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This research investigated the use of reclaimed rubber (RR) from waste tires to partially replace the rubber compound (RC) when making wood fiber-rubber composites (WRCs). Ninety panels of WRC containing RR were manufactured with RR contents of 0% to 40%, mixing times of 6 min to 14 min, and vulcanizing temperatures of 150 °C to 170 °C. There were three steps, which were the fiber-rubber mixing, tabletting, and vulcanization molding processes. Four regression equations for the tensile strength, elongation at break, hardness, and rebound resilience as functions of the RR content, mixing time, and vulcanizing temperature were derived, and a nonlinear programming model was developed to obtain the optimum panel properties. It was found that when the RR content was within 20%, the wood fibers were well encapsulated and embedded in the RC/RR blends, and the processability of the WRCs were improved by adding RR. The incorporation of RR into the WRCs increased the average tensile strength and hardness by 33.9% and 2.3%, respectively, while the swelling ratio in toluene and 24-h water absorption were reduced by 13% and 42%, respectively. [ABSTRACT FROM AUTHOR]

The behaviors of the mechanical, hydrophobic, and thermal properties of the molded fiber product (MFP) were examined after the removal of residual lignin. The fibers resulting from the chemi-thermomechanical pulping and bleaching processes were treated by extended delignification, namely by their reaction with glacial acetic acid and sodium chlorite. The changes in surface composition, chemical structure, crystallinity, microstructure, and thermal stability of the MFP were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), respectively. Results showed that the composition and structure of carbohydrates on the fiber surface were not changed significantly, the lignin in fibers was almost completely removed, the relative content of intermolecular hydrogen bonds in cellulose and the contact area between fibers was increased, and the crystallinity index increased from 79.5% to 81.4% after the extended delignification. When the content of lignin decreased from 5.78% to 0.02%, the tensile strength of the MFP increased 25.6%, but little changes were found in the bending strength. The onset thermal decomposition temperature of MFP increased from 242 °C to 250 °C and the maximum rate of degradation temperature increased from 347 °C to 350 °C. [ABSTRACT FROM AUTHOR]

The kenaf fiber/polyester composites, owning the comparable mechanical properties with commercial glass-fiber sheet molding compounds (SMC) for automotive application, were achieved through the high pressure-assisted magnesium carbonate impregnated fibers and the vacuum-assisted resin transfer molding process. The in situ inorganic nanoparticle impregnation (INI) process was performed by immersing the alkali retted fibers into magnesium chloride solution with various pressures and then treated by sodium carbonate to yield the INI-treated fibers. The magnesium carbonate content was increased by 180.3%, when a 13.79 MPa pressure was applied during the magnesium carbonate immersing process, resulting in lower porosity of fibers. Compared to the un-treated fiber/polyester composite, the mechanical properties of the high pressure-assisted INI-treated fiber/polyester composites were enhanced by 18.6–277.3%, and the 24-h thickness swelling and water absorption were reduced by 64.4% and 62.2%, respectively. The mechanical properties and specific mechanical properties were comparable with or excessed to that of glass-fiber SMC. [ABSTRACT FROM AUTHOR]

This work was to apply the vacuum-assisted resin infusion (VARI) process and use calcium carbonate inorganic nanoparticle impregnation (INI) to improve the mechanical properties and water resistance of the kenaf fiber/polyester composites. The results show that the modulus of elasticity (MOE), modulus of rapture (MOR), tensile modulus (TE) and tensile strength (TS) of the composites made with INI-treated fibers are increased by 33.1%, 64.3%, 22.3% and 67.8%, respectively, compared with the composites made with un-treated fibers. The thickness swelling of 24-h water submersion is reduced from 19.7% to 1.9%. The moisture contents of the composites after the conditioning and water submersion are reduced from 5.8% to 1.5% and 18.3% to 2.2%, respectively, when INI-treated fibers are employed. The improvement makes the kenaf fiber/polyester composites possible to replace the glass fiber SMC for the automobile application. [ABSTRACT FROM AUTHOR]

