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This study investigated the effect of various stacking sequences on the mechanical and acoustic characteristics of hemp and kenaf fibers reinforced hybrid composites. The mechanical study was done by using universal testing machine and izod imact tester. Further, acoustic study was done by using impendence tube method. Hemp/kenaf/kenaf/hemp hybrid laminates outperformed the other composites in terms of tensile strength, flexural strength and impact strength. In the mono reinforcements, hemp/epoxy composites demonstrated superior mechanical characteristics than the epoxy matrix and kenaf/epoxy composites. However, hybrid composites have superior mechanical behavior compared to pure composites. From the acoustic results revealed that the pure hemp and kenaf/hemp/hemp/kenaf hybrid composites exhibitted highest sound transmission loss level at lowest and highest frequency region. The bestmechanical characteristics of hybrid composites will be suggested for use in automobile door panels. Also, the optimal sound transmission coefficent values signifying their appropriateness for use in applications that encompass many frequency bands. Highlights: Hybridization of kenaf/hemp fibersImproved mechanical properties over the single fiber compositesBetter acoustic properties [ABSTRACT FROM AUTHOR]

In this study, kenaf natural fibers were coated with acetone‐thinned epoxy resin before compounding with high‐temperature polyethylene terephthalate (PET). Thus, composites of sodium hydroxide treated and epoxy‐resin coated kenaf fibers (KF) reinforced PET (CTKF‐PET) were manufactured using extrusion and compression molding techniques at an optimized 10 wt% constant fiber loading and processing temperatures of 240, 250, and 260°C, and were characterized for mechanical, thermal, and morphological performances. The obtained results showed an optimum processing temperature of 240°C with maximum mechanical and thermal properties with good interfaces between the coated fillers and the matrix, compared to those obtained at 250 and 260°C. Thermogravimetric analysis recorded maximum onset degradation and decomposition temperatures of 338.9 and 381°C with 9.5% and 13% improvements respectively after resin coating which positively impacted the constituent coated composites compared to the uncoated KF. Differential scanning calorimetry glass transition (Tg) and melting temperatures (Tm) for the CKF‐PET composites was maximum at 119.0 and 262.8°C with 2.18% and 2.8% improvements respectively compared to uncoated composites. The overall properties of all coated kenaf‐reinforced PET (CKF‐PET) and coated‐treated (CTKF‐PET) composites were higher with improved morphological properties irrespective of the processing temperature compared to the raw kenaf (KF‐PET) composites. Hence, natural fibers can be treated with resin coating to improve the thermal stabilities of natural fiber engineering plastic composites, and the interfacial adhesion between the coated‐KF and the engineering plastic matrix. The resultant composites are suitable for high‐temperature engineering applications such as the automotive and construction industries. [ABSTRACT FROM AUTHOR]

Natural fiber‐based materials are widely accepted in the composite sector as a substitute for synthetic fiber, particularly in structural and semi‐structural implementations in the automotive and aerospace industries, reflecting a recent trend and increased awareness of the importance of sustainable product design. Hand lay‐up was used to create natural fiber bilayer hybrid composites with epoxy matrix reinforcing oil palm empty fruit bunch (EFB) and kenaf fiber matting. The overall effect of this hybridization of the natural fiber and the thermal characterizations were studied experimentally. Both the hybrid combinations kenaf fiber and oil palm EFB were made by maintaining the fiber loading at 50% (weight) and weight ratios at 1:1, 1:4 and 4:1. The Tan delta, loss modulus (E″), storage modulus (E′), and Cole‐Cole plot were found to be useful in investigating dynamic mechanical properties. Dynamic mechanical analysis results like coefficient of performance and Cole‐Cole plot clearly show that hybrid pure kenaf composite has the significant complex modulus because interfacial bond between fiber and matrix is strong. As a result, it has been determined that kenaf fibers have the best mixing ratio for improving the dynamic mechanical properties of these hybrid type composites and can be used for aerospace, automotive, and civil engineering applications requiring high dimensional stability and excellent mechanical properties. The thermal gravimetric analysis data demonstrated that as compared to pure, the kenaf fibers and hybrid oil palm empty fruit bunch composites have the best thermal stability, with the highest beginning and ultimate breakdown temperatures of 200 and 450°C, respectively. [ABSTRACT FROM AUTHOR]

The effect of jute, kenaf, and banana fiber reinforced epoxy hybrid composites with different stacking sequences were fabricated by compression molding techniques. The pure epoxy, pure jute, pure kenaf, pure banana composites are also fabricated for comparison purposes. Tensile, flexural, inter‐laminar shear strengths, and hardness properties of the fabricated composites were investigated. Physical parameters like density, water absorption, and thickness swelling were also examined. From mechanical properties, the results are evident that when compared to hybrid composites pure banana composites have the highest tensile, flexural, interlaminar shear strength and shore D hardness value of 41, 67, 18, and 86 MPa respectively. Also, pure banana composites have better water absorption and thickness swelling percentage of 4% and 1.6%. However, KBJJBK hybrid composites exhibit a maximum tensile strength of 34 MPa, flexural strength of 54 MPa. Further BJKKJB hybrid composites possess the highest hardness value of 87, intralaminar shear strength of 17 MPa and lowest water absorption of 8% and thickness swelling percentage of 2%. Certain pure and hybrid configuration have enhanced mechanical strength, stiffness, and lower water absorption and thickness swelling properties, indicating that they are suitable for automotive structural applications. [ABSTRACT FROM AUTHOR]

