Tensile,Flexural and Chemical Resistance Properties of Sisal Fibre Reinforced Polymer Composites: Effect of Fibre Surface Treatment

In this study, effect of fibre surface treatment on tensile, flexural and chemical resistance properties were studied for sisal fibre reinforced composites. Natural ligno cellulosic sisal fibre reinforced composites were prepared by different surface treatments by hand lay-up method. Fibre surface treatments were carried out to produce good interface between the fibre and the matrix to improve the mechanical properties. Fibre surface treatments were done by boiled the sisal fibres in different % of NaOH and treated the fibres in different % of NaOH, treated in acetic acid and methanol. Unsaturated polyester resin was used as the matrix for preparing the composites. For comparison, these properties for untreated sisal fibre reinforced composites were also studied. From the results it was observed that 18% aqueous NaOH boiled sisal fibre reinforced composites have higher tensile, flexural properties than other composites. Untreated sisal fibre composites show lower properties than treated composites. Chemical resistance properties indicate that all sisal fibre reinforced composites are resistance to all chemicals except carbon tetra chloride. The tests are carried out as per the ASTM standards.     

The Effect of Silane Treated Fibre Loading on Mechanical Properties of Pineapple Leaf/Kenaf Fibre Filler Phenolic Composites

The aim of the present study is to investigate mechanical and morphological properties of pineapple leaf fibres (PALF) reinforced phenolic composites and its comparison with kenaf fibre (KF)/phenolic composites. Mechanical properties (tensile, flexural and impact) of untreated and treated PALF phenolic composites at different fibre loading were investigated. Tensile, flexural and impact properties of PALF and kenaf/phenolic composites were analyzed as per ASTM standard. Morphological analysis of tensile fracture samples of composites was carried out by scanning electron microscopy. Obtained results indicated that treated PALF/phenolic composites at 50% PALF loading exhibited better tensile, flexural and impact properties as compared to other untreated PALF/phenolic composites. Treated kenaf/phenolic composites at 50% fibre loading showed better tensile, flexural and impact properties than untreated kenaf/phenolic composite. It is concluded that treated 50% fibre loading kenaf and PALF/phenolic composites showed better mechanical properties than untreated kenaf and PALF/phenolic composites due to good fibre/matrix interfacial bonding. Results obtained in this study will be used for the further study on hybridization of PALF and KF based phenolic composites.     

End-Of-Life Textiles as Reinforcements in Biocomposites

A number of attempts have been made to recycle cotton/polyester blend woven fabrics after use; however, most of these fabrics are disposed of in landfills. Major part of these blend fabrics are not recycled due to complexity of the fibre arrangement and cannot be separated economically. This study shows that these discarded woven fabrics could be directly used as reinforcements in composites without fibre separation. Uniform alignment in the woven fabric provided consistent properties to the composites. The fabrics were reinforced by soybean-based-bioresins to produce biocomposites. The composites were analysed for mechanical, thermal, viscoelastic and morphological properties. Porosity and wettability of the composites were also evaluated. Results demonstrate that the tensile strength and modulus of over 100 and 10 MPa, respectively, can be obtained without any fibre treatment. Furthermore, impact strength over 70 kJ/m² was obtained without any chemical treatment on fibres. The porosity of the composites produced was less than 9 vol%. Additionally, the fabrics were treated with alkali in order to improve the fibre–matrix interface and the composite properties were studied. From the economical perspective, these composites can be produced at a low cost as the major component is available for free or low cost.     