This work was aimed at applying vacuum-assisted resin transfer molding (VARTM) technique to reinforced polymer molding products made of vegetable fibers. Kenaf ( Hibiscus cannabinus L. Malvaceae) bast fibers were preformed into mat by means of a cold press. The unsaturated polyester resin was infused into the preforms at a vacuum pressure of 1.3-1.6 kPa. The examination of the mechanical properties and microstructure of the prepared composites indicated that the modulus of elasticity (MOE), modulus of rapture (MOR), and tensile strength (TS) of the VARTM composites were increased by 65.5%, 30.7%, and 41.7%, respectively, compared to the traditional hot-pressing composites. The dynamic mechanical analysis (DMA) revealed that the VARTM composite moduli in the temperature range of -50°C-200°C were doubled. The observations by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and mercury porosimetry confirmed that the interfacial compatibility between the kenaf fibers and the polyester resin was substantially improved. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate an inorganic nanoparticle impregnation (INI) technique to improve the compatibility between kenaf bast fibers and polyolefin matrices. The Scanning Electron Microscopy (SEM) was used to examine the surface morphology of the INI-treated fibers showing that the CaCO3 nanoparticle crystals grew onto the fiber surface. Energy-dispersive X-ray spectroscopy (EDS) was used to verify the CaCO3 nanoparticle deposits on the fiber surface. The tension tests of the individual fiber were conducted, and the results showed that the tensile strength of the fibers increased significantly (more than 20%) after the INI treatments. Polymer composites were fabricated using the INI-treated fiber as reinforcement and polypropylene (PP) as the matrix. The results showed that the INI treatments improved the compatibility between kenaf fibers and PP matrix. The tensile modulus and tensile strength of the composites reinforced with INI-treated fibers increased by 25.9% and 10.4%, respectively, compared to those reinforced with untreated kenaf fibers. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop a hermetical alkali digestion process to obtain single cellulosic fibers from kenaf bast. Kenaf bast were hermetically digested into single fiber using a 5% sodium hydroxide solution for one hour at four different temperatures (80°C, 110°C, 130°C, and 160°C). The hermetical digestion process used in this study produced fibers with high cellulose content (84.2-92.3%) due to the removal of lignin and hemicelluloses. The surface hardness and elastic modulus of the fibers digested at 130°C and 160°C were improved significantly compared with those digested at 80°C. The tensile modulus and tensile strength of the individual fibers reduced as the digestion temperature increased from 110°C to 160°C. Micropores were generated in fiber cell wall when the fibers were digested at 130°C and 160°C. The studies on the composites that were made from polypropylene reinforced with the digested fibers indicated that the compatibility between the digested fibers and polypropylene matrix was poor. [ABSTRACT FROM AUTHOR]

Fabricating bamboo fiber‐reinforced epoxy composites (BFREs) using the vacuum‐assisted resin transfer molding (VARTM) process has many advantages, such as low cost, high product quality, controllability, and broad applicability. However, the immature fabrication process seriously affects product performance and hinders the full exploitation of the advantages of the VARTM process. The effects on the physical‐mechanical and thermal properties of BFREs by molding sequence and fiber content were investigated in this study. The molding sequence of fiber compression followed by resin injection was beneficial to ensure hermeticity, thus reducing the voids in the BFREs. The mechanical properties of BFREs gradually increased with increasing fiber content. With 50 wt% fiber content, the bending strength and modulus, shear strength, and impact toughness of BFREs reached 71.27 MPa, 6.78 GPa, 11.68 MPa, and 5.45 kJ/m2, respectively. Although the thermal stability of the BFREs was slightly lower than that of pure epoxy, the bamboo fibers' high rigidity evidentially increased the epoxy's dynamic mechanical properties. The life cycle assessment indicated that the BFREs effectively reduced the environmental impacts and production energy consumption compared to the glass fiber correspondent. The VARTM‐fabricated BFREs have great potential for construction, transportation, household items, packaging, sports equipment, and leisure goods applications. Highlights: Fiber compression followed by resin injection could ensure great hermeticity.Micro‐CT accurately measured the void characteristics of the composites.Voids had detrimental effects on the properties of the composites.Dense bamboo fiber preforms enhanced the mechanical properties of epoxy.Bamboo fibers reinforcing epoxy reduced the impact on the environment. [ABSTRACT FROM AUTHOR]

The combination of continuous natural fiber and fused filament fabrication (FFF) 3D printing enables the manufacturing of low carbon emitting, environment friendly, lightweight, and high strength biomass composites with designated geometry characteristics. In current literature, reviews associated with continuous fiber 3D printing primarily cover synthetic fibers, such as carbon fiber, Kevlar, and glass fiber. Very few pieces of literature on the FFF printing of continuous natural fibers are available. Techniques/methodologies for incorporating continuous natural fiber reinforcements in FFF is an emerging field of research. A comprehensive review and discussion on current progress and the future prospects of continuous natural fiber 3D printing would be beneficial to its development. This article summarizes the current research status of continuous natural fiber 3D printing, including information on printing techniques, materials, and the influence of printing parameters on composite properties, so as to provide reference for the future development of FFF technology using continuous natural fiber and thermoplastic composites. [ABSTRACT FROM AUTHOR]