The current research has produced engineering plastics composite for automotive applications using waste recycled plastic recycled polyethylene terephthalate (RPET) bottles as the matrix and compounded with chemically modified natural kenaf fibers in comparison with virgin polyethylene terephthalate (PET) composites under the same processing conditions. Kenaf fibers were surface modified by alkali and epoxy coating treatment methods. The waste RPET bottles which were mechanically recycled were pulverized using a 5 mm mesh size aperture into flakes and melt‐mixed with 10 wt% of short kenaf fibers in a twin‐screw extruder and compression‐molded at 240°С optimized temperature. Mechanical and thermal analyses were performed on both RPET, virgin PET (VPET), and their constituent kenaf composites. Scanning electron microscopy (SEM) was carried out to assess the composite's morphological characteristics. The results show that both treated (TKF/RPET and TKF/VPET) composites gave higher mechanical properties compared to untreated (KF/RPET and KF/VPET) composites. RPET and its constituent composites show higher impact properties than VPET composites. However, the tensile and flexural strength of VPET composites was higher than that of recycled RPET composites. RPET and VPET showed melting peak temperatures of 252.9°C and 245.8°C respectively. Both treated TKF/RPET and TKF/VPET composites were more thermally stable and decomposed at higher temperatures compared to the untreated composites. The SEM results for both treated composites showed a strong fiber/matrix adhesion with no clear evidence of fiber degradation as compared to untreated composites. It can be concluded that RPET possessed similar thermal properties compared to its virgin counterpart and can serve as a substitute for virgin PET in the composite formulation. [ABSTRACT FROM AUTHOR]

This work aims to optimize the mechanical performance of ramie and kenaf fibers in epoxy composites developed using the hand layup technique. Fiber reinforcement at 0–10 wt% and benzoyl chloride treatment at 0–5 wt% were incorporated with this composites. Taguchi‐based grey relational analysis (GRA) and technique for order preference by similarity to ideal solution (TOPSIS) methods were used to determine the optimized conditions for overall mechanical properties of the developed composites. Optimization techniques concluded that 10 wt% ramie (R)/10 wt% kenaf (K) with 5 wt% benzoyl chloride treatment (T) based epoxy composites observed good mechanical properties with ultimate tensile strength of 37.39 MPa, ultimate flexural strength of 63.53 MPa, and impact strength of 70.36 J/m due to hybridization and the reduction in hydrophilic nature by the surface treatment process. The optimized GRA and TOPSIS combination with 10 wt% R/10 wt% K/5 wt% of T observed reduced water absorption nature with a contact angle of 64.72°. [ABSTRACT FROM AUTHOR]

Kenaf cellulose fiber was extracted from kenaf locally grown in Thailand as a potential local renewable resource for the cellulose fiber. In this study, the biodegradable polymer composites, poly(butylene succinate) (PBS)/cellulose fiber composites with different types of cellulose were prepared. The kenaf fiber treated with hydrochloric acid (KTH), extracted cellulose fiber (EC), and commercial cellulose fiber (CC) were selected as alternative renewable fillers in the PBS (the biodegradable polymer). Regarding the fiber characteristics, the aspect ratio of the EC (11.5) was found to be higher than that of the CC (6.1). In a similar manner, the EC contained 65.9% crystallinity, which was higher than that of the CC (37.0%) and the KTH (58.9%). Moreover, the EC exhibited higher thermal stability (Td[Max] = 362.9°C) than the CC (Td[Max] = 302.0°C) and the KTH (Td[Max] = 353.8°C). For PBS/cellulose fiber composites, the rheological, tensile, and thermal properties were studied. The rheology results revealed that the addition of the fiber changed the PBS microstructure. The EC fiber dispersion in the PBS seemed to be better than the others; however, the KTH fiber dispersion was poor. The addition of the fiber raised the elastic moduli of the composites by 5‐26%; however, it reduced the tensile strengths (by 14‐53%) and the decomposition temperatures (by 1‐2%). Furthermore, the addition of the fiber slightly affected the crystallization temperatures and melting temperatures of the composites. The yellowness and whiteness of the composites were marginally reduced. The composite with the EC fiber showed a significant improvement in the elastic modulus as compared to the composite with the CC fiber, while the tensile strength and the strain at maximum stress were comparable. Thus, according to the rheological, thermal, and tensile properties of the composites, the EC fiber showed a possibility of using as an alternative reinforcement material from a local renewable resource. [ABSTRACT FROM AUTHOR]

