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In this work, twin-screw extruder and compression moulding techniques were utilized to fabricate polymer blends: polypropylene (PP), polybutadiene (PB), and composites using glass fibre (GF) and flax fibre (FF). During fabrication, the polymer ratios maintained between PP and PB were 90:10, 80:20, and 70:30. Likewise, the composites were fabricated by varying the ratios between the PP, PB, and GF, which were 90PP:10PB:10GF, 80PP:20PB:10GF, and 70PP:30PB:10GF. Additionally, a hybrid composite was fabricated by adding 20% FF to the 90PP/10PB/10GF blend. The mechanical characterization revealed that the tensile strength and modulus increased by approximately 24% and 23%, respectively, for the hybrid combination (90PP/10PB/10GF/20FF) compared to pure PP (from 21.47 MPa and 1123 MPa to 26.54 MPa and 1382 MPa). Similarly, flexural strength and impact resistance showed significant improvements in hybrid samples, with flexural strength increasing by approximately 15%. Scanning electron microscopy (SEM) was also carried out for impact-tested samples to understand the fibre-to-matrix adhesion behaviour. Regarding the DSC results, PP exhibited a melting peak between 160 °C and 170 °C. When incorporating PP into PB, a reduction in crystallinity was observed. Further, by adding GF to polymer blends, the crystallinity was increased. HDT and Vicat softening temperature results reported that the hybrid samples showed higher values of 79.3 °C and 88.2 °C, respectively, resulting in improvements of approximately 3.9% and 2.9% over standard PP. Findings from this study suggest that the novel combinations offer a promising synergy of flexibility, strength, and thermal resistance, making them suitable for medium engineering applications. [ABSTRACT FROM AUTHOR]

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Although there is no doubt that composite materials are the future of lightweight structures and components, most of composites currently produced are made from thermoset polymers, which are not able to be recycled or reprocessed. In contrast, thermoplastic polymers offer the possibility to recycle and reprocess and when combined with a fibrous reinforcement, provide interesting mechanical properties. This work reviews the production of two thermoplastic pre-impregnated materials in a tape form, one of which is produced on new prototype equipment developed in our laboratories. The method for the production of tape is described, and the prepregs presented here were subjected to two processing techniques. The first processing method, pultrusion, is an efficient and autonomous method to produce composite profiles, marking itself as a continuous and cost-effective way to produce these materials. Pultrusion bars were then subjected to heated compression moulding, a process that allows to obtain more complex-shaped parts. The second method, heated compression moulding, is a relatively simple process which was used to obtain composite laminates. The pultrusion bars and composite laminates were then subjected to mechanical testing to evaluate the levels of consolidation of the final material. A microscope testing was also carried out to analyse the dispersion of fibres and polymer, as well as the amount of voids present in the composite. [ABSTRACT FROM AUTHOR]

Pervious concrete remains a sustainable solution for effective water management in urban scenarios. Owing to the absence of fine aggregates, properties of pervious concrete rely much on the properties of aggregates and porosity. This article is aimed at determining the effect of aggregate size on the performance of pervious concrete mixes using 12.5 and 20 mm nominal-sized aggregates. In addition to that, the effects of polypropylene and glass fibre were experimented by varying their proportion in volumetric increments of 0.1% up to 0.4%. The aggregate to cement ratio and water to cement ratio were retained constant at 3.54 and 0.35, respectively. Results indicated that the fall in aggregate size improves mechanical properties but decreases porosity and permeability values. The presence of fibres in pervious concrete mixes was observed to improve flexural and split tensile strength but has no significant effect on the compressive strength, porosity and permeability. [ABSTRACT FROM AUTHOR]

