Heat shrinkability

Manufactured PVDF parts can be cross-linked using high energy radiation to produce high temperature wire insulation, and heat-shrinkable tubing or film. 

A triangular shaped wheel cover with the center cut out to provide hub access was then applied to a wheel. The cover was constructed from a heat shrinkable poly- 10 olefin ftlm. Tape was attached to the apex points of the triangle. The tape liner was removed and the three adhesive sites were fastened to the spokes. As an identical complementary cover was then applied to the opposite face of the wheel in a mirror image fashion. The 1 adhesive contact points were positioned to encapsulate the spoke on either side within the adhesive contact point. Heat was then used to shrink the covers and achieve a wrinkle-free condition. This example demonstrates that design can play a part in providing a stylish wheel cover that is capable of individualizing the bicycle to meet a wide variety of consumer tastes. 

A heat shrinkable aerodynamic wheel cover comprising... 

The vehicle wheel of claim 13, comprising a second heat shrinkable wheel cover positioned over the second side of the wheel. 

Thin coatings consist of paints and varnishes, which are applied as liquids or powdered resin with a thickness of about 0.5 mm [e.g., epoxy resin (EP) [2]]. Typical thick coatings are bituminous materials [3] and polyolefins [e.g., polyethylene (PE) [4]], thick coating resin combinations [e.g., EP tar and polyurethane (PUR) tar [2]] as well as heat-shrinkable sleeves and tape systems [5]. 

Electron beam-initiated modification of polymers is a relatively new technique with certain advantages over conventional processes. Absence of catalyst residue, complete control of the temperature, a solvent-free system, and a source of an enormous amount of radicals and ions are some of the reasons why this technique has gained commercial importance in recent years. The modification of polyethylene (PE) for heat-shrinkable products using this technique has been recently reported [30,31]. Such modification is expected to alter the surface properties of PE and lead to improved adhesion and dyeability. 

Fluorocarbons (PTFE, FEP, PVF2) Powder, emulsions Excellent high temperature properties. TFE to 500 F. FEP is easier to mold, but maximum use temperature is 400 F. Nearly inert chemically. Nonflammable. Loading with conductive filler improves creep resistance. Low coefficient of friction. High-temperature cable shielding, gaskets, heat-shrinkable tubing. 

Polyolefins (Polyethylene, Polypropylene) Powder, pellets Tough and chemical resistant. Weak in creep and thermal resistance. Polyethylene maximum use temperature 210 F, polypropylene 260 F. May be injection and extrusion molded, vacuum formed. Low cost. Antistatic sheet and tiles, heat-shrinkable tubing, deicer boots. 

PVC, PVA, PVAC, Copolymers) organosols forms available including hard and flexible types. Properties are highly dependent on plasticizer used. May be injection, extrusion, compression molded, vacuum formed. Low cost. antistatic sheet and hose, RF gaskets, heat-shrinkable tubing. 

Over the last few decades, the use of radiation sources for industrial applications has been widespread. The areas of radiation applications are as follows (i) Wires and cables (ii) heat shrinkable tubes and films (iii) polymeric foam (iv) coating on wooden panels (v) coating on thin film-video/audio tapes (vi) printing and lithography (vii) degradation of polymers (viii) irradiation of diamonds (ix) vulcanization of mbber and rubber latex (x) grain irradiation. 

The radiation-treated cables find wide applications in control instmmentation of nuclear power reactors, particle accelerators, aviation, and telephone equipments. Usually PE and PVC are radiation cross-linked for production of such cables. The heat shrinkable foils are widely used in packaging, electrical and electronic industries. The radiation cross-linked PE possesses the property of elastic memory which is utilized to produce heat shrinkable products. 

Cross-linking of wire and cables, heat shrinkable polymeric tubes and films, and PE foam. 

Thermoplastic Films. Recently, thermoplastic film [1342,1343] materials have been developed to reduce the proppant flowback that can occur after fracturing treatments. A heat-shrinkable film cut into thin slivers provides flowback reduction over broad temperature ranges and closure stress ranges... 

Heat-shrinkable films, 28 46 Heat shrinkable polymers, 22 364 Heat sinks, 26 756 silver in, 22 658 Heatsink slugs, 24 864 Heats of reaction, in DR Processes,... 

Wire and cable insulation consumes 4% of all PVC with construction and automotive wires, electrical cord jacketing, fibre optic sheathing, heat-shrinkable sleeves. .. Components in phone systems, power tools, refrigerators, washing machines, air conditioners, computers, keyboards, housings. .. 

ICT machines produced recently have energy ratings from 0.3 to 3.0 MeV and beam power capabilities up to 100 kW. Nearly 180 of these machines, the majority of them rated for less than 1 MeV, have been installed as of the early 1990s. They are used mainly for cross-linking of heat-shrinkable film, plastic tubing, and electric wire. ... 

The formation of carbon-carbon cross-links is by far the most important effect and is the basis of the applications in wire and cable industry and for heat-shrinkable products. The factors affecting the changes of polyethylene by irradiation are the molecular weight distribution, branching, degree of unsaturation, and morphology. °... 

Electron Beam Process in the Production of Heat-Shrinkable Materials... 

Heat-shrinkable tubing is made typically from polyolefins, PVC, polyvinyl fluoride, PTFE, their blends, or blends with other plastics and elastomers. The formulations may be designed for chemical resistance, heat resistance, flame resistance, etc. ... 

Original Raychem patent for heat-shrinkable tubing. 

---