Hybrid composites have shown innumerable benefits to the research communities in terms of environmental friendliness and mechanical properties. This research study presents the mechanical characterization and moisture uptake of kenaf/pineapple leaf fiber‐reinforced polypropylene hybrid composites with several relative fiber ratios. A comparison was also made between nonhybrid and hybrid kenaf/pineapple leaf fiber‐reinforced composites to investigate the hybridization effect. In this work, the composite materials were fabricated via the hot compression technique. Mechanical tests were performed to obtain the tensile, flexural, and Charpy impact properties of nonhybrid and hybrid kenaf/pineapple leaf fiber‐based composites. The water absorption characteristics were then obtained by immersing the composite materials in the water until the saturation point was reached. The findings concluded that the mechanical properties and moisture uptake behaviors of the composites were improved through the hybridization. The hybrid composites with a relative fiber ratio of 25:75 were particularly promising with the improvement of 10.90% in tensile strength; 16.13% in flexural strength; and 6.80% in impact strength in both flatwise and edgewise orientations compared to nonhybrid kenaf‐based composites. Meanwhile, the diffusion coefficient of hybrid composites (25:75) was 56.12% lower than nonhybrid pineapple leaf fiber‐based composites. Thus, the results indeed demonstrated that the balance between mechanical properties and moisture sensitivity can be obtained through the hybridization of kenaf and pineapple leaf fiber in the composite materials. [ABSTRACT FROM AUTHOR]

The type of reinforcement used in polymer composite is one of the main governing parameters to ascertain the performance of a polymer composite. Green composites using fiber mat as reinforcement have shown promising results. In the present study, three different types of kenaf fiber mat (ie, bidirectional, unidirectional, and randomly oriented) have been incorporated with polylactic acid (PLA) for fabrication of green composite laminates through compression molding. Static mechanical characterization (tensile, flexural, and impact) of the developed composites has shown that type of fiber mat affects the mechanical performance of laminated composites markedly. Unidirectional fiber reinforced PLA composite has shown the highest tensile strength in comparison to bidirectional fiber reinforced PLA composite (BDFRPC) and randomly oriented fiber reinforced PLA composite (ROFRPC). BDFRPC has shown better flexural properties whereas ROFRPC achieved higher impact strength. Dynamic mechanical analysis of different kenaf/PLA laminates was performed to investigate the visco‐elastic nature with respect to temperature. Results show that ROFRPC has observed the best results under dynamic loading condition. The morphological study of the fractured surfaces during various testing was performed using scanning electron microscope to investigate mechanisms and reasons of failure of composites. [ABSTRACT FROM AUTHOR]

The aim of this work is to develop a Finite Element Model based on continuum damage mechanics to predict the structural response of Kenaf composite when subjected to high‐velocity impact. The stress–strain response of the Kenaf composite through the fiber direction was simulated to examine prediction accuracy of this simulation approach. A combined elastic‐damage material model, incorporating the 3D Hashin's failure criteria, was implemented into the ABAQUS/Explicit finite element code by user‐defined VUMAT material subroutines. The results from the model predictions were compared with experimental data obtained by SHPB compression testing. The developed Finite Element Model of the full‐scale test presented an accurate prediction of the strain waves in the bars and successfully replicated the structural impact response of Kenaf composite over the range of impact loadings studied. The model also provides a reasonably good agreement between numerical and experimental results on the effect of strain rate on the failure stress and failure strain. POLYM. COMPOS., 40:909–915, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The aim of this work is to study the effect of kenaf volume content and fiber orientation on tensile and flexural properties of kenaf/Kevlar hybrid composites. Hybrid composites were prepared by laminating aramid fabric (Kevlar 29) with kenaf in three orientations (woven, 0o/90o cross ply uni-directional (UD), and non-woven mat) with different kenaf fiber loadings from 15 to 20% and total fiber loading (Kenaf and Kevlar) of 27-49%. The void content varies between 11.5-37.7% to laminate with UD and non-woven mat, respectively. The void content in a woven kenaf structure is 16.2%. Tensile and flexural properties of kenaf/Kevlar hybrid composites were evaluated. Results indicate that UD kenaf fibers reinforced composites display better tensile and flexural properties as compared to woven and non-woven mat reinforced hybrid composites. It is also noticed that increasing volume fraction of kenaf fiber in hybrid composites reduces tensile and flexural properties. Tensile fracture of hybrid composites was morphologically analysed by scanning electron microscopy (SEM). SEM micrographs of Kevlar composite failed in two major modes; fiber fracture by the typical splitting process along with, extensive longitudinal matrix and interfacial shear fracture. UD kenaf structure observed a good interlayer bonding and low matrix cracking/debonding. Damage in composite with woven kenaf shows weak kenaf-matrix bonding. Composite with kenaf mat contains the high void in laminates and poor interfacial bonding. These results motivate us to further study the potential of using kenaf in woven and UD structure in hybrid composites to improve the ballistic application, for example, vehicle spall-liner. POLYM. COMPOS., 36:1469-1476, 2015. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]