Sandwich structures, consisting of a short glass fibre–reinforced polypropylene film as skin layer and chemically blown polypropylene as the core material, were produced via injection moulding. The skin layers of the sandwich structures, which contain polypropylene as well as 30 wt% and 50 wt% of glass fibres namely polypropylene–glass fibres 30 and polypropylene–glass fibres 50 respectively, were produced by film extrusion using a coat hanger die. The properties of the films were investigated by dynamic mechanical analysis. Furthermore, the influence of different glass fibre contents in the skin layers and chemical blowing agent contents in the core material of sandwich structures was studied to compare them with the compact polypropylene and the polypropylene foams. The sandwich structures were characterized with regard to density, microstructure, weight reduction, surface roughness and bending properties. In general, distinctive reinforcement effect was achieved by use of the short glass fibre with the strong influence of processing direction of the film. For the sandwich structures, it was found that a good adhesion between the skin layers and the core material can be achieved during injection moulding. The microstructure and the bending properties of the sandwich structures depend on the glass fibre–reinforced film and the chemically blown core. It was found that the use of the skin layers led to lower cell intensity in the foam core. Nevertheless, a high modulus and strength to weight ratio could be accomplished by a high stiffness of the glass fibre–reinforced film and a low density of the chemically blown core. Additionally, it was found that the surface roughness of the films could be reduced due to processing in injection moulding. [ABSTRACT FROM AUTHOR]

Banana fibre is a secondary crop fibre that could be profitably used in the manufacturing of fibre reinforced composites because they possess attractive mechanical and physical properties. The mechanical properties of banana-glass fibre reinforced polypropylene composite were studied. The composites were prepared using a hot press with four types of stacking sequence. Mechanical tests were carried out according to American Society for Testing and Materials (ASTM) D3039 for tensile test, ASTM D790 for flexural test and ASTM D6264 for quasi-static indentation. The results showed that banana fibre (B) reinforced composite was enhanced by incorporating glass fibres (G) by 302.27% and 24.45% for GBG, in terms of tensile and flexural strength respectively. For quasi-static indentation, the energy absorbed increased by 122.22% with the incorporation of glass fibre for GBG. The results show a positive hybrid effect on the mechanical properties, where hybrid GBG is comparable to GGG in the flexural application. [ABSTRACT FROM AUTHOR]

Interfacial adhesion of basalt and glass fibre reinforced polypropylene composites was studied using microdebond testing technique. A focus was put on a simple approach of applying extruded thermoplastic films as a matrix material for microdroplet formation. The ability of different viscosity and thickness polypropylene films to form symmetrical droplets under a temperature range of 200–240℃ was evaluated. Emphasis was put on polypropylene matrix chemistry, silane fibre surface treatment and testing loading rate impact on interfacial performance change in polypropylene-basalt fibre and polypropylene-glass fibre microcomposites. It was found that it was possible to obtain high symmetrical droplet yield out of polypropylene films of melt flow rate 50 and 125 g/10 min and 55–85 µm thickness at 240℃. The presence of maleic anhydride grafted polypropylene coupling agent increased the interfacial shear strength significantly. Microcomposites with glass fibre had higher interfacial shear strength in comparison with the used basalt fibre, mainly due to the difference in their sizing. Various silane-based fibre surface coatings did not result in significant interfacial adhesion changes. Polypropylene-glass fibre microcomposite interfacial shear strength at 0.5, 3.0 and 10.0 mm min–1 loading rates had similar values with high maximum pull-out force scatter at 0.5 and 3.0 mm min–1 loading rates and low scatter at 10.0 mm min–1. [ABSTRACT FROM AUTHOR]

Natural fibres have emerged as a lightweight, low cost, and comparable property-wise alternative to glass fibres in composites. In this communication, natural fibres enhanced by chemical treatments for composite applications were evaluated for their environmental impacts using SimaPro 8.0. Hemp fibres were treated with two novel sulfonic acid methodologies and compared to accepted methods for fibre enhancement in the literature (mercerization treatment, acetic and propionic anhydride treatment). The tested experimental methods had a comparably lower environmental footprint than the literature approaches. Also, when further compared to the industry standard (glass fibre), the methods were superior. In the end, when used to reinforce poly(lactic) acid (renewable polymer) and polypropylene (non-renewable polymer), the experimental treatments had less of an environmental burden. In summary, through assessment with established methodology and standardized assumptions, we have proven that natural fibres can be enhanced using sulfonic acids, at the same time producing fibres with similar properties, but lower environmental burden than the compared alternatives. [ABSTRACT FROM AUTHOR]

