Determination of Thermal Conductivity of LDPE Using Dual Hot Wire Probe Method

Abstract

Thermal conductivity is the one of most significant parameters in materials when it comes to the industrial applications, it is important to know the thermal conductivity of materials for materials selection, especially when thermal insulation is required. However, the techniques available in laboratory scale to measure the thermal conductivity of poor thermal conductors like polymers, meeting reliability and economy are not available. This research focuses on developing an instrument to measure the thermal conductivity of polymers that overcome the inherent problems in the existing methods. Measuring of the thermal conductivity can be done either at the steady state conditions or transient conditions. The temperature measurements of the polymer specimen in the transient state were done based on the well-known "Transient Hot-Wire Probe Theory". Here, basically the temperature of a linear heat source embedded in the specimen, which is read at different time intervals and supplied energy to the heat element were the interested quantities and a programmed micro-controller was used to control the sensing elements of the system (thermocouples, current and voltage sensors) by performing pre-defined or user intended functions. Likewise micro-controller then reads out the sensor signals accordingly, to process and produce results in a useful manner (temperature vs time behavior) so that the thermal conductivity can be calculated according to the theory.