Hand lay-up technique

An interest has been developed in the use of vanadium naphthenates as accelerators. In 1956 the author found that if MEKP was added to a polyester resin containing vanadium naphthenate the resin set almost immediately, that is, while the peroxide was still being stirred in. Whereas this effect was quite reproducible with the sample of naphthenate used, subsequent workers have not always obtained the same result. It would thus appear that the curing characteristics are very dependent on the particular grade of resin and of vanadium naphthenate used. It was also observed by the author that the gelation rate did not always increase with increased temperature or accelerator concentration and in some instances there was a retardation. Subsequent workers have found that whilst the behaviour of the naphthenate varies according to such factors as the resin and catalyst used, certain vanadium systems are of value where a high productivity in hand lay-up techniques is desired. 

The major process today is the hand lay-up technique in which resin is stippled and rolled into the glass mat (or cloth) by hand. Moulds are easy to fabricate and large structures my be made at little cost. 

For mass production purposes matched metal moulding techniques are employed. Here the preform or mat is placed in a heated mould and the resin poured on. The press is closed and light pressure ( 501bf/in ) applied. Curing schedules are usually about three minutes at 120°C. It is possible to produce laminates using less resin with pressure moulding than with hand lay-up techniques and this results in better mechanical properties. 

What is the advantage of using BMC and SMC over hand lay-up techniques such as those used to make boat hulls ... 

Corrosion-Resistant Binder for Fiberglass Composites. A second application of furan resins is as a premium, corrosion-resistant binder for fiberglass for fabrication of FRP structures for the chemical process industry. Structures can be easily fabricated using "hand lay-up" techniques used to fabricate polyester composites (see Figure 4). In this fashion, pipes, ducts, tanks, scrubbers, etc., are produced for use with process media which quickly... 

The composites made with hand lay-up technique. Short fibres with weight fraction 30% and 50% for eacth length mixed with the rain and then put in a vacuum jar and degassed until "boiled" and all bubbles in the resin are remove. After that poured the mixture to the mold, spacer were used in order to produce 2 mm thick of composite. The mold was press with 20 N/cm. Cured was carried out at room temperature for 16 hours and then post curing was done in an air oven at 80 0 for 5 hours. 

Boat hulls were among the earliest applications of modern reinforced plastics. The United States Navy introduced their first 8.5 m (28 foot) fibreglass personnel boat in 1947, and was contracted to pass 3000 vessels by 1966. The orders for the first two vessels specified construction by the pressure bag method and by the vacuum injection system in order to achieve higher quality than was obtained by the then current hand-lay-up technique [1]. One of the earliest large GRP structures for submerged... 

Various methods of fabrication can be used. With large diameter moulds, glass and resin can be applied by the hand lay-up technique using a slow gel resin system so that the whole mold can be coated and the mould spun before gelation of the resin takes place. Here, it is necessary to tailor the reinforcement to shape to avoid overlaps. 

Yusoff et al. [30] reported the mechanical properties of oil palm fiber/epoxy. The fiber used was in the form of short random fibers. A hand lay-up technique was conducted to produce 5,10,15, and 20% fiber by volume. A decreasing trend of tensile and flexural properties was reported as fiber loading increased. 

A hand lay-up technique followed by compression molding was adopted for composite fabrication. The netted luffa (L) mat and non-woven coir (C) fibers of 1 cm length were used in the preparation of hybrid composites. ENR was impregnated into fiber within a mold cavity (dimensions 100 mm 100 mm 5 mm). In each formulated composite, the... 

In the hand lay-up technique the fibers are placed in a mold and the resin is later applied by rollers. One option is to cure using a vacuum bag. This removes the excess air and the atmospheric pressure exerts pressure to compact the part. The simplicity, low cost of tooling and flexibihty of design are the main advantages of this procedure. On the other hand, the long production time, intensive labor, and low automation potential are some of the disadvantages. 

To increase the production rate, spray-up technique is used instead of a hand lay-up technique. This technique employs a multiple-headed spray gun. The resin mixture and chopped fibres are discharged simultaneously by using the spay gun on the surface of the mould where they are deposited to a uniform thickness. Sheets, storage vessels, auto body parts, boat hulls, truck bodies and building components are made using this process. 

Unsaturated polyester (Butanox M-60) mixed with 1.5% of Methyl Ethyl Ketone Peroxide (MEKP) as catalyst was selected as a resin for the current work. Treatedbetelnut fiber reinforced polyester (T-BFRP) composite was fabricated using hand lay-up technique. In composite preparation, a metal mould (100 x 100 x 12 mm) was fabricated. The inner walls of the mould were coated with a thin layer of wax as release agent. The first layer of the composite was built by pouring a thin layer of polyester. A prepared mat was placed carefully on the polyester layer. Steel roller was used to arrange the mat and eliminate trapped bubbles. This process was repeated until the composite block was built containing 13 layers of fiber mats and 14 layers of polyester. The prepared blocks were pressed at approximate pressure of 50 kPa in order to compress the fiber mats and to force out the air bubbles. The blocks were cured for 24 hr and then machined into specimens in the size of 10 x 10 x 20 mm. 

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