Effect on physical characteristics of jute fibres with cellulase and specific mixed enzyme systems

This research investigated the effect of using cellulase enzyme and a mixture of enzymes (cellulase, xylanase and pectinase), under specific treatment conditions, on the physical characteristics of jute fibres. The physical characteristics such as tenacity, elongation to break, flexural rigidity and structural analysis using scanning electron microscopy and colour measurements using colour spectroscopy were studied. Tensile characteristics of these enzyme-treated jute fibres in terms of tenacity (cN/tex) were found to decrease by approximately 9.05%, 14.76% and 19.83% for cellulase enzyme treatment and 11.96%, 13.47% and 23.81% for mixed enzymes at 2%, 3% and 4% concentration levels, respectively. Significant improvements in physical characteristics such as elongation, whiteness index, brightness index and reflectance of these enzyme-treated jute fibres were noticed when compared to those of raw jute fibres. The significant reduction in flexural rigidity and yellowness index of these enzyme-treated jute fibres was also noticed. Scanning electron microscopy reveals the degradation of the jute fibre at surface level and along with the removal of the gummy substances present on the surface; this degradation depends on the various concentrations of the enzyme.     

黄麻纤维增强混凝土的抗压和抗折性能研究

在混凝土中添加黄麻纤维,以增强混凝土的抗压和抗折性能。通过测定纤维增强混凝土的抗压和抗折强度,并与素混凝土进行对比,进而研究黄麻纤维的长度和掺量对混凝土的增强作用。结果表明:黄麻纤维长度为30mm,掺量为0.5～0.6kg/m3时,对混凝土的抗压及抗折强度增强作用最为显著。     

熔融纺聚乳酸/聚丙烯纤维的制备及其性能

为提高聚乳酸(PLA)纤维的力学性能,采用聚丙烯(PP)与聚乳酸(PLA)通过熔融纺丝制备PLA/PP纤维,并借助差示扫描热量仪、热重分析仪、万能材料测试仪、纤维双折射仪对其热学性能、热稳定性、拉伸性能和纤维取向度进行表征。结果表明:PP的引入对PLA的玻璃化转变温度和熔融温度没有显著影响,但促进了PLA的结晶,结晶度提高了585.9%;随着PP质量分数的增加,PLA的热稳定性降低(特别是在初始分解阶段),但其残炭率提高,同时PLA/PP共混纤维的取向度提高,力学性能得到改善;当PP质量分数为20%时,PLA/PP共混纤维的取向度、断裂强度和断裂伸长率分别提高了55.6%,98.2%和44.4%。     

Studies on Mechanical and Morphological Characterization of Developed Jute/Hemp/Flax Reinforced Hybrid Composites for Structural Applications

In the present study, an attempt has been made to develop and characterize natural fiber-based composites (jute/epoxy, hemp/epoxy, flax/epoxy) and their hybrid composites (jute/hemp/epoxy, hemp/flax/epoxy, and jute/hemp/flax/epoxy) using hand-lay-up technique. Mechanical characterization (tensile, flexural, impact, and hardness test) of the developed composites was performed. The interface between fiber and matrix was examined using scan electron microscopy (SEM). Among (jute/epoxy, hemp/epoxy, flax/epoxy), flax/epoxy composite has shown higher hardness (98 Shore-D) and tensile strength (46.2 MPa) whereas better flexural and impact strength have been shown by hemp/epoxy (85.59 MPa) and jute/epoxy (7.68 kJ/m²) composites respectively. Results showed that hybrid composites observed better mechanical properties. Jute/hemp/flax/epoxy hybrid composite showed the highest tensile strength, modulus and impact strength of 58.59 MPa, 1.88 GPa, and 10.19, kJ/m², respectively. Jute/hemp/epoxy hybrid composite achieved the maximum flexural strength of 86.6 MPa.     