New Multi-Scale Hybrid System Based on Maple Wood Flour and Nano Crystalline Cellulose: Morphological,Mechanical and Physical Study

In the first part of this work, composites based on polypropylene (PP) and maple wood flour (MF) were prepared by melt compounding using twin-screw extrusion followed by compression molding. The morphological and mechanical properties of the composites were analyzed for three samples: PP, MF/PP and MF/PP containing maleic anhydride grafted polypropylene (MAPP) as coupling agent. The results showed that MF/PP composites have improved mechanical properties, especially tensile modulus (+33 %), with only 8 % increase in density. The addition of MAPP further improved the mechanical properties, in particular tensile modulus (up to 51 %), which could be related to better fiber/matrix adhesion. In the second step, nano crystalline cellulose (NCC) was added to all samples to produce NCC-MF/PP hybrid composites. From the mechanical analysis performed, the hybrid composites with MAPP have improved properties, especially tensile (+53 %) and flexural (+40 %) moduli. These results confirmed that multi-scale hybrid NCC-MF composites can substantially improve the mechanical properties of polyolefins with limited increase in density (14 %) leading to high specific properties.     

Soda-Treated Sisal/Polypropylene Composites

Treated sisal fibers were used as reinforcement of polypropylene (PP) composites, with maleic anhydride-grafted PP (MAPP) as coupling agent. The composites were made by melting processing of PP with the fiber in a heated roller followed by multiple extrusions in a single-screw extruder. Injection molded specimens were produced for the characterization of the material. In order to improve the adhesion between fiber and matrix and to eliminate odorous substances, sisal fibers were treated with boiling water and with NaOH solutions at 3 and 10 wt.%. The mechanical properties of the composites were assessed by tensile, bend and impact tests. Additionally, the morphology of the composites and the adhesion at he fiber–matrix interface were analyzed by SEM. The fiber treatment led to very light and odorless materials, with yields of 95, 74 and 62 wt.% for treatments with hot water, 3 and 10 wt.% soda solution respectively. Fiber treatment caused an appreciable change in fiber characteristics, yet the mechanical properties under tensile and flexural tests were not influenced by that treatment. Only the impact strength increased in the composites with alkali-treated sisal fibers.     

Influence of Hygrothermal Ageing on the Physico-Mechanical Properties of Alkali Treated Industrial Hemp Fibre Reinforced Polylactic Acid Composites

30 wt% aligned untreated long hemp fibre/polylactic acid (AUL) and aligned alkali treated long hemp fibre/polylactic acid (AAL) composites were produced by film stacking and subjected to hygrothermal ageing environment along with neat polylactic acid (PLA). Hygrothermal ageing was carried out by immersing samples in distilled water at 25 and 50 °C over a period of 3 months. It was found that both neat PLA and composites followed Fickian diffusion. Higher temperature generally increased the Diffusion coefficient, D of neat PLA and composites, as well as shortening the saturation time. Neat PLA had the lowest D value followed by AAL composites and then AUL composites. After hygrothermal ageing, tensile and flexural strength, Young’s and flexural modulus and K _Ic were found to decrease and impact strength was found to increase for both AUL and AAL composites. AUL composites had greater overall reduction in mechanical properties than that for AAL composites after hygrothermal ageing. Crystallinity contents of the hygrothermal aged composites support the results of the deterioration of mechanical properties upon exposure to hygrothermal ageing environment.     

Mechanical,Morphological and Dynamic Mechanical Analysis of Pineapple Leaf/Washingtonia Trunk Fibres Based Biophenolic Hybrid Composites

In this article, flexural, impact and dynamic mechanical properties of the Pineapple leaf fibres (PALF) and Washingtonia trunk fibres (GW) based bio-phenolic hybrid composites were examined. The pure and hybrid composites were fabricated using the hand lay-up technique with an overall fibre weight ratio of 50% in which GW and PALF were maintained in the fibre weight ratios of 50:50, 30:70, and 70:30 denoted as 1G1P, 3G7P, and 7G3P, respectively. Hybrid composites displayed better flexural strength, flexural modulus and impact strength than the GW composites and better viscoelastic properties than the PALF composites. Results revealed that 1G1P hybrid composites exhibited 25% and 12% improvements in flexural strength and modulus compared to the GW composites. 3P7K composites showed a twofold increase in impact strength than GW composites. The storage modulus of the pure and hybrid composites declined rapidly beyond the glass transition temperature. Furthermore, it was observed that the values of storage modulus for all the composites at 150 °C were similar regardless of the composite configuration. The Peak of loss modulus was found to increase in the following order: GW?>?7G3P?>?3G7P?>?1G1P?>?PALF. Furthermore, the temperature at the peak tan delta was improved, and a reduction in the tan delta peak was observed for hybrid composites compared to the pure composites. Finally, the PALF and GW hybrid combinations can be suitable for use in various applications such as textiles, machinery part production industries, medicine, automobiles, etc.

