Natural fibers based composites - Technical and social issues

Brazil is the only country in South America to have an automotive supplier sector based on natural fibers. New opportunities are arising due to an increase demand by the car makers in applying natural fibers in their parts. Several crop fibers have been developed in Brazil. Among them can be listed caroa, piacava, pupunha, mutum and others of regional application. For the automotive industry, which requires large quantities with uniform quality, the alternatives are sisal (170,000 ton/yr), curaua (150 ton/yr in 2003), malva, 200 ton/yr; Brazil is the single largest producer country of sisal, and commercially, the only one in curaua. For South America, the alternatives are fique in Colombia, abaca in equator, flax in Argentina and curaua in Venezuela. It must be understood by the target countries of drugs, is that crop fiber can be an economic alternative to coca in the Andes region, therefore an instrument of land reform and drug reduction plantations. Several companies have a strong program of apply natural fibers based components in their products: Volkswagen do Brazil, DaimlerChrysler, General Motors do Brazil. Among their suppliers can be listed companies such Pematec (curaua), Toro (sisal, coir and jute), Incomer (sisal and jute), Ober (jute, curaua), Indaru (jute and sisal), Antolin (imported kenaf,) Tapetes Sao Carlos (sisal), Poematec (coir) and Art-Gore, with Woodstock'' wood and natural fibers). Figures about production and demand are discussed in the paper.

LDPE/EVA Composites for Antimicrobial Properties

Composites with antimicrobial activity are of great interest nowadays and the development of titanium dioxide with these functional properties presents interest in academic and industrial sectors.An approach to develop PE composite containing silver microparticles to have an antimicrobial effect is presented. To obtain such antimicrobial composites, LDPE/EVA were processed with Ag particles on TiO2 particles as inorganic carrier substance. Titanium dioxide nanoparticles (P-25) were covered with silver particles using Turkevich Method or citrate reduction method. The Ag/TiO2 particles were dispersed at concentration of 0,8 wt% and 1% wt% in LDPE/ethylene vinyl acetate copolymer (EVA)-(50% w/w) at the melt state in a Haake torque Rheometer. Silver microparticles were characterized with UV-Vis Spectroscopy. The composites thus prepared were characterized through XRD, Ares Rheometer, Scanning Electronic Microscopy (SEM) and JIS Z 2801 antimicrobial tests to study the effects of the addition of particles on rheological properties, morphological behavior and antimicrobial properties. The results showed that incorporation of silver/titanium dioxide particles on composites obtained systems with differents dispersions. The Ag/TiO2 particles showed uniform distribution of Ag on TiO2 particles as observed by SEM-EDX and antimicrobial tests according to JIS Z 2801 shows excellent antimicrobial properties.

Production of reinforced composites with natural fibers for industrial applications - Extrusion and injection WPC

The aim of this work is to study the replacement of currently used thermoplastics by composites reinforced with vegetable fibers with several advantages, mainly better mechanical properties, low weight and competitive cost compared to its counterparts. Extrusion and injection molding processes were studied using polypropylene (PP) matrix. The raw materials used were sugar cane bagasse, elephant grass, wood, milk cartons and recycled polypropylene. The composites were tested for bending, tension, hardness and impact resistance, following ASTM standards. The results obtained were extremely positive since they proved that natural fibers as reinforcement can be an important alternative to replace talc and other fillers.

Efeitos do envelhecimento ambiental acelerado em compósitos poliméricos

The advantages of the use of vegetable fibers on the synthetic fibers, such as glass fibers, in the reinforcements in composites are: low cost, low density, good tenacity, good thermal properties and reduced use of instruments for their treatment or processing. However, problems related to poor performance of some mechanical natural fibers, have hindered its direct use in structural elements. In this sense, the emergence of alternative materials such as hybrids composites, involving natural and synthetic fibers, has been encouraged by seeking to improve the performance of structural composites based only on natural fibers. The differences between the physical, chemical and mechanical properties of these fibers, especially facing the adverse environmental conditions such as the presence of moisture and ultraviolet radiation, is also becoming a concern in the final response of these composites. This piece of research presents a comparative study of the strength and stiffness between two composite, both of ortoftalic polyester matrix, one reinforced with fibers of glass-E (CV) and other hybrid reinforced with natural fibers of curauá and fiberglass-E (CH). All the comparative study is based on the influence of exposure to UV rays and steam heated water in composites, simulating the aging environment. The conditions for the tests are accelerated through the use of the aging chamber. The composites will be evaluated through tests of uniaxial static mechanical traction and bending on three points. The composite of glass fiber and hybrid manufacturing industry are using the rolling manual (hand lay-up) and have been developed in the form of composites. All were designed to meet possible structural applications such as tanks and pipes. The reinforcements used in composites were in the forms of short fiber glass-E quilts (450g/m2 - 5cm) of continuous wires and fuses (whose title was of 0.9 dtex) for the curauá fibers. The results clearly show the influence of aging on the environmental mechanical performance of the composite CV and CH. The issues concerning the final characteristics of the fracture for all types of cargoes studied were also analyzed

