ULTRASONIC DECROSSLINKING OF CROSSLINKED POLY (ETHYLENE)
Decrosslinking of crosslinked polyethylene with the aid of ultrasonics is considered in this study. Polyethylene is crosslinked with peroxide by heating and compression molding and then subjected to various levels of ultrasonic energies to break the bonds in the crosslinked polyethylene network. Properties of the resulting materials are then compared to original properties to determine the usefulness of the process. Apparatus used to perform continuous decrosslinking includes a one-inch single screw Killion extruder for pumping of the crosslinked polyethylene into a die fitted with the ultrasonic device. The die is designed to allow the material to pass through an area where it is uniformly subjected to ultrasonic energies of various levels. The ultrasonic energy is introduced to the material through a stepped horn using a Branson power source. During processing, conditions were set that included pressures and time for the static experiments, barrel temperatures, flow rates, and ultrasonic power consumption for the continuous experiment. Static experiments on crosslinked polyethylene were performed where specific amounts of crosslinked material were exposed to controlled ultrasound energy. This apparatus used the same power source but was discontinuous. Properties of treated and untreated material such as gel fraction, crosslink density, viscosity, and mechanical properties were measured. Comparisons of collected samples showed that the process is highly effective for decreasing linking of crosslinked polyethylene at specific processing conditions. Further study of this process will surely be beneficial.
School:The University of Akron
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:crosslinking decrosslinking ultrasonic polyethylene
Date of Publication:01/01/2007