Page 75 - 《橡塑技术与装备》英文版2026年1月

MATERIALS AND FORMULATIONS

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increase in hardness was the greatest for 5 and the smallest
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for 4 . Furthermore, the elongation at break change rate of
the modified EPDM/MVQ blends was lower than that of the
unmodified blends. That is, considering both change rates, the
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aging resistance of 4 blend was the best, and compared to the
unmodified 1 blend, the aging resistance of 2 ~5 blends was
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slightly better.

Figure 3 Wear resistance of EPDM/MVQ blends

2.5 Aging resistance

The samples of EPDM/MVQ blend were subjected to
thermo-oxidative aging at 120 ℃ for 72 hours. During this
process, the crosslinking density of the blend increased, and its
hardness and modulus at a fixed extension increased compared
Figure 4 Change rate of hardness and elongation at
to before aging. The mechanical property data of the aged break of the blend before and after aging
blend is shown in Table 4. The decrease in tensile strength
and elongation at break of blends 1#, 3#, and 4# is due to
the excessive crosslinking density, which leads to an uneven
crosslinking network. Under external forces, the number of
stress concentration points increases, making them prone to
fracture. The increase in tensile strength of blends 2# and 5#
indicates that their vulcanization degree increased during the
thermo-oxidative aging process, and the crosslinking network
structure is relatively uniform. Overall, under the same aging
conditions, the tensile strength and elongation at break of the
modified blend are higher than those of the unmodified one.
Table 4 Mechanical properties of aged EPDM/MVQ
blends Figure 5 Comparison of tensile behavior of blends
Serial number 1 # 2 # 3 # 4 # 5 # before and after aging
Hardness / Shore A 65 64 65 63 65
Tensile strength / MPa 5.6 5.7 5.7 5.8 6.8 Note: 1 ~5 represent the mechanical behavior curves
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Elongation at break /% 257 355 328 302 275
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50% modulus at fixed extension / MPa 1.4 1.2 1.2 1.4 1.3 of EPDM/MVQ blends at room temperature, while 1 ~5
100% modulus at fixed extension / MPa 2.0 1.7 1.7 1.8 2.1 represent the mechanical behavior curves of EPDM/MVQ
200% modulus at fixed extension / MPa 3.9 2.7 2.9 3.3 4.1
300% modulus at fixed extension / MPa - 4.4 5.0 5.7 - blends after aging at 120 ℃ for 72 hours.
Permanent set at break /% 5.8 13.3 10.0 7.5 2.5
Tear strength /(kN·m ) 23.8 22.4 21.3 17.6 23.0 In addition, by comparing the tensile behavior curves
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of EPDM/MVQ blends before and after aging, as shown in
The aging resistance of EPDM/MVQ blends was Figure 5, it can be observed that the tensile behavior of the
evaluated based on the changes in hardness and elongation unmodified EPDM/MVQ blend changes significantly before
at break before and after aging. As shown in Figure 4, the and after aging, once again verifying that the addition of

Vol.52，2026 ·29·