Short Aramid Fibers Research Articles

Effect of Fiber Surface Treatment on the Interface and Bending Strength of Aramid Short Fiber Composite

Composite materials used in the present study are fabricated by Aramid short fibers and Unsaturated Polyester resin. The bending strength and energy absorption properties of the composite are studied in this paper. From the single-fiber pull-out test it is found that I mm fiber is not long enough to reinforce the polyester, thus the strength of the composite made of 1 mm fiber does not increase when compared to that of the resin. But the streagth of the composite made of 3 mm fiber starts to increase when compared to that of the resin. The strength and absorbed energy always increases with the length and content of the fiber. Some fiber surface treatments are done in order to increase the bonding between the fiber and the matrix, It is found that these treatments affect the interfacial shear strength and fiber strength simultaneously. As strength is an important property of a new material, the effect of these treatments on the strength is discussed in this paper. The bending strength of the composite is assumed to depend not only on the interfacial shear strength but also on the fiber strength, depending upon the length of the short fibers.

Bending Properties of Aramid Short Fiber Composite and Modeling of Strength.

The bending properties of composites made of aramid short fiber and unsaturated polyester resin are investigated. The strength of the composite increases with the length and content of the fiber. The fibers are considered to be oriented randomly in the composite. In order to analyse the strength of the composite, we consider a simple model of the composite, that is, the classical single-fiber pull-out test. We modify the conventional equation by considering the results of the pull-out test in the calculation of the strength of the short-fiber composite. The experimental results show good agreement with the results provided by the theoretical model.

1719 アラミド短繊維 FRP のレーザ加工性に関する基礎的研究

1719 アラミド短繊維 FRP のレーザ加工性に関する基礎的研究

Comparison of carbon fibre/epoxy composites reinforced by short aramid and carbon fibres

This study is designed to examine and compare the toughening effects of short aramid and carbon fibers in carbon fiber/epoxy composites. The primary objective being to identify the toughening mechanisms associated with the two different short fibers. The detailed information on toughening mechanisms will provide a general guide on the relationship between composite interlaminar design and composite performance. Composite design and processing, delamination testing and SEM study of fracture surfaces are used in conjunction in the current study for a better understanding of the short fiber interlaminar reinforcement technique.

アラミド短繊維充てん多官能性エポキシ樹脂の動力学的性質に及ぼす熱処理と吸水処理の影響

The composite materials were made from three multi-functional epoxy resins (EP) cured with five hardeners and filled with aramid (Technora®) short fibers (AFP) by 2.44 wt%. Effects of aging (heat-treated) at 130°C for 5, 000 h and wetting at 21°C for 5, 000 h in distilled water on the dynamic mechanical properties were studied. The morphology of the fiber dispersion in AFP-filled specimens did not change during the aging. Weight of the aged specimens decreased for a prolonged aging time. The maximum decrease during the aging for 5, 000h was 3.5wt%. The glass transition temperature (Tg) of all the specimens shifted to higher temperature by the aging. The dynamic storage moduli (E') of most of aged specimens decreased at lower temperature (-140°C) and room temperature (25°C) compared with those of unaged specimens. At higher temperature (200°C), the moduli of specimens almost increased and in particularly those of the specimens cured with diamines increased significantly. Absorbed water of wet specimens reached a maximum value of 5.0wt%, and values of the specimens cured with diamines were larger than those of the specimens cured with acid anhydrides. The Tgof all the specimens shifted to lower temperature by the absorption of water. E' of many wet specimens increased in the range of lower temperature to room temperature, but E' of all the specimens at higher temperature extremely fell down.

Short aramid-fiber reinforced ultra-high molecular weight polyethylene

Ultra-High Molecular Weight Polyethylene (UHMWPE) is frequently used in artificial joints because of its high wear resistance. To extend the lifetime of these joints even further, it is necessary to decrease the wear rate. The wear rate may be decreased by blending UHMWPE with short aramid fibers. On account of the extremely high viscosity of UHMWPE mixing was accomplished by swirling the UHMWPE powder and the chopped fibers with compressed dry nitrogen, and a composite with fairly uniformly distributed and randomly oriented fibers was obtained by compression moulding. The failure behaviour of the composite changes from ductile for low fiber content to brittle failure for higher fiber content. The deviation of the experimental Young's modulus from the theoretical value can be explained by, among others, the void content. Preliminary results show that the wear rate of UHMWPE indeed decreases with incorporation of the aramid fibers.

Dynamic mechanical properties of multi-functional epoxy resin filled with aramid short fibers

Three heat resistant multi-functional epoxy resin were filled with Aramid (Technora®) short fibers (AFP) by 2.4 wt% using four kinds of hardeners. AFPs observed by SEM on the fracture surface were dispersed randomly. Dynamic mechanical properties and flexural strength of those composites were measured. Although the glass transition temperatures Tg of the multi-functional epoxy resin matrix varied when combined with different hardeners, they were all high (over 200° C) and the highest temperature reached 260° C. The storage modulus E' of the material increased when AFP was added and remained at over 2 GPa even at 150° C. The value of E' in the glassy region was higher than the estimated value by the rule of mixtures which shows that the effect of AFP filling was remarkable. The relative modulus at Tg and the ratio of the peak height of tan δ implied that the affinity of epoxy resin with AFPs was large. The flexural strength of the matrix (epoxy resin) for less tough materials was larger than that for tough...

Cytotoxic effects of aramid fibres on rat pulmonary macrophages: Comparison with chrysotile asbestos

Aramid fibres have been proposed as a substitute for many asbestos uses. Although dimensional characteristics of aramid fibres vary with the type of application, some of the commercial grades proposed contain fibres whose geometry is clearly in a range where biological reactivities have been reported for other natural or man-made fibres. We wish to report that short aramid fibres, when tested on cultures of rat pulmonary alveolar macrophages (PAMs), induce the commonly recognized signs of a cytotoxic effect, that is: leakage of cytoplasmic and lysosomal marker enzymes, concomittant with a decreased ATP cell content.