The influence of sizing constituent distribution on the properties of sized glass fibres (GFs) and corresponding polypropylene (PP) composites was studied by two-stage sizing application, i.e. applying silane coupling agent and polymeric film former at separate stages and with different sequences, in comparison with one-stage sizing application usually used. Surface properties of sized GFs and transverse tensile strength of unidirectional GF reinforced composites were studied using various surface and interface analysis methods and tensile testing, respectively. Two-stage technology achieved sized GFs with lower loss-on-ignition (LOI) and resulted in poor fibre-matrix adhesion strength. However, applying silane coupling agent at the first sizing stage with an increased roller speed achieved sized GFs with lower LOI but composites with mechanical properties quite close to those of composites based on one-stage technology. Moreover, the difference in surface properties of sized GFs is discussed in terms of the wetting ability difference of sizing constituents and the interactions between sizing components.

Ankle-foot orthotics need ideal specification of being light-weight, high strength, tough, stiff, and durable. Reinforced polypropylene (PP) composites with enhanced mechanical properties are the most favorable materials being used in this field, but still, it is challenging to achieve balanced blend of strength and toughness in the composites. The present study thus aims to achieve the challenging task of simultaneous improvement in stiffness and toughness in reinforced PP composites exploring the synergistic reinforcement effect of glass fibers (GFs) and nano silica (SiO2) as multiscale fillers and ethylene propylene diene monomer (EPDM) as impact modifier. EPDM is used as toughness modifier, addressing the brittle behavior, but at the cost of the strength of the polymer. Combined use of micro and nanofillers as reinforcement in toughened polypropylene provides a potential approach to balance the strength while maintaining the toughness. GFs could offer high strength and nanofillers offer ductile fracture to the material. PP, PP/GF, PP/EPDM/GF composites and PP/EPDM/GF/SiO2 nanocomposites are fabricated through melt blending technique and are characterized through SEM, mechanical evaluation, nanoindentation and dynamic mechanical analysis. Mechanical properties are evaluated in accordance with ASTM standards. PP/EPDM/GF/SiO2 nanocomposites exhibits remarkable enhancement in Tensile strength, tensile modulus, impact strength and percent elongation at break by 49 MPa (55% increase over PP), 2450 MPa (145% increase), 145 J/m (13% increase) and 156% (160% increase) respectively. The exceptional improvement in reduced modulus and hardness reveals good interfacial properties. Loss factor decrement reveals elastic behavior of nanocomposites suitable for thermoforming of nanocomposites for orthotic device fabrication. [Display omitted] • Durable, strong, low-cost PP/EPDM/GF/SiO 2 nanocomposites for orthotic applications. • Incorporation of EPDM, Glass fibers and silica nanoparticles in PP nanocomposites for balanced strength and toughness. • Increased storage modulus and decrement in loss factor provides required elastic behavior for orthotic application. • PP/EPDM/GF/SiO 2 nanocomposites exhibits 55% increase in tensile strength, 145% increase in tensile modulus, 13% increase in impact strength, 160% increase in % elongation at break, 207% increase in elastic modulus, and 963% increase in hardness over neat PP. [ABSTRACT FROM AUTHOR]

This study presents an experimental overview of thermoplastic polymer-coated glass fibre and scrap-reinforced hot-mix asphalt (HMA) mixtures. The toughening effects of the reinforced HMA mixtures were characterised using indirect tensile and Hamburg wheel-tracking tests. The indirect tensile loading tests were used to calculate the relative indirect tensile strengths of samples and to compare their moisture susceptibilities. The fibre’s relative contributions to increasing the indirect tensile strength and the resistance to rutting are quantified by comparing the maximum indirect peak tensile stress and tensile strength ratio (TSR). The indirect tensile strength and TSR of the fibrous mixtures are nearly two times higher than those of the plain mixtures, demonstrating the lower moisture susceptibility and superior field performance of the fibrous asphalt mixture. Accelerated rutting tests using the Hamburg wheel test setup for the fibrous mixtures caused at least three times more loading passes to be required to reach the rut-depth criteria compared to the number of loading passes required for the plain mixtures. [ABSTRACT FROM AUTHOR]

