노화조건에 따른 NR가황체의 가교밀도와 가교구조 변화

김상구; 이석현

Polymer(Korea), Vol.18, No.2, 172-187, March, 1994

Export Citation

노화조건에 따른 NR가황체의 가교밀도와 가교구조 변화

Changes of the Crosslink Density and Crosslink Structures of NR Vulcanizates with Various Aging Conditions

김상구, 이석현

초록

노화전 전체가교밀도가 비슷하면서 가교구조가 아주 다른 conventional, semi-efficient, efficient 그리고 dicumyl peroxide 가교계의 비충전 및 카본블랙 충전 고무에 대해 100℃ 공기중과 질소중에서 168시간까지 11단계로 노화시켜 전체가교밀도의 변화와 polysulfide, disulfide, 그리고 monosulfide 가교결합들의 변화를 조사하였다. 아울러 노화에 따른 유기용매 추출물의 함량변화도 조사하였다. 노화에 따른 전체가교밀도의 변화를 가교구조들의 변화와 관련지음으로써 네가지 가교계의 노화거동의 차이를 특징적으로 밝혔다. 황으로 가교된 고무의 경우 노화시간이 길어질수록 polysulfide는 감소하고 monosulfide는 증가하였으며, 카본블랙이 배합된 경우 주쇄절단이 덜 일어났다. 공기중에서 열노화시킨 고무들의 유기용매에 의한 추출물은 산소나 오존이 네트워크의 절단이나 가교결합의 파괴를 촉진시키기 때문에 질소중에서 열노화시킨 고무보다 훨씬 크게 증가하였다. 미반응 황분자와 polysulfide를 가장 많이 함유한 conventional 가황고무가 노화에 따라 가교밀도와 가교구조에서 가장 큰 변화를 보였으며. 이 경우 산소는 노화초기의 미반응 황분자들에 의한 polysulfide의 생성과 탈황반응에 의한 polysulfide의 monosulfide와 disulfide로의 전환을 증가시키는 것으로 나타났다.

Changes of total crosslink density and of poly-, di- and monosulfidic crosslinks of unfilled and HAF-filled vulcanizates were investigated as a function of aging period at 100℃ in air and nitrogen. The aging periods studied were 11 steps from 0 to 168 hours. Various vulcanizates. which are conventional, semi-efficient, efficient and dicumy peroxide cure systems, were prepared to have a similar level of total crosslink density with the quite different crosslink structures. Also, changes of extract weight of the vulcanizates were analyzed by extraction in the pyridine-acetone-acetone/cyclohexane mixture as a function of aing conditions. In this study, different aging behaviours of the 4types of cure systems were characterized by relating the changes in the crosslink structures to the changes of the total crosslink density. The sulfur vulcanizate showed the decrease in polysulfidic crosslink levels and the increase in monosulfidic crosslink levels as increasing the aging period. For the HAF-filled vulcanizates, the network-chain scissions were reduced by the incoporation of carbon blacks. For the vulcanizates aged in all, the amount of extracts In the organic solvent were significantly increased due to the accleration of the network-chain scission by oxygen or ozone. The conventional vulcanizate showed highest changes in the total crosslink density and the crosslink structures because of the high concentration of unstable polysulfides and unreacted sulfur molecules after the vulcanization. Oxygen significantly promoted the formation of polysulfides at the beginning of aging and the desulfuration of polysulfides during the aging.

[References]

