Heat-Shrinkable Tubing

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

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. 

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

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. ... 

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. 

Alternative patented method of producing heat-shrinkable tubing. 

Production and application of heat-shrinkable tubing on a wire splice. (Radiation Processing of Polymers (Singh, A., and Silverman, Eds.) Carl Hanser Publishers, p. 20 (1992). With permission from Carl Hanser Publishers.)... 

Heat-shrinkable sheets (thickness 0.040 to 0.120 in., or 1-3 mm) and films (thickness 0.001 to 0.020 in., or 0.025 to 0.5 mm) are fabricated from many of the same materials as shrinkable tubing. They are produced by extrusion as a tube, sheet, or blown film. Irradiation is done by the equipment shown... 

Heat shrink sheets are used for many of fhe same applications as heavy wall shrink tubing. The advantage of the sheet over a tube is that it can be conveniently slipped over the area to be protected, for example, over continuously installed cable. There are many methods to close the heat-shrinkable sheets, such as zippers, rail and channel, heat-sealable bonds, etc., some of them patented. ... 

FIGURE 8.9 The process of producing heat-shrinkable polyethylene tubing and the use of the tubing to cover a wire joint Two-sided irradiation of a wire by electron beam. (Singh, A. and Silverman, 1, Eds., Radiation Processing of Polymers, Hanser, Munich, 1992. With permission.)... 

Polyethylene was also susceptible to picking up radionuclides from the primary coolant. This interference was eliminated by sealing the sealed polyethylene vials into heat-shrinkable tubing which was easily removed after sample irradiation. 

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