1. Royce International
3400 S Tamiami Trl
Sarasota, FL 34239
info@royceintl.com
941-894-1228

2. 1. Diluents Selected
 Aliphatic difunctional diluents
Neopentyl glycol diglycidyl ether (RoyOxy RAD 968)
1,4-butane-diol diglycidyl ether (RoyOxy RAD 77)
1,6-hexane-diol diglycidyl ether (RoyOxy RAD 968)
 Aliphatic trifunctional diluent
Trimethylol propane triglycidyl ether (RoyOxy RAD 948)
 Aromatic difunctional diluent
Resorcinol diglycidyl ether (RoyOxy RAD 981)

3. 2. Viscosity & Epoxy Equivalent Weight of Diluents used
Diluent EEW Viscosity at 25oC
RoyOxy RAD 968 137 14
RoyOxy RAD 77 110 13
RoyOxy RAD 986 124 16
RoyOxy RAD 948 128 230
RoyOxy RAD 981 113 165

4. 3. Efficiency of Diluents
(phr of diluent added to RoyOxy RAR 928 epoxy resin to obtain a viscosity of 2000 cP)
NPGDGE 19.8
BDGE 18.5
HDGE 14.3
TMPTGE 42.9
RDGE 50

5. 4. Viscosity of Mix with RoyOxy RAC 9923 and RoyOxy RAC 9924
Reactive Diluent RoyOxy RAC 9923 RoyOxy RAC 9924
Mix
Ratio phr
Viscosity Mix
Ratio phr
Viscosity
RAR 928 epoxy /
NPGDGE
30.1 2038 27.2 1812
RAR 928 epoxy /
BDGE
32.6 1223 29.4 996
RAR 928 epoxy/
HDGE
31.3 1857 28.3 1449
RAR 928 epoxy /
TMPTGE
34.1 2491 30.8 1857
RoyOxy RAR 928
epoxy / RDGE
36.5 2165 33 1882
RoyOxy RAR 928 29 5689 27 4587

6. 5. Gel Time and Pot-life in minutes
Gel Time at 80oC Pot Life at 25oC
Diluent RAC 9923 RAC 9924 RAC 9923 RAC 9924
NPGDGE 48 11 178 39
BDGE 43 9 127 33
HDGE 43 8 113 27
TMPTGE 29 8 110 29
RDGE 22 6 76 22
B-11 31 9 156 37

7. 6. Tg before and after post-curing
Tg before post curing Tg after post curing
RAC 9923 RAC 9924 RAC 9923 RAC 9924
NPGDGE 97 108 120.5 122
BDGE 100.5 107.5 118 134
HDGE 113.2 118.6 121.2 124.8
TMPTGE 105.5 111.8 132 135.9
RDGE 106.7 121.2 132.3 138
B-11 121.3 131.3 134.1 141.4
Tg after Gel time +24 hrs at
RT, (°C)
Tg after Gel time +24 hrs at
RT+100°C/3h +140°C/2h
(°C)

8. 7. Water Absorption
Diluent RAC 9923 RAC 9924 RAC 9923 RAC 9924
NPGDGE 0.1 0.09 0.46 0.42
BDGE 0.13 0.06 0.5 0.37
HDGE 0.1 0.07 0.32 0.33
TMPTGE 0.13 0.08 0.52 0.37
RDGE 0.08 0.04 0.3 0.2
RAR 928 0.1 0.06 0.05 0.03
Water absorption after 24 hrs
at RT % w/w
Water absorption after
100°c /2h % w/w

9. 8. Shear strength after post-curing (kgf/mm2)
Diluent RAC 9923 RAC 9924
NPGDGE 0.4844 0.4328
BDGE 0.7414 0.688
HDGE 0.565 0.5612
TMPTGE 0.5895 0.5736
RDGE 0.555 0.5575
RAR 928 0.6117 0.6015

10. 9. Tensile strength after post-curing (kgf/mm2)
Diluent RAC 9923 RAC 9924
NPGDGE 5.48 5.44
BDGE 7.55 6.62
HDGE 7.60 6.43
TMPTGE 6.99 5.87
RDGE 8.59 7.74
RAR 928 7.56 7.3

11. 10. Tensile elongation at break after post-curing (%)
Diluent RAC 9923 RAC 9924
NPGDGE 4.11 3.98
BDGE 4.58 4.31
HDGE 4.25 4.01
TMPTGE 4.65 4.57
RDGE 4.98 4.85
RAR 928 4.8 4.78

12. 11. Compressive strength after post-curing (kgf/mm2)
Diluent RAC 9923 RAC 9924
NPGDGE 11.25 10.98
BDGE 12.24 11.87
HDGE 11.95 11.52
TMPTGE 12.78 12.25
RDGE 13.02 12.65
RAR 928 14.22 13.52

13. 12. Impact strength after post-curing (kgf cm/cm2)
Diluent RAC 9923 RAC 9924
NPGDGE 8.8 6.5
BDGE 10.8 9.6
HDGE 9.7 8.9
TMPTGE 9.0 7.0
RDGE 11.4 11.0
RAR 928 10.7 7.8

14. 13. Electrical Properties of RAR 928 / RAD 77 / RAC 9924
Dielectric constant at 50 Hz 3.05
Dissipation Factor (tan delta) at 50 Hz 0.005
Dielectric strength 18 kV/mm

15. 14. Conclusions
 Resorcinol Diglycidyl Ether gives the highest Tg but very poor dilution
efficiency. Because of health hazards, it is ruled out.
 Trimethylol propane triglycidyl ether gives next best Tg. Good
mechanical properties as well. If high dilution ratio (~40 phr diluent) is
acceptable, it can be recommended.
 1,4-butane-diol diglycidyl ether is the best difunctional aliphatic diluent
with good efficiency, moderately high Tg (134oC) and best overall
mechanical properties. Hence it is ideal for filament winding,
pultrusion, casting and encapsulation.