Abstract: Method to improve the barrier properties of composite gas cylinders and high pressure gas cylinder having enhanced barrier properties. The instant invention pertains to a new method for improving the barrier properties of composite gas cylinders for the storage of gas, by wrapping the outer surface of a composite gas cylinder with a plastic film comprising a barrier material in a winding process. The composite gas cylinder comprises an inner liner made of polyolefin and an outer fibre-reinforced, pressure supporting layer. The barrier material may comprise polyamide, polyester, halogen substituted polymer, EVOH or a metallization. The invention pertains also to a high pressure composite gas cylinder having enhanced barrier properties and its use as a fuel tank in gas driven automotive vehicles equipped with a combustion engine.

Abstract: Method to improve the barrier properties of composite gas cylinders and high pressure gas cylinder having enhanced barrier properties The instant invention pertains to a new method for improving the barrier properties of composite gas cylinders for the storage of gas, by sheathing the outer surface of a composite gas cylinder with a tubular plastic film comprising a barrier material and shrinking it by heat treatment to approach a strong connection. The composite gas cylinder comprises an inner liner made of polyolefin and an outer fibre-reinforced, pressure supporting layer. The barrier material may comprise polyamide, polyester, halogen substituted polymer, EVOH or a metallization. The invention pertains also to a high pressure composite gas cylinder having enhanced barrier properties and its use as a fuel tank in gas driven automotive vehicles equipped with a combustion engine.

Abstract: This invention relates to a process for increasing the molecular weight of polyesters, copolyesters or polyester blends by adding an organic phosphate to the processing apparatus and fusing the mixture to above the melting point, in which process the processing apparatus is a single-screw extruder, twin-screw extruder, planetary-gear extruder, ring extruder or co-kneader having at least one vent zone to which underpressure is applied.