Descontinuidade na seção transversal em laminados compósitos poliméricos: efeitos e propriedades

The growing demand in the use of composite materials necessitates a better understanding its behavior to many conditions of loading and service, as well as under several ways of connections involved in mechanisms of structural projects. It is know that most of the structural elements are designed with presence of geometric discontinuities (holes, notches, etc) in their longitudinal sections and / or transversals, and that these discontinuities affect the mechanical response of these elements. This work has aims to analyze a study of the mechanical response, when in the presence geometric discontinuity, of polymer matrix composite laminates (orthophthalic polyester) to the uniaxial tensile test. The geometric discontinuity is characterized by the presence of a center hole in the transversal section of the composite. In this study, different kinds of stacking sequences are tested, with and without the presence of the hole, so as to provide better understanding of the mechanical properties. This sense, two laminates were studied: the first is only reinforced by with seven layers short mats of fiberglass-E (CM) and the second where the reinforcement of fiberglass-E comes in the form of bidirectional fabric (CT), with only four layers. The laminate CT has the presence of anisotropy (sense of continuous fibers with respect to the applied load) as the main parameter influencing its mechanical behavior, behavior this, not observed for the CM. In addition to the mechanical properties was also studied the fracture characteristics developed in each composite laminated. The results also showed that the presence of the hole in the transversal section decreased the ultimate strength of laminates and changed the final characteristic of fracture in all kinds of composite laminated studied

Desenvolvimento de um laminado compósito híbrido a base de fibras de vidro/licurí

This research work is based, in search of reinforcement s vegetable alternative to polymer composites. The idealization of making a hybrid composite reinforced with vegetable fibers licuri with synthetic fibers is a pioneer in this area. Thus was conceived a hybrid composite laminate consisting of 05 (five) layers being 03 (three) webs of synthetic fibers of glass and E-02 (two) unidirectional fabrics of vegetable fibers licuri. In the configuration of the laminate layers have alternating distribution. The composite laminate was manufactured in Tecniplas Commerce & Industry LTD, in the form of a card through the manufacturing process of hand lay up. Licuri fibers used in making the foil were the City of Mare Island in the state of Bahia. After cooking and the idealization of the hybrid composite laminate, the objective of this research work has focused on evaluating the performance of the mechanical properties (ultimate strength, stiffness and elongation at break) through uniaxial tensile tests and three point bending. Comparative studies of the mechanical properties and as well as among other types of laminated hybrid composites studied previously, were performed. Promising results were found with respect to the mechanical properties of strength and stiffness to the hybridization process idealized here. To complement the entire study were analyzed in terms of macroscopic and microscopic characteristics of the fracture for all tests.

Avaliação do comportamento tribológico de compósitos poliéster/fibra de vidro utilizando resíduos de poliéster/fibra de vidro e carbonato de cálcio como carga

The use of composite materials and alternative is being increased every day, as it becomes more widespread awareness that the use of renewable and not harmful to the environment is part of a new environmentally friendly model. Since its waste (primarily fiberglass) can not be easily recycled by the difficulty that still exists in this process, since they have two phases mixed, a polymeric matrix thermoset difficult to recycle because it is infusible and phase of fiber reinforcements. Thermoset matrix composites like Polyester + fiberglass pose a threat due to excessive discharge. Aiming to minimize this problem, aimed to reuse the composite Polyester + fiber glass, through the wastes obtained by the grinding of knifes and balls. These residues were incorporated into the new composite Polyester/Fiberglass for hot compression mold and compared tribological to composites with filler CaCO3, generally used as filler, targeting a partial replacement of CaCO3 by such waste. The composites were characterized by thermal analysis (TGA, DSC and DMA), by the surface integrity (roughness determination, contact angle and surface energy), mechanical properties (hardness) and tribological tests (wear and coefficient of dynamic friction) in order to evaluate the effect of loads and characterize these materials for applications that can take, in the tribological point of view since waste Polyester + fiberglass has great potential for replacement of CaCO3