     

Lightweight Polypropylene Composites Reinforced by Long Switchgrass Stems

Switchgrass (SG) stems with lengths up to 10 cm have been used as reinforcement to make lightweight composites with polypropylene (PP) webs. The long SG stems, with simple cut or split and without chemical treatment, were used directly in the composites. Utilizing SG stems for composites not only increases the values of SG but also provides a green, sustainable and biodegradable material for the composites industry. Lightweight composites are preferred, especially for automotive applications due to the potential saving in energy. In this research, the effects of manufacturing parameters on the properties of composites have been studied. Although the tensile properties of SG stem are significantly worse than jute fiber, SG stem with low bulk density is found to better reinforce the lightweight composites. Compared with the jute-PP composites of the same density (0.47 g/cm³), composites reinforced by the split SG stems have 56% higher flexural strength, 19% higher modulus of elasticity, 15% higher impact resistance, 63% higher Young’s modulus, 52% lower tensile strength, and similar sound absorption property. The SG-PP composites with optimized properties have the potential to be used for industrial applications such as the support layers in automotive interiors, office panels and ceiling tiles.     

Biodegradable Polyester-Based Blend Reinforced with Curauá Fiber: Thermal,Mechanical and Biodegradation Behaviour

Biodegradable composites can be produced by the combination of biodegradable polymers (BP) as matrix and vegetal fibers as reinforcement. Composites of a commercial biodegradable polymer blend and curauá fibers (loaded at 5, 15 and 20 wt%) were prepared by melt mixing in a twin-screw extruder. Chemical treatments such as alkali treatment of the fiber and addition of maleic anhydride grafted polypropylene (MA-g-PP) as coupling agent were performed to promote polymer/fiber interfacial adhesion so that mechanical performance can be improved. The resulting composites were evaluated through hardness, melt flow index and tensile, flexural and impact strengths as well as water absorption. Thermal analysis and Fourier transform infrared spectroscopy were also employed to characterize the composites. The polymer/fiber interface was investigated through scanning electron microscopy analysis. The biodegradability of composites was evaluated by compost-soil burial test. The addition of curauá fiber promoted an increase in the mechanical strengths and composites treated with 2 wt% MA-g-PP with 20 wt% curauá fiber showed an increase of nearly 75% in tensile and 56% in flexural strengths besides an improvement in impact strength with respect to neat polymer blend. Nevertheless, treated composites showed an increase in water absorption and biodegradation tests showed that the addition of fiber retards degradation time. The retained mass of BP/20 wt% fiber composite with MA-g-PP and neat BP was 68 and 26%, respectively, after 210 days of degradation test.     

Processing Stability and Biodegradation of Polylactic Acid (PLA) Composites Reinforced with Cotton Linters or Maple Hardwood Fibres

Polylactic acid (PLA) composites comprising up to 25 wt% cotton linter (CL) or up to 50 % maple wood fibre (WF) were prepared by compounding and injection moulding. A reduction of crystallinity in the PLA matrix was observed as a result of the thermal processing method. These PLACL and PLAWF composites provided excellent improvements in both stiffness (with increases in tensile and flexural modulus) and toughness (increases in notched impact strength) properties over the neat PLA resin, while the tensile and flexural strengths of the composites were generally unchanged, while the strain at break values were reduced in comparison to the neat PLA. DMA results indicated incorporating these fibres caused the mechanical loss factor (tan δ) to decrease, suggesting better damping capabilities were achieved with the composites. SEM analysis of the impact fractured surfaces of the PLACL composites showed debonding-cavitation at the matrix-fibre interface while the PLAWF composites showed good wetting along its matrix-fibre interface. The composting of these composites up to 90 days showed that the degradation onset time was increased when increasing the fibre loadings, but the maximum degree of degradation and the maximum daily rates of degradation were decreased compared to neat PLA. On a weight basis of fibre loading, the PLACL composites had a quicker onset of biodegradation, a higher maximum daily rate of biodegradation and, overall, a higher degree of biodegradation at 90 days than the PLAWF composites, possibly due to the quicker thermal hydrolysis observed in the PLA matrix of the PLACL composites during processing and composting.     