A new assessment on mechanical properties of jute fiber mat with egg shell powder/nanoclay-reinforced polyester matrix composites

ABSTRACT

Natural fiber polymer matrix composites occupy the major percentage in applications due to its ecofriendly and low-cost nature. This study investigates the mechanical properties of a polyester matrix nanocomposite reinforced by the NaOH-treated jute fabric mat (NJM) and untreated jute fabric mat (UJM). In addition, the effects of egg shell powder (ESP) and nanoclay (NC) to the above has also been studied. The matrices were prepared with different combinations of presence and absence of the ESP, NC, and both as well as different weight percentage using compression molding process. The mechanical and morphological properties of the composites were determined. The tensile strength, flexural strength, and impact strength of NJM with NC 1.5%wt and ESP 1.5%wt were found to be 29.28 MPa, 39.51 MPa and impact strength 3.03 J, respectively. This composition is superior to the other compositions. Morphological analysis of tensile fractured surface showed interfacial adhesion between UJM and NJM composites. NJM composites contained smaller amount of pullouts and the splits compared with the UJM composites, which hold up the better performance.     

碳纤维/聚丙烯/聚乳酸增强复合材料的力学性能

为在不改变碳纤维/聚丙烯(PP)复合材料力学性能前提下,降低复合材料中PP含量以减轻环境降解压力,通过在碳纤维/PP复合材料树脂体系中掺杂可降解的聚乳酸(PLA)形成共混树脂体系,并经热压成型制备碳纤维增强共混树脂复合材料。探究了PLA、PP共混体系质量比对复合材料冲击、弯曲和拉伸性能的影响。结果表明:随着树脂体系中PLA质量分数的增加,复合材料的冲击强度和弯曲强度都呈先降低后升高、再降低的趋势,拉伸强度呈现先升高后降低的趋势;当PLA质量分数为60%时,复合材料的冲击强度和弯曲强度最高,分别为21.8 kJ/m²和112.5 MPa,拉伸强度为37.2 MPa,复合材料的综合物理力学性能最优,与未添加PLA的复合材料的力学性能相近。     

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.     

Preparation and characterization of polypropylene/wood flour/nanoclay composites

In this study, the effects of coupling agent and nanoclay loading on the mechanical properties and water absorption of composites are investigated. Composites based on polypropylene (PP), wood flour, nanoclay, and maleated polypropylene (MAPP) were made by melt compounding and then injection molding. The mechanical analysis showed that the biggest improvement of the tensile and flexural strengths can be achieved for the nanoclay loading at 3%. However, further increasing of the loading of nanoclay resulted in a decrease of all the mechanical properties. The maximum tensile and flexural strengths (increase of ??46%, compared to the pure PP) were achieved in the composites when 7.5% MAPP was used as coupling agent in the manufacture of the composites. Finally, it was found that addition of nanoclay or MAPP reduced the water absorption property of the composites. However, the extent of improvement in the water absorption is more prominent with MAPP.     

公路护坡生态毯的研制

以废棉纤维、聚丙烯(PP)纤维和麻纤维为原料,采用非织造技术加工成不同结构性能的针刺非织造材料,用作公路护坡生态毯。以纤维配比、层叠结构和针刺密度为因素,以非织造生态毯纵/横向断裂强力、纵/横向断裂伸长率、透水水流量和表面摩擦因数为考核指标,通过正交试验设计方案优选加工工艺,得出最佳工艺组合是A2B3C1。试验结果表明:最佳配比为m(棉)∶m(麻)∶m(PP)=2∶3∶5;最佳结构为棉、PP和黄麻纤维分别单独成网,按黄麻在第一层,PP纤维在中间,棉为基层叠加的三层结构;最佳针刺密度为325刺/cm2。在上述条件下制得的生态毯性能最好,能够满足生态护坡的要求。     

可降解黄麻/PBS复合材料的结构与力学性能

为解决当前环境污染和可持续发展问题,采用模压成型工艺制备可降解黄麻/PBS复合材料,通过拉伸、弯曲性能测试、红外分析和SEM观察,探讨纤维含量和碱处理对材料性能的影响。结果表明:随着纤维含量的增加,复合材料的拉伸强度先增大后减小,在纤维含量为10%时达到最大值,比纯PBS提高了30.1%;拉伸模量、弯曲强度和弯曲模量均随纤维含量的增大而提高,在纤维含量为30%时分别比纯PBS提高了24.2%、185.5%和107.7%。碱处理后黄麻纤维表面杂质被去除,表面部分刻蚀变粗糙,复合材料的综合力学性能得到提高,其中弯曲模量提高显著,比未处理的黄麻复合材料提高了58%。     