This work was to apply the vacuum-assisted resin transfer molding (VARTM) process and use aluminum hydroxide inorganic nanoparticle impregnation (INI) to improve the mechanical properties and water resistance of the kenaf fiber reinforced composites. As a novel technique, a two-step aluminum hydroxide impregnation was used in the fabrication of composites, including the alkali retting and aluminum hydroxide loading. After the alkali retting, the cellulose content of the kenaf fibers went up to 94.2%, the ash content was 2.7%. The tensile strength and modulus of individual fiber were 810 MPa and 13.5 GPa, respectively. The results showed that, with a loading amount of 2.2% aluminum hydroxide, the modulus of elasticity, modulus of rupture, tensile modulus and tensile strength of the composites made with INI-treated fibers were increased by 67.2%, 55.7%, 32.5% and 36.3%, respectively, compared with those of composites made from un-treated fibers. When the INI-treated fibers were employed, the thickness swelling of 24-h water submersion was reduced from 19.7 to 6.3%, and the moisture contents of the composites after the conditioning and water submersion were reduced from 5.8% to 1.9%, and 18.3% to 6.6%, respectively. The improvement makes the kenaf fiber reinforced composites possible to replace the glass fiber composites for the automotive application. [ABSTRACT FROM AUTHOR]

To replace glass-fiber sheet molding compound (GF-SMC) using natural fiber-reinforced composites (NFRCs) in the automotive industry, this work intended to enhance mechanical properties and water resistance of NFRCs by impregnating magnesium hydroxide (MH) to kenaf fibers and fabricating composites using the vacuum bag resin transfer molding (VBRTM) technology. The modulus of rupture and tensile strength of modified composites were significantly increased by 73.9% and 54.6% compared with that of the regular NFRCs, respectively. Based on the scanning electron microscope observation, it was found that the MH impregnation significantly enhanced the compatibility of kenaf fibers and polymer matrix, benefiting to the mechanical-property improvements of the composites. Compared to the regular NFRC, the 24-h water absorption and thickness swelling of MH impregnated NFRC (MH-NFRC) were significantly reduced by 83.9% and 84.2%, respectively. When the composite density was factored in the comparison of MH-NFRC and GF-SMC, the specific modulus of rupture and tensile strength of MH-NFRC were 116.4% and 109.0% of the GF-SMC, respectively. Apart from the mechanical properties, the advantages of replacing GF-SMC by MH-NFRC were reflected in the reductions of energy consumption and environmental impacts. It was calculated that the energy consumption of fabricating MH-NFRC was decreased by 33.1% compared with GF-SMC. The comparisons of environmental impacts of MH-NFRC and GF-SMC were performed by life-cycle assessment (LCA) using the SimaPro software. The results demonstrated that the environmental burdens of the composites were reduced by 22.8%, when kenaf fibers were used. All major indices of environmental impacts of MH-NFRC, including the total Global warming, Acidification, Human Health (HH) cancer, HH noncancer, HH criteria air pollutants, Eutrophication, Ecotoxicity, Smog, Natural resource depletion, Habitat alteration, Water intake and Ozone depletion, were reduced by 13.66–51.91%, respectively. It was concluded that the newly developed NFRC had great potential for replacing the GF-SMC in automobile applications, with reduced energy consumption and environmental impacts. [ABSTRACT FROM AUTHOR]

Natural materials (like teeth, bone, wood, bamboo, etc.) with organized hierarchical structures usually exhibit exceptional characteristics of both high stiffness and toughness. Bioinspired by this structure, design of functionalized hierarchical fibers has become an effective reinforcement strategy in fiber-reinforced polymer composites. In this work, bioinspired functionalized hierarchical fibers were constructed by anchoring catechol-modified metal-organic frameworks (MOFs) onto bamboo fiber surfaces which were then used as efficient strengthening phases to enhance the performance of soybean meal-based adhesives. The catechol-modified MOFs on fibers can form multiple interactions with a soybean meal matrix, whilst a hierarchical structures design for fibers can create a material gradient at the interval with a largely mismatched elasticity, which, remarkably, can decrease the stress concentration and thereby enhance energy dissipation in this region. As a result, the wet/dry shear strengths of the resultant adhesives were increased by 96.87% and 66.46%, and reached to 1.26 and 2.68 MPa, respectively. Also, the reinforcing mechanism of functionalized hierarchical fibers modified adhesives was proposed. We conceive that the functionalized hierarchical fibers as a bioinspired structural reinforcement has great potential for bionic adhesive applications. It also provides an effective reinforcement strategy for structural composites. [Display omitted] [ABSTRACT FROM AUTHOR]