Synergistic Effect of Oil Palm Based Pozzolanic Materials/Oil Palm Waste on Polyester Hybrid Composite

This research work aims to investigate the synergistic effect of pozzolanic materials such as oil palm ash (OPA) and oil palm empty fruit bunch (OPEFB) on the developed hybrid polymer composites. The OPEFB and OPA fillers of different particle sizes (250, 150, and 75 µm) were mixed at OPEFB:OPA ratios of (0:100; 20:80; 40:60; 60:40; 80:20 and 100:0) and incorporated into an unsaturated polyester resin. Furthermore, both mechanical and morphological properties of the composites were analyzed and it was found that tensile, flexural, and impact properties were significantly improved at OPEFB:OPA of 75 µm particle size hybridization of the polymer. The increase of OPEFB to OPA filler ratio up to 80:20 significantly improved the tensile properties of the composites while 40:60 ratio of 75 µm gave the optimum filler ratio to obtain the highest flexural and impact properties of the composites among all studied samples. Scanning electron micrograph images showed strong particle dispersion of the embedded fillers with resin which explained the excellent mechanical strength enhancement of the composite.     

Hybrid Composites Made from Oil Palm Empty Fruit Bunches/Jute Fibres: Water Absorption,Thickness Swelling and Density Behaviours

In this research, hybrid composite materials were prepared from combination of oil palm Empty fruit bunches (EFB) fibre and jute fibre as reinforcement, epoxy as polymer matrix. This study intended to investigate the effect of jute fiber hybridization and different layering pattern on the physical properties of oil palm EFB-Epoxy composites. Water absorption and thickness swelling test reveal that hybrid composite shows a moderate water absorption which is 11.20% for hybrid EFB/Jute/EFB composite and 6.08% for hybrid Jute/EFB/Jute composite. The thickness swelling and water absorption of the hybrid composites slightly increased as the layering pattern of hybrid composites changed. Hybrid composites are more water resistance and dimensional stable compare to the pure EFB composites. This is attributed to the more hydrophilic nature of EFB composites. Hybridization of oil palm EFB composites with jute fibres can improve the dimensional stability and density of pure EFB and Jute fibre reinforced composites has higher density of 1.2 g/cm³ compared to all other composites.     

Polylactic Acid Composites Utilising Sequential Surface Treatments of Lignocellulose: Chemistry,Morphology and Properties

Polylactic acid (PLA)—maple fibre composites have been synthesised using a series of sequentially modified cellulose fibres (namely alkylation followed by either acetylation or silanation). Confirmations of the sequential modifications were made using Fourier Transform Infrared Spectroscopy and Inductively Coupled Plasma—Atomic Emission Spectroscopy and the new surface morphologies analysed using Scanning Electron Microscopy. The key advantage of the use of sequential treatments (with initial alkali treatment) was the allowance for direct grafting of suitable chemical groups onto the cellulose in the fibre due to the removal of lignin, hemicellulose and other surface impurities. However, a balance was found to exist between alkali exposure time, concentration and resulting fibre integrity. The conditions used resulted in a loss in fibre weight, fibre moisture content and tensile strength. Sequential treatments with acetylation or silane resulted in a 15–21% strength recovery from that of the alkali treated composite. Factors that influenced this recovery in strength were the improved fibre-polymer interface, namely the hydrophilic balancing of the fibres and this further affected the thermal-hydrolysis of the PLA during composite fabrication.     

