Polyethylene tetrafluoroethylene plastics

The authors of the above-discussed results consider the constant rate of heparin elution to be absolutely necessary for a successful functioning of the implant. Catheters made of these copolymers are much better, in respect of their thromboresistant properties, than the commercially available poly(tetrafluoroethylene) polyethylene, and plasticized polyvinyl chloride catheters (Table 8). The tested catheters were clotted in 9 cases of 81 (11 %), whereas usual silicone rubber catheters were clotted in 5 cases of 8 (63 %)70). 

Liquid polyalurninum chloride is acidic and corrosive to common metals. Suitable materials for constmction of storage and handling facilities include synthetic mbber-lined steel, corrosion resistant fiber glass reinforced plastics (FRP), ceramics, tetrafluoroethylene polymer (PTFE), poly(vinyhdene fluoride) (PVDF), polyethylene, polypropylene, and poly(vinyl chloride) (PVG). Suitable shipping containers include mbber-lined tank tmcks and rail cars for bulk shipment and plastic-lined or aH-plastic dmms and tote bins for smaller quantities. Except for aluminum chlorohydrates, PAG products are shipped as hazardous substances because of their acidity. 

Fig. 11. Effect of polyolefin primers on bond strength of ethyl cyanoacrylate to plastics. All assemblies tested in accordance with ASTM D 4501 (block shear method). ETFE = ethylene tetrafluoroethylene copolymer LDPE = low-density polyethylene PFA = polyper-fluoroalkoxycthylene PBT = polybutylene terephthalate, PMP = polymethylpentene PPS = polyphenylene sulfide PP = polypropylene PS = polystyrene PTFE = polytetrafluoroethylene PU = polyurethane. From ref. [73].

Abbreviations for plastics ABS, acrylonitrile-butadiene-styrene CPVC, chlorinated poly vinyl chloride ECTFE, ethylene-chlorotrifluoroethylene ETFE, ethylene-tetrafluoroethylene PB, polybutylene PE, polyethylene PEEK, poly ether ether ketone PFA, perfluoroalkoxy copolymer POP, poly phenylene oxide PP, polypropylene PVC, polyvinyl chloride PVDC, poly vinylidene chloride PVDF, poly vinylidene fluoride. 

In spite of Baekeland s success, it was another two decades before the Age of Polymers can really be said to have been born. The 1920s and 1930s saw the invention and/or commercialization of a number of new polymeric products ("plastics") that most consumers now consider to he essential chemicals in their lives. These products include the urea formaldehyde plastics (1923), polyvinyl chloride (PVC 1926), polystyrene (1929), nylon (1930), polymethylmethacrylate (acrylics 1931), polyethylene (1933), the melamine plastics (1933), polyvinylidene chloride (Saran 1933), polyvinyl acetate (PVA 1937), and tetrafluoroethylene (Teflon 1938). 

Figure 10.17 DSC curves of plastic waste containing several polymers low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), Nylon-6 , Nylon-66 and poly-tetrafluoroethylene (PTFE). (Reproduced with kind permission of Springer Science and Business Media from M. Brown, Introduction to Thermal Analysis, Kluwer Academic Publishers, Dordrecht. 2001 Springer Science.)...

The polymer may be represented as CH3(CH2—CH2) CH3, where n is approximately 400. Polyethylene is a tough, flexible plastic. It is widely used as an electrical insulator and for the fabrication of such items as unbreakable refrigerator dishes, plastic cups, and squeeze bottles. Polypropylene is made by polymerizing propylene, CH3—CH=CH2, in much the same way. Teflon is made by polymerizing tetrafluoroethylene in a similar reaction. 

The experimental protocol of our studies involved the exposure of fresh healthy platelet-rich plasma (PRP) of young males to 9 pure synthetic polymers, namely polyethylene, ethylene-butylene copolymer, ethylene-propylene copolymer, ethylene-ethylacrylate copolymer, ethylene-vinylacetate copolymer, ethylene-methylmethacrylate sodium ionomer, nylon 12, polyurethane, and tetrafluoroethylene-hexafluoropro-pylene copolymer ( Figure-1). Polymer pellets tested have been especially synthesized under clean conditions and were substances of known composition, free of plasticizers and... 

However, the curiosity-motivated research on fluoro-oleftn polymers was well rewarded and a variety of novel products tumbled out. First came plastic polyvinyl fluoride and polyvinylidene fluoride each of which had remarkable physical properties. Then Tom Ford discovered that flexible but leathery products were produced when he copolymerized vinylidene fluoride with some unsaturated monomers[3]. Hanford and Roland discovered that a copolymer of propylene with tetrafluoroethylene was rubbery and even recommended that it be cured with radiation or peroxide (Figure 2). About the same time 1 found that plastic polyethylene could be changed to a limp rubbery material by attachment of as little as 5 mol percent of trifluoromethylethylene (Figure 3)[5]. However, with the urgent pressures of the war, there wasn t enough manpower to pursue these leads. Then in the press of the post World War II industrial boom these developments were put aside. There were just too many ripe apples on the tree. 

Poly(Ethylene-Tetrafluoroethylene) n (PE-TFE) A crystalline resin in which the proportion of ethylene to tetrafluoroethylene (E/TFE) may range, for the best combination of properties, between 2 3 and 3 2, modified with a vinyl copolymer for better toughness. It is stronger than either low-density polyethylene or polytetrafluoroethylene, has good electrical properties, high Izod-impact strength, and plastic memory that makes it useful for heat-shrinkable packaging. 

An abbreviated list of medical applications for commodity polymers (Table 13.6) is an indication of the wide scope of both materials and their uses. Since many of these uses require small volumes of premium materials, it is often feasible to supplement commodity plastics by developing specialty polymers that would not otherwise be justified on an economic basis. In the examples that follow, one encounters both commodity polymers such as ultrahigh-molecular-weight polyethylene (UHMWPE) and poly(tetrafluoroethylene) (PTFE), and specialty polymers such as the polyanhydrides and poly(glycolic acid). 

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