Solvents thermoplastic resins

Phase Separation. Microporous polymer systems consisting of essentially spherical, intercoimected voids, with a narrow range of pore and ceU-size distribution have been produced from a variety of thermoplastic resins by the phase-separation technique (127). If a polyolefin or polystyrene is insoluble in a solvent at low temperature but soluble at high temperatures, the solvent can be used to prepare a microporous polymer. When the solutions, containing 10—70% polymer, are cooled to ambient temperatures, the polymer separates as a second phase. The remaining nonsolvent can then be extracted from the solid material with common organic solvents. These microporous polymers may be useful in microfiltrations or as controlled-release carriers for a variety of chemicals. 

Other Materials. Benzoguanamine and acetoguanamine may be used in place of melamine to achieve greater solubiHty in organic solvents and greater chemical resistance. Aniline and toluenesulfonamide react with formaldehyde to form thermoplastic resins. They are not used alone, but rather as plasticizers (qv) for other resins including melamine and urea—formaldehyde. The plasticizer may be made separately or formed in situ during preparation of the primary resin. 

Chisso-Asahi Fertilizer Company, Ltd. This company utilizes thermoplastic resins, such as polyolefins, poly(vinyhdene chloride), and copolymers, as their coating materials. The coatings are dissolved in fast-drying chlorinated hydrocarbon solvents and are appHed to a variety of substrates including urea, diammonium phosphate [7783-28-0] potassium sulfate [7778-80-3], potassium chloride [7447-40-7], and ammonium nitrate/potassium sulfate-based N—P—K fertilizers. 

The polymers can be categorised as formaldehyde containing and formaldehyde free and as thermoset or thermoplastic resins. Typical formaldehyde containing resins are melamine formaldehyde sulfonamide resins, where the sulfonamide is ortho and para toluenesulfonamide. The sulfonamide, which is a solvent for the dye, undergoes a condensation polymerisation with formaldehyde and melamine, the latter acting as a cross-linking agent. Non-formaldehyde, thermoplastic resins are usually polyamides and polyesters. 

To process formulations, thermoplastic and thermosetting resins are used. For thermoplastic resins such as VAAR, the binder is dissolved in a solvent and then mixed with Mg and sodium nitrate until the solvent is evaporated. This formulation can then be stored and used whenever needed. No curing is required after consolidation. On the other hand, the epoxy-PS blend is mixed with an amine... 

ETHYL CELLULOSE. A versatile, thermoplastic cellulose ether that is compatible with a wide variety of solvent systems, resins, oils, and... 

Poly(vinyl acetal)s can be formulated with other thermoplastic resins and with a variety of multifunctional cross-linkers. When cross-linking takes place the resin becomes thermoset. Thermosetting generally increases thermal stability, rigidity, and abrasion resistance, and improves resistance to solvents ancl to acids and bases. It also severely limits proccssibility by making the resin insoluble and impossible to extrude. 

The thermoplastic resins are usually blended with the epoxy resin in a solvent solution. Early researchers realized that to make this approach effective, it was necessary to increase the compatibility and interfacial adhesion of the thermoplastic modifier and the epoxy resins. The problem of poor miscibility of the thermoplastic resins and poor processabihty of the final product are the main reasons that these materials have not achieved commercial success. 

Unlike the thermosetting resins, the thermoplastic resins will soften on heating or on contact with solvents. They will then harden on cooling or on evaporation of the solvent from the material. This is a result of the noncrosslinked chemical structure of thermoplastic molecules. The following are important characteristics of thermoplastic resins that can affect their joining capability. 

Applications of 1,4-butanediol include the manufacture of THF (tetrahydrofuran), used as a solvent, and of poly(butylene terephtha-late), used in thermoplastic resins. 

Selvedge glues, based on a non-thermoplastic resin dissolved in a non-flammable solvent to be applied on slitting machines for circular knits or at the stenter avoids curling of selvedges... 

Non-structural adhesives used on CELCXDN arc usually one-component, room-temperature-curing systems based either on thermoplastic resins or elastomeric materials dispersed in solvents. They are normally used in applications which will not be exposed to temperatures over 180°F. Neoprene rubber adhesives are examples. (7). 