Biopolymers Based Green Composites: Mechanical, Thermal and Physico-chemical Characterization

Natural cellulosic fibers are one of the smartest materials for use as reinforcement in polymers possessing a number of applications. Keeping in mind the immense advantages of the natural fibers, in present work synthesis of natural cellulosic fibers reinforced polymer composites through compression molding technique have been reported. Scanning Electron microscopy (SEM), Thermo gravimetric/Differential thermal/Derivative Thermogravimetry (TGA/DTA/DTG), absorption in different solvents, moisture absorbance, water uptake and chemical resistance measurements were used as characterization techniques for evaluating the different behaviour of cellulosic natural fibers reinforced polymer composites. Effect of fiber loading on mechanical properties like tensile strength, flexural strength, compressive strength and wear resistances has also been determined. Reinforcing of the polymer matrix with natural fibers was done in the form of short fiber. Present work indicates that green composites can be successfully fabricated with useful mechanical properties. These composites may be used in secondary structural applications in automotive, housing etc.     

Utilization of Sunflower Stalk in Manufacture of Thermoplastic Composite

Dimensional stability and mechanical performance of polypropylene thermoplastic composites filled with sunflower stalk (SS) flour at 30, 40, 50, and 60 wt% contents of the SS flour were investigated. The thickness swelling and water absorption of the specimens increased with increasing SS flour content. The modulus in the flexural and tensile improved with increasing SS flour content while the tensile and flexural strengths of the specimens decreased. The use of maleic anhydride polypropylene (3 wt%) had a positive effect on the dimensional stability and mechanical properties of the polypropylene thermoplastic composites filled with SS flour. The melting temperature of polypropylene decreased with increasing content of the SS flour. The degree of crystallinity of filled polypropylene composites between fibre loading of 0–30 % by weight was higher than that of unfilled polypropylene composites. However, further increment in the filler content decreased the degree of crystallinity. The obtained results showed that SS flour could be potentially suitable raw material in the manufacture of polypropylene composites.     

Cure,Mechanical and Swelling Properties of Biocomposites from Chicken Feather Fibre and Acrylonitrile Butadiene Rubber

Biocomposites of acrylonitrile butadiene rubber (NBR) reinforced with chicken feather fibre (CF) were prepared using dicumyl peroxide (DCP) as vulcanizing agent. Composites with three series of chicken feather fibres were studied i.e., raw (RCF), sterilized (SCF) and alkali treated (ACF). The cure characteristics of composites were studied. The mechanical properties of NBR were found to be improved by the incorporation of chicken feather fibre in all forms. Surface modification of the fibre was done by alkaline treatment to improve the interfacial adhesion and it characterised by FTIR. Better properties are shown by the composites with ACF. The swelling behaviour of the composites in N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide and water were analyzed for the swelling coefficient values. The biodegradable characteristics of CF reinforced NBR composites were studied by soil burial test which indicated that it is an eco-friendly and acceptable material. Scanning electron microscopy studies support the results of mechanical properties. The outcome obtained from this study is believed to assist the development of environmentally–friendly composites especially for specific product applications like oil seals, hoses and automobile bushes etc.     

Utilization of Porous Carbons Derived from Coconut Shell and Wood in Natural Rubber

The porous carbons derived from cellulose are renewable and environmentally friendly. Coconut shell and wood derived porous carbons were characterized with elemental analysis, ash content, X-ray diffraction, infrared absorbance, particle size, surface area, and pore volume. The results were compared with carbon black. Uniaxial deformation of natural rubber (NR) composites indicate the composites reinforced with the porous carbon from coconut shell have higher tensile moduli at the same elongation ratio than the composites reinforced with wood carbon. 40 % coconut shell composite showed a fivefold increase in tensile modulus compared to NR. Polymer–filler interactions were studied with frequency dependent shear modulus, swelling experiments and dynamic strain sweep experiments. Both linear and non-linear viscoelastic properties indicate the polymer–filler interactions are similar between coconut shell carbon and wood carbon reinforced composites. The swelling experiments, however, showed that the polymer–filler interaction is greater in the composites reinforced with coconut shell instead of wood carbon.     