Tubulações de PRFV com adição de areia quartzosa visando sua aplicação na indústria do petróleo

Fillers are often added in composites to enhance performance and/or to reduce cost. Fiberglass pipes must meet performance requirements and industrial sand is frequently added for the pipe to be cost competitive. The sand is added to increase pipe wall thickness, thus increase pipe stiffness. The main goal of the present work is to conduct an experimental investigation between pipes fabricated with and without de addition of sand, to be used in the petroleum industry. Pipes were built using E-glass fibers, polyester resin and siliceous sand. The fabrication process used hand lay up and filament winding and was divided in two different parts: the liner and the structural wall. All tested pipes had the same liner, but different structural wall composition, which is the layer where siliceous sand may be added or not. The comparative investigation was developed considering the results of longitudinal tensile tests, hoop tensile tests, hydrostatic pressure leak tests and parallel-plate loading stiffness tests. SEM was used to analyze if the sand caused any damage to the glass fibers, during the fabrication process, because of the fiber-sand contact. The procedure was also used to verify the composite conditions after the hydrostatic pressure leak test. The results proved that the addition of siliceous sand reduced the leak pressure in about 17 %. In the other hand, this loss in pressure was compensated by a stiffness increment of more than 380 %. MEV analyses show that it is possible to find damage on the fiber-sand contact, but on a very small amount. On most cases, the contact occurs without damage evidences. In summary, the addition of sand filler represented a 27.8 % of cost reduction, when compared to a pipe designed with glass fiber and resin only. This cost reduction combined to the good mechanical tests results make siliceous sand filler suitable for fiberglass pressure pipes

Panels Produced from Thermoplastic Composites Reinforced with Peach Palm Fibers for Use in the Civil Construction and Furniture Industry

In order to cooperate in minimizing the problems of the current and growing volume of waste, this work aim at the production of panels made from industrial waste -thermoplastic (polypropylene; polyethylene and acrylonitrile butadiene styrene) reinforced with agro-industrial waste - peach palm waste (shells and sheaths). The properties of the panels like density, thickness swelling, water absorption and moisture content were evaluated using the ASTM D1037; EN 317; and ANSI A208.1 standards regarding particle boards. Good results were obtained with formulations of 100% plastic waste; 70% waste plastics and 30% peach palm waste; and 60% waste plastics and 40% peach palm waste.

State-of-the-art for extrusion and injection moulding FPC: natural Fibre Plastics Composites in Brazil

Environmental and economical concerns are stimulating research of new materials for construction, furniture, packaging and automotive industries. Particularly attractive are the new materials. This paper presents results about the properties of composites of polyhydroxybutyrate (PHB), polypropylene (PP) and High Density Polyethylene (HDPE) reinforced with natural fibres. The composites were prepared through the extrusion with natural fibres, in an ratio of 30% by weight. The quality of samples was tested utilising injection moulded samples, according to ASTM standards. Results showed that natural fibres can act as an excellent reinforcing material, resulting in low cost composites and improving economical and ecological interests.

Preparation and characterization of PVDF/CaCO3 composites

The contribution of new materials, involving composites and blends, has been reaching the most varied fields of science, as much of the scientific as technological point of view. This is due to the man's needs in applications, especially in medicine areas. Thus, this work shows the preparation and characterization of poly(vinylidene fluoride) (PVDF) and calcium carbonate (CaCO3) Composite films in order to analyse the incorporation of CaCO3 in PVDF for future application in bony restoration and bony filling. The films were prepared by casting method, where the PVDF pellet shape was dissolved in dimethylacetamide (DMA) and in a separate container CaCO3/DMA emulsion was also made. Soon afterwards they were mixed in several proportions 100/00, 95/05, 85/15, 70/30 in weight and left to dry in greenhouse. Homogeneous and flexible films were obtained and structurally characterized by attenuated total reflection infrared spectroscopy (FT-IR/ATR), thermal analyses (DSC, TGA), X-ray diffractometry, optical and scanning electron microscopies. The results showed that the material was a composite with good thermal stability until around 400 degrees C, the crystallinity of PVDF was non-polar alpha-phase and the obtained films were porous, being these filled with CaCO3. (c) 2006 Elsevier B.V. All rights reserved.

