Casting epoxy

P.Y.97 is also used to lend color to cast epoxy resins and to unsaturated polyester resins it considerably accelerates the hardening process in the latter (Sec. 1.8.3.7). 

Expandable PS Thermoplastic urethane Abietic acid derivatives Polyester fiber Chlorinated polyether resins Butadiene-acrylonitrile copolymers Melamine resin Polyurethane filament Cast epoxy Nylon-6... 

Materials used for insulating sheaths should be inert and easy to machine they are generally plastics or casting epoxy resins. Epoxy resins are easier to handle because of their moulding ability but they are not chemically inert to certain species, including many non-aqueous solvents. Additionally, care must be taken when preparing the epoxy resins that air bubbles do not appear in the mixture prior treatment of the adhesive and hardener mixture under vacuum for a short while reduces the problem. 

Figure 27 shows the expansivity variations as a function of thermal history. As-cast epoxy has a value of 5.43 x 10 5 K-1, (below Tg). Expansivity below Tg decreased... 

Figure 28 shows the thermal expansivity of epoxy above its Tg as a function of thermal history. Rubbery-state expansivity is generally an order of magnitude larger compared to the glassy-state expansivity (see Table 2). As-cast epoxy has an expansivity above Tg of 3.22 x 10-4 K-1. With postcuring and quenching, this parameter tends... 

The EPR/ENDOR measurements described here have been performed on single crystals which are accurately oriented with an x-ray precession camera, x-ray irradiated, and observed at ca. 10 K. The schematic diagram of the X-band EPR apparatus is shown in Figure 18-1 [12], This cavity is a modification of one previously described by Weil et al. [13], The EPR cavity is essentially a cast epoxy, wire wound TE011 cylindrical cavity with external 100 kHz modulation coils. The Cryo-Tip portion of the cavity can be raised 6 cm for x-irradiation and subsequently lowered into the microwave cavity for EPR measurements [14], In the microwave cavity the lowest temperature of the sample is approximately 6 K. However in the irradiation position the lowest temperature is about 10 K because the sample is not as effectively heat-shielded from the room temperature vacuum shroud. 

In the second set of experiments, two polymer systems were tested. One system consisted of cast epoxies which were toughened by the incorporation of chemically bound siloxanes ( 5). The friction and wear were measured as functions of the percentage of the slloxane PSX in the epoxy, the percentage of the slloxane which had a polytrlfluoropropyl group TFP, and the normal load (10, 5 and 2 N). 

ASTM Test Method Phenol-Formaldehyde (Cellulose Fill) Melamine-Formaldehyde (Cellulose Fill) Cast Epoxy Glass Fiber Fill... 

Source of sample Bisphenol A-based casting epoxy... 

Reinforced epoxy resins are the basis of printed circuit boards, tanks, pipes, and aerospace materials. Cast epoxies are very useful in electrical potting and encapsulation of transistors, switches, coils, integrated circuits, transformers, and switchgears. 

Casting. Epoxy, polysulfide, polyester, polyurethane, and silicone A-stage liquids can be poured into a mold, cured, and removed from the mold as finished products. Typical products are simulated wood frames, figurines, and furniture decoration electrical and electronic products and solid polyurethane rubber tires for industrial equipment. 

Phenol-formaldehyde resin Cast epoxy resin Nylon 6,6... 

Centrifugally cast Epoxy, glass-fiber-reinforced Epoxy liner RTRP-21CT RTRP-21CU 10,000 12,500 —... 

The RIM process involves relatively low tool pressures and temperatures so that low-cost tooling such as cast epoxy may be used for short runs. This is very attractive for large items in small quantities and is especially suited to the production of prototype housings. For example, certain business equipment housings were moulded as prototypes in polyurethane, but larger quantities were injection moulded in foamed modified PPO. 

Table 4.9 Typical properties of cast epoxy resins...

Fig. 35. Dissipation factor vs frequency for polar polymers at 25°C. A, Clear cast phenolic B, plasticized PVC C, poly(vinyl chloride-co-vinylidene chloride) (saran) D, unplasticized PVC E, poly(methyl methacrylate) G, poly(hexamethylene adipamide) (nylon) H, poly(2-chlorobutadiene) I, plasticized ethyl cellulose J, cast epoxy K, methyl silicone rubber L, polyurethane foam (d = 33 g/L) and M, 50% polystyrene-50% chlorinated biphenyl.

Figure 5.4 Thermodynamic glass transition of two cast epoxy samples showing the increase in Tg (lower...

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