and despite the chemical incompatibility between the polar fiber and the PP matrix, the tensile strength increased with jute content because of the use of long woven fibers. The interfacial adhesion between jute and PP was improved by the addition of different commercial maleated polypropylenes to the neat PP matrix. The effect of these coupling agents on the interface properties was inferred from the resulting composite mechanical properties. Out‐of‐plane instrumented falling weight impact tests showed that compatibilized composites had lower propagation energy than uncompatibilized ones, which was a clear indication that the adhesion between matrix and fibers was better in the former case since fewer mechanisms of energy propagation were activated. These results are in agreement with those found in tensile tests, inasmuch as the compatibilized composites exhibit the highest tensile strength. Scanning electron microscopy also revealed that the compatibilized composites exhibited less fiber pullout and smoother fiber surface than uncompatibilized ones. The thermal behavior of PP–compatibilizer blends was also analyzed using differential scanning calorimetry, to confirm that the improvements in the mechanical properties were the result of the improved adhesion between both faces and not due to changes in the crystallinity of the matrix. Copyright © 2006 Society of Chemical Industry     

Influence of electron beam treatment of jute on the thermal properties of random and two-directional jute/poly(lactic acid) green composites

In the present study, randomly aligned jute fiber/poly(lactic acid) (PLA) and two-directionally aligned jute fabric/PLA green composites with jute (50% by weight) treated with electron beam at different dosages (0, 5, 10, 30, 50, and 100?kGy) were fabricated by compression molding technique and the effect of electron beam treatment on their thermal properties was investigated in terms of thermal expansion, thermal stability, dynamic mechanical thermal property, and heat deflection temperature (HDT). The dynamic storage modulus and HDT of neat PLA were significantly increased by incorporating jute fibers or fabrics into PLA, whereas the coefficient of thermal expansion (CTE) and the damping property were decreased, reflecting the enhancement in the interfacial adhesion between the jute and the PLA by electron beam treatment with an optimal dosage of 10?kGy and the reinforcing effect by jute. The result exhibited that the thermal stability, storage modulus, and HDT of jute/PLA green composites were highest with the electron beam irradiation of jute at 10?kGy and lowest at 100?kGy, whereas the CTE and tan δ were lowest at 10?kGy and highest at 100?kGy. The thermal behavior of random jute/PLA green composites shows a similar tendency to that of 2D jute/PLA counterparts and the influence of electron beam irradiation on the thermal properties studied was consistent with each other. The thermomechanical analysis, dynamic mechanical thermal analysis, thermogravimetric analysis, and HDT results were in agreement with each other, showing a comparable effect of electron beam irradiation on composites thermal characteristics.     

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。     

FTIR spectra and physico-chemical behavior of vinyl ester participated transesterification and curing of jute

In this article we report the transesterification of jute with n-Butylacrylate (BA) under appropriate condition using NaOH, Pyridine (Py), and a Pyridine–acetone mixture as a catalyst. The modified vinylog jute was subsequently cured with benzoylperoxide (BPO) in acetone at 50–60°C. The parent and chemically modified jute were characterized by FTIR spectra. The percent moisture regain, mechanical strength, and behavior to common chemical reagents of the parent and modified fibers have also been tested. Transesterification and curing of jute lowered the percentage of moisture regain, imparted mechanical strength, and resistance to common chemical reagents. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 575–581, 2001     

Fabrication and evaluation of some mechanical and electrical properties of jute‐biomass based hybrid composites

Hybrid composites based on bisphenol‐C‐formaldehyde resin and jute mat with rice, wheat, sugar cane, and jamun husks have been fabricated at 150°C under 30.4 MPa pressure for 2 h. The resin content in composites was 50% of fibers. Tensile strength, flexural strength, electric strength, and volume resistivity of hybrid composites have been evaluated and compared with those of jute‐bisphenol‐C‐formaldehyde composites. It is observed that the tensile strength of composites is found to decrease by 53–72%, which is mainly due to random orientation of sandwiched fibers. Flexural strength has increased by 53–153% except jute–rice husk composite for which it is decreased by 26%. A little change in dielectric breakdown strength (1.89–2.11 kV/mm) is found but volume resistivity of Jute–wheat husk and Jute–jamun husk composites has improved by 437–197% and it is slightly decreased(2.3–25.2%) for the remaining two composites. Thus, hybrid composites possess good mechanical and electrical properties signifying their importance in low strength and light weight engineering applications as well as low cost housing units such as partition and hard boards. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1754–1758, 2006     

