Reinforced-plastic moisture content

ISO 2558 1974 Textile glass chopped-strand mats for reinforcement of plastics -Determination of time of dissolution of the binder in styrene ISO 3344 1997 Reinforcement products - Determination of moisture content... 

U.S. Pat. No. 5,288,772 [75] discloses a cellulose-fiber-reinforced thermoplastic composition for compression molding, where thermoplastic material is polypropylene, or a mixture of polypropylene, polystyrene, and polyethylene (40-90% of plastic by weight), and the cellulosic material (10-60% by weight) was milled scrap newspaper with an initial moisture content of at least 30% by weight. The patentees suggest that lignin present in the cellulosic scrap provides a coherent mass of thermoplastic and cellulosic material. 

Thick laminates are obviously much less affected than thin ones in a given period and this explains the durability of many early reinforced plastics structures. It has been calculated that an epoxy-based reinforced plastics material with a typical diffusivity towards moisture of lO m s would require 13 months to reach saturation if left in a tropical climate at 35°C and 95% relative humidity (RH) if the thickness was 2 mm, but a 90 mm thick section would need 1342 years. During the approach to saturation, there is a through-the-thickness variation in moisture content and therefore in properties. 

Unfilled and unreinforced plastics have high calorific values, low moisture contents and therefore gasify, ignite quickly and incinerate at low temperatures [22]. The calorific value of reinforced plastics depends on their chemical composition and the portion of mineral filling and reinforcing materials. Table 8 provides an overview of the calorific values of different materials. 

All natural fibers are hydrophihc and their moisture content ranges from 3 to 13%. This leads to a very poor interface between natural fiber and the hydrophobic matrix and very poor moisture resistance. Several fiber surface treatments are used to improve the interface viz-thermal treatment, chemical treatment, and use of coupling agents (Bledzki and Gassan, 1999). Fillers are added to composites for technical and chemical reasons (Milewski and Katz, 1980). Calcium carbonate has maximum usage as filler in plastics and FRP due to its low cost, non-toxicity and lack of odor. Present work gives effectiveness of jute fabric treatment and addition of filler on properties of jute reinforced polyester composites (JFRP). 

Summerscales J (1987) Shear modulus testing of composites. In Proceedings 4th international conference on composite structures, vol 2, Paisley, 27-29 July 1987. Elsevier, pp 305-316 Summerscales J (ed) (1987/1990) Non-destructive testing of fibre reinforced plastics composites, 2 vols. Kluwer Academic, Dordrecht, ISBN 1-85166-093-3 ISBN 1-85166-468-8 Summerscales J (1990) NDT of advanced composites—an overview of the possibilities. Br J Non-Destr Test 32(ll) 568-577 Summerscales J (1994) Non-destructive measurement of the moisture content in fibre-reinforced plastics. Br J Non-Destr Test 36(2) 64-72 Summerscales J (1994) Manufecturing defects in fibre-reinforced plastics composites. Insight 36( 12) 936-942... 

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