Natural fiber reinforced composites with dual-functional properties, including electromagnetic shielding and paramagnetic functions, as well as improved water-resistant property, were fabricated using vacuum assisted resin transfer molding (VARTM) process. Magnetite particles were firstly mixed with kenaf fibers to form a mat, followed by resin intrusion and compression for the composite fabrication. The obtained kenaf fiber/magnetite/polyester composites were endowed with electromagnetic shielding and paramagnetic properties, without compromising the mechanical properties. When 35.2% magnetite was incorporated into the composites, the electromagnetic interference shielding effectiveness reached 79.2% with the range 8–12 GHz, and the saturation magnetization was 29.2 emu g −1 . The 24-h thickness swelling and water absorption of the composites after introducing magnetite were drastically reduced from 19.7% to 2.4% and 18.3% to 2.6%, counting as the decreases of 87.6% and 73.4%, respectively. It was indicated that the water resistance of the composite was improved significantly. [ABSTRACT FROM AUTHOR]

The veneer preprocessing densification is a vital procedure in the manufacturing process of long-span bamboo-based engineering material, bamboo-bundle laminated veneer lumber (BLVL). The adhesive used in the preprocessing densification process was the mixture of phenol formaldehyde (PF) resin and polyvinyl acetate (PVAC) resin. The objective of this study was to investigate the effect of PF/PVAC weight ratio on the moisture absorption performance of BLVL, as well as the effect of ambient temperature on the hygroscopic swelling performance for BLVLs with a PF/PVAC ratio of 6:1. The results indicated that the water absorption swelling rate and weight gain rate of the BLVLs decreased as PF/PVAC ratio increased at 63°C. The absorption behavior of BLVL was found to obey Fick's law at 63°C approximately. The higher the PF/PVAC ratio, the lower swelling parameter KSR and D values were obtained. However, PF/PVAC ratio exerted little effect upon the bending properties(modulus of rupture and elasticity) of BLVL. Temperature has a significant effect on the moisture absorption performance of BLVL (6:1 PF/PVAC ratio). The higher the temperature, the greater swelling and weight gain rate was obtained, as well as KSR and D values. The calculated swelling activation energies ( ES) were 25.79 and 22.45 KJ mol−1 for BLVLs with 6:1 PF/PVAC ratio and the ones with neat PF resin, respectively, while the diffusion activation energies ( ED) were 10.62 and 8.47 KJ mol−1. POLYM. COMPOS., 37:955-962, 2016. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Developing highly efficient and convenient nanofiber composites toward oil adsorption is of great significance for the treatment of oily wastewater. Herein, a reusable, porous, and fiber composite is obtained via one-step fabrication method involving non-solvent-induced phase separation-assisted electrospinning of polyvinylidene fluoride/nanocellulose (PVDF/CNC). The incorporation of CNC significantly enhances the mechanical properties of the nanofiber composites. By adjusting the relative humidity, a large number of nano-micro spheres are generated on the surface of PVDF/CNC fibers, and porous structure formed inside the fibers are interconnected. Benefiting from this unique structure, the specific surface area of the composite is increased up to 12.22 m2 g−1, enabling adsorption capacity up to 73.04 g/g for engine oil. The adsorption capability of the nanofiber composite to toluene under high humidity retains over 95% after ten cycles. The one-step electrospinning manufacture of mechanically robust and highly porous PVDF/CNC nanofiber composites provides a new approach to develop high-performance nanofiber composite materials for adsorption and separation of oil-bearing wastewater. [Display omitted] • A reusable, porous, fibrous PVDF/CNC composite is obtained via one-step manufacturing method. • Nano-micro spheres are self-assembled on the surface of PVDF/CNC fibers with interconnected porous structure. • The incorporation of CNC significantly enhances the mechanical properties of the composites. • The nanofiber composite exhibit high oil adsorption capacities and adsorption stability. [ABSTRACT FROM AUTHOR]

A polyacrylate-based wetting agent, BYK-358N, was used to improve the interfacial bonding between the bamboo fibers and epoxy matrix. Fourier transform infrared spectrometer and differential scanning calorimetry were used to study the curing process of epoxy resin. The wettability of the treated bamboo fiber, which by the untreated and wetting agent treated epoxy, was studied using the surface tension of epoxy and bamboo fiber. The analysis of dynamic contact angle and interfacial shear stress confirmed that the composite interface was improved. Finally, Vacuum-assisted resin transfer molding was used to prepare bamboo fiber reinforced epoxy resin (BF/EP) composites, and the tensile properties were measured. The results showed that the addition of the wetting agent could effectively improve the interface compatibility of BF/EP composites. The interfacial shear stress of BF/EP composites treated with 1% wetting agent was 24.36 MPa, tensile strength was 111.54 MPa, and Young's modulus was 3.90 GPa, which was 165.7%, 99.7%, and 66.7% higher than that of untreated BF/EP composites. [Display omitted] [ABSTRACT FROM AUTHOR]