Thermosets diallyl phthalate

Durez SI-75 Thermoset diallyl phthalate compounds, DAP Cain Chem. Inc. 

A plastics material of particular application in electrical components. It consists of a thermosetting polyester resin, mineral fillers, fibrous reinforcement and a hquid crosslinking medium such as diallyl phthalate. Down-Stroking Press... 

Diallyl isophthalate (DAIP), 2 258, 261 physical properties of, 2 258t thermoset molding properties of, 2 262t Diallyl phthalates (DAP), 2 258-263 20 110 copolymerization, 2 259-260 Diallyl terephthalate (DATP), 2 259 DIALOG file, 18 246 DIALOG OneSearch, 18 244 -dial suffix, 2 58 Dialysate, 26 814, 815 composition of, 26 817 Dialysis. See also Hemodialysis alternative modes of, 26 832-833 requirements for adequate, 26 821-822 treatment time and frequency of, 26 833-834... 

Diallyl phthalate when heated to 100°C with an initiator like t-butyl per benzoate yields a linear polymer linked through one allyl unit per monomer. This polymer having mol. wt. 10000-25000 is then compounded with fillers to get thermosetting moulding powder. Mouldings have thermal stability upto... 

The crosslinking of unsaturated polyesters (Sec. 2-12a) is carried out by copolymerization [Selley, 1988]. Low-molecular-weight unsaturated polyester (prepolymer) and radical initiator are dissolved in a monomer, the mixture poured, sprayed, or otherwise shaped into the form of the desired final product, and then transformed into a thermoset by heating. Styrene is the most commonly used monomer. Vinyltoluene, methyl methacrylate, diallyl phthalate, a-methylstyrene, and triallyl cyanurate are also used, often together with styrene. 

The most common and widely used thermoset molding compounds are classified as follows (a) alkyd, (b) allylic (diallyl phthalate), (c) amino (melamine and urea), (d) epoxy, (e) phenolic, (f) polyester, and (g) silicone. There may be other specialty thermoset resin materials used on specific applications. 

Some of the common types of plastics that are used are thermoplastics, such as poly(phenylene sulfide) (PPS) (see POLYMERS CONTAINING SULFUR), nylons, liquid crystal polymer (LCP), the polyesters (qv) such as polyesters that are 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diallyl phthalate and phenolic resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials are available in several variations which have a range of physical properties. 

Phenolic, Melamine, and Urea. The phenolics are heavily commercialized thermosetting materials that find their way into many applications. They have an excellent combination of physical strength and high-temperature resistance. They have good electrical properties and dimensional stability. Like epoxies and diallyl phthalate, phenolic resins are often found to contain fillers and reinforcement. 

The power-law model is the most extensively used shear-mte model for thermosets and has been used for unfilled (Ryan and Kamal, 1976, Kascaval et al., 1993, Riccardi and Vazquez, 1989) and filled (Ryan and Kamal, 1976, Knauder et al., 1991) epoxy-resin systems. Sundstrom and Burkett (1981) showed that there was a good fit of the viscosity of diallyl phthalate to the Cross model. The viscosity of polyesters has been modelled by Yang and Suspene (1991) using a Newtonian model. The WLF model has been used by Pahl and Hesekamp (1993) for a moderately filled epoxy-resin system. Rydes (1993) showed that the viscosity of DMC polyesters followed a power-law relationship at high shear rate. 

Whereas monoallyl derivatives sdeld thermoplastic polymers, allyl esters containing two or more unsaturated groups yield thermosetting resins. Thus, monoallyl esters of unsaturated acids, e.g., allyl acrylate, allyl methacrylate, allyl crotonate, and allyl itaconate, and diallyl esters of dibasic acids, e.g., diallyl oxalate, diallyl phthalate, and diallyl itaconate, yield thermoset resins, which generally combine solvent resistance, toughness, hardness, transparency, and heat resistance. The cross-linking tendency of the allyl esters makes them useful in copolymerization wherein they impart these properties to normally linear polymers. 

Other thermosetting polymers are cyanate esters (CEs), benzoxazines, PU acrylates, bismaleimides (BMIs), dicy-clopentadienes (DCPDs), diallyl phthalates (DAPs), etc. Formulations based on these polymers are used for specific applications where their particular properties are required. For example, DAP has long been the material of choice for electrical components where long-term reliability is required. 

Reinforced plastics are composites in which a resin is combined with a reinforcing agent to improve one or more properties of the resin matrix. The resin may be either thermosetting or thermoplastic. Typical thermosetting resins used in RPs include unsaturated polyester, epoxy, phenolic, melamine, silicone, alkyd, and diallyl phthalate. In the field of reinforced thermoplastics (RTFs), virtually every type of thermoplastic material can be, and has been, reinforced and commercially molded. The more popular grades include nylon, polystyrene, polycarbonate, polyporpylene, polyethylene, acetal, PVC, ABS, styrene-acrylonitrile, polysulfone, polyphenylene sulfide, and thermoplastic polyesters. 

All TP or TS matrix property can be improved or changed to meet varying requirements by using reinforcements. Typical thermoplastics used include TP polyesters, polyethylenes (PEs), nylons (polyamides/ PAs), polycarbonates (PCs), TP polyurethanes (PURs), acrylics (PMMAs), acetals (polyoxymethylenes/POMs), polypropylenes (PPs), acrylonitrile butadienes (ABSs), and fluorinated ethylene propylenes (FEPs). The thermoset plastics include TS polyesters (unsaturated polyesters), epoxies (EPs), TS polyurethanes (PURs), diallyl phthalates (DAPs), phenolics (phenol formaldehydes/PFs), silicones (Sis), and melamine formaldehydes (MFs). RTSs predominate for the high performance applications with RTFs fabricating more products. The RTPs continue to expand in the electronic, automotive, aircraft, underground pipe, appliance, camera, and many other products. 

Diallyl Phthalate Resin Thermoset supplied as diallyl phthalate prepolymer or monomer. Has high chemical, heat and water resistance, dimensional stability, and strength. Shrinks during peroxide curing. Processed by injection, compression, and transfer-molding. Used in glass-reinforced tubing, auto parts, and electrical components. Also called DAP. 

These modifications are necessary to provide the working time-temperature relationship required for screw plasticating. The most commonly used injectionmolding thermosetting materials are the phenolics. Other thermosetting materials often molded by the screw-injection process include melamine, urea, polyester, alkyd, and diallyl phthalate (DAP). (Source Chanda, M. and S. K. Roy, Plastics Technology Handbook, Marcel Dekker, Inc., New York, NY, 1987). 

Liquid injection molding (LIM) A process of injection-molding thermosetting resins in which the uncured resin components are metered, mixed, and injected at relatively low pressures through nozzles into mold cavities, the curing or polymerization taking place in the mold cavities. The process is most widely used with resins that cure by addition polymerization such as polyesters, epoxies, silicones, alkyds, diallyl phthalate, and (occasionally) urethanes. 

After removal of water and cooling, the fluid polyester may be dissolved in a reactive monomer in the same kettle, or it may be shipped to users who add the monomer and catalyst in their plants. Styrene is most widely used as the reactive monomer. Others sometimes used as diallyl phthalate, diallyl isophthalate, and triallyl cyanurate. A peroxide catalyst is generally used for the final co-polymerization. These unsaturated polyesters are thermosetting and are most widely used in reinforced plastics for making boat hulls, trays containers, and panels, and in potting of electrical assemblies. 

Thermosetting plastics (epoxies, diallyl phthalate, polyesters, melamine, phenol and urea formaldehyde, polyurethanes, etc.)... 

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