Waste printed circuit boards (WPCBs) are composed of nearly 70% non-metals, which are generally recycled as low-value filling materials or even directly dumped in landfills. In this study, polypropylene (PP) composites reinforced by recycled pure glass fibres (RGF) from pyrolysed WPCBs were successfully produced. The manufacturing process, mechanical properties and thermal behaviour of the composites were investigated. The results showed that the appropriate addition of RGF in the composites can significantly improve the mechanical properties and thermal behaviour. When the added content of RGF was 30%, the maximum increment of tensile strength, impact strength, flexural strength and flexural modulus of the glass fibre (GF)/PP composites are 25.93%, 41.38%, 31.16% and 68.42%, respectively, and the vicat softening temperature could rise by 4.6°C. Furthermore, leaching of the GF/PP composites was also investigated. The GF/PP composites exhibited high performance and non-toxicity, offering a promising method to recycle RGF from pyrolysed WPCBs with high-value applications. [ABSTRACT FROM PUBLISHER]

To improve the interfacial bonding between polypropylene (PP) and glass-fibre (GF), the surface modified glassfibre (SMGF) was prepared with the self-designed sizing containing organofunctional silanes and a copolymer. Then the SMGF-PP composites were prepared and those properties were observed by mechanical testing, light microscopy, X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mechanical tests displayed that SMGF-PP composites had an increase in tensile strength, tensile modulus, bending strength, bending modulus and notched impact strength compared to the pure PP. Light micrographs showed that the average fibre length of the composite was 397 μm. XRD data indicated that the crystal size of SMGF-PP composites became smaller compared to pure PP, and β form crystals of PP disappeared with the addition of SMGF to PP matrix. DSC data showed that SMGF could promote the crystallization temperature of PP. TGA analyses showed that the thermal stability of SMGF-PP was better than that of pure PP. [ABSTRACT FROM AUTHOR]

Abstract: Using textile composites with straight fibre orientation in-plane, improved lightweight structures can be designed and produced, where the fibres are specifically positioned in line with the flux of force induced by external loads. Here, the structural properties are dominated by the material properties of the 0°-fibres under static as well as under fatigue loading. It is well known, the failure behaviour in fibre direction is affected by textile loop threads and adjacent plies, for example by notch effects of inter fibre cracks. For the experimental characterisation of the influence of 3D-loop threads as well as adjacent plies on the fatigue performance, the degradation behaviour of unidirectional and textile glass fibre reinforced polypropylene in tension-tension fatigue loading has been analysed. The material configurations have selectively been chosen to achieve identical fibre volume fraction of the reinforcement fibres in loading direction and therefore gain a high comparability in fatigue loading. The driving damage mechanisms are observed using imaging methods, such as light microscopy and computer tomography. The achieved experimental results will be incorporated into the failure mode dependent fatigue analysis models already been published by the authors. [Copyright &y& Elsevier]

Abstract: Recycled polypropylene (RPP) based hybrid composites of date palm wood flour/glass fibre were prepared by different weight ratios of the two reinforcements. Mixing process was carried out in an extruder and samples were prepared by injection molding machine. Recycled PP properties were improved by reinforcing it by wood flour. The tensile strength and Young’s modulus of wood flour reinforced RPP increased further by adding glass fibre. Glass fibre reinforced composites showed higher hardness than other composites. Morphological studies indicated that glass fiber has good adhesion with recycled PP supporting the improvement of the mechanical properties of hybrid composites with glass fiber addition. Addition of as little 5wt% glass fibre to wood flour reinforced RPP increases the tensile strength by about 18% relative to the wood flour reinforcement alone. An increase in wood particle content in the PP resulted in a decrease in the degree of crystallinity of the polymer. The tensile strength of the composites increased with an increase in the percentage of crystallinity when adding the glass fibre. The improvement in the mechanical properties with the increase in crystallinity percentage (and with the decrease of the lamellar thicknesses) can be attributed to the constrained region between the lamellae because the agglomeration is absent in this case. [Copyright &y& Elsevier]

