HCR 970 U is silicone master-batch, heat vulcanizing after the addition of a vulcanizing agent (chosen according to the transformation process).

Details

HEAT CURED SILICONE RUBBER HCR 970 U

Description: HCR 970 U is silicone master-batch, heat vulcanizing after the addition of a vulcanizing agent (chosen according to the transformation process).

Applications: HCR 970 U is recommended for moulding, injecting and extruding articles with good mechanical properties (in particular a low compression set, high resiliency and a
remarkably low tack).

Special properties:
Slight replastification after prolonged storage
Easy to process
Without post-cure or slight post-cure
Good heat stability, up to 225°C, or even 250°C with additive 744
Wide range of blends possible with other master-batches

Characteristics:
Type (in accordance with GB/T 5576-1997) ………………… VMQ
Density at 25°C, g/cm3, approx………………………..………… 1.17
Natural color………………………………………………….…………… Translucent

Properties after working:
(1) After addition of 1.25% 2,4-dichloro-benzoyl peroxide (50%), and vulcanization for 8 minutes at 115°C
(2) After addition of 1.0% 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (45%), and vulcanization for 10 minutes at 170°C

1. Mechanical properties
1.1 Properties without post-cure                          (1)   (2)
Shore A hardness, approx…………………………………  68   67
Tensile strength, MPa, approx……………………………  8.5   8.8
Elongation at break, %, approx…………………………. 380   500
Modulus at 100% elongation, MPa, approx………..      2.1  1.8
Tear strength, kN/m, approx………………………………. 20   21
Compression set (22 h/177°C/25 %), % approx……      60   25
Rebound resilience, %, approx…………………………… 51   53
Linear shrinkage, %, approx………………………………. 0.7   0.7
1.2 Properties after post-cure for 4 hours at 200°C
Shore A hardness, approx………………………………… 70   70
Tensile strength, MPa, approx…………………………… 8.3  8.5
Elongation at break, %, approx……………………….  350   450
Modulus at 100% elongation, MPa, approx………… 2.3  1.9
Tear strength, kN/m, approx…………………………….. 18   20
Compression set (22h/177oC/25%), %, approx……    42   21
Rebound resilience, %, approx…………………………… 54   52
Linear shrinkage, %, approx……………………………… 2.0   4.0

2. Heat stability
2.1 Properties after ageing 7 days at 177°C
Shore A hardness, approx………………………………… 69   70
Tensile strength, MPa, approx…………………………… 8.1   7.6
Elongation at break, %, approx…………………………. 325   370
Tear strength, kN/m, approx…………………………….. 15   18
2.2 Properties after ageing 10 days at 200°C
Shore A hardness, approx………………………………… 70   72
Tensile strength, MPa, approx………………………..…  6.2   6.1
Elongation at break, %, approx………………………... 230  270
Tear strength, kN/m, approx…………………………..…13   15
2.3 Properties after ageing 3 days at 225°C
Shore A hardness, approx……………………………..… 74    77
Tensile strength, MPa, approx……………………….…  5.1   5.8
Elongation at break, %, approx…………………….…. 135   120
Tear strength, kN/m, approx…………………………..… 9    8

3. Heat resistance with the addition of 0.4 parts of additive 744
3.1 Properties after ageing 7 days at 177°C
Shore A hardness, approx……………………………..…. 70   70
Tensile strength, MPa, approx…………………………… 8.0   8.2
Elongation at break, %, approx……………………..…. 330  400
Tear strength, kN/m, approx……………………………. 17   19
3.2 Properties after ageing 10 days at 200°C
Shore A hardness, approx………………………………… 69   71
Tensile strength, MPa, approx…………………………..  6.4   6.4
Elongation at break, %, approx……………………….   310   360
Tear strength, kN/m, approx……………………………. 16   19
3.3 Properties after ageing 3 days at 225°C
Shore A hardness, approx……………………………… 67   68
Tensile strength, MPa, approx………………………..… 8.0   8.2
Elongation at break, %, approx………………………. 325   390
Tear strength, kN/m, approx……………………….…… 13    16
3.4 Properties after ageing 7 days at 225°C
Shore A hardness, approx....................................         67   70
Tensile strength, MPa, approx………………………….. 5.6   5.6
Elongation at break, %, approx……………………..…. 210  240
Tear strength, kN/m, approx…………………………….. 13   16
3.5 Properties after ageing 3 days at 250°C
Shore A hardness, approx………………………………… 67    71
Tensile strength, MPa, approx…………………………… 6.4   6.4
Elongation at break, %, approx…………………………. 210   360
Tear strength, kN/m, approx………………………….…. 13   19

4. Electrical properties:
Dielectric strength (on 2 mm thick slabs), kV/mm, approx… 21
Breakdown voltage, kV, approx…………………………….…… 45
Dielectric constant at 1 MHz, approx…………………….…… 2.8
Dissipation factor at 1 MHz, approx……………………………3.5×10-3
Volume resistivity, OhmNaN, approx……………………………… 2.2×1014

Packing: HCR 970 U is delivered in 20 kg carton boxes.

Storage and shelf life:
HCR 970 U may be stored in its original unopened packaging at a temperature
below 40°C for up to 18 months from the date of manufacture marked clearly on the packaging.

Past this date, no longer guarantee that the product meets the sales specifications.