Polyesters injection molding

Maloy, Thermoplastic polyester, injection molding alloys, M.A. Industries Inc., Polymer Div. 

Premi-Ject, Thermoset polyester injection molding compounds. Premix, Inc. 

Polyester Injection Moldings General purpose grade 0.36—0.55... 

Polyester Injection Moldings Glass Reinforced Grades 2.7—3.3x10" ... 

Polyester Injection Moldings General Purpose Grade 4.9—13.0x10 ... 

Polyester Injection Moldings Glass reinforced grades 17—25... 

Polyester Injection Moldings Asbestos—filled grade 19... 

PEN film for audio- and videotape and various electronic appHcations and blow molded PEN containers for hot-fill appHcations are already being marketed in Japan. NDA is unlikely to ever become as inexpensive as terephthaUc acid but novel NDA-based polyesters will become available if a market need exists. One example could be the experimental polyester PBN (Celanese Corp.) this is the NDA analogue of PBT, poly(l,4-butylene naphthalene-2,6-dicarboxylate) [28779-82-0]. It has a high rate of crystallization, faster even than that of PBT, and its combination of physical properties is weU-suited for injection molding. 

Polymer-matrix materials include a wide range of specific materials. Perhaps the most commonly used polymer is epoxy. Other polymers include vinyl ester and polyester. Polymers can be either of the thermoset type, where cross-linking of polymer chains is irreversible, or of the thermoplastic type, where cross-linking does not take place but the matrix only hardens and can be softened and hardened repeatedly. For example, thermoplastics can be heated and reheated, as is essential to any injection-molding process. In contrast, thermosets do not melt upon reheating, so they cannot be injection molded. Polyimides have a higher temperature limit than epoxies (650°F versus 250°F or 350°F) (343°C versus 121°C or 177°C), but are much more brittle and considerably harder to process. 

Properties shown also apply to some polyesters formulated for thermoplastic processing by injection molding... 

The number-average molar mass of thermoplastic polyesters varies from about 20,000 for film and fiber applications to 40,000 for injection-molding or blowmolding resins. Relationships between intrinsic or molten viscosity and molar mass have been published for PET,131-136 PBT,135,137 and PEN.138... 

Siloxane containing polyester, poly(alkylene oxide) and polystyrene type copolymers have been used to improve the heat resistance, lubricity and flow properties of epoxy resin powder coatings 43). Thermally stable polyester-polysiloxane segmented copolymers have been shown to improve the flow, antifriction properties and scratch resistance of acrylic based auto repair lacquers 408). Organohydroxy-terminated siloxanes are also effective internal mold release agents in polyurethane reaction injection molding processes 409). 

Polyesters, which are a class of engineering thermoplastics, are found in a wide variety of applications including carbonated drink bottles, fibers for synthetic fabrics, thin films for photographic films and food packaging, injection molded automotive parts, and housings for small appliances. In this chapter, we svill explore the synthesis of this class of polymers. We will also look at the typical properties and end uses for the most common of these resins, polyethylene terephthalate and polybutylene terephthalate, which are commonly known as PET and PBT, respectively. 

Typically, polyester resins are used for high-end applications that require excellent electrical and thermal resistance. When dimensional stability under load is more critical, glass fibers are incorporated to increase the heat distortion temperature and the stiffness of the part. Examples of glass fiber reinforced parts include electrical housings, electrical adapters, computer components, telephone housings, and light bulb sockets. When impact modified, polybutylene terephthalate can be injection molded to make car bumpers. 

Polyesters exhibit excellent high temperature strength and electrical properties making them a good choice for many demanding applications. They also are physiologically inert allowing them to be used in food contact applications. The two common polyesters, polyethylene terephthalate and polybutylene terephthalate, are both used in injection molded products. Polyethylene terephthalate is often used in both extrusion and blow molded processes also. 

Reimer-Tiemann reaction, 6 236 of salicylic acid, 22 5 Reinforced composites flax fiber in, 22 594 silylating agents and, 22 701-703 Reinforced plastics, 26 750-751 asbestos applications, 3 311 Reinforced polyester composites, 20 114 Reinforced reaction injection molding (RRIM), 25 456 Reinforcement... 

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