Influence of fiber surface modifications on the mechanical behavior of Vetiveria zizanioides reinforced polymer composites

The natural fiber is pretreated with chemicals namely, alkali, peroxide, and benzoyl chloride. Composites are prepared using chemically treated fibers as reinforcements and mechanical characteristics are tested. The results confirmed that, benzoylation improved the tensile, compressive, and impact strengths of the composite by 113%, 56.78%, and 95%, respectively. Peroxide treatment has improved the flexural strength by 56.13% and improved the elongation of the composite during tension, flexure, and compression tests. The surface morphology showed minimal defects in the benzoylated composite and hence, benzoylation is suggested for the best overall behavior and peroxidation for enhanced bending and elongation.     

薄型黄麻/低熔点纤维复合地膜材料的研制

为解决传统塑料地膜对土壤及环境的污染问题,采用非织造成形技术,将黄麻纤维∕ 皮芯型低熔点纤维混合后经气流成网制成薄型纤维网,然后通过使皮芯型纤维的皮层熔融固化可以完全降解的复合地膜材料。系统地研究了模压温度、时间和压力对复合地膜力学性能的影响规律。结果表明：当低熔点纤维和黄麻纤维质量比为3：7,模压压力为 5 MPa,模压时间为30 s 时,得到力学性能较好的复合地膜材料。     

Lengthwise jute fibre properties variation and its effect on jute–polyester composite

In this study, the jute reeds were equally divided lengthwise from root to tip in three portions namely root, middle and tip. The fibre diameter, fineness, tensile strength and bundle strength of the three portion jute were evaluated and compared. Unidirectional composites containing about 35(wt/wt)% jute fibre by weight were produced in unsaturated polyester resin matrix. The effect of fibre property variation in composite’s mechanical properties was studied. Tensile and flexural properties of composites made from three portions of jute reed were studied. It was observed that tensile and flexural strength of root portion based composites are 44% and 35% higher than tip portion based composites. Tensile and flexural modulus of tip portion based composites is 18% and 17% higher than root portion based composites.     

A Comparative Study of the Mechanical Properties of Jute Fiber and Yarn Reinforced Concrete Composites

ABSTRACT

A relatively better performance of jute fiber and yarn reinforced concrete composites can open up a wide access to application of natural resources in concrete strengthening. In order to achieve this goal, an experimental investigation on the flexural, compressive and tensile strengths of Jute Fiber Reinforced Concrete Composites (JFRCC) and Jute Yarn Reinforced Concrete Composites (JYRCC) has been conducted. To draw a specific conclusion, the mix ratios of 1:1.5:3 and 1:2:4 (by volume) of concrete have been maintained with incorporation of jute fiber and yarn in concrete mortar having different cut lengths with distinct volumetric ratios. Finally, a comparison of the JFRCC and JYRCC strength increments with respect to the plain concrete has been investigated. A significant increment of compressive, flexural and tensile strength was observed only for a short cut length having a low volumetric ratio, where JYRCC increment value was always found progressive. A far more regular arrangement and adequate mixture of JYRCC was also visualized compare to JFRCC in concrete mortar. All the principal increment values were found only in case of JYRCC with a mix ratio of 1:1.5:3. So, it can be concluded that the presence of jute yarn and more cement content can strengthen the concrete to a great extent.     

山棕纤维的回弹性能研究

采用弯曲、定负荷拉伸和定伸长反复拉伸方法,对山棕纤维进行回弹性测试,分析研究其弯曲和拉伸回弹性。结果表明:增加作用时间和负荷都将降低山棕纤维的回弹性,回复时间的延长有助于回弹率提高;山棕纤维的弯曲回弹率在回复时间的前5 min增加较快,之后趋于缓慢,弯曲缓弹性形变完全回复需要较长时间,弯曲时间对于弯曲回弹率的影响大于负荷的影响;定负荷回弹率随负荷增加基本呈现线性下降,而随拉伸时间延长下降的趋势由缓变急;随着循环拉伸进行,定伸长回弹率下降速度由大变小,最终拉伸次数不再明显影响回弹率。     

