Ethylene terephthalate, effect

Komolprasert V and Lawson A, 1995, Residual contaminants in recycled poly(ethylene terephthalate) -effects of washing and drying. In ACS Symposium series 609, Plastics, Rubber and Paper Recycling A pragmatic approach. K.W. Hutchinson and N.R. Foster (editors), American Chemical Society Washington DC, 1995, pp. 435-444. 

The ethylene glycol liberated by reaction (5.L) is removed by lowering the pressure or purging with an inert gas. Because the ethylene glycol produced by reaction (5.L) is removed, proper stoichiometry is assured by proceeding via the intermediate, bis(2-hydroxyethyl) terephthalate otherwise the excess glycol used initially would have a deleterious effect on the degree of polymerization. Poly(ethylene terephthalate) is more familiar by some of its trade names Mylar as a film and Dacron, Kodel, or Terylene as fibers it is also known by the acronym PET. 

The packaging (qv) requirements for shipping and storage of thermoplastic resins depend on the moisture that can be absorbed by the resin and its effect when the material is heated to processing temperatures. Excess moisture may result in undesirable degradation during melt processing and inferior properties. Condensation polymers such as nylons and polyesters need to be specially predried to very low moisture levels (3,4), ie, less than 0.2% for nylon-6,6 and as low as 0.005% for poly(ethylene terephthalate) which hydrolyzes faster. 

Biaxial orientation effects are of importance in the manufacture of films and sheet. Biaxially stretched poly(ethylene terephthalate) (e.g. Melinex),... 

When dipoles are directly attached to the chain their movement will obviously depend on the ability of chain segments to move. Thus the dipole polarisation effect will be much less below the glass transition temperature, than above it Figure 6.4). For this reason unplasticised PVC, poly(ethylene terephthalate) and the bis-phenol A polycarbonates are better high-frequency insulators at room temperature, which is below the glass temperature of each of these polymers, than would be expected in polymers of similar polarity but with the polar groups in the side chains. 

In addition to the nucleating agents discussed in Section 18.4, many other materials have been found to be effective. Whilst the nylons may be self-nucleating, partieularly if there is some unmelted crystal structure, seeding with higher melting point polymers can be effective. Thus nylon 66 and poly(ethylene terephthalate) are reported to be especially attractive for nylon 6. 

The solubility parameter of poly(ethylene terephthalate) is about 21.8 MPa but because it is a highly crystalline material only proton donors that are capable of interaction with the ester groups are effective. A mixture of phenol and tetrachloroethane is often used when measuring molecular weights, which are about 20 000 in the case of commercial polymers. 

As with poly(ethylene terephthalate) there is particular interest in glass-fibre-filled grades. As seen from Table 25.8, the glass has a profound effect on such properties as flexural modulus and impact strength whilst creep resistance is also markedly improved. 

In Chapters 3 and 11 reference was made to thermoplastic elastomers of the triblock type. The most well known consist of a block of butadiene units joined at each end to a block of styrene units. At room temperature the styrene blocks congregate into glassy domains which act effectively to link the butadiene segments into a rubbery network. Above the Tg of the polystyrene these domains disappear and the polymer begins to flow like a thermoplastic. Because of the relatively low Tg of the short polystyrene blocks such rubbers have very limited heat resistance. Whilst in principle it may be possible to use end-blocks with a higher Tg an alternative approach is to use a block copolymer in which one of the blocks is capable of crystallisation and with a well above room temperature. Using what may be considered to be an extension of the chemical technology of poly(ethylene terephthalate) this approach has led to the availability of thermoplastic polyester elastomers (Hytrel—Du Pont Amitel—Akzo). 

Reed AM and Gilding DK. Biodegradable polymers for use in surgery-poly(ethylene oxide) poly (ethylene terephthalate) (PEO/PET)copolymers 2. in vitro degradation [J]. Polymer, 1981, 22,499-504. Van Blitterswijk CA, Brink JVD, Eeenders H, et al. The effect of PEG ratio on degradation, calcification and bone bonding of PEO/PBT copolymer (Polyactive). Cell Mater, 1993, 3(1), 23-36. 

