The rheometer curing curves of 50/50 blends of natural rubber (NR) and two different halogenated rubbers with a combination of conventional accelerated sulfur (CV) and 3 phr of a bismaleimide (MF3) at 170 °C indicates that a co-curing reaction has been taken place between NR and the halogenated rubbers via Diels-Alder reaction. To further confirm whether the co-curing reaction has taken place in the early stage of curing, a complex test methodology was applied with the help of a rubber process analyzer. In this test, the blends with CV and with CVMF3 were subjected to cure at 170 °C for a predetermined time so that both the CV and CVMF3 cured blends will have the same magnitude of curing torque. It is then cooled down to 40 °C and the storage modulus (G') was evaluated as a function of strain from 0.5% to 100% at a constant frequency of 1 Hz. The results reveal that the blends cured with CVMF3 exhibit a higher G' due to the enhanced network strength because of the formation of bismaleimide crosslinks than the same cured with only the CV system. The swelling resistance and the mechanical properties of the blends cured with CVMF3 were significantly higher than those cured with only the CV system.

Centre of Polymer Systems Tomas Bata University in Zlín Třida Tomáše Bati 5678 760 01 Zlín Czech Republic

Zobrazit více v PubMed

Decker G.E., Wise R.W., Guerry D. An oscillating disk rheometer for measuring dynamic properties during vulcanization. Rubber Chem. Technol. 1963;36:451–458. doi: 10.5254/1.3539572. DOI

Dick J., Pawlowski H. Application for the curemeter maximum cure rate in rubber compound development, process control, and cure kinetic studies. Polym. Test. 1996;15:207–243. doi: 10.1016/0142-9418(95)00033-X. DOI

Dick J., Vare A., Harmon C. Quality assurance of natural rubber using the rubber process analyser. Polym. Test. 1999;18:327–362. doi: 10.1016/S0142-9418(98)00026-9. DOI

Barick A.K., Tripathy D.K. Effect of organically modified layered silicate nanoclay on the dynamic viscoelastic properties of thermoplastic polyurethane nanocomposites. Appl. Clay Sci. 2011;52:312–321. doi: 10.1016/j.clay.2011.03.010. DOI

Kittur M.I., Andriyana A., Ang B.C., Ch’ng S.Y., Mujtaba M.A. Swelling of rubber in blends of diesel and cottonseed oil biodiesel. Polym. Test. 2021;96:107116. doi: 10.1016/j.polymertesting.2021.107116. DOI

Crabtree J., Kemp A.R. Weathering of soft vulcanized rubber. Rubber Chem. Technol. 1946;19:712–752. doi: 10.5254/1.3557514. DOI

Anggaravidya M., Akhmad A., Arti D.K., Kalembang E., Susanto H., Hidayat A.S., Limansubroto C.D. Properties of natural rubber/chloroprene rubber blend for rubber fender application: Effects of blend ratio. Macromol. Symp. 2020;391:1900150. doi: 10.1002/masy.201900150. DOI

Quang N.T., Hung D.V., Linh N.P.D., Chuong B., Duong D.L. Detailed study on the mechanical properties and activation energy of natural rubber/chloroprene rubber blends during aging processes. J. Chem. 2020;2020:7064934.

Hayeemasae N., Salleh S.Z., Ismail H. Utilization of chloroprene rubber waste as blending components with natural rubber: Aspect on metal oxide contents. J. Mater. Cycles Waste Manag. 2019;21:1095–1105. doi: 