Synthetic resins may be either thermoplastic or thermosetting. Thermoplastic resins are sensitive to temperature (i.e., they will melt and flow at elevated temperatures and are generally soluble in a variety of neutral organic solvents). Thermosetting resins, on the other hand, will decompose before they will melt and are not truly soluble. Treatments with thermosetting resins are therefore completely irreversible, but sometimes their use cannot be avoided. Epoxy resins are the best examples of thermosetting resins used in conservation, particularly in architectural preservation, where their excellent strength properties are required for the repair of fully functional structural elements. 

Thermoplastic resins can be introduced into wood either in solution or as liquid monomers, which are then polymerized in situ (2, 3). Cross-linking agents can be included with the monomer to produce a thermosetting resin upon polymerization, initiated by heat, catalyst, or 7 irradiation (4), Even if there is no cross-linking, the prospects for reversibility are not very good for such systems (3). Surface residuals of poly(methyl methacrylate), polystyrene, and polyester mixtures could only be removed with some diflSculty with solvents (5). The present discussion will be limited to thermoplastic resins that can be introduced into wood in solution. 

It was not until the commercialization of synthetic plastics resins in the 1930s that an almost unlimited variety of base materials became available for compounding into adhesives and sealants. Most of the thermoplastic resins were soluble in organic solvents and were used as solvent adhesives for molded plastic articles of the same base composition and sometimes for other materials. Poly(vinyl chloride) (PVC), a thermoplastic developed in 1927, is used today in solvent formulations to bond PVC articles such as coated fabrics, films, foams, and pipe. In the early 1930s, phenolics came into importance as adhesive resins. Before that time they were used as coating varnishes [9, p. 239). About 1931 development of the use of a new phenolic resin for plywoods and veneers began [9, p. 239]. 

Certain general categories are also listed, such as alloys, aromatic polymer, conductive, delayed-tack, elastomeric adhesives, anaerobic, film and tape adhesives, hot-melt adhesives, inorganic glues, microencapsulated adhesives, rubber-based adhesives, solvent-based systems, thermoplastic resin adhesives, thermosetting-resin adhesives, and water-based adhesives. 

Polystyrene is a transparent, colorless thermoplastic resin available in solvent-solution or aqueous-emulsion form. In both forms, appUcations are limited to conditions where at least one of the adherends is porous. An example is sticking polystyrene tiles onto a plaster wall. Polystyrene adheres well to wood, but not to plastics, except itself. For bonding polystyrene, a low-molecular-weight styrene polymer with a peroxide catalyst is used. This adhesive polymerizes in the glue Une. ° ... 

Solvents, or solvents containing small amounts of hodying resin, are used for bonding thermoplastic resins and film adhesives. An example is toluol, which can he used to soften and dissolve polystyrene molded articles to allow joining the softened pieces. Ketones can be used to bond PVC films in a similar manner. A small amount of resin can be used to thicken the solvent so that a sufficient amount would stay in place to dissolve the substrate. It should be noted, however, that solvent welding of molded plastics can cause stress cracking and weakening of the structure as the parts age. ... 

Adhesive, hot-melt— An adhesive that is applied in a molten state and forms a bond on cooling to a solid state. A bonding agent which achieves a solid state and resultant strength by cooling, as contrasted with other adhesives which achieve the solid state through evaporation of solvents or chemical cure. A thermoplastic resin which functions as an adhesive when melted between substrate and cooled. 

Acrylics are thermoplastic resins based on acrylates or derivatives such as amides and esters. Acrylics are available as emulsions, solvent solutions, and monomer—polymer mixtures (one or two components) with a catalyst. Emulsion—solvent types set by evaporation and absorption of a solvent. Polymer mixtures set through polymerisation by heat, ultra-violet radiation and/or the action of a chemical catalyst. 

Introducing a thermoplastic resin [53,54] into the matrix such as a thermoplastic polyimide Matrimid 5218 [55,56], polyethersidfone [54-57], polyetherimide [55-56,58-61] and poly (arylene ether) [58-59,61-63]. All these polymers however, cause an attendant loss of processability coupled with poorer solvent resistance. 

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