Reinforced Polypropylene Composites Research Articles

Environmental durability of carbon/flax fiber hybrid composites

Hybridization of synthetic fibers with natural fibers is receiving more attention in recent years. Experimental study on the durability of carbon/flax fiber reinforced polypropylene composites and single flax fibers was carried out. Three composite lay-ups were designed by altering the position of the carbon fiber ply, i.e., pure flax/polypropylene laminates, laminates with flax ply at the surface and laminates with the carbon ply at the surface. Samples were exposed to water immersion ageing at elevated temperature until saturation. The transport law of moisture in hybrid composites and mechanisms of possible change in microstructures and mechanical properties were particularly explored. Carbon fibers reduced the amount of water absorption in flax/polypropylene composites and improved their mechanical properties. These beneficial effects were optimum when carbon fibers were placed at the outer layers. However, the interface between the carbon ply and flax ply was vulnerable to both hygrothermal attack and delamination. After hygrothermal ageing, the tensile and flexural properties of the laminates decreased while the tensile failure strain increased, primarily due to plasticization and fiber/matrix interface deterioration. Single flax fibers which were exposed to the same ageing condition also experienced decrease in strength and modulus. However, elongation-at-break of single flax fiber decreased after ageing.

Effects of Surface Modifications on the Mechanical Properties of Reinforced Pineapple Leaf Fibre Polypropylene Composites

Pineapple Leaf Fibre (PALF) is one of the natural fibres that have high potential in the industry. Natural fibres have become the main alternative source for reinforced polymer composites. The objective of this study is to observe the effect of chemical treatments using Sodium Hydroxide (NaOH) solution, Zinc chloride, Acetic Anhydride and Nitric acid on the mechanical properties of pineapple leaf fibre reinforced polypropylene composites. The tensile test was conducted by using the ASTM D638-10 to obtain the tensile strength (TS) and Young’s modulus (YM), Flexural properties were conducted to determine the flexural strength (FS) and flexural modulus (FM) of the reinforced composites using the ASTM D256-10 method, and impact test was conducted to determine the impact strength (IS) of the reinforced composites using the Izod ASTM D790-17 method. From the results obtained, the composites with surface modified PALF fillers show enhanced mechanical properties over the untreated PALF fillers in this order; for TS untreated composite C3H6O3 3. For YM untreated composite 3 C3H6O3 3 3H6O3. For FM, untreated reinforced PALF/PP composites C3H6O3 3. For IS, the untreated reinforced PALF/PP composites 3 C3H6O3. SEM analysis was carried out on the PALF before the compounding to analyze the effect of the surface modification agents.

Mechanical properties of plain woven kenaf/glass fiber reinforced polypropylene hybrid composites

Abstract There has been an increasing interest among researchers on natural/synthetic hybrid fiber reinforced composites due to their extensive advantages such as enhanced mechanical properties as compared to natural fiber reinforced composites. The balance between environmental friendliness and mechanical strength can be achieved through hybrid composite materials. This study aims to investigate the effects of stacking sequences on the mechanical properties of woven kenaf/glass hybrid composites. Woven kenaf/glass hybrid composites with two different stacking sequences were fabricated in the hot compression process. Non-hybrid glass and kenaf fiber reinforced polypropylene composites were also prepared for comparison. Tensile, flexural and Charpy impact tests were conducted in accordance with ASTM D 3039, ASTM D 790 and ASTM D 6110, respectively. The results showed that the tensile strength of glass/kenaf/glass hybrid laminates was only 3.4 % lower than that of non-hybrid glass fiber reinforced composites. The flexural strength of hybrid glass/kenaf/glass laminates was 32.5 % higher than non-hybrid glass fiber reinforced composites. In terms of impact strength in edgewise and flatwise orientations, hybrid glass/kenaf/glass laminates showed 8.6 % and 51.9 % improvement, respectively, as compared to non-hybrid glass fiber reinforced composites. This showed that the hybrid laminates exhibited superior mechanical properties as compared to non-hybrid glass fiber reinforced composites.

The Effect of Temperature and Strain Rate on the Interfacial Behavior of Glass Fiber Reinforced Polypropylene Composites: A Molecular Dynamics Study.

