가교구조가 다른 NR가황체의 노화조건에 따른 물성 변화

김상구; 이석현

Polymer(Korea), Vol.18, No.2, 188-198, March, 1994

Changes of the Physical Properties of NR Vulcanizates Having Different Crosslink Structures with Various Aging Conditions

김상구, 이석현

초록

노화전 전체가교밀도가 비슷하면서 가교구조가 아주 다른 conventional, semi-efficient, efficient 그리고 dicumyl peroxide 가교계의 카본블랙 충전 고무에 대해 100℃ 공기중과 질소중에서 168시간 까지 10단계로 노화시켜 100% 신장시 모듈러스와 절단 신장비를 측정하였다. 이와 함께 전체 가교밀도의 변화와 polysulfide, disulfide, 그리고 monosulfide 가교결합들의 변화를 조사하였다. 또한 노화전 고무들에 대해 여러온도에서 가교구조가 Demattia 크랙성장 속도에 미치는 영향도 조사하였다. Demattia 크랙성장 속도는 가교구조의 지배를 받으며 이때 conventional 가교계가 가장 높은 저항성을, dicumyl peroxide 가교계가 가장 낮은 저항성을 보였다. 100% 모듈러스는 가교구조의 차이 때문에 동일한 노화 시간에서 차이가 있지만, 가교구조와 노화조건에 관계없이 전체가 교밀도의 함수로 나타낼 수 있으며 가교밀도의 수준에 따라 기울기가 다른 두 개의 영역으로 구분되었다. 이 사실은 가교구조와 노화조건이 네트워크 사슬의 절단과 가교구조의 변화에 미치는 영향이 다른 데서 기인하였다.

Measurement of modulus at 100% elongation and extension ratio at break with the total-, poly-, di- and monosulfidic crosslink density of HAF-filled vulcanizates before and after aging at 100℃ in air and nitrogen for up to 168 hours were carried out. Also, the influence of the crosslink structures on the Demattia crack growth rate was investigated at various temperature. The conventional (Conv), semi-efficient(Semi-EV) and dicumyl peroxide(DCP) cure systems showed the similar level of total crosslink density ant the quite different crosslink structures before aging. The crosslink structures dominated the Demttia crack growth rate. The Conv vulcanizate showed the highest resistance whereas the DCP vulcanizate showed the lowest resistance to the Demattia crack growth. When the vulcanizates of 4-cure systems were aged for the same periods at 100℃, the modulus at 100% elogation was significantly changed. However, this modulus at 100% elongation could be expressed and as a function of the total crosslink density regardless of the different crosslink structures and aging conditions. In this study, the slope of the plot of modulus at 100% elongation and total crosslink density in logarithmic scale were changed by the levels of total crosslink density. The relationships between the extension ratio at break and modulus at 100% elongation of 4-cure systems were different due to the degree of network chain scissions and changed of the crosslink structure during the aging.

[References]

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[1] Kuvshinskii EV, Sidorovich EA, Rubber Chem. Technol., 32, 662 (1959)

[2] Bueche F, J. Polym. Sci., 24, 189 (1957)

[3] Bueche F, J. Polym. Sci., 33, 259 (1958)

[4] Studebaker ML, Rubber Chem. Technol., 39, 1359 (1966)

[5] Cox WL, Parks CR, Rubber Chem. Technol., 39, 785 (1966)

[6] Bateman L, Cunneen JI, Moore CG, Mullins L, Thomas AG, "The Chemistry and Physics of Rubber-like Substances," ed. by L. Bateman, Applied Science Publisher, London, p. 715 (1963)

[7] Flory PJ, "Principles of Polymer Chemistry," Cornell University Press, Ithaca (1969)

[8] Ahagon A, Kautschuk Gummi Kunstst., 38, 505 (1985)

[9] Ahagon A, Rubber Chem. Technol., 59, 187 (1986)

[10] Treloar LRG, "The Physics of Rubber Elasticity," 2nd ed., Oxford University Press, London (1958)

[11] Lal J, J. Polym. Sci. C: Polym. Lett.(16), 3391 (1968)

[12] Tobolsky AV, Lyons PF, J. Polym. Sci. A: Polym. Chem., 2(6), 1561 (1968)

[13] Young DG, Rubber World, 204(1), 30 (1991)

[14] Cunneen JI, Russell RM, Rubber Chem. Technol., 43, 1215 (1970)

[15] Smith TL, Chu WH, J. Polym. Sci. A: Polym. Chem., 2(10), 133 (1972)

[16] Cooper W, J. Polym. Sci., 28, 195 (1958)

[17] Cooper W, Chem. Ind., 1741 (1955)

[18] Kim SG, Lee SH, Rubber Chem. Technol., to submitted

[19] Lee DJ, Donovan JA, Rubber Chem. Technol., 60, 910 (1987)

[20] Ahagon A, Kida M, Kaidou H, Rubber Chem. Technol., 63, 683 (1990)