Ethylene terephthalate plastic properties

Poly(ethylene terephthalate). PET is a crystalline material and hence difficult to plasticize. Additionally, since PET is used as a high strength film and textile fiber, plasticization is not usually required although esters showing plasticizing properties with PVC may be used in small amounts as processing aids and external lubricants. Plasticizers have also been used to aid the injection mol ding of PET, but only at low concentrations. 

Recycled poly(ethylene terephthalate) (PET), which offers excellent properties at potentially lower cost, is finding wider use as a raw material component and meeting increasing demands for environmentally compatible resins (see POLYESTERS,THERMOPLASTIC Recycling, PLASTICS). 

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

Poly(trimethylene terephthalate). Poly(trimethylene terephthal-ate) (PIT) is a crystalline polymer that is used for fibers, films, and engineering plastics. The polymer has an outstanding tensile elastic recovery, good chemical resistance, a relative low melting temperature, and a rapid crystallization rate. It combines some of the advantages of poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT). Disadvantageous are the low heat distortion temperature, low melt viscosity, poor optical properties, and pronounced brittleness low temperatures. 

Among polyesters synthesized from 1,4-benzenedicarboxylic acid and aliphatic diols, poly (ethylene terephthalate) (PET) and poly (butylene terephthalate) (PBT) are the most frequently applied ones. Hydrolysis is evidently the easiest chemical recycling technique of polyesters, however they may be mixed with other waste plastics, thus it is useful to know the properties of their pyrolysis product. 

Another motivation for measurement of the microhardness of materials is the correlation of microhardness with other mechanical properties. For example, the microhardness value for a pyramid indenter producing plastic flow is approximately three times the yield stress, i.e. // 3T (Tabor, 1951). This is the basic relation between indentation microhardness and bulk properties. It is, however, only applicable to an ideally plastic solid showing no elastic strains. The correlation between H and Y is given in Fig. 1.1 for linear polyethylene (PE) and poly(ethylene terephthalate) (PET) samples with different morphologies. The lower hardness values of 30-45 MPa obtained for melt-crystallized PE materials fall below the /// T cu 3 value, which may be related to a lower stiff-compliant ratio for these lamellar structures (BaM Calleja, 1985b). PE annealed at ca 130 °C... 

In this entry, the effect of blending recyclable poly-(propylene) (PP) and poly(ethylene terephthalate) (PET) with lignin on carbon fiber production is presented. We discuss the effects of lignin structure and specific intermolecular interactions on lignin thermal properties as well as the effect of blend composition on surface morphology, mechanical properties, and the manufacturing process of lignin/recyclable plastic-based carbon fibers. 

Linear Polymers Long chains are necessary to confer the mechanical properties of fibers, plastics, and elastomers that make polymers so valuable. Fibers such as cellulose and polyester arc semicrystalline materials in which the same chemical stmeture exists in both rigid microcrystalline and flexible amorphous phases. Plastics may be either semicrystalline, such as poly(ethylene terephthalate) (the same polyester of fibers is also the PET of beverage bottles), or completely amorphous and glassy, such as polystyrene or poly(methyl methacrylate) (PMMA, Plexiglas or Lucite ). Elastomers are completely amorphous and flexible and would flow as a viscous mbbery liquid except that the polymer chains are cross-hnked to prevent macroscopic flow but allow reversible stretching. As an example, poly(dimethylsiloxane)... 

Most bioinert rigid polymers are commodity plastics developed for nonmedical applications. Due to their chemical stability and nontoxic nature, many commodity plastics have bwn used for implantable materials. This subsection on rigid polymers is separated into bioinert and bioerodable materials. Table 11.6 contains mechanical property data for bioineit polymers and is roughly ordered by elastic modulus. Polymers such as the nylons and poly(ethylene terephthalate) slowly degrade by hydrolysis of the polymer backbone. However, they are considered bioinert since a significant decrease in properties takes years. 

Interest in environmentally degradable polymers began more than thirty years ago, when it was first recognized that the commonly used commodity packaging plastics such as polyolefins, poly(vinyl chloride, polystyrene, and poly(ethylene terephthalate) were accumulating in the environments in which they were discarded, after use. Since these polymers were developed for their resistance properties, it should not have been surprising that they were recalcitrant in landfills and as litter when disposed of in a negligent manner. 

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