To make better use of fiber reinforced polymer composites in automotive applications, a clearer knowledge of its interfacial properties under dynamic and thermal loadings is necessary. In the present study, the interfacial behavior of glass fiber reinforced polypropylene (PP) composites under different loading temperatures and strain rates were investigated via molecular dynamics simulation. The simulation results reveal that PP molecules move easily to fit tensile deformation at higher temperatures, resulting in a lower interfacial strength of glass fiber–PP interface. The interfacial strength is enhanced with increasing strain rate because the atoms do not have enough time to relax at higher strain rates. In addition, the non-bonded interaction energy plays a crucial role during the tensile deformation of composites. The damage evolution of glass fiber–PP interface follows Weibull’s distribution. At elevated temperatures, tensile loading is more likely to cause cohesive failure because the mechanical property of PP is lower than that of the glass fiber–PP interface. However, at higher strain rates, the primary failure mode is interfacial failure because the strain rate dependency of PP is more pronounced than that of the glass fiber–PP interface. The relationship between the failure modes and loading conditions obtained by molecular dynamics simulation is consistent with the author’s previous experimental studies.

Modeling the Stiffness of Coupled and Uncoupled Recycled Cotton Fibers Reinforced Polypropylene Composites.

The stiffness of a composite material is mainly affected by the nature of its phases and its contents, the dispersion of the reinforcement, as well as the morphology and mean orientation of such reinforcement. In this paper, recovered dyed cotton fibers from textile industry were used as reinforcement for a polypropylene matrix. The specific dye seems to decrease the hydrophilicity of the fibers and to increase its chemical compatibility with the matrix. The results showed a linear evolution of the Young’s moduli of the composites against the reinforcement contents, although the slope of the regression line was found to be lower than that for other natural strand reinforced polypropylene composites. This was blamed on a growing difficulty to disperse the reinforcements when its content increased. The micromechanics analysis returned a value for the intrinsic Young’s modulus of the cotton fibers that doubled previously published values. The use of two different micromechanics models allowed evaluating the impact of the morphology of the fibers on the Young’s modulus of a composite.

Accelerated weathering and decay resistance of heat-treated wood reinforced polypropylene composites

The aim of this study was to determine the accelerated weathering and decay resistance of the heattreated wood reinforced polypropylene composites (HT-WPC). Polypropylene (PP) was used as a matrix and the heat-treated wood treated at 180 °C and 220 °C as reinforcement filler. The effect of three filler type, such as 40, 60 and 100 mesh, on the outdoor performance of composites was also investigated. The composites were prepared with twin screw extruder, and the test samples were obtained with compression molding. Lightness index (L*), color changes (ΔE*) and physical changes on the surface of the composites after the accelerated weathering, and decay resistance of the composites were investigated. According to the results, the effects of heat-treated wood on color changes were found to be more than its filler size, and while the filler loadings were increased from 5 % to 20 %, it was determined to increase the color changes of the composites. In scanning electron microscopy (SEM) images, crack formation and deterioration on the surface of the composites were determined. In FTIR spectra, no difference was determined between the composites, and all peaks were similar to each one. The addition of heattreated wood improved the antifungal efficiency of the composite, and the mass losses decreased with the increasing of heat treatment temperature. As a result, adding heat-treated wood to PP was found to improve the outdoor performance of the HT-WPCs.

Measurement and analysis of thrust force and delamination in drilling glass fiber reinforced polypropylene composites using different drills

Fiber Reinforced Plastic (FRP) composites are widely used in various engineering fields and applications. FRPs were initially fabricated using thermoset polymers owing to ease of manufacturing. Of late, FRP based thermoplastics is gaining importance due to various factors such as impact resistance, recycling, and an absence of any chemical reaction. In the present investigation, Glass Fiber Reinforced Plastic (GFRP) laminates of woven glass fabric reinforcements with Polypropylene (PP) thermoplastic matrix is manufactured using film stacking technique. To analyze the performance in machining, drilling studies are carried out using a 6 mm diameter twist drill of High Speed Steel (HSS) drill, tipped carbide and solid carbide drill. The drilling experiments are conducted on a CNC Vertical Machining Centre (VMC) to measure and assess the drilling induced thrust force and the respective exit delamination. The drill spindle speed and feed rate are considered as process parameters. To correlate the process parameters with responses, the regression models are developed. The results indicate that the most significant control parameter for process responses and also it shows the developed regression models are highly reliable. The influence of drill materials on the performance of the responses is also discussed in detail.

