Poly ethylene terephthalate properties

Most of the polymer s characteristics stem from its molecular stmcture, which like POE, promotes solubiUty in a variety of solvents in addition to water. It exhibits Newtonian rheology and is mechanically stable relative to other thermoplastics. It also forms miscible blends with a variety of other polymers. The water solubiUty and hot meltable characteristics promote adhesion in a number of appHcations. PEOX has been observed to promote adhesion comparable with PVP and PVA on aluminum foil, cellophane, nylon, poly(methyl methacrylate), and poly(ethylene terephthalate), and in composite systems improved tensile strength and Izod impact properties have been noted. 

Polyimide. Polyimide is a biaxiaHy oriented high performance film that is tough, flexible, and temperature- and combustion-resistant. Its room temperature properties compare to poly(ethylene terephthalate), but it retains these good characteristics at temperatures above 400°C. Its electrical resistance is good and it is dimensionally stable. The principal detriment is fairly high moisture absorbance. The main uses are for electrical insulation, particularly where high temperatures are prevalent or ionizing radiation is a problem. The films may be coated to reduce water absorption and enhance... 

The film tube is collapsed within a V-shaped frame of rollers and is nipped at the end of the frame to trap the air within the bubble. The nip roUs also draw the film away from the die. The draw rate is controlled to balance the physical properties with the transverse properties achieved by the blow draw ratio. The tube may be wound as such or may be sHt and wound as a single-film layer onto one or more roUs. The tube may also be direcdy processed into bags. The blown film method is used principally to produce polyethylene film. It has occasionally been used for polypropylene, poly(ethylene terephthalate), vinyls, nylon, and other polymers. 

In conventional tenter orientation, the sequence of steps is as described above (MD—TD). In some cases it is advantageous to reverse the draw order (TD—MD) or to use multiple draw steps, eg, MD—TD—MD. These other techniques are used to produce "tensilized" films, where the MD tensile properties are enhanced by further stretching. The films are generally unbalanced in properties and in extreme cases may be fibrillated to give fiber-like elements for special textile appHcations. Tensilized poly(ethylene terephthalate) is a common substrate for audio and video magnetic tape and thermal transfer tape. 

BiaxiaHy oriented films have excellent tensile strength properties and good tear and impact properties. They are especially well regarded for their brilliance and clarity. Essentially all poly(ethylene terephthalate) film is biaxiaHy oriented, and more than 80% of polypropylene film is biaxiaHy oriented. Polystyrene film is oriented, and a lesser amount of polyethylene, polyamide, poly(vinyl chloride), and other polymers are so processed. Some of the specialty films, like polyimides (qv), are also oriented. 

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

Polyester. Poly(ethylene terephthalate) [25038-59-9] (PET) polyester film has intermediate gas- and water- vapor barrier properties, very high tensile and impact strengths, and high temperature resistance (see Polyesters, thermoplastic). AppHcations include use as an outer web in laminations to protect aluminum foil. It is coated with PVDC to function as the flat or sealing web for vacuum/gas flush packaged processed meat, cheese, or fresh pasta. 

Of practical interest are detailed studies to influence the magnetooptical properties of RE-TM materials by the substrate material and the substrate adhesion of RE-TM layers by the selected deposition technique (226). Accordingly, measurements have been performed on glass, BPA-polycarbonate, and poly(ethylene terephthalate) (as a flexible substrate). 

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. 

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. 

Properties of PET Molding Resins. The fliU crystal stmcture of poly(ethylene terephthalate) has been estabhshed by x-ray diffraction (134—137). It forms triclinic crystals with one polymer chain per unit cell. The original cell parameters were estabhshed in 1954 (134) and numerous groups have re-examined it over the years. Cell parameters are a = 0.444 nm, b = 0.591 nm, and c = 1.067 nm a = 100°, (3 = 117°, and 7 = 112° and density = 1.52 g/cm. One difficulty is determining when crystallinity is fliUy developed. PET has been aimealed at up to 290°C for 2 years (137). 

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). 

Property Polypropylene Poly(ethylene terephthalate) Nylon-6,6... 

Two often used polymers have adequate properties for some appHcations. Poly(ethylene terephthalate) (PET) is used to make films and bottles. 

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. 

Blends of the polysulfone tesia have been made with ABS, poly(ethylene terephthalate), polytetrafluoroethylene (PTFE), and polycarbonate. These ate sold by Amoco under the Miadel trademark. Additional materials ate compounded with mineral filler, glass, or carbon fiber to improve properties and lower price. 

Although it is a polar polymer, its electrical insulating properties at room temperature are good even at high frequencies owing to the fact that since room temperature is well below the transition temperature dipole orientation is severely restricted. Some data on the crystallinity of poly(ethylene terephthalate) are presented in Table 25.5. 

This polymer has a slightly stiffer chain and hence slightly higher melting point and heat distortion temperatures than poly(ethylene terephthalate). Films are available (Kodel-Kodak) which have been biaxially stretched about 200% from polymer with molecular weights of about 25 000. They are similar electrically to poly(ethylene terephthalate), are weaker mechanically but have superior resistance to water and in weathering stability. Some properties are given in Table 25.6. 

Table 25.7 Some properties of poly(ethylene terephthalate) moulding material ( Amite ) (ASTM Test Methods unless otherwise stated.)...

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. 

Multilayered materials owe their properties and behavior to the properties of and the interactions between the components (5). Each of the two or more components contributes its particular property to the total performance of the multilayered material. For example, in Pouch 1, Table II, the aluminum foil provides high oxygen and water vapor permeability resistance, poly (ethylene terephthalate) provides structural strength and stiffness, and the ethylene-butene copolymer provides a heat sealable layer. If the components of the multilayered materials interact then the whole would be something different than the sum of its parts. In other words, the properties of the components of the multilayered materials are not independent of one another but rather are interdependent. 

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