Fiber-reinforced polymer methods

A.2.4 Discontinuous-Fiber-Reinforced Polymer-Matrix Composites Sheet Molding Compound. Of the parameters influencing the mechanical properties in short-fiber-reinforced polymer-matrix composites, fiber composition, matrix composition, fiber geometry, and manufacturing method will be elaborated upon here. 

ASTM D 5528-94a. Standard test method for mode I interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites. Annual Book of ASTM Standards, American Society for Testing and Materials, Philadelphia. 

Fibers have been widely used in polymeric composites to improve mechanical properties. Cellulose is the major substance obtained from vegetable fibers, and applications for cellulose fiber-reinforced polymers have again come to the forefront with the focus on renewable raw materials. Hydrophilic cellulose fibers are very compatible with most natural polymers. The reinforcement of starch with ceUulose fibers is a perfect example of a polymer from renewable recourses (PFRR). The reinforcement of polymers using rigid fillers is another common method in the production and processing of polymeric composites. The interest in new nanoscale fillers has rapidly grown in the last two decades, since it was discovered that a nanostructure could be built from a polymer and layered nanoclay. This new nanocomposite showed dramatic improvement in mechanical properties with low filler content. Various starch-based nano-composites have been developed. 

Standard test method for Mode I interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites... 

Devalapura, R. K., M. E. Greenwood, J. V. Gauchel and T. J. Humphrey (1998). Evaluation of GERP performance using accelerated test methods. First International Conference on Durability of Fiber Reinforced Polymer Composites for Construction, Sherbrooke, Quebec, Canada, pp. 107-116. 

One of the most important focus areas of research in the development of natural fiber-reinforced polymer composites is characterisation of the fiber-matrix interface, since the interface alone can have a significant impact on the mechanical performance of the resulting composite materials, in terms of the strength and toughness. The properties of all heterogeneous materials are determined by component properties, composition, structure and interfacial interactions [62]. There have been a variety of methods used to characterize interfacial properties in natural fiber-reinforced polymer composites, however, the exact mechanism of the interaction between the natural fiber and the polymeric matrix has not been clearly studied on a fundamental level and is presently the major drawback for widespread utilization of such materials. The extent of interfacial adhesion in natural fiber-reinforced polymer composites utilizing PLA as the polymer matrix has been the subject of several recent investigations, hence the focus in this section will be on PLA-based natural fiber composites. 

Some investigations [105-107] on micron-.size particle-filled composites demonstrated that fracture toughness is dramatically influenced by the particle shape, size, volimie fraction, and particle/matrix interfacial strength. Brunner et al. [108] reviewed the development of fracture mechanics test methods in determination of fracture toughness and delamination resistance of fiber-reinforced polymer composites. 

ACI 440.3R-12 Guide Test Methods for Fiber-Reinforced Polymer (FRP) Composites for Reinforcing or Strengthening Concrete and Masonry Structures... 

All bast (stem) fibers (flax, kenaf, ramie, nettle, hemp, jute) as well as hard fibers (caroa, sisal) are suitable as for reinforcing fibers for natural fiber reinforced polymer composites, if they have a high tensile modulus and sufficient tensile strength. In addition to cultivation site, type and harvest, the properties of natural fibers depend significantly on the fiber extraction method. An extraction to technical fiber grades, i.e. production of bundles with different number of single fibers, is generally sufficient for use in plastics composites. The properties of such extracted fibers may be described as follows ... 

Pultrusion Forming method in which a bundle of fibers of glass or other suitable support material in a mobile plastic matrix is drawn through a die to form an fiber-reinforced polymer composite structure the shape of which is determined hy the die profile. 

Fiber-reinforced polymer structures are typically laid up by hand, consolidated (compressed together) with the polymer resin matrix material, and cured with heat and pressure. This method is capable of producing uniquely shaped, strong, and lightweight structural pieces. Fiber-reinforced polymers can also be used in mass-production methods thermoplastic materials can be employed to produce many relatively simple shapes that do not call for high strength. Variations on these methods, such as extrusion and pultrnsion, represent combinations of these methodologies. 

Pultrusion. Another method by which thermoplastic fiber-reinforced polymers are produced is pultrusion. In pultrusion, an appropriately designed bundle of continuous fiber strands is drawn through a die along with a molten thermoplastic matrix material. The die serves to consolidate the material combination, and as the matrix material solidifies on exiting the die, a continuous fiber-reinforced structure is produced. Examples of pultruded products include fiberglass rods and reinforced water hoses. 

ASTM D 7291/D 7291M-07 (2007), Standard test method for through-thickness flatwise tensile strength and elastic modulus of a fiber-reinforced polymer matrix composite material, ASTM, West Conshohocken, PA. 

ACI 440.3R Guide test methods for fiber-reinforced polymers for reinforcing or strengthening concrete structures. 

The PIP method includes the slurry infiltration of fiber preforms by means of resin transfer molding (RTM) with suitable precursors such as polycarbosUane (PCS) or pol-yvinylsilane (PVS) followed by subsequent crosslinking to thermosets (resulting in fiber-reinforced polymers). The polymer composite is then pyrolyzed at temperatures below 1400°C in inert atmospheres to yield a CMC (Fig. 12.9(c)). 

Muscolino G, Palmeri A (2007) An earthquake response spectrum method for linear light secondary substructures. ISET J Earthq Technol 44 193-211 Nakashima M, Saburi K, Tsuji B (1996) Energy input and dissipation behaviour of structures with hysteretic dampers. Earthq Eng Struct Dyn 25 483-496 Ozcan O, Binici B, Ozcebe G (2008) Improving seismic performance of deficient reinforced concrete columns using carbon fiber-reinforced polymers. Eng Struct 30 1632-1646... 

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