An Investigation on the Comprehensive Property Assessment and Future Directions of Single Bamboo Fiber Reinforced Polypropylene Composites Fabricated by a Non-Woven Paving and Advanced Molding Process.

The demand for eco-friendly renewable natural fibers has grown in recent years. In this study, a series of polypropylene-based composites reinforced with single bamboo fibers (SBFs), prepared by non-woven paving and a hot-pressing process, were investigated. The influence of the content of SBF on impact strength, flexural strength, and water resistance was analyzed. The properties of the composites were greatly affected by the SBF content. Impact strength increased as SBF content increased. The modulus of rupture and modulus of elasticity show an optimum value, with SBF contents of 40% and 50%, respectively. The surface morphology of the fractured surfaces of the composites was characterized by scanning electron microscopy. The composites showed poor interfacial compatibility. The water resistance indicates that the composites with higher SBF contents have higher values of water absorption and thickness swelling, due to the hydrophilicity of the bamboo fibers. The thermal properties of the composites were characterized by thermal gravimetric analysis and by differential scanning calorimetry. The thermal stability of the composites was gradually reduced, due to the poor thermal stability of SBFs. In the composites, the maximum decomposition temperature corresponding to SBF shows an increasing trend. However, the maximum decomposition temperature of polypropylene was not influenced by SBF content. The melting point of the polypropylene in the composites was lower relative to pure polypropylene, although it was not affected by increasing SBF content.

Effect of Strain Rates on Tensile Properties of Kenaf Fiber and Rice Husk Silica Reinforced Polypropylene Composites

The expanding interest for eco-accommodating materials, expanding exhaustion rate, and squeezing ecological controls have all set off a developing enthusiasm toward the field of composites. There is a demand for composites which not only possess good mechanical properties but also low cost, eco-friendly and lightweight. The objective of this study is to investigate the tensile behavior under elevated strain rates of kenaf fiber and rice husk silica reinforced polypropylene composites at different grades of rice husk silica (89.09% and 94.05%) content. The samples of composite materials were prepared by using injection molding at different composite percentage of kenaf fiber, rice husk silica and polypropylene composites. Tensile test was carried out to determine the tensile stresses of the composite at the best composition ratio of kenaf fiber and rice husk silica. Generally, the sample with 20 wt.% of kenaf fiber and 20 wt.% of rice husk silica which have high silica content exhibited the best yield stress, ultimate tensile strength and elongation which are 20.31MPa, 20.86MPa and 13.05% respectively. The result shows that 2nd grade with high silica content of rice husk silica has better behavior with increases the yield and ultimate tensile strength compared to results of 1st grade of rice husk silica.

Oxidative induction and performance of oil palm fiber reinforced polypropylene composites – Effects of coupling agent and UV stabilizer

Reinforced polypropylene/empty fruit bunch (EFB) fiber composites were prepared through extrusion and injection moulding. Maleic anhydride grafted polypropylene (MAPP) and CESA-light PPADOL 12020 (PDOL) were used as compatibilizer and UV stabilizer respectively. The samples were subjected to accelerated UV irradiation and the simultaneous effects of compatibilization and PDOL were investigated. Results showed that PDOL slightly improved the adhesion between PP and EFB, but did not offer mechanical strength improvement. However, oxidative induction time analysis and discoloration analysis revealed that the incorporation of PDOL plays significant role in preventing the composites from discoloration as well as UV degradation. In addition, dynamic mechanical analysis indicated that compared with ternary composites, the quaternary composite containing PDOL and MAPP exhibits lower loss modulus, accrued to good interrelationship between PP, EFB, PDOL and MAPP. Generally, it is evident herein that PDOL may be used in applications requiring higher colour stability.

