Meaning
International standardization protocols define transient planar source methods for determining thermal conductivity and thermal diffusivity of plastics. Compliance with ISO 17744 provides accurate thermal property data required for mold cooling simulations and heat transfer calculations. Steady-state thermal test methods often struggle with low-conductivity polymers, producing measurement errors due to contact resistance.
Standardized transient testing measures heat dissipation across solid, molten, and anisotropic plastic specimens under controlled temperature conditions.
Testing Protocol
A planar heating element sandwiched between two flat polymer samples generates a short heat pulse. Temperature-dependent resistance changes in the sensor track heat diffusion through the material over time. Test parameters adjust electrical power input to limit temperature rises within two degrees Celsius, preserving isotropic material conditions.
Specimen surfaces must be flat and parallel to eliminate air gaps at the sensor interface.
Thermal Transfer
Thermal conductivity values vary with melt temperature, polymer crystallinity, and filler orientation. Glass-filled resins display significant thermal anisotropy parallel and perpendicular to fiber flow lines. Standard testing procedures capture direction-dependent heat transfer properties by orienting sensor probes relative to processing direction.
Accurate thermal conductivity data prevents underestimating required mold cooling times during injection tool design.
Specification Utility
Reliable thermal transport data enables precise cycle time prediction in mold flow software. Polymer compounders publish standardized conductivity values to support toolmakers in designing efficient cooling channels. Rigorous thermal characterization reduces tooling modification costs and optimizes molding cycles.
