Thermoplastics density

Walsh, E. B Gallucci, R. R. and Courson, R., High density thermoplastic polyesters, in Proceedings of the 49th SPE ANTEC 91 Conference, May 5-9, 1991, Montreal, QC, Canada, Society of Plastics Engineers, Brookfield, CT, 1991, pp. 1334-1339. 

Miscellaneous applications of poly(phosphazenes) include ter-butoxycarbonyl protected materials for chemically amplified resists in microlithographythin film electroluminescent devices,optical wave guides, aryloxy derivatives as components of fire-, heat- and impact-resistant materials and components of a low-density, thermoplastic elastomeric, ablative insulation for rocket motors. ... 

S. Costeux, L. Zhu, Low density thermoplastic nanofoams nucleated by nanoparticles. Polymer (United Kingdom) 54 (11) (2013) 2785-2795. 

Decreased density is possible through use of fillers such as wood flour (or fibre), hollow glass microspheres, hollow polymer microspheres [22] (e.g., Expancel ) or hollow spheres from fly ash. Eow-density thermoplastic composites are useful for products that must float. 

Low-density thermoplastic foam cannot be heated to a forming temperature appropriate for the plastic without excessive cell collapse and poor product quality. Inadequate heating yields low secondary expansion and products that do not replicate the mold cavities with just vacuum. Pressure forming will collapse the foam cell structure. As a result, foam sheet is usually heated in roll-fed machines on traditional pin-chain rails. The ovens are usually extended in length and have heaters that gradually heat the sheet to temperatures where the increasing internal gas... 

Low-density thermoplastic foam sheet is thermoformed into products that are used primarily for thermal insulation, as in fast food takeaway containers, or for shock mitigation, as in egg cartons. The density of low-density foam sheet is typically 20% or less of the density of the unfoamed plastic sheet. Low-density foam sheet is usually produced by metering low-boiling liquids into the molten plastic through a port in the extruder barrel. Fine cells are... 

Ffigh-density polyethylene (HDPE) Thermoplastic elastomers... 

Polyurethane is pulverized to iacrease its bulk density, mixed with 30—80% of a thermoplastic mol ding material, gelled, and then granulated to give coated urethane foam particles 0.1 to 0.15 mm in size (48). The particle bulk density is three times that of the polyurethane, while the volume is 15% less. This material may be injection molded or extmsion molded into products (49). Other technologies for recycling polyurethanes have also been reported. 

This type of adhesive is generally useful in the temperature range where the material is either leathery or mbbery, ie, between the glass-transition temperature and the melt temperature. Hot-melt adhesives are based on thermoplastic polymers that may be compounded or uncompounded ethylene—vinyl acetate copolymers, paraffin waxes, polypropylene, phenoxy resins, styrene—butadiene copolymers, ethylene—ethyl acrylate copolymers, and low, and low density polypropylene are used in the compounded state polyesters, polyamides, and polyurethanes are used in the mosdy uncompounded state. 

HDPE, high density polyethylene PP, polypropylene EVA, ethylene—vinyl alcohol SMC, sheet-molding compound ERP, fiber-reinforced plastic LDPE, low density polyethylene PE, polyethylene BMC, bulk mol ding compound TPE, thermoplastic elastomer. 

Thermoplastics. The highest consumption of color concentrates is in thermoplastic resins, such as low and high density polyethylene, polypropylene, PVC, and polystyrene. Processing techniques for thermoplastics are usually based on dry color dispersion in a compatible resin (36). 

The physical properties of polyurethanes are derived from their molecular stmcture and deterrnined by the choice of building blocks as weU as the supramolecular stmctures caused by atomic interaction between chains. The abiHty to crystalline, the flexibiHty of the chains, and spacing of polar groups are of considerable importance, especially in linear thermoplastic materials. In rigid cross-linked systems, eg, polyurethane foams, other factors such as density determine the final properties. 

Crystallization and Melting Point. The abihty of PVA to crystallize is the single most important physical property of PVA as it controls water solubiUty, water sensitivity, tensile strength, oxygen barrier properties, and thermoplastic properties. Thus, this feature has been and continues to be a focal point of academic and industrial research (9—50). The degree of crystallinity as measured by x-ray diffraction can be directly correlated to the density of the material or the swelling characteristic of the insoluble part (Fig. 2). 

