Continuous strand mat

Several layers of dry, continuous-strand mat, woven roving, or cloth called preform are placed in the bottom half of a two-part mold, either by a hand-layup or by an automated technique (see Figure 7.90). The mold is closed, and a catalyzed liquid... 

Thermoforming is the most commonly used method for volume production today [10]. In this method a special type of reinforcement that is already impregnated with a preforming powder is heated before it is clamped in a cold preforming tool [11], The most common type of reinforcement is continuous strand mat which is manufactured by e.g. Vetrotex and Owens Coming. 

Thermoforming is faster and higher fiber contents can be achieved than they can for the spray-up technique. Moreover, if continuous strand mat is used in thermoforming, it can be combined with patches of directional reinforcement. The major drawback with thermoforming is the relatively high level of waste material. 

The constant k is called the Kozeny constant and it attains a value of 0.7 for well-ordered reinforcements with uniformly distributed fibers, (e.g. unidirectional prepreg) [17]. For commonly used fabrics in LCM (e.g., continuous strand mat or weaves) R2/4k should be seen as an adjustable model parameter with only weak coupling to the fiber or fiber bundle diameter. 

Continuous strand mats are approximately isotropic and have almost the same permeability in all directions (in the plane of the fabric). Many other fabrics, however, are strongly anisotropic and have different permeability in different directions. Gebart [18] proposed a model for this class of fabrics derived theoretically from a simplified fiber architecture. The model, which is valid for medium to high fiber volume fractions, was developed for unidirectional fabrics, but it can also be used for other strongly anisotropic fabrics. In this model the permeability in the high permeability direction (which is usually, but not always, in the direction of the majority of fibers) follows the Kozeny-Carman equation (Eq. 12.2). In the perpendicular direction, however, it is ... 

Figure 51, Different types of glass fibers. (1) Continuous strand mat, (2) Surfacing mat, (3) Chopped-strand mat, (4) Woven roving). (Courtesy of Ownes Coming Fiberglass Corp.)...

FRU-L after a sheet of glass-fiber continuous-strand mat was placed in an open mold, the prescribed amount of PUF solution, prepared by hand mixing was poured into the mold and the contents were pressed to the fixed thickness (3 mm). 

Another example of the two-dimensionally reinforced foamed composite was developed by Celotex Corp., USA. The production process consists of the use of continuous-glass-strand mat and a horizontal conveyer process. Continuous-strand mat is supplied on a moving horizontal conveyer. The foaming mixture is then applied onto the glass mat through the mixing head of a dispensing machine (35). 

A random oriented continuous strand mat, precut to panel dimensions, is placed over the vacuum-formed vinyl skin prepared in a mold. 

Two-dimensionally reinforced foamed composites were developed by Nisshinbo Ind., Inc. The foamed composites consist of different types of glass fibers, e.g., continuous strand mat, or chopped strand. Table 50 shows typical properties of Airlite FRU (trade mark of Nisshinbo Ind.) (2). 

The use of long fibers - such as in continuous strand mat (RIM Mat Molded) affords conposite material with potentially... 

Most commercial SRIM applications have been in general industry or in the automotive industry. The reinforcement material most commonly used has been fiberglass, due to the low cost. Fiberglass has been used in the form of woven cloth, continuous strand mat, or chopped glass. 

There are several ways in that GMT materials can be manufactured, with various forms of reinforcement providing different properties (Table 4.8 and Figure 4.4). Continuous strand mats impregnated with a TP melt have only limited flow capabilities and cannot be used for deep-draw moldings, products with variations in wall thickness, or with ribs or bosses. Better flow properties are obtained when the sheet is reinforced with needled mats, which are usually produced as part of the main production process. 

Continuous strand mats are produced by continuously depositing the uncut strands in a swirling pattern onto a moving belt where a binder is applied. Continuous strand mats exhibit better physical properties than cut strand mats, but the material is less homogenous. Continuous mats vary in weight from 0.75 to 4.5 oz./ft. and are available in widths up to 6 ft. 

The moulds are cleaned and prepared by the application of a suitable release agent. Previously prepared reinforcement, usually continuous strand mat but other reinforcement types may be used, is placed in the lower mould and the two mould halves are brought together and clamped. The reinforcement must fit the contours and perimeter of the mould accurately. Hence pre formed mat is often the preferred option. 

Fibres may be in the form of continuous strand mat or chopped strand mat with insoluble binder. Preforms may be used which are produced... 

United States, glass fiber chopped strands and rovings for composite reinforcement applications, continuous strand mats... 

Reinforcement Continuous strand mat. Continuous Chopped strand Continuous strand mat, Continuous strand Continuous roving... 

Pultrusion is a simple technique which is employed mostly for fabrication of products based on unsaturated polyester resins (or other resins like epoxy, vinyl ester) and continuous strand mats (fibre or fabric). A pultrusion machine consists of creel for supplying fibre, a resin tank, forming dies, machined dies with a temperature control facility, a puller and a saw for cutting the product from a continuous composite product. The continuous strand mats are passed through a bath containing a mixture of resin and curatives. In the resin bath, the fibre is passed through a series of rods to remove entrapped air and excess resin to ensure complete wetting of the fibre. 

The continuous strand mat provides much stronger reinforcement to the composites than the chopped strand mat. The mat can be formed directly under the bushings or from forming cakes. In either case, glass strands are continuously placed onto a moving conveyer in a random pattern. Additional binder is applied as with the chopped strand mat. The product is widely used in the reaction injection molding (RIM) application. The Azdel stampable sheet is made from this process. 

PPG Industries has introduced MatVantage - a continuous strand mat for pultrusion, offering unique laminate characteristics - and new low-catenary conventional rovings plus three new chopped strands for thermoplastics. Type 2016 roving is for direct-draw filament winding for oilfield composite pipe and... 

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