The behaviour of a composite with a polymeric matrix subjected to fatigue was analysed. The study was conducted at ambient temperature, as well as at 50 and 100 °C. The material was observed to behave differently at each temperature. Furthermore, a statistical analysis was performed using Castillo's model. Although certain similarities in behaviour were observed at ambient temperature and 50 °C, the material behaved differently at 100 °C. Structural modifications were found in the thermal analysis that justify these differences. [ABSTRACT FROM AUTHOR]

The influence of sizing constituent distribution on the properties of sized glass fibres (GFs) and corresponding polypropylene (PP) composites was studied by two-stage sizing application, i.e. applying silane coupling agent and polymeric film former at separate stages and with different sequences, in comparison with one-stage sizing application usually used. Surface properties of sized GFs and transverse tensile strength of unidirectional GF reinforced composites were studied using various surface and interface analysis methods and tensile testing, respectively. Two-stage technology achieved sized GFs with lower loss-on-ignition (LOI) and resulted in poor fibre-matrix adhesion strength. However, applying silane coupling agent at the first sizing stage with an increased roller speed achieved sized GFs with lower LOI but composites with mechanical properties quite close to those of composites based on one-stage technology. Moreover, the difference in surface properties of sized GFs is discussed in terms of the wetting ability difference of sizing constituents and the interactions between sizing components. [ABSTRACT FROM AUTHOR]

Quasi-static and intermediate rate axial crush tests were conducted on tubular specimens of Carbon/Epoxy (Toray T700/G83C) and Glass/Polypropylene (Twintex). The quasi-static tests were conducted at 10 mm/min (1.67×10-4 m/s); five different crush initiators were used. Tests at intermediate rates were performed at speeds of 0.25, 0.5, 0.75, 1, 2, and 4 m/s. Modes of failure and specific energy absorption (SEA) values were studied. The highest SEA measured was 86 kJ/kg. This value was observed using Carbon/Epoxy samples at quasi static rates with a 45° chamfer initiator. The highest energy absorption for Twintex tubes was observed to be 57.56 kJ/kg during 45° chamfer initiated tests at 0.25 m/s. Compared with steel and aluminium, SEA values of 15 and 30 kJ/kg, respectively, the benefits of using composite materials in crash structures become apparent. [ABSTRACT FROM AUTHOR]

The dependence of physical and mechanical properties on microstructure is well known. Various numerical and analytical methods are routinely employed to predict the properties of multiphase materials but these models make certain simplifying assumptions about the microstructure of the material, such as homogeneity, that are not accurate. In the present work, a microstructure based finite element code called object oriented finite element method (OOF) has been used to investigate the longitudinal elastic modulus of a long fibre reinforced thermoplastic (LFT) composite (glass fibre/polypropylene). The modulus value predicted by OOF was then compared with the experimental value and values predicted by various models. It is shown that by taking into account the important microstructural parameters in the composite, i.e. the actual fibre orientation and distribution, accurate prediction of modulus can be obtained. [ABSTRACT FROM AUTHOR]

A recently developed coating-line (Nunes et al., Thermoplastic Composite Materials 17(6), 523, 2003) was used to fabricate low-cost glass fibre reinforced polypropylene (GF/PP) towpregs, which were subsequently processed into composites by compression moulding and filament winding. The mechanical properties determined on the final composites are compared with the theoretical predictions. Filament wound prototypes of domestic gas pressure vessels were also produced from the GF/PP towpregs and submitted to internal pressure burst tests. These prototypes have shown accomplishing easily all requirements of the applicable European standards. The excellent obtained results clearly demonstrated that the thermoplastic matrix towpregs have potential to enlarge significantly future applications of composites in large consumption end-use markets. [ABSTRACT FROM AUTHOR]