Fracture behavior of vinylester resin matrix composites reinforced with alkali‐treated jute fibers

Jute fibers were treated with 5% NaOH solution for 4 and 8 h, respectively, to study the mechanical and impact fatigue properties of jute‐reinforced vinylester resin matrix composites. Mechanical properties were enhanced in case of fiber composites treated for 4 h, where improved interfacial bonding (as evident from scanning electron microscopy [SEM]) and increased fiber strength properties contributed effectively in load transfer from the matrix to the fiber; but their superior mechanical property was not retained with fatigue, as they showed poor impact fatigue behavior. The fracture surfaces produced under a three‐point bend test and repeated impact loading were examined under SEM to study the nature of failure in the composites. In case of untreated fiber composites, interfacial debonding and extensive fiber pullout were observed, which lowered the mechanical property of the composites but improved their impact fatigue behavior. In composites treated for 4 h under repeated impact loading, interfacial debonding occurred, followed by fiber breakage, producing a sawlike structure at the fracture surface, which lowered the fatigue resistance property of the composites. The composites with fibers treated with alkali for 8 h showed maximum impact fatigue resistance. Here, interfacial debonding was at a minimum, and the fibers, being much stronger and stiffer owing to their increased crystallinity, suffered catastrophic fracture along with some microfibrillar pullout (as evident from the SEM micrographs), absorbing a lot of energy in the process, which increased the fatigue resistance property of the composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2588–2593, 2002     

Jute fabric reinforced engineering thermoplastic sandwich composites. I. The effect of molding time

Jute fabric‐reinforced sandwich composites were fabricated using engineering thermoplastics. The jute fabrics were precoated with thermosetting resin to improve their thermal resistance before molding of the composites. Thermal gravimetric analysis (TGA) studies revealed that the resin coated fabrics decomposed at higher temperature than the uncoated jute. The onset of degradation of the coated fibers also falls between that of jute fibers and the thermoset resins. This indicates the presence of good interfacial bonding between jute fibers and both resins. Isothermal TGA studies revealed that jute could withstand brief exposure to higher temperature at 270 and 290°C. The sandwich composites were fabricated at 270°C by compression molding for 1.5 and 3 min in each case, and then characterized by flexural, tensile and morphological studies, i.e., SEM and optical microscopy. The uncoated jute fabric yielded composites of superior mechanical properties even with 3 mins molding at 270°C which is close to the degradation temperature of uncoated jute fibers. This is an indication that it is feasible to prepare jute fiber filled engineering polymer composites provided the exposure time at high temperature during processing does not exceed 3 mins as determined by TGA isothermal studies. SEM studies revealed strong fiber/matrix interfacial bonding between jute and the thermoset resins while the inferior mechanical properties of the resin coated sandwich composites could be attributed to the poor interfacial bonding between the already cured thermoset coating and the matrix based on optical microscopy of the polished cross‐sections. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

熔融浸渍法制备PE-HD/黄麻纤维复合材料工艺及性能研究

采用特殊设计的天然纤维熔融浸渍模具制备黄麻长纤维颗粒,通过注塑工艺,制备了长黄麻纤维增强高密度聚乙烯（PE-HD）复合材料。研究了纤维含量、浸渍模具温度对PE-HD/黄麻纤维复合材料力学性能、微观断面形貌的影响。结果表明,利用熔融浸渍工艺制备PE-HD/黄麻纤维复合材料,有效地保障了黄麻纤维的长度,可显著提高复合材料的力学性能;当黄麻纤维含量为45 %,浸渍模具温度为210 ℃时,PE-HD/黄麻纤维复合材料的拉伸强度和弯曲强度最优,相对纯PE-HD分别提高了49.1 %和137 %。