Thermal Analysis
Laboratory instrumentation measures the difference in the amount of heat required to increase the temperature of a sample and a reference as a function of temperature. Through differential scanning calorimetry, technicians identify the thermal transitions of polymers used in flexible packaging and rigid containers. Thermal analysis defines the melting points, glass transition temperatures, crystallization temperatures and heat of fusion for various resin grades.
Measurement Principle
Two separate furnaces or a single heat flux plate ensure that both the sample and the reference stay at the same temperature throughout a programmed heating or cooling ramp. The resulting data shows endothermic and exothermic peaks that correspond to specific molecular movements within the polymer chain.
Material Identification
Comparing the measured heat profile against known standards allows for the verification of resin purity and the detection of recycled content or contaminants. A mismatch in the melting peak often indicates the presence of a secondary polymer that might compromise the seal integrity or mechanical strength of a finished bag. This technique cannot identify chemical elements but provides a clear picture of the thermal history and crystalline structure of the substrate.
It also helps in determining the optimal temperature settings for heat sealing bars on a production line where a narrow operating window exists for multi-layer structures.
