Testing Item

Index

Test Method

Superior Grade

First Grade

Qualified

Volatile matter(%)≤

0.60

0.80

1.00

ASTM D-5668(GB/T6737)

Ash content(%)

≤0.50

ASTM D-5667(GB/T4498)

Organic acid(%)

3.90~5.70

ASTM D-5574(GB/T8657)

Soap content(%)

≤0.50

  ASTM D-5774(GB/T8657)

Oil content(%)

25.3~29.3

24.3~30.3

ASTM D-5774 (SH/T1718)

Combinated Styrene content(%)

22.5~24.5

ASTM D-5775(GB/T8658)

Raw rubber mooney viscosity

ML(1+4)100°C

44~54

43~55

42~56

ASTM D-1646(GB/T1232.1)

Compounded rubber mooney viscosity

ML(1+4)100°C≤

70

ASTM D-1646(GB/T1232.1)

    ASTM IRB NO.7

300% Stretching Stress

(145°C)/MPa

25min

9.8~13.8

9.3~14.3

ASTM D-412(GB/T8656)

ASTM IRB NO.7

35min

12.1~16.1

11.6~16.6

50min

13.0~17.0

12.5~17.5

Tensile strength

(145°C, 35min)/MPa

≥19.4

≥18.4

Elongationg at break

(145°C, 35min)/%

≥380

≥370