Porter RS, Macknight WJ, Johnson JF, Rubber Chem. Technol., 41, 1 (1968)
Porter M, "Organic Chemistry of Sulfur," ed. by S. Oae, Chap. 3, Plenum Press, New York (1977)
Cunneen JI, Russell RM, Rubber Chem. Technol., 43, 1215 (1970)
Kruger FWH, McGill WJ, J. Appl. Polym. Sci., 45, 1545 (1992)
Cunneen JI, Rubber Chem. Technol., 41, 182 (1968)
Lal J, J. Polym. Sci. C: Polym. Lett.(16), 587 (1968)
Ahagon A, Nippon Gomu Kyokaishi, 62, 71 (1989)
Ahagon A, J. Appl. Polym. Sci. Appl. Polym., 50, 351 (1992)
Mooney M, J. Appl. Phys., 11, 582 (1940)
Rivlin RS, Saunders DW, Phil. Trans. Royal Soc., A243, 251 (1951)
Gumbrell SM, Mullins L, Rivlin RS, Trans. Faraday Soc., 49, 1495 (1953)
Flory PJ, Rehner J, J. Chem. Phys., 11, 521 (1943)
Flory PJ, J. Chem. Phys., 18, 108 (1950)
Cluff EF, Gladding EK, Pariser R, J. Polym. Sci., 45, 341 (1960)
Polmanteer KE, Helmer JD, Rubber Chem. Technol., 38, 123 (1965)
Saville B, Watson AA, Rubber Chem. Technol., 40, 100 (1967)
Yamashida S, Nippon Gomu Kyokaishi, 48, 609 (1975)
ASTM D297
Campbell DS, Saville B, Proc. Int. Rubber Conf., Brighton (1967)
Porter M, Rubber Chem. Technol., 40, 866 (1967)
Mullins L, J. Appl. Polym. Sci., 2(4), 1 (1959)
Barnard D, Bateman L, Cunneen JI, Smith JF, "The Chemistry and Physics of Rubber-like Substances," L. Batemaned, Chap. 17, p. 597, Applied Science Publishers, Ltd., London
Bateman L, Cunneen JI, Moore CG, Mullins L, Thomas AG, "The Chemistry and Physics of Rubber-like Substances," L. Bateman ed., Chap. 19, p. 739, Applied Science Publishers Ltd., London

[Referenced By]

[1] Porter RS, Macknight WJ, Johnson JF, Rubber Chem. Technol., 41, 1 (1968)

[2] Porter M, "Organic Chemistry of Sulfur," ed. by S. Oae, Chap. 3, Plenum Press, New York (1977)

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

[4] Kruger FWH, McGill WJ, J. Appl. Polym. Sci., 45, 1545 (1992)

[5] Cunneen JI, Rubber Chem. Technol., 41, 182 (1968)

[6] Lal J, J. Polym. Sci. C: Polym. Lett.(16), 587 (1968)

[7] Ahagon A, Nippon Gomu Kyokaishi, 62, 71 (1989)

[8] Ahagon A, J. Appl. Polym. Sci. Appl. Polym., 50, 351 (1992)

[9] Mooney M, J. Appl. Phys., 11, 582 (1940)

[10] Rivlin RS, Saunders DW, Phil. Trans. Royal Soc., A243, 251 (1951)

[11] Gumbrell SM, Mullins L, Rivlin RS, Trans. Faraday Soc., 49, 1495 (1953)

[12] Flory PJ, Rehner J, J. Chem. Phys., 11, 521 (1943)

[13] Flory PJ, J. Chem. Phys., 18, 108 (1950)

[14] Cluff EF, Gladding EK, Pariser R, J. Polym. Sci., 45, 341 (1960)

[15] Polmanteer KE, Helmer JD, Rubber Chem. Technol., 38, 123 (1965)

[16] Saville B, Watson AA, Rubber Chem. Technol., 40, 100 (1967)

[17] Yamashida S, Nippon Gomu Kyokaishi, 48, 609 (1975)

[18] ASTM D297

[19] Campbell DS, Saville B, Proc. Int. Rubber Conf., Brighton (1967)

[20] Porter M, Rubber Chem. Technol., 40, 866 (1967)

[21] Mullins L, J. Appl. Polym. Sci., 2(4), 1 (1959)

[22] Barnard D, Bateman L, Cunneen JI, Smith JF, "The Chemistry and Physics of Rubber-like Substances," L. Batemaned, Chap. 17, p. 597, Applied Science Publishers, Ltd., London

[23] Bateman L, Cunneen JI, Moore CG, Mullins L, Thomas AG, "The Chemistry and Physics of Rubber-like Substances," L. Bateman ed., Chap. 19, p. 739, Applied Science Publishers Ltd., London