Effect of High Content of Deinking Paper Sludge (DPS) on the Reinforcement of HDPE

Deinking paper sludge (DPS)/high density polyethylene (HDPE) composites with and without coupling agent (3 % of maleated polyethylene (MAPE)) were manufactured by twin-screw extrusion followed by injection molding with high percentages of DPS (0, 20, 30 and 40 %). The effects of DPS content and MAPE on the mechanical, thermal, and morphological properties of the DPS/HDPE composites were investigated. Increasing DPS content in composites increased the tensile and flexural modulus (E; MOE), tensile and flexural strength (Rm; MOR), while decreased elongation at break and Un-notched impact resistance due to a poor adhesion between the DPS and HDPE. The addition of DPS also improved the thermal stability and increased the composites crystallinity. High content of DPS (40 %) and 3 % MAPE achieved good interfacial adhesion between fibres of DPS and HDPE. Therefore, an increase is observed for Rm, MOR, ductility, and impact toughness.     

Fatigue Life Behaviour of Glass/Kenaf Woven-Ply Polymer Hybrid Biocomposites

Investigation on the fatigue life of hybrid composites is critical to extend their applications and acceptance among industries; however, there is a lack of research focus on fatigue performance of the hybrid composite. In this study, the fatigue life of glass/kenaf woven-ply hybrid composite with thermoplastic and thermoset polymer matrix was investigated. Hybrid composites consist of two different fibre configurations: kenaf/glass/kenaf and glass/kenaf/glass. Thermoplastic hybrid composites were manufactured through the hot press moulding compression method, while thermoset hybrid composites were fabricated through the vacuum-assisted resin infusion method. The tensile strength and fatigue strengths of the kenaf/glass/kenaf composite have been identified to be significantly lower than those of the glass/kenaf/glass composite regardless of the types of matrix used. However, thermoplastic-based kenaf/glass/kenaf composites are less fatigue sensitive compared to glass/kenaf/glass composites; however, this phenomenon is vice versa for thermoset composites due to the epoxy matrix, which limits the stiffening effect in natural fibres.     

Fabrication Mechanical Properties of Unidirectional Jute/PP Composites Using Jute Yarns by Film Stacking Method

This paper mainly focuses on the fabrication process of long fibre reinforced unidirectional thermoplastic composites made using both natural (untreated) treated jute yarns. Jute yarns were wound in layers onto a metallic frame. Polypropylene films were inserted between these layers and compression moulded to fabricate unidirectional jute/PP composite specimens. Static mechanical properties were evaluated from tensile three point bending tests. Pre- post-failure examination were carried out on the test specimens using optical scanning electron microscopy to analyse the test results and investigate the correlations between their impregnation state, processing conditions, mechanical performances and fracture morphologies. For the unidirectional jute/PP film-stacked composites, the results indicated that the processing condition at the moulding temperature of 160°C and moulding pressure of 2.0 MPa for 15 min was ideally suited to obtain optimized properties. Improved wettability of resin melts due to complete matrix fusion at this processing condition facilitated thorough impregnation with minimum microstructural imperfections (microvoids) being generated. Jute/PP composites that contained treated jute yarns have shown superiority in tensile bending properties. Jute yarns polished or coated with PVA/PP (polyvinyl alcohol/polypropylene) must have contributed positively to fibre/matrix interfacial interactions leading to matrix to fibre effective stress transfer, thereby improving their reinforcing effects. Tensile strength and modulus of PP resin increased by approximately 285% and 388%, respectively, due to 50 wt% reinforcement by natural jute yarns. Further improvements in strength and modulus were achieved by approximately 14% and 10%, respectively, when treated yarns were used . The maximum bending stress modulus of jute/PP composites containing untreated yarns were approximately 190% and 460% higher than those of the virgin PP materials, and bending properties were improved by further 11% and 23%, respectively, due to coating treatments on the yarn surface.