PP/IPN相变纤维的结构与性能

以聚乙二醇丙烯酸酯(PEGA)为相容剂,将聚N-羟甲基丙烯酰胺/聚乙二醇-2000互穿网络聚合物(IPN-PNHMPA/PEG)与聚丙烯(PP)共混并纺丝,制得PP/IPN相变调温纤维。对共混纤维的结构与性能进行了研究,结果表明:IPN在纤维基体中分布均匀,纤维表面基本光滑;共混纤维的力学性能较纯PP略有下降;相变焓随加入的IPN含量的增大而提高;随着IPN含量的增加,共混体系的热稳定性有所下降;IPN的加入可提高共混体系的抗冲击性能,还可增加PP的阻尼性能。     

玻璃纤维/光敏树脂复合材料的3D打印及其力学性能

为解决光固化3D打印树脂材料强度低的问题,将玻璃纤维与光敏树脂复合,采用光固化3D打印技术制备玻璃纤维增强复合材料,分析了玻璃纤维经硅烷偶联剂改性处理以及玻璃纤维的铺层方式对复合材料力学性能的影响。结果表明:玻璃纤维可提升复合材料的拉伸强度和弯曲强度,相比于未处理的玻璃纤维,经硅烷偶联剂处理的玻璃纤维对复合材料力学性能的提升更为显著,复合材料的拉伸强度提高了50%,弯曲强度提高了143%;相较于连续长纤维的铺层方式,采用模拟三维正交的铺层方式对于复合材料力学性能影响更为显著,拉伸强度提升了110%,而弯曲强度增加了147%。     

聚乳酸/聚丙烯共混纺粘纤维的制备及其性能

为探寻聚乳酸用量对聚乳酸（PLA）/ 聚丙烯（PP）共混纺粘纤维性能的影响,以PLA和PP为原料,采用实验室纺粘小样机制备了多种混比的PLA/PP共混纺粘纤维。采用扫描电子显微镜、电子单纤维强力仪、恒温烘箱、接触角测试仪、X射线衍射仪对所得各种纤维的形态特征、力学性能、吸湿性、接触角、结晶度进行测试和分析。结果表明：随着PLA含量的增加,共混纤维的强力下降,断裂伸长增加,但断裂功基本保持不变;随着PLA含量的增加,纤维的回潮率增加,接触角减小,结晶度下降;PLA质量分数为7%的共混纺粘纤维较纯PP纺粘纤维的结晶度下降21%,吸湿性则达到纯PLA, 可在不降低其耐用性的同时,提高其吸湿性能。     

A study of the mechanical properties of pre-oxidized fiber felt/epoxy resin composite material

In this article, the pre-oxidized fiber felt composite material was firstly prepared by a mold press process, and the pre-oxidized fiber and resin were used as the reinforcing material and substrate of composite material, respectively. The pretreatment method of the pre-oxidized fiber felt and the impact of the amount of curing agent and the curing pressure on the mechanical properties of the composite material were studied, and the tensile and flexural properties were assessed to optimize the preparation process of composite material. Results show that when the curing agent accounts for 60% of the epoxy resin and the curing pressure is 3 MPa, the best tensile and flexural properties of the prepared composite material are achieved. The mechanical properties for the pretreated composite sheet prepared from pre-oxidized fiber were superior to those for the untreated sheet.     

高强度聚氯乙烯中空纤维膜的制备及其性能

针对溶液相转化法制备的聚氯乙烯(PVC)膜存在强度及通透性能难以同步提高的问题,以MT-I型复合粉为成孔剂,邻苯二甲酸二辛酯为稀释剂,采用螺杆挤出法制备了PVC中空纤维膜,研究了拉伸和萃取过程对纤维膜形貌及结构的影响,并通过水通量、碳素墨水截留率及拉伸强力测试分析了纤维膜的分离性能和力学性能。结果表明:随着拉伸倍数的增加,PVC中空纤维膜的断裂强度增大,断裂伸长率减小;经乙醇萃取后纤维膜表面出现了更多微孔,纤维膜的通透性能提高;当拉伸倍数为3时,纤维膜具有较高通透性和较好的力学性能,水通量为798 L/(m²·h),拉伸断裂强度为17.7 MPa,断裂伸长率为70.67%。