Recycling of sisal fiber reinforced polypropylene and polylactic acid composites: Thermo-mechanical properties, morphology, and water absorption behavior

The effect of recycling on the thermo-mechanical and water absorption behavior of polypropylene (PP)/sisal fiber and polylactic acid (PLA)/sisal fiber composites were studied. The PP-based non-biodegradable composites and PLA-based biodegradable composites were recycled for four times. The effect of recycling was determined by examining the morphology, thermo-mechanical properties, and water absorption behavior and the obtained results were compared. The results showed that the incorporation of sisal fibers in the PP and PLA matrix enhances the tensile modulus and percentage crystallinity of the composites. The tensile strength and modulus of the sisal fiber reinforced PP composites were not affected with recycling. Even though the tensile properties of PLA and PLA/sisal fiber reinforced composites are superior to PP and PP/sisal fiber composites, the PLA-based composites show a dramatic decrease in tensile strength and modulus after the first recycling due to the degradation of the polymer. The thermal stability of the PP/sisal fiber composites was not affected by the repeated recycling process. On the other hand, the PLA-based composites with higher sisal fiber content show a bit lower thermal stability after recycling. The PP-based composites show fluctuations in percentage crystallinity with recycling. On the other hand, a remarkable increase in percentage crystallinity for PLA and PLA-based composites was observed with increasing recycling times. Water diffusion study divulges that the diffusion of water into the polymer composites was reduced with recycling, irrespective of the polymer matrix.

Effect of Subang Pineapple Leaf Fiber Loading on Flammability and Mechanical Properties of Pineapple Leaf Fiber Reinforced Polypropylene Composites

Environmentally friendly composites are composites with one or all of the constituent elements being natural materials. Indonesia with high biodiversity resources produces a lot of various types of natural fibers as reinforcements, one of them is pineapple leaf fiber (PALF). This study aimed to determine the effect of Subang PALF contents on flammability, impact resistance, and hardness of polypropylene (PP) / Subang PALF composites. Three compositions of PALF in PP were fabricated by hot press method. Pristine PP samples were also prepared for comparison. Flammability, impact, and hardness test results showed that composites with 40 wt.% PALF were the best with their respective values of (15.7 ± 0.4) mm/minute, (31.6 ± 4.5) J/cm2, and (60.5 ± 2.01) HD.

Flexural Properties and Mean Intrinsic Flexural Strength of Old Newspaper Reinforced Polypropylene Composites.

Newspapers have a limited lifespan, and therefore represent a focus of used and disposed paper. While these refuses have a considerable value and can be easily recycled, a considerable fraction ends in landfill. The authors show the possibility of adding value to used newspaper and enlarge its value chain. Old newspaper incorporates a high amount of wood fibers able to be used as reinforcement. On the other hand, this material also incorporates inks and other components inherent to newspaper production. In this work, the authors disintegrate old newspaper to recover and individualize wood fibers. A morphological analysis showed that the recovered fibers had aspect ratios higher than 10, revealing, a priori, their strengthening capabilities. Thereupon, these fibers were compounded with polypropylene at different contents, ranging from 20% to 50% w/w. It is well known that wood fibers are hydrophilic, while polyolefin are hydrophobic. This is a drawback to obtaining strong interfaces. Thus, two sets of composites were produced, with and without a coupling agent. The results showed that uncoupled composites increased the flexural strength of the matrix but reached an equilibrium point from which adding more reinforcement did not changer the flexural strength. On the other hand, the coupled composites showed a linear increase of the flexural strength against the reinforcement content. The flexural moduli of the coupled and uncoupled composites were very similar and evolved linearly with the reinforcement content.

Effect of Fiber Content and Screw Speed on Mechanical Characterization of Sisal Fiber Reinforced Polypropylene Composites

The present paper researches the impact of differing fiber content and speed on tensile flexural, HDT and effect properties of characteristic fiber (sisal) fortified polypropylene composites (NF). The support fiber (Sisal-Fiber) was gathered from the foliage of locally accessible tree through the procedure of water retting and mechanical extraction. Poor adhesion among fiber and matrix is regularly experienced issue in characteristic fiber-strengthened composites and to conquer this issue, physical and substance medicines were performed for surface adjustment of fibers. The expansion of compatibilizer to the matrix like, is enhanced the adhesion attributes of the fiber. The outcomes it proposes that the high level of fibers combined with a higher screw speed improves the mechanical properties of the Sisal Fiber-Polypropylene plastic composite due to a high interaction between the fiber and the matrix and an even distribution of the fiber in the matrix.

