Thermal lamination

It was decided to febricate these parts from epoxy-glass laminates, as their properties are more than adequate for the intended application. In order to select between NEflA grade G-10 and G-11 types of epoxy-glass laminates, thermal shock tests were performed. Samples of the two types of laminates 2.5cm thick were obtained from the Micarta Division of Westinghouse Electric Corporation. 

As a tme thermoplastic, FEP copolymer can be melt-processed by extmsion and compression, injection, and blow molding. Films can be heat-bonded and sealed, vacuum-formed, and laminated to various substrates. Chemical inertness and corrosion resistance make FEP highly suitable for chemical services its dielectric and insulating properties favor it for electrical and electronic service and its low frictional properties, mechanical toughness, thermal stabiUty, and nonstick quaUty make it highly suitable for bearings and seals, high temperature components, and nonstick surfaces. 

Phenol—formaldehyde resins are used as mol ding compounds (see Phenolic resins). Their thermal and electrical properties allow use in electrical, automotive, and kitchen parts. Other uses for phenol—formaldehyde resins include phenoHc foam insulation, foundry mold binders, decorative and industrial laminates, and binders for insulating materials. 

Unsaturated resias based on 1,4-cyclohexanedimethanol are useful ia gel coats and ia laminating and molding resias where advantage is taken of the properties of very low water absorption and resistance to boiling water (6). Thermal stabiHty is imparted to molding resias, both thermoplastic (71,72) and thermoset (73—76), enabling retention of physical and electrical properties at elevated temperatures (77). Additionally, resistance to chemical and environmental exposure is characteristic of products made from these resias (78). 

PBI is being marketed as a replacement for asbestos and as a high temperature filtration fabric with exceUent textile apparel properties. The synthesis of whoUy aromatic polybenzimidazoles with improved thermal stabUities was reported in 1961 (12). The Non-MetaUic Materials and Manufacturing Technology Division of the U.S. Air Force Materials Laboratory, Wright-Patterson Air Force Base, awarded a contract to the Narmco Research and Development Division of the Whittaker Corp. for development of these materials into high temperature adhesives and laminates. 

Aesthetic properties are of greatest concern in decorative laminates. These include gloss, appearance, cleanabiUty, wear resistance, stain resistance, and other surface properties. Physical properties are of most importance for industrial laminates. These include strength, electrical and thermal properties, expansion coefficient, and punchabiUty. The definitions of the laminate grades in these standards foUow. 

Ziac foil coated with a conductive, pressure-sensitive adhesive is used for repair of other ziac coatings or for imparting corrosion resistance at field sites. The 0.08-mm ziac tape or sheet has a 0.025-mm coaductive adhesive. The laminate is cut to size and pressed tightly to activate the adhesive. Conductive tape can be wrapped around pipe, especially around welds or connections. The corrosion resistance of this material is iatermediate between galvanized or thermally sprayed coatings and zinc-filled paints (21,50). 

Copper is universally used as the metal plating for tape because it can be easily laminated with copper and the various plastic tapes. Copper is readily etched and has excellent electrical and thermal conductivity in both electrodeposited and roUed-annealed form. The tape metal plating is normally gold- or tin-plated to ensure good bondabiUty during inner- and outer-lead bonding operations and to provide better shelf life and corrosion resistance. 

Laminate T °C GTE below ppm/°C Water uptake, MIL-P-13949F, mg Dielectric constant at IMH2 Dissipation factor at 1 MH2 Tensde strength, MPa " Modulus of elasticity, GPa Thermal conductivity, W/(m-K)... 

Carbon-Fiber Composites. Cured laminates of phenoHc resins and carbon-fiber reinforcement provide superior flammabiHty resistance and thermal resistance compared to unsaturated polyester and epoxy. Table 15 shows the dependence of flexural strength and modulus on phenoHc—carbon-fiber composites at 30—40% phenoHc resin (91). These composites also exhibit long-term elevated temperature stabiHty up to 230°C. 

Cross-linked polyester composites have a relatively low coefficient of thermal conductivity that can provide beneficial property retention in thick laminates at high temperatures as well as remove the need for secondary insulation. The coefficient of thermal expansion of glass-reinforced composites is similar to aluminum but higher than most common metals. 

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