Acetaldehyde Generation in Processing PET by Means of Hot Runner Systems

Polyethylene terephthalate (PET) is a polyester widely used as packaging material in drink-bottling application. PET is rather sensitive to heat and oxidation and during processing it may undergo degradation reaction with generation of acetaldehyde. In this work the generation of acetaldehyde in a hot runner system has been measured. A special test apparatus was developed to separate the contributions due to the action of the extruder screw from those due to the melt residence at high temperature. Results showed that the acetaldehyde content non-linearly increases with temperature and residence time. A model has been proposed to provide for the generation of acetaldehyde as a function of temperature and residence time regardless of the geometry and other specific conditions of the process.

BOEHLER UDDEHOLM ALLOY BeCu172

Boehler Uddeholm alloy BeCu172 is a high-strength beryllium copper mold with high thermal conductivity. BeCu Alloy 172 can be supplied in the high-hard (HH) condition at approximately 40 HRC and in the low-hard (LH) condition at approximately 30 HRC. This alloy is used for applications such as pinch-offs and neck rings for blow molds, cores, and inserts in injection molds and injection nozzles and manifolds for hot runner systems. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming, heat treating, machining, joining, and surface treatment. Filing Code: CU-781. Producer or source: Böhler-Uddeholm Corporation.