Branched polyethylene terephthalate

BPET branched polyethylene terephthalate CA cellulose acetate (CAc)... 

BLCT Basic lattice cluster theory (LCT) bPET Branched polyethylene terephthalate BR Polybutadiene, butadiene rubber... 

In this section, copolymers of polyethylene are discussed, starting with low-density, branched polyethylene and culminating with crystallization, melting, and annealing of poly(ethylene-co-octene-l), also described as linear-low-density polyethylene, LLDPE. Furthermore, partial phase diagrams of poly(ethylene terephthalate-co-oxybenzoate), PETcoOB, andpoly(oxybenzoate-co-oxynaphthoate), POBcoON, are presented. The latter systems are examples of increasing chain stiffness by cocrystalUzation which leads to mesophase behavior (see Sect. 5.5). 

Polyester, saturated n. Any polyester in which the polyester backbone has no double bonds. The class includes low-molecular-weight liquids used as plasticizers and as reactants in forming urethane polymers and linear, high-molecular-weight thermoplastics such as polyethylene terephthalate. Usual reactants for the saturated polyesters are (1) a glycol such as ethylene-, propylene-, diethylene-, dipropylene-, or butylene glycol (2) An acid or anhydride such as adipic, azelaic, or terephthalic acid or phthalic anhydride. Some saturated, branched polyesters are used in high-temperature varnishes and adhesives. 

The list of polymers known to respond satisfactorily to permanganic etching is now long and continually growing. It consists of linear and branched polyethylene, four isotactic polyolefins (polypropylene, polystyrene, poly(4-methylpentene-l) and poly(butene-l)), related atactic polymers, poly(vinylidene fluoride) (hereafter denoted PVF2), PEEK, and poly(ethylene terephthalate) (PET), together with various copolymers and others such as ethylene propylene rubbers and ethylene-propylene-diene (EPDM) terpolymer. 

In this A is a hydrocarbon radical and A is an organic or inorganic acid radical (for example, polyethylene terephthalate, nucleic acids). They are prepared by polycondensation of glycols with dibasic acids or their anhydrides, or hydroxy acids. Branched polyesters (for example, alkyd resins) or cross-linked polyesters are produced by using polyhydric alcohols (more than two OH groups for example, glycerol, and pentaerythritol and various polyols). 

All polymers can be divided into two major groups thermoplastics and thermosets) based on their thermal processing behavior. Thermoplastics soften and flow when heated. Upon cooling, thermoplastic polymers harden and assume the shape of the mold. Examples of commercial thermoplastics include polystyrene, polyolefins (e.g. polyethylene and polypropylene), nylon, poly(vinyl) chloride (PVC), and poly (ethylene) terephthalate (PET). Thermoplastics make up 80% of the plastic produced today and these polymers are linear or branched in their structure. 

Thermoplastics soften when heated (and eventually liquefy) and harden when cooled — processes that are totally reversible and may be repeated. On a molecular level, as the temperature is raised, secondary bonding forces are diminished (by increased molecular motion) so that the relative movement of adjacent chains is facilitated when a stress is applied. Irreversible degradation results when a molten thermoplastic polymer is raised to too high a temperature. In addition, thermoplastics are relatively soft. Most linear polymers and those having some branched structures with flexible chains are thermoplastic. These materials are normally fabricated by the simultaneous application of heat and pressure (see Section 15.22). Examples of common thermoplastic polymers include polyethylene, polystyrene, poly(ethylene terephthalate), and poly(vinyl chloride). 

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