Testing.8 – Transient Plane Source Polymer Series Summary

Oct 2, 2015 | Blog, Testing |

Various samples of plastic polymers were tested in a Transient Plane Source (TPS) polymer series. High temperature and general plastics were tested for thermal conductivity and thermal diffusivity using the Hot Disk Transient Plane Source 2500 S instrument. This instrument has the capability of measuring absolute bulk and directional thermal conductivity and thermal diffusivity for solids, liquids, pastes and powders without the need for calibration or contacts agents.

Having only one piece of sample material for each plastic made thermal properties testing an ideal job for the Hot Disk TPS single-sided sensor. This sensor was designed specifically for performing tests when only one sample piece is available or when testing large, hard to handle samples.

Polymers that were tested are: polyetherimide, polyphenyl sulfone, polyphenylene sulfide, polyvinyl chloride, fluorinated ethylene propylene, and polyamide-imide.

Table 1.  Summary table of polymers measured with corresponding bulk thermal properties values and reference thermal conductivity value.

Polymer Name

 
Bulk Thermal Conductivity
(W/m•K)

Bulk Thermal Diffusivity
(mm2/s)
 
General/ High Temperature
 
Isotropic/ Anisotropic
Reference Thermal Conductivity
(W/m•K)
Polyetherimide (Ultem) 0.22377 0.17325 High Temperature Isotropic 0.221
Polyphenyl sulfone (PPSU) 0.3097 0.2043 High Temperature Isotropic 0.302
Polyphenylene sulfide (PPS) 0.2989 0.1928 High Temperature Isotropic 0.303
Polyvinyl chloride (PVC) 0.18716 0.14783 General Isotropic 0.164
Fluorinated ethylene propylene (FEP) 0.21953 0.13689 High Temperature Isotropic 0.20 ± 0.045

Polyamide-imide (Torlon) was measured using the Hot Disk TPS anisotropic module after discovery that the measured bulk thermal conductivity value was quite high in comparison to the reference. An important consideration when comparing bulk to through-thickness values, like measured values by ASTM C177*, is the possibility that the materials may be anisotropic. It was then decided the Torlon sample should be investigated for anisotropy.

Table 2. Summary table for Torlon with corresponding through-thickness thermal properties values and reference thermal conductivity value.

 
Polymer
Name
 
Through-Thickness Thermal Conductivity
(W/m•K)
 
Through-Thickness Diffusivity
(mm2/s)
 
General/ High Temperature
 
Isotropic/ Anisotropic

Reference Thermal Conductivity
(W/m•K)
Polyamide-imide (Torlon) 0.55045 0.45871 High Temperature Anisotropic 0.546

The experimental results showed the accuracy of the Hot Disk transient plane source (TPS) method for testing low conductivity materials such as plastic polymers. It is also a valid indication of the high precision and accuracy of the Hot Disk single-sided sensor when double-sided testing is not favourable.