5 - Glass fibers

UV, FIRT and surface properties of fiber reinforced low-density polyethylene laminated composites

The performance/weight ratio of fiber reinforced polymer matrix composites makes them the material of choice for structural applications in many fields such as aerospace, aeronautics, automotive and civil engineering...etc. In polymer matrix composites, the fibers used as reinforcement are mainly synthetic fibers such as carbon and/or glass fibers. To ensure the low cost of using fiber-reinforced materials in motor vehicles, it is proposed to selectively incorporate carbon fibers to enhance glass fiber composites along the roadway, and to enhance glass fiber composites along the main load path. For this purpose, we conducted a behavioral study of hybrid epoxy thermoset polymer matrix laminates to highlight the influence of alternate hybridization of glass and carbon fibers on the physical-mechanical behavior of the materials.The results obtained show that the alternated hybridation of the fibers has a significant influence on the tensile properties; and it affected the density, hardness and flexural properties significantly.

A comparative analysis of the flexural performance of FRC mixes with either glass or synthetic fibers is presented in this paper. The data used for such analysis were obtained from an experimental programme which comprised 42 notched prismatic specimens, produced and tested to EN 14651 at the age of 28 days. Different fibre dosages up to 15 kg/m3 were considered in two series of mixes with water/cement ratios of 0.26 and 0.39, which yielded average compressive strength values of 65 MPa and 50 MPa respectively. A direct correlation between fibre content and residual flexural strength was confirmed. However, statistically significant differences were observed between the two fibre types considered. FRC mixes with glass fibre contents up to 5 kg/m3 failed immediately after the first crack and showed no residual flexural strength. In general, specimens reinforced with synthetic fibres showed better levels of residual flexural strength and toughness than their glass fibre counterparts. The ratio between the residual flexural strength and the limit of proportionality provides a good illustration of such observations: it was 61% on average for FRC mixes with synthetic fibers at 10 kg/m3, whilst it was only 33% for FRC mixes with the same amount of glass fibers.

In this study, three novel thermoplastic impregnation processes were analyzed towards automotive applications. The first process is thermoplastic compression resin transfer molding in which a glass fiber mat is impregnated in through thickness by a thermoplastic polymer. The second process is a melt-thermoplastic Resin Transfer Molding (RTM) process in which the glass fibers are impregnated in plane with the help of a spacer. The third process, stamp forming of hybrid bicomponent fibers, coats the fibers individually during the glass fiber production. The coated fibers are used to produce a fabric, which is then further processed by stamp forming. These three processes were compared in a life cycle analysis (LCA) against conventional resin compression resin transfer molding with either glass or carbon fibers and metal processes with either steel or aluminum that can be new, partly or fully recycled using the case study of the production, life and disposal of a car bonnet.The presented LCA includes the main phases of the process: extraction and preparation of the raw materials, production and preparation of the mold, process, and energy losses. To include the life of the analyzed bonnet, the amount of diesel that is used to drive the weight of the bonnet for 300′000 km is calculated. In this LCA, the disposal of the bonnet is integrated by analyzing the used energy for the recycling and the incineration. The results show the potential of the developed thermoplastic impregnation processes producing automobile parts, as the used energy producing a thermoplastic bonnet is in the same range as the steel production.

Synopsis Glassfibre strands were immersed in polymer latex or silica fume dispersions before incorporating them in a cement matrix, in order to improve the ageing performance of the composite. These treatments always enhanced the performance, their effectiveness depending on the type of dispersion and fibre. In composites reinforced with alkali-resistant (AR) glass fibres, both dispersions were equally effective in eliminating almost any loss in strength during accelerated ageing, but the silica fume treatment was more effective in limiting the loss in toughness. The treatment of E glass fibres with polymer latex enhanced the ageing performance to levels better than those of untreated AR glassfibre reinforced composites, although the polymer did not completely eliminate chemical attack of the E glass. The influence of the two treatments is discussed in terms of their effectiveness in providing a barrier to chemical attack and their ability to preserve the flexibility of the reinforcing strands by slowing down or preventing enhanced fibre-matrix bond due to growth of hydration products around the filaments in the strand.

Utilization fiber reinforced composite materials has become quite common in various fields of applications like automobile, aerospace, industrial, structural and military. Such materials when reinforced in polymer matrix and turned into composite materials have a greater potential to act as a substitute for wood, metal and other traditionally used materials. Such demand has kindled the current day researchers to determine the tribological behavior of fiber reinforced polymeric materials (FRPs). Since the strength of the composite with natural and synthetic fibers was proven to be on par with the metallic materials, their usage has seen greater heights these days. Current chapter focuses in enunciating the tribological behavior of natural/synthetic fiber reinforced polyester composites. Specifically focus was given to individual sisal fiber, glass fiber and hybrid sisal/glass fibers reinforced polyester composites. Generally, sisal/glass composites were fabricated by compression moulding method with the fiber volume fraction varying in between 20 and 40%. Tribological tests were commonly performed by making the composite specimen to rub against a hard steel counter facing disc. From the general experimental results, composite materials reinforced with sisal fibers only showcased better tribological behavior which could be attributed to the thin tribo-layers formed between the composite and the counterfacing disc. Because of the presence of moisture content in the sisal fiber, the coefficient of friction values were observed to be minimum as the moisture presence instigated lubricating action. Besides the above fact, individual glass fiber reinforced composites portrayed minimal wear resistance due to the brittleness and high abrasive effect of glass fibers. In the current article, the influence of fiber content increase which led to increase in coefficient of friction along with the interrelationship between the wear parameters are discussed in detail.