Effect of water absorption on the mechanical properties of cross-ply hybrid pseudo- stem banana/glass fibre reinforced polypropylene composite

The initiative to reduce the consumption of non-renewable resources increases the awareness of being green in composites. The synthetic fibres are currently substituted by natural fibres applicable in various industries such as automotive and building. In this study, the effects of water absorption on the tensile and flexural properties of cross-ply hybrid pseudo-stem banana/glass fibre reinforced polypropylene composites are investigated. The hybrid banana (B)/glass (G) polypropylene composites and the reference specimens of the non-hybrid composites of the plain banana and glass fibres termed the BBB and GGG specimens were fabricated using hot compression moulding method. Water absorption test was conducted according to ASTM D570 until the specimens reached saturation. Tensile (ASTM D3039) and flexural (ASTM D790) test were carried out on the dry specimens as well as the wetted specimens. It can be observed that non-hybrid GGG has the best water absorption properties and hybrid specimen with glass as outermost skin shows a comparable result. However, water absorption reduced the mechanical properties of the composites. The incorporation of glass fibre in the composites improved overall properties of the composites. The hybrid GBG dry specimen tensile strength and wet specimen flexural strength is 136.28 and 73.86 MPa respectively. The hybrid composite GBG shows comparable flexural properties to GGG composite.

Influence of filler loading on the mechanical and morphological properties of carbonized coconut shell particles reinforced polypropylene composites

The high cost of mineral-based fillers and their processing difficulties have necessitated the search for alternative and cheaper filler materials, usually agro-waste materials such as coconut shells. The coconut shells were carbonized, pulverized, and sieved into four particles sizes, namely; 63 μm, 150 μm, 300 μm, and 425 μm. The carbonized coconut shell particles of each particle size were used as fillers in the preparation of polypropylene-filled composites at filler loadings of 0, 10, 20, 30, and 40 wt. %. The control was the neat polypropylene of 0% filler addition. The polypropylene/carbonized coconut shell particles composites were prepared via melt blending of polypropylene and the filler in an injection molding machine to obtain composite sheets. The influence of filler loading on the mechanical properties was evaluated. The addition of fillers was found to improve the yield strength, tensile strength, tensile modulus, flexural strength, flexural modulus, and hardness of polypropylene as these mechanical properties increased with increase in filler loading. The elongation at break and modulus of resilience of the prepared polypropylene/carbonized coconut shell particles composites were, however, observed to decline with an increase in the filler loading. Compared with the neat polypropylene, the filler showed enhanced mechanical properties in the prepared composites. SEM revealed good filler–matrix interaction because of good interfacial adhesion. The incorporation of more filler resulted in the formation of more spherulite-producing nuclei, reduction of pore sizes, and enhanced particle size distribution with improved mechanical properties. Experimental data modeling showed the addition of more than 48% carbonized coconut shell particles to polypropylene would compromise property enhancement.

Effects of decoppering pretreatment on accelerated weathering behaviors of waste printed circuit boards powders reinforced polypropylene composites

ABSTRACTWaste printed circuit boards powders (WPCBP), the critical by‐products in the dispose process of waste electrical and electronic equipment, were selected as reinforcing fillers in polypropylene (PP) composites, which brought forward a new way to reuse WPCBP for a sustainable world. However, the multivalent metals in WPCBP could accelerate the degradation of PP molecule chains. In this study, nitric acid was selected as copper removal to pretreat WPCBP, and most of the metals were removed after decoppering pretreatment, which was evidenced by X‐ray fluorescence (XRF). The ensuing compound was characterized by oxidation induction time, scanning electron microscopy, Fourier transform infrared spectroscopy, and mechanical analysis. As expected, the accelerate weathering behaviors of PP composite with nitric acid treated WPCBP were substantially improved, for instance, the notched impact strength and tensile strength of untreated PP/WPCBP composite after 21 days thermal aging were just 0.85KJ/m2 and 9.3 MPa, while the PP composite with 6 wt % nitric acid‐treated WPCBP was 3.47KJ/m2 and 32.1 MPa. We envisage this facile strategy, that is, using proper concentration of nitric acid to pretreat WPCBP could improve the accelerate weathering properties of PP/WPCBP composites, which would broaden the potential applications of WPCBP in polymer compounds. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48224.