Abstract: In this experimental work, the influence of silane coated glass fibres added to polypropylene (PP) and polyamide 6 (PA6) plastics was investigated. These plastics were reinforced with (15 and 30 wt%) silane coated glass fibres. For this purpose, a die was designed and manufactured to produce tension and notched impact species using various injection parameters. Based on the results of this work, which investigates the influence of fibre reinforcement and injection parameters on the tensile strength and impact strength, PP and PA6 plastics reinforced with glass fibre exhibited improvement in their mechanical strength with the fibre reinforcement. However, improvement in the mechanical strength did not show a linear relationship with the fibre weight fraction on account of inhomogeneous fibre distribution and fibre fracture. In addition, tensile strength increased with increasing injection feeding zone temperature and decreased with increasing injection speed and extruder screw speed. [Copyright &y& Elsevier]

Micro-braided yarn was prepared by using glass bundle, the reinforcement material, as the axial fibres and polypropylene filaments, the matrix, as the shell. The impregnation behaviour of the thermoplastic polypropylene during fabrication was investigated. [Copyright &y& Elsevier]

Several different composite plastics were pyrolysed in a fixed bed reactor at final temperatures between 350 and 800°C. The composites studied were polyester, phenolic, epoxy, vinylester, polypropylene and PET resins, reinforced with glass and/or carbon fibre. The product yields of oil, gas and solid residue were determined together with a detailed composition of the derived gases. There was evidence to suggest that calcium carbonate filler, present in the polyester and phenolic composites, decomposed to form carbon dioxide at 800°C, which was subsequently involved in char gasification reactions. Polyester, phenolic and epoxy composites generated highly aromatic, oxygenated condensable products. There was no noticeable correlation between the composition of these products and the final pyrolysis temperature. The tensile strength of recovered glass fibre was lower than that of virgin fibre and decreased markedly as the final pyrolysis temperature increased from 650 to 800°C. [ABSTRACT FROM AUTHOR]

For glass fibre–polypropylene (PP) composites, the non-polar nature of polypropylene presents a problem. The present investigation shows that it is necessary to introduce a functionalised PP, for example PP-g-MAH, in order to enhance the bond strength between the PP matrix and aminosilane treated glass fibre. To achieve a better bonding between the substances, three different systems (1–3) in addition to a reference system (0), have been investigated in this study. The two first are based on PP-g-MAH coupling agents, with different concentrations of acid anhydride groups, and the third is a directly reacting system. In the first system, the silane treated glass fibre is exposed to molten mixture of 95 wt% PP homopolymer and 5 wt% PP-g-MAH. In the second system, the silane treated glass fibre is covered by a thin layer of PP-g-MAH and thereafter exposed to the molten PP. The interfacial shear strength is highest for the systems with the pre-compounded graft-copolymer. The resulting influence of the selected coupling systems on the interfacial bond strength of single fibre composite is studied by fragmentation testing. The intermolecular shear strength between fibre and matrix increases with the intermolecular entanglement length of the PP-g-MAH and not by the degree of functionalisation. The PP-g-MAH mixed into the PP gave better results than the route of first covering the glass fibre with a thin layer of PP-g-MAH. This is explained in terms of the probability of generating entanglements and in terms of a weak boundary layer at the glass surface. This conclusion is also supported by the results from using the third principle, i.e. direct reaction between the PP matrix and azidosilane treated glass fibres. [ABSTRACT FROM AUTHOR]

The unidirectional thermoplastic commingled yam composites have been fabricated from three different varieties of yams in a hot press and then studied for the bending properties on DCS-500 tester using three-point loading system. It is observed that the bending properties of composites, especially the transverse bending properties, are affected by the mixing degree of reinforcing fibre/matrix fibres and bulkiness of reinforcing fibres bundle. [ABSTRACT FROM AUTHOR]