Processing and hygrothermal effects on viscoelastic behavior of glass fiber/epoxy composites

Fiber reinforced epoxy composites are used in a wide variety of applications in the aerospace field. These materials have high specific moduli, high specific strength and their properties can be tailored to application requirements. In order to screening optimum materials behavior, the effects of external environments on the mechanical properties during usage must be clearly understood. The environmental action, such as high moisture concentration, high temperatures, corrosive fluids or ultraviolet radiation (UV), can affect the performance of advanced composites during service. These factors can limit the applications of composites by deteriorating the mechanical properties over a period of time. Properties determination is attributed to the chemical and/or physical damages caused in the polymer matrix, loss of adhesion of fiber/resin interface, and/or reduction of fiber strength and stiffness. The dynamic elastic properties are important characteristics of glass fiber reinforced composites (GRFC). They control the damping behavior of composite structures and are also an ideal tool for monitoring the development of GFRC's mechanical properties during their processing or service. One of the most used tests is the vibration damping. In this work, the measurement consisted of recording the vibration decay of a rectangular plate excited by a controlled mechanism to identify the elastic and damping properties of the material under test. The frequency amplitude were measured by accelerometers and calculated by using a digital method. The present studies have been performed to explore relations between the dynamic mechanical properties, damping test and the influence of high moisture concentration of glass fiber reinforced composites (plain weave). The results show that the E' decreased with the increase in the exposed time for glass fiber/epoxy composites specimens exposed at 80 degrees C and 90% RH. The E' values found were: 26.7, 26.7, 25.4, 24.7 and 24.7 GPa for 0, 15, 30, 45 and 60 days of exposure, respectively. (c) 2005 Springer Science + Business Media, Inc.

Hygrothermal effects on the shear properties of carbon fiber/epoxy composites

The environmental factors, such as humidity and temperature, can limit the applications of composites by deteriorating the mechanical properties over a period of time. Environmental factors play an important role during the manufacture step and during composite's life cycle. The degradation of composites due to environmental effects is mainly caused by chemical and/or physical damages in the polymer matrix, loss of adhesion at the fiber/matrix interface, and/or reduction of fiber strength and stiffness. Composite's degradation can be measure by shear tests because shear failure is a matrix dominated property. In this work, the influence of moisture in shear properties of carbon fiber/epoxy composites ( laminates [0/0](s) and [0/90](s)) have been investigated. The interlaminar shear strength (ILSS) was measured by using the short beam shear test, and Iosipescu shear strength and modulus (G(12)) have been determinated by using the Iosipescu test. Results for laminates [0/0](s) and [0/90](s), after hygrothermal conditioning, exhibited a reduction of 21% and 18% on the interlaminar shear strenght, respectively, when compared to the unconditioned samples. Shear modulus follows the same trend. A reduction of 14.1 and 17.6% was found for [0/0](s) and [0/90](s), respectively, when compared to the unconditioned samples. Microstructural observations of the fracture surfaces by optical and scanning electron microscopies showed typical damage mechanisms for laminates [0/0](s) and [0/90](s).

Hygrothermal effects on damping behavior of metal/glass fiber/epoxy hybrid composites

Continuous fiber/metal laminates (FML) offer significant improvements over current available materials for aircraft structures due to their excellent fatigue endurance and low density. Glass fibers/epoxy laminae and aluminum foil (Glare) are commonly used to obtain these hybrid composites. The environmental factors can limit the applications of composites by deteriorating the mechanical properties during service. Usually, epoxy resins absorb moisture when exposed to humid environments and metals are prone to surface corrosion. Therefore, the combination of the two materials in Glare (polymeric composite and metal). can lead to differences that often turn out to be beneficial in terms of mechanical properties and resistance to environmental influences. In this work. The viscoelastic properties. such as storage modulus (E') and loss modulus (E'), were obtained for glass fiber/epoxy composite, aluminum 2024-T3 alloy and for a glass fiber/epoxy/aluminum laminate (Glare). It was found that the glass fiber/epoxy (G/E) composites decrease the E' modulus during hygrothermal conditioning up to saturation point (6 weeks). However, for Glare laminates the E' modulus remains unchanged (49GPa) during the cycle of hygrothermal conditioning. The outer aluminum sheets in the Glare laminate shield the G/E composite laminae from moisture absorption. which in turn prevent, in a certain extent, the material from hygrothermal degradation effects. (c) 2005 Elsevier B.V. All rights reserved.