Traditional fiber-reinforced composites

Favorable attention has been drawn to polymer composites in the field of dental restorative materials because of their tailored load bearing capability characteristics. An increasing number of applications varying from dental restoration posts to maxillofacial implants and dental fixtures are reported for what an experienced scientist would call traditional fiber-reinforced composites. This is just a measure of the advancement of the composite technology nowadays. 

Modem machining deals with an increasingly wide range of materials which includes, in addition to the traditional metals, high-chromium and nickel stainless steels, titanium, intermetallics, refractory metals, ceramics, glasses, fiber-reinforced composites, and many others. These materials have widely different properties. They react differently to machining and each presents a special machining problem. 

FIBERS. The field of fibers is an evolving one. with new technologies being developed constantly. With ihe increasing use of fibers in non-traditional textile applications, such as geoiexliles (qv). fiber-reinforced composites, specialty absorption media, and as materials of construction, new fiber types and new processing technologies can be anticipated. 

Epoxy resins have found application in carbon fiber reinforced composites for some 30 years or more and the benefits are well documented (Table 5). The traditional limitations are also summarized simply in the same table. 

Eulaliopsis binata fiber-reinforced polymer composites are more eco-friendly and cost effective compared to the traditional synthetic fiber-reinforced composites. The aim of the present work was to study the reinforcing potential of the Euiaiiopsis binata fibers in the short fiber form. The mechanical performance of these Euiaiiopsis binata fiber polymer composites was found to be higher than that of the pure polymer. However challenges still exist In further improving the mechanical properties of these composites to make them competitive to their synthetic counterparts. 

In situ polymerization to prepare immiscible blends was pioneered by Watkins and McCarthy [108], stimulating other researchers to apply this methodology to prepare novel polymer blends [109-112], fiber-reinforced composite materials[39], and electrically conducting composites [66, 67, 113-116]. Polymer blends produced in this manner include polystyrene/poly(vinyl chloride) [117, 118], polysty-rene/PET [119], nanometer-dispersed polypropylene/polystyrene interpenetrating networks [120], polypropylene/polystyrene [121] and polyethylene/polystyrene [122]. The resultant polymer blend may have a unique morphology compared to the traditionally prepared counterpart (if it is feasible to prepare such a blend via conventional procedures) and therefore demands a thorough investigation. 

Photopolymerizable epoxies using onium salt photoinitiators also show considerable promise for use in high performance composite applications. Traditional thermally cured epoxy resins are already well entrenched in these applications however, the use of the recently developed photocurable epoxy materials offers considerable potential for rapid fabrication of fiber-reinforced composites without the need for cumbersome ovens and long cure times. Photopolymerized epoxy laminates and filament wound pipe have already been demonstrated in our laboratory. 

This view of traditional composite micromechanics, underlies the widely accepted rule-of-mixtures approach to modeling fiber reinforced composite materials. It states that the modulus of the composite is a linear combination of the moduli of the materials from which it is composed, and weights each modulus with the volume fraction of that component. Its basis lies in continuity of parallel strain between the fibers and matrix provided a linearly elastic response of the composite occurs for small strains. 

In conclusion, the first expectation was that using the same manufacturing techniques from previous MFC research, MFCs can be made with reinforcement orientations such that it can withstand stresses in multiple directions and that these would approximate the reinforcement effects in a traditional composite with the same orientations. MFCs can definitely be made using these techniques with essentially any fibril orientation desired, as the manufacturing process lends itself to creating MFCs with multiple plies. And as the reinforcement effects of the fibrils in MFC samples approximates the behavior of a standard fiber reinforced composite, we can therefore assume that the body of experience in the optimization of laminates can be applied to MFCs as well. 

The use of nanocomposites to reinforce traditional composites has also been increasing and will continue to be a near-term trend. The emphasis for these applications, however, has been on additional mechanical reinforcement rather than flammability reduction.Since more traditional fiber-filled composites are exposed to fire risk scenarios, it makes sense to use a nanocomposite with the traditional composite to improve both mechanical and flammability performance. Of course, this does create an additional level of complexity, especially in handling the large increases in viscosity seen with nanocomposites used with thermoset composites. At this time, most nanocomposite-fiberglass/carbon fiber composites are used for military and aerospace applications, but the benefit of lightweight materials may also move these materials into automotive and mass transportation (e.g., bus, rail), where flammability performance is strongly needed. 

Compared to bulk materials, fiber-reinforced composites have already proven to exhibit superior properties in numerous applications. However, various desired combinations of properties, e.g., strong reinforcing effects at high optical transparency combined with electrical conductivity or reinforced micro-injection molded parts, cannot be achieved by traditional composites. The further improvement of the fracture toughness of resin matrices is another important task. Nanocomposites possess the potential to fill this existing gap. 

Zihlif and Ragosta produced short (1-3 mm) BF-reinforced polystyrene (PS) composite plates and found that the strength of the composite went through a maximum whereas both Young s modulus and the impact resistance increased monotonically with increasing BF content. Bashtannik et alP investigated the fiber-matrix interfacial adhesion in BF composites with high density polyethylene (HDPE) matrix. It was found that the properties of BF-reinforced polymer composites were much more sensitive to the BF surface treatment than traditional fiber-reinforced systems. 

Aromatic polyamide fiber, commonly known as aramid liber or Kevlar , is one of the latest wear-resistant additives to be used in thermoplastic composites. Unlike the traditional fiber reinforcements of glass and carbon, aramid is the softest and least abrasive fiber. This is a major advantage in wear applications, particularly if the mating surface is sensitive to abrasion. 

Fiber-reinforced composite materials are composed of dispersed fibrous materials (e.g. glass, Kevlar, PET, flax, hemp, sisal, etc.) set within a continuous polymer matrix. The primary benefit of fiber-reinforced composites over traditional engineering materials comes from their impressive strength-to-weight ratio and the ability to design the micro-structure so as to optimize their macro-stmctural properties. These advantageous properties were first exploited by the space and aerospace industries. 

Liquid crystalline polymers (LCP) have excellent mechanical properties in addition to dimensional and chemical stability. These materials form in-situ composites during processing under elongational flow and are starting to replace traditional fiber reinforced systems [1, 2]. Combined with their ease of processing, LCPs are ideal for applications in aerospace, automobile, marine and other markets requiring high performance composites [2, 3]. 

The production of carbon fibers or filaments by decomposing a hydrocarbon gas over a transition metal catalyst has been the subject of extensive research. The product consists of filaments with diameters in the range of 1-100 pm and lengths up to 100 mm. In microstructure, it is different from traditional carbon fibers, resulting in a sword and sheath fracture mode without catastrophic failure. Since, in addition, these fibers are produced in a single step with no really expensive processing, they are attractive candidates for reinforcing composites. 

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