Crystallization Behavior and Properties of Glass Fiber Reinforced Polypropylene Composites.

Glass fiber with different content and different kinds of compatibilizers were used to prepare glass fiber-reinforced polypropylene (GFRP) composites. β-nucleating agent with different content was used to prepare β-polypropylene (PP), after which the toughness, crystallization ability and heat resistance were all enhanced. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) showed that the crystallite degree and crystallization ability were all greatly improved and β-PP was in dominant position. At last, both β-nucleating agent and glass fiber were used to modify the PP composites (β-GFRP). The formation of β-form PP made the matrix softer, which was beneficial for energy absorption and enhancement of toughness. The tensile strength, flexural strength and flexural modulus were improved dramatically, which were attributed to the coeffect of framework structure of GF and β-form PP.

Morphology, thermal and mechanical properties of extruded injection molded kenaf fiber reinforced polypropylene composites

The aim of this study is to explore the effect of coupling agent and surface treatment of natural fibers on the correlations among structural, thermal and mechanical behavior of injection molded composites. Polypropylene (PP)-based composites reinforced with kenaf fiber as a biodegradable filler were fabricated. Kenaf composites were prepared by adding 10, 20, 30, and 40 wt% of kenaf fibers into the matrix using melt mixing and injection molding considered as a simple, scalable, conventional, and efficient process, that is. Different concentrations of NaOH were applied to modify kenaf fibers. The scanning electron microscope (SEM), Fourier Transform Infrared (FTIR), and x-ray Diffraction (XRD) analysis were conducted in order to find the optimum concentration of NaOH for the chemical treatment and to study the morphology of the fabricated specimens. Maleic anhydride polypropylene (MAPP) was employed as the coupling agent. Moreover, the tensile, flexural and impact tests were conducted to evaluate the mechanical properties of the specimens. Results showed that by the incorporation of kenaf fibers of up to 40 wt%, the tensile and flexural strength significantly improved by 100% and 120%, respectively, with respect to those exhibited by the neat PP. It was shown however that the impact strength decreased by around 18%. Moreover, the results of thermal analysis using the differential scanning calorimetry (DSC) showed that the addition of kenaf fibers into the PP matrix increases the melting and crystallization temperature, and the degree of crystallinity. The XRD analysis of composites further confirmed the influence of fibers on the PP crystallization behavior. The results of this work can further extend the use of natural fiber-reinforced PP composites for structural applications such as automotive interior parts.

Static and fatigue behaviors of short glass fiber–reinforced polypropylene composites aged in a wet environment

In this paper, a new experimental study of the bending static and fatigue behaviors of a composite material reinforced with 40% by mass of short glass fibers (type E) and polypropylene matrix is presented. The composite material is obtained in the form of plates by an injection process, which inevitably affects the distribution of the fibers and therefore the behavior of the material studied. To do this, several techniques are implemented on specimens by cutting them in transverse and longitudinal directions. The effect of aging in distilled water at 40℃ on the mechanical characteristics is studied under static and fatigue loading conditions. The static tests, three-point flexure up to failure, allow us to choose the levels of stress for the fatigue tests. The endurance curves as a function of the number of cycles are plotted by adapting the end-of-test criteria N5, N10, and N20, which represent a rigidity drop of 5%, 10%, and 20%, respectively. An interpretation of the Wöhler curve equations defined for the end-of-test criteria allows defining the kinetics of material damage. The results highlighted the influence of distilled water on the mechanical behavior and the lifetime of the material. We also perform macroscopic observations of fracture and microscopic facies in order to identify the damage mechanisms of the composite material.