Polyethylenes crosslinked

Crosslinked polyethylene consists of molecular chains that are linked at random points to form a network, as shown schematically in F. 18.2 f). The crosslinks can consist of carbon-carbon bonds, which directly link adjacent chains, or short bridging species, such as siloxanes, which may link two, three, or four chains. We often refer to these materials as XLPE. 

---

R. B. Blodgett, "Ethylene—Propylene Rubber and Crosslinked Polyethylene as Insulations for 90°C Rated Medium Voltage Cables," Rubber Chem. Technol, 52, 410-424 (1978). 

Heat-shrink crosslinked polyethylene DIN 30672 Flame or heat gun in fieid 1-25-2-25 Utiiised for coating of field weld joints and repairs on extruded polyethylene coated pipes. Careful application required to achieve consistent bond. 

Weld joints may be coated in the field with FBE powder, utilising a portable blast cleaning/induction heating and powder application system. Alternatively joints may be provided with self-adhesive laminate tapes or heat-shrink crosslinked polyethylene sleeves. 

Repairs to the coating are made with either hot-melt polyethylene sticks or polyethylene sheet patches with mastic profiling compounds for small damaged areas. Large repair areas are best treated as for field weld joint coating, where either heat-shrink crosslinked polyethylene sleeves or cold-applied self-adhesive laminate tapes are employed. 

The very first studies with radiation crosslinked polyethylene oxide (PEO) have shown that SAH is able to substantially reduce the sensitivity of plants to water shortage [7], to promote their growth, particularly, under conditions of water deficiency [8], to improve seedling survival and the final crop [9], These results stimulated a more detailed analysis of the effects of SAH in the water balance of... 

Sometimes, part design requires multiple polymer layers. For example, an automotive gasoline tank can consist of both nylon and crosslinked polyethylene to provide combined chemical [-, resistance and strength, To produce multilayered parts, the first polymer, which will form... 

Polyethylene is, by far, the most commonly used resin in rotational molding processes. Low density, high density, and linear low density polyethylene are all used extensively. Additionally, crosslinked polyethylene is used for parts that require high chemical or heat resistance or enhanced impact resistance. 

We typically crosslink polyethylene using one of two different strategies we can create direct crosslinks between chains via a free radical mechanism or we can create short chemical bridges between chains. 

The continuous use temperatures in an unstressed state are generally estimated from 90°C for LDPE up to 110-120°C for HDPE and 130°C for crosslinked polyethylenes if the softening or melting temperatures are higher. For example, the sealing temperature of a given grade of VLDPE is 83°C. 

ISO 10146 1997 Crosslinked polyethylene (PE-X) pipes - Effect of time and temperature on the expected strength... 

ISO 15875-1 2003 Plastics piping systems for hot and cold water installations - Crosslinked polyethylene (PE-X) - Part 1 General... 

ISO 15875-5 2003 Plastics piping systems for hot and cold water installations - Crosslinked polyethylene (PE-X) - Part 5 Fitness for purpose of the system ISO/TS 15875-7 2003 Plastics piping systems for hot and cold water installations - Crosslinked polyethylene (PE-X) - Part 7 Guidance for the assessment of conformity... 

PolyEthyleneGlycol/cyclohexylene-dimethylenediolTerephthalate PhenylEthynyl with Imide Terminations Crosslinked PolyEthylene Phenolic resin... 

Denning s three papers in the late 1960s (a.2-a.4) reviewed the development of closed-cell polyolefin foams, and their mechanical properties. Some of his predictions on materials development turned out to be true. In Part I he explains that non-crosslinked polyethylene (PE) foams have inferior creep properties to crosslinked foams this appeared to be the tensile creep of the melt, rather than compressive creep of the... 

Journal of Polymer Science Polymer Physics Edition 39, No.18, 15th Sept.2001, p.2159-67 RHEOLOGICAL PROPERTIES AND FOAM PROCESSABILITY FOR BLENDS OF LINEAR AND CROSSLINKED POLYETHYLENES Yamaguchi M Susuki K-I Tosoh Corp. 

Journal of Cellular Plastics 36, No.l, Jan./Feb.2000, p.29-44 NONISOTHERMAL MELTING AND CRYSTALLISATION OF FOAMED CROSSLINKED POLYETHYLENE Kotzev G Touleshkov N Christova D Nedkov E Bulgarian Academy of Sciences... 

EXPERIMENTS AND MODELLING OF THE EXPANSION OF CROSSLINKED POLYETHYLENE FOAMS... 

Mainz, Germany, 4th-5th Nov.1997, p.65-85. 6124 LABORATORY EVALUATION OF METALLOCENE RESINS IN CROSSLINKED POLYETHYLENE (XLPE) FOAM HeckRL... 

Toronto, 27th April-2nd May 1997, p.2000-4. 012 CHARACTERISATION OF CROSSLINKED POLYETHYLENE FOR FOAM EXPANSION USING BUBBLE MACHINE Park C P... 

Cellular Polymers 111. Conference proceedings. Coventry, 27th-28th April 1995, paper 13. 6124 CELL STRUCTURE DEVELOPMENT IN COMPRESSION MOULDED CROSSLINKED POLYETHYLENE AND ETHYLENE-VINYL ACETATE FOAM Sims G L A Khunniteekool C UMIST... 

Patent Number US 5350544 A 19940927 METHOD OF PREPARING A CROSSLINKED, POLYETHYLENE FOAM PRODUCT BY SURFACE EXPANSION OF A FOAM... 

ASTM D2513 specifies requirements for thermoplastic materials for buried fuel gas and relining applications. Materials addressed include PE, PVC, and crosslinked polyethylene (PEX). Tubing sizes covered are through IV4 in. IPS sizes covered are J through 12 in. Size availability depends upon the material. 

Preparation of crosslinked polyethylene glycol a-cyclodextrin polyrotaxane... 

New theories and findings on the formation of ionic species and radicals, which become trapped in the polymers, are discussed in the first two chapters, written by the two European authorities, Chapiro and Charlesby. The kinetics of crosslinking polyethylene is the subject of the American authority, Dole. A higher yield of crosslinking polyolefins was observed in the presence of nitrous oxide by the Japanese scientist, Okada. 

In order to investigate the structure of crosslinked polyethylene by, 3C NMR the model compound l,l,2,2-tetra(tridecyl)ethane, i.e. two molecules of n-C27H56 linked at the C-14 atoms, was prepared. The tertiary 13C-14 atoms give rise to a resonance signal at 39.5 ppm. Spectra of long chain n-paraffins eicosane (C20H42) and hexacosane (C26H54) exposed to 5 MGy y-radiation above their respective... 

---