Heat-shrinkable materials

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

Irradiation of LDPE/EVA blends has been extensively studied because of their particular interest as heat-shrinkable materials for the wire and cable industry. ° Heat-shrinkable materials are a kind of shape mem-... 

Production sequence for heat-shrinkable materials is as follows. 

Ash D.O. and Solomon R.G., HV Cable Jointing with Heat Shrinkable Materials, Electrical Times, 10 Aug. 1972. 

The following examples show thermally induced shape-memory. The first three examples are exclusively physically cross-linked. These examples are two polyurethanes representing thermoplastic shape-memory polymers with Ttrans = Tm or Tg, and a high molecular weight, amorphous polynorbornene. Examples of covalently cross-linked shape-memory networks are so-called heat-shrinkable materials and a shape-memory network with a crystallizable switching segment (Ttrans = Tm) that has been developed for biomedical application. 

The main aim of this review is to highlight the various smart polymeric materials and the drug delivery systems (DDS) that exploit them. These are useful to realize biomimetic devices [18], intelligent medical instruments and auxiliaries [19, 20], electrochemical devices [21], artificial muscles [22], heat shrinkable materials for electronics packaging [23], microelectromechanical systems [24] and actuators and sensors [25],... 

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]. 

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 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... 

An example system is PVC and polyethylene wire and cabling irradiated to improve stresscracking resistance, abrasion resistance, high-temperature properties and flame retardance, via controlled electron-beam crosslinking (Loan, 1977). Additionally electron-beam crosslinking is utilized to impart memory into a polymer system, such as crosslinked PE materials for heat-shrinkable films and pipe applications (Baird, 1977). The control of electron-beam processing has advanced the quality of cell size and shape of PE foams via control of crosslink distribution (Paterson, 1984). 

Slot liners, for example, are used in motor and generator construction to separate and insulate coils of magnet wire from the slot walls in the steel stator, and films are also used to separate different coils of wire from one another (phase separation) in motors. For these applications, materials with good electrical, thermal, and mechanical properties are required. Special grades are applied in capacitors and heat-shrinkable tubing. 

Structures of two different materials have been made in which the heat-shrinkable tubing has a lining of a hot-melt adhesive. Upon heating, the combined melting of the adhesive and the shrinking of the tubing produce a tight and firmly bonded jacket around the object to be protected. 

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