Hybrid composites with synthetic and natural fibers are a good choice in the field of composites, as they combine the good mechanical performance of synthetic fibers with the advantages of natural fibers. In this work, polymeric hybrid composites associating glass fiber and natural fibers were developed. Three hybrid composites were developed: sisal/glass, coir/glass and Luffa/glass. The composites are five-layer laminate, three layers of E-glass interspersed with two layers of natural fibers that can be sisal, coir, or Luffa sponge (Luffa Cylindrica). In addition to hybrid composites, a five-layer fiberglass composite was also manufactured. The composites were manufactured by compression molding technique using orthophthalic polyester resin as matrix. Tensile and flexural tests were performed to characterize the composites. Considering the three hybrid composites, the best behavior was observed for the sisal/glass composite, being a potential replacement for fiberglass. The order of performance was the same in the tensile and flexural tests, sisal/glass, coir/glass, and luffa/glass, in this order. In the specimen’s fracture analysis, for both tests, it was observed that the fracture was quite located with no damage in regions far from the fracture. This behavior indicates good adhesion between the layers of natural and synthetic fibers, despite the discrepancy of their properties.

Hybridization of natural and synthetic fibers has the ability to improve composite performance. It means that the combination of natural fibers such as coir, jute, bamboo, and sisal with synthetic or glass fiber can broaden the role of the composite material, especially for structural application. This study developed a finite element simulation to investigate the damage to the bow structure of the fishing boat hull, which was produced using hybrid coir-glass fiber composite (HCGFRP) material subjected to front collision load. The experimental measurement was conducted to determine the mechanical properties of four hybrid composite laminates defined based on the differences in their layers number, fiber types, and orientation angle. Moreover, a numerical simulation model was applied to the traditional fishing boat colliding with fishery harbor quay, and the scenario was defined by varying the boat speed and the types of laminates adopted on the hull structure. The results showed the damage level for the bow structure of the HCGFRP boat due to the collision accidents, while the numerical findings are expected to be used as the basic knowledge in applying the hybrid coir-glass fiber laminates composite as an alternative hull construction material.

Many manufacturers have recently become interested in using fiber-reinforced polymer composites (FRPs) in structural applications. Synthetic fibres, such as carbon and glass fibres, have been commercialised internationally for decades, but they cause environmental issues because synthetic fibres are non-biodegradable and difficult to recycle once they have served their purpose, potentially polluting the environment. Thus, natural fibre composites like kenaf is a possible replacement for synthetic fibre due to their superior physical and mechanical properties. Kenaf appears to be the best candidate for replacing synthetic fibres in order to accomplish the goal of environmental preservation while also displaying excellent properties such as equivalent specific strength, low density, and renewable resources. The kenaf fiber was treated in KOH and added to ABS matrix to produce new composites at different loading (10, 15, 20 and 25 wt.%) by using Two Roll Mill machine. The influence of the fiber on the composites properties was evaluated. The produced material was subjected to SEM, MFI, TGA and DSC analysis. The incorporation of the treated kenaf fiber has an influence on the properties of kenaf/ABS composites. The addition of 10 wt.% kenaf was found to be the best loading with MFI value, initial degradation temperature and glass transition temperature at 0.8208 g/10 min, 322.63°C and 130°C respectively. The fiber was well dispersed in the matrix and shown good adhesion to the ABS. The addition of treated fiber contribute to a reduction in the MFI, improved the thermal stability of the composites and typical effects of Tg of the composite compare to pure ABS. The results suggest the need to continue the study in order to further analyse higher kenaf loading and shed more light on the properties of the composites to improve understanding of kenaf/ABS composites. Obtained results are a solution to alternative of synthetic fibers, which may contribute to the sustainable development of composites materials industry through the utilization of kenaf fiber with ABS matrix.

Background: The present review deals with the recent development of kenaf hybrid composites. Kenaf reinforced polymer composites are made up of either thermoplastic or thermoset matrix, depending on their applications. The combination of kenaf fibre with more than two fibres in hybrid composites enhances the potential uses of kenaf in many applications. The well-known limitations of natural fibres, such as lack of thermal stability, strength degradation, water absorption and poor impact properties, encourage the exploration of hybridisation with high performance fibres. Methods: We review the researches on kenaf reinforced composites and kenaf reinforced hybrid biocomposites. This review covers the types of matrix used, methods applied in manufacturing the hybrid composites and the potential application of the hybrid composites. Results: Kenaf fibres are widely used in fibre reinforced composites. There are limitations in the use of kenaf in polymeric composites, including high moisture absorption, non-uniformity and poor mechanical properties. Hybridisation of kenaf fibre with other fibres resulted in the hybrid composites with comparable strength, stiffness, strength to weight ratio, resistance and other physical and mechanical properties. The selection of matrix materials also plays an important role in fibre reinforced composites materials. There will be an increase in the use of natural fibre hybrid composites in areas such as household products and automotives. Conclusion: Kenaf fibres play an important role in multi-application composites. This fibre is used solely in polymer matrix or in combination either with other natural fibres or with synthetic fibres. Kenaf hybrid composites are being developed as a potential alternative to reduce the use of synthetic fibres such as aramid or glass fibres.