Reactive compatibilization is also carried out by adding a monomer which in the presence of a catalyst can react with one or both phases providing a graft copolymer in situ that acts as a compatibilizer. Beaty and coworkers added methyl methacrylate and peroxide to waste plastics (containing polyethylene [PE], polypropylene [PP], PS, and poly(ethylene terephthalate) [PET]). The graft copolymer formed in situ homogenized the blend very effectively [19]. 

Figure 4. Effect of radiation on the poly(ethylene terephthalate-co-2,6-naphthalene-dicarboxylate) yarns mole % of 2,6-DMN (%) 0.0 (X) 0.5 fA) 1-0 (O) 2.0 ...

Collins, S., Peace, S. K. and King, S. M, Transesterification in poly (ethylene terephthalate). Molecular weight and end group effects, Macromolecules, 33, 2981-2988 (2000). 

Tant, M. R. and Culberson, W. T., Effect of molecular weight on spherulite growth rate of poly(ethylene terephthalate) via real-time small angle light scattering, Polym. Eng. Sci., 33, 1152-1156 (1993). 

Figure 5.5 Effect of temperature on the SSP reaction rate for (a) small, and (b) large chips of PET [13]. Reprinted from Polymer, 39, Huang, B. and Walsh, J. J., Solid-phase polymerization mechanism of poly(ethylene terephthalate) affected by gas flow velocity and particle size, 6991-6999, Copyright (1998), with permission from Elsevier Science...

Figure 18.13 Effect of fluorescent device exposure on hydroperoxide production in Spectar copolymer [11]. Reprinted from Polymer, 41, Grossetete, T., Riva-ton. A., Gardette, J.-L., Hoyle, C. E., Ziemer, M., Fagerburg, D. R. and Clauberg, H., Photochemical degradation of poly(ethylene terephthalate)-modified copolymer, 3541-3554, Copyright (2000), with permission from Elsevier Science...

This article is an overview of the novel technology of self-reinforced LCPs with polyesters, poly(ethylene terephthalate) (PET) and poly(ethylene naphtha-late) (PEN) [10-13, 21, 23], LCP/polyester blends in a polyester matrix form in situ fibrils which improve the mechanical properties. LCPs have an inherently low melt viscosity, and provide LCP/polyester blends that effectively lower the melt viscosity during melt spinning [24], and fast injection-molding cycles. The miscibility between the LCP and polyesters can be controlled by the degree of transesterification [25] in the reactive extrusion step, and fibril formation in LCP-reinforced polyester fibers has been studied. 

Blends of poly (ethylene terephthalate) (PETP) and polypropylene (PP) with different rheological properties were dry blended or compounded, and extrusion foamed using both physical blowing and chemical agents, and the foam properties compared with those of foam produced from the individual components in the absence of compatibilisers and rheology modifiers. The foams were characterised by measurement of density, cell size and thermal properties. Low density foam with a fine cell size was obtained by addition of a compatibiliser and a co-agent, and foamed using carbon dioxide. The presence of PP or a polyolefin-based compatibiliser did not effect... 

T. Bhaskar, M. Tanabe, A. Muto, and Y. Sakata, Pyrolysis study of a PVDC and HIPS-Br containing mixed waste plastic stream Effect of the poly(ethylene terephthalate), /. Anal. Appl. Pyrolysis, 77(l) 68-74, August 2006. 

Wang, D.Y., Ge, X.G., Wang, Y.Z., Wang, C., Qu, M.H., and Zhou, Q. 2006. A novel phosphorus-containing poly(ethylene terephthalate) nanocomposite with both flame retardancy and anti-dripping effects. Macromol. Mater. Eng. 291 638-645. 

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