Hardness tests

The hardness of the resins were measured using a Shore S1-D hardness tester, factory calibrated and checked against the supplied reference block.

An epoxy hardness pit

Ten readings were taken from each resin disk. The highest and lowest readings were rejected and the average and standard deviation of the remaining eight are listed here. The hardness of ProbeMet and KonductoMet was not tested because of the inhomogeneity of the material.

Notes on Hardness

There are many scales used in the measurement of hardness. The unit most frequently used for resins is the Shore D scale. Some values from everyday objects (apart from Indium) are listed below:

Perspex

87.84 +/- 0.12​

PVC

81.10 +/- 0.47

Indium

29.5 +/- 0.42

Yellow BIC Biro Case

81.5 +/- 0.25

 

Epoxy Resin Supplier Specification (If Known) Shore D Hardness Avg (+/- Stdev)
EpoThin 78 79.1 +/- 0.71
EpoHeat 85 80.1 +/- 0.50
EpoxiCure (Room Temperature Cure) 82 85.3 +/- 0.46
EpoxiCure (Cured at 65'C) 82 84.9 +/- 0.18
TransOptic - 82.4 +/- 0.53
SpeciFix-20 84 82.8 +/- 0.45
EpoFix 78 80.1 +/- 1.10
Ciba Geigy  MY778 & HY951 - 82.1 +/- 1.23
Robnor Resin  PX771c 85 81.4 +/- 0.63
Korapox 439 - 79.4 +/- 0.84
Petropoxy - 85.3 +/- 0.78
Domestic Rapid Set Araldite - 78.9 +/- 0.34
Domestic Araldite - 78.5 +/- 0.76
Varian  Torr Seal - 83.8 +/- 0.97
Epotek 85 87.5 +/- 0.14

 

Nanoindentation Tests

Experiments were carried out by Wenzhong Zhu at the University of the West of Scotland. Two sets of indentation test were carried out on each specimen: One test batch of three test points at maximum load of 100 mN, the other batch of nine test points at a maximum load of 10 mN. The spacing between the indentation points is 100 µm.

Indent Load ~10mN

Epoxy Resin Youngs Modulus GPa Avg (+/- Stdev) Hardness GPa Avg (+/- Stdev)
Korapox 439 2.335 +/- 0.050 0.084 +/- 0.001
Transoptic 2.737 +/- 0.056 0.094 +/- 0.002
EpoThin 3.495 +/- 0.098 0.126 +/- 0.007

Indent Load ~100mN

Epoxy Resin Youngs Modulus GPa Avg (+/- Stdev) Hardness GPa Avg (+/- Stdev)
Korapox 439 2.323 +/- 0.039 0.079 +/- 0.001
Transoptic 2.777 +/- 0.015 0.090 +/- 0.002
EpoThin 3.506 +/- 0.016 0.123 +/- 0.001

 

This article was published on