Exploring mechanical properties of eco-friendly hybrid epoxy composites reinforced with sisal, hemp, and glass fibers

This work aims to evaluate experimentally different fibers and resins in a topologically optimized composite component. The selected ones are made of carbon, glass, basalt, flax, hemp, and jute fibers. Tailored Fiber Placement (TFP) was used to manufacture the textile preforms, which were infused with two different epoxy resins: a partly biogenic and a fully petro-based one. The main objective is to evaluate and compare the absolute and specific mechanical performance of synthetic and natural fibers within a component framework as a base for improving assessments of sustainable endless-fiber reinforced composite material. Furthermore, manufacturing aspects regarding the different fibers are also considered in this work. In assessing the efficiency of the fiber-matrix systems, both the specific stiffness and the specific stiffness relative to carbon dioxide equivalents (CO2eq.) as measures for the global warming potential (GWP) are taken into account for comparison. The primary findings indicate that basalt and flax fibers outperform carbon fibers notably in terms of specific stiffness weighted by CO2eq.. Additionally, the selection of epoxy resin significantly influences the assessment of sustainable fiber-plastic composites.

Sustainability is becoming a priority for developers and the use of environmentally friendly materials is increasing. Nowadays, the application of raw materials from renewable sources to building materials has gained a significant interest in this research area. Lignocellulosic aggregates and cellulosic fibers are coming from many different sources such as wood, plants and waste. They are promising alternative materials to replace synthetic, glass and asbestos fibers as reinforcement in inorganic matrix of composites. Natural fibers are renewable resources so their cost is relatively low in comparison to synthetic fibers. With the consideration of environmental consciousness, natural fibers are biodegradable so their using can reduce CO<sub>2</sub> emissions in the building materials production. The use of cellulosic fibers in cementitious matrices have gained importance because they make the composites lighter at high fiber content, they have comparable cost - performance ratios to similar building materials and they could be processed from waste paper, thus expanding the opportunities for waste utilization in cementitious materials. The main objective of this work is to find out the possibility of using different wastes: hemp hurds as waste of hemp stem processing and recycled fibers obtained from waste paper for making cement composite products such as mortars based on cellulose fibers. This material was made of cement mortar containing organic filler based on hemp hurds and recycled waste paper. In addition, the effects of fibers and their contents on some selected physical and mechanical properties of the fiber-cement plaster composites have been investigated. In this research organic material have used to mortars as 2.0, 5.0 and 10.0 % replacement of cement weight. Reference sample is made for comparison of physical and mechanical properties of cement composites based on recycled cellulosic fibers and lignocellulosic aggregates. The prepared specimens were tested after 28 days of curing in order to investigate density, compressive strength and water absorbability. Scanning Electron Microscopy examination was also carried out.

Composite materials are widely used for their superior properties such as high strength to weight ratio, high tensile strength, low thermal expansion, low density etc. Due to environmental issues the eco-friendly composites are being explored. Natural fibers as reinforcement for polymer composites are widely studied. But natural fibers lack better mechanical properties when compared with synthetic fibers. Hence mixing the natural fiber with a synthetic fiber such as glass fiber will improve mechanical properties of the composites. In this study banana fiber is mixed with glass fiber, and the mixture is used as reinforcement in epoxy matrix. The composite specimens were prepared using hand layup technique, the fibers were randomly oriented. Further the fiber length was varied as 10, 15, 20 and 25mm and volume fraction as 10%, 15%, 20% and 25%. Experiments were conducted to find the effect of fiber length and volume fraction on tensile strength, flexural strength, water absorption properties of the composites. It is observed that a fiber length of 20mm and 20% fiber volume fraction gave better mechanical properties.

Glass fibres are well‐known reinforcing agents for different kinds of materials. For example, plastics, polyesters and epoxy resins can be reinforced using glass fibres originally developed for electrical applications; the resistance of bituminous materials is increased with the addition of chemically resistant glass fibres, and alkali resistant fibres are used in reinforced concrete. The price of conventional glass fibres is high because of the cost of the raw materials and of the high energy cost involved in the melting process. Therefore, a process which would allow the substitution of the natural raw materials with secondary products such as certain inorganic industrial wastes which have a lower melting temperature, would be of interest because it could increase the saving of energy and natural resources. Moreover, the disposal of industrial wastes in landfill would be reduced.© 2002 Society of Chemical Industry