High Density Polyethylene. High density polyethylene (HDPE), 0.94—0.97 g/cm, is a thermoplastic prepared commercially by two catalytic methods. In one, coordination catalysts are prepared from an aluminum alkyl and titanium tetrachloride in heptane. The other method uses metal oxide catalysts supported on a carrier (see Catalysis). 

Polystyrene. Polystyrene [9003-53-6] is a thermoplastic prepared by the polymerization of styrene, primarily the suspension or bulk processes. Polystyrene is a linear polymer that is atactic, amorphous, inert to acids and alkahes, but attacked by aromatic solvents and chlorinated hydrocarbons such as dry cleaning fluids. It is clear but yellows and crazes on outdoor exposure when attacked by uv light. It is britde and does not accept plasticizers, though mbber can be compounded with it to raise the impact strength, ie, high impact polystyrene (HIPS). Its principal use in building products is as a foamed plastic (see Eoamed plastics). The foams are used for interior trim, door and window frames, cabinetry, and, in the low density expanded form, for insulation (see Styrene plastics). 

EiaaHy, a new aluminum fire-resistant paneling consists of a composite design that iacludes a soHd thermoplastic compound core covered with a high density polyethylene adhesive film and an aluminum skin. The product is easily formable. It has sound deadening abiHties, and an optional poly(vinyHdene fluoride) resia coatiag provides damage resistance. 

EthylceUulose [9004-57-3], a cellulose either (qv), as prepared commercially, ie, of high DS, is thermoplastic and has alow density (1.14 g/cm ). It forms films of good thermostabiUty and excellent flexibiUty and toughness. EthylceUulose is used in lacquers, inks, and adhesives and is combined with waxes and resins in the preparation of hot-melt plastics. It is also used as a pharmaceutical tablet binder. 

Blends of isobutylene polymers with thermoplastic resins are used for toughening these compounds. High density polyethylene and isotactic polypropylene are often modified with 5 to 30 wt % polyisobutylene. At higher elastomer concentration the blends of butyl-type polymers with polyolefins become more mbbery in nature, and these compositions are used as thermoplastic elastomers (98). In some cases, a halobutyl phase is cross-linked as it is dispersed in the polyolefin to produce a highly elastic compound that is processible in thermoplastic mol ding equipment (99) (see Elastomers, synthetic-thermoplastic). ... 

In the mid-1950s a number of new thermoplastics with some very valuable properties beeame available. High-density polyethylenes produced by the Phillips process and the Ziegler process were marketed and these were shortly followed by the discovery and rapid exploitation of polypropylene. These polyolefins soon became large tonnage thermoplastics. Somewhat more specialised materials were the acetal resins, first introduced by Du Pont, and the polycarbonates, developed simultaneously but independently in the United States and Germany. Further developments in high-impact polystyrenes led to the development of ABS polymers. 

Polyethylene is a wax-like thermoplastic softening at about 80-130°C with a density less than that of water. It is tough but has moderate tensile strength, is an excellent electrical insulator and has very good chemical resistance. In the mass it is translucent or opaque but thin films may be transparent. 

The specific heat of polyethylene is higher than for most thermoplastics and is strongly dependent on temperature. Low-density materials have a value of about 2.3 J/g at room temperature and a value of 2.9 J/g at 120-140°C. A somewhat schematic representation is given in Figure 10.9. The peaks in these curves may... 

Chlorination may be carried out with both high-density and low-density polyethylene. When carried out in solution the chlorination is random but when carried out with the polymer in the form of a slurry the chlorination is uneven and due to residual crystalline zones of unchlorinated polyethylene the material remains a thermoplastic. 

Thermoplastics grades have a norbomene content in the range 60-80% with Tg values from 60-180°C, in this range the glass transition being almost linearly related to the norbomene content. The modulus of elasticity increases with norbomene content and for commercial materials is in the range 2600-3200 MPa but density (1.02g/cm), tensile strength 66 MPa and water absorption (<0.01 %) is little affected by the monomer ratio. 

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