Wetting Thermoset Resins

The polymer resins used are of two types thermoplastics and thermosets. Thermoplastic resins are very viscous, usually about 10 to 10 more viscous than water. Hence it is very difficult to drive the resin with the help of capillary pressure into the empty spaces between the fibers. Consequently, external pressure is usually used to promote resin flow. Capillary action may help but is not the dominant mechanism of wetting. Thermoset resins are only about 10 to 10 times more viscous than water and capillary action can play a role in... 

Thermosetting resins are combined with fibers and other fillers to form composites.19 Thermosetting resins with low viscosities are necessary to wet fibers or... 

The typical resin systems include thermoset polyesters, vinyl esters, epoxies, polymi-dies, bismaleimide, and phenolics. Thermoplastics are also finding their way into filament winding. Wet thermoset filament winding requires a resin with viscosity in the range of 1000-3000 cpoise. Resin components are chosen on the basis of pot life, winding temperature, viscosity, gel time, and cure time. 

If a thermoset resin is selected for wet winding, desirable characteristics include ... 

ARIDRY SN-25 is a fine silicone emulsion which produces highly durable water repellency on treated fabrics. ARIFIX SN is the catalyst recommended for use with ARIDRY SN-25. These products can be run alone or in conjunction with thermosetting resins, cationic dye fixtures and most all of the organic and inorganic accelerators. Some of the waxy type softeners are compatible with a resin-silicone mix, but each must be checked carefully to be sure that it does not cause back-wetting. 

Unlike thermoplastics, which are simply melted, thermoset resins chemically react from low-viscosity liquids to solid materials during processing, a process termed curing. Structurally, thermosets differ from thermoplastics because of the presence of cross-links in the former, which means that thermosets cannot be reshaped or recycled once the chemical reaction occurs. One advantage of thermosets vs. thermoplastics is that wetting the filler becomes much easier with a low-viscosity material. By far the most common thermoset composite is automobile tires, which consist of a polymer made from styrene and butadiene monomers and carbon-black filler. The actual recipe used is much more complicated, and can include other monomers or polymers, as well as other fillers. In the absence of filler, the cured resin is rubbery at room temperature, which makes tires a... 

Wet layup consists of placing a layer of dry reinforcement inside a mold and then applying an uncured, low-viscosity thermoset resin as shown in Fig. 2. Woven glass fibers are the prevalent reinforcing preform utilized in layup processes, although carbon and aramid fibers are also used to a lesser extent. Typical fiber volume fraction of composites manufactured via wet layup range between 30% and 50%. The resin can be poured, sprayed, or brushed on top of the preform layer either by hand or by machine. The fiber preform layer is rolled on or pressed after the application of resin to evenly distribute the resin and remove air pockets. Resin is applied on top after each layer of fiber mats is properly placed. This process is repeated until the desired thickness is reached. To provide a smooth surface finish on the mold side, a thin layer of mold release is often applied prior to starting the layup. Thereafter, pressure and heat are applied to allow the composite to cure. Pressure can be applied... 

Toluenesulfonamide ortho-Toluenesulphonamide ortho-Toluol-sulfonamid Tolu-ene-2-sulfonamide Toluene-2-sulphonamide 2-Tolyl-sulfonamide Uniplex 171. Plasticizer for thermoplastic and thermoset resins imparts gloss and wetting to melamine, urea and phenolic resins. Component (with p-isomer) of Uniplex 171. Crystals mp= 156-158°. Unitex. 

OTHER COMMENTS used as a solvent for cellulose ethers and esters, dyes, and natural resins used in the manufacturing of phenolic resins and dark-colored thermosetting resins chemical intermediate for tetrahydrofurfuryl alcohol also used in the manufacture of wetting agents, furan polymers, corrosive resistant sealants and cements useful as a liquid propellant. 

A high-Tg hot/ wet resistant resin A toughened high-Tg BMI formulation A tough BMI system A BMI thermoset with thermoplatic-like toughness... 

Uses Mfg. of phenolic and thermosetting resins, furan polymers, urea-formaldehyde resins wetting agent foundry sand binders corrosion-resist, resins intermediate for esterification and etherification paints solvent, plasticizer for phenolic resins solvent for dyes and resins nonreactive epoxy resin diluent vise, reducer, cure promoter, and carrier in amine-cured epoxy resins gel retarder in casein/protein glues polymer sealants/cements synthetic flavoring agent in foods and pharmaceuticals cosmetics ingred. in food-pkg. adhesives... 

Fiber glass is modified by the application of a thermosetting resin in two pass process. Thus treated, these fibers meet the dust free requirement for use in microchip substrate. Epoxy resin is applied from a solution in methyl ethyl ketone. In another invention, cellulose fibers are treated with an aqueous solution to prevent fibrillation. Fibrillation gives a hairy appearance and occurs due to the mechanical abrasion of fibers when they are processed in a wet and swollen state. 

Finishes on reinforcing fibers notably improve the inherent dry strength of the composite, but often they are used to retain physical properties after exposure to a wet environment. Finishes generally can be formulated to work with both thermoplastic and thermosetting resins and various types of glass fiber reinforcements. 

Many matrix choices are available, and each type has an impact on the processing techniques, physical and mechanical properties, and enviromnental resistance of the finished part. Thermoplastic and thermoset materials can be resin matrices. Thermoplastic matrices have been developed to increase hot/wet use temperature and the fracture toughness of composites. Thermosetting resins, however, are more common. The common thermoset matrices for composites include polyester and vinyl esters, epoxy, bismaleimide, polyimide, and cyanate ester and phenolic triazine resins. 

Reinforcing filaments saturated with thermosetting resin are pulled through an orifice in a heated die. Polymerization of the resin occurs as the wet bundle passes through the die, forming a continuous, rigid profile corresponding to the orifice shape. 

Some authors have studied the wet aging of four thermoset resins (orthophthalic polyester, isophthalic polyester, vinyl ester and epoxy) and their composites reinforced with glass fibers. In particular, resins and composites were aged for 18 months, under three immersion conditions i.e. 20°C and 50°C in seawater, and 50°C in distilled water. The experimental tensile tests have shown the inflnence on weight changes particularly of the matrix resin and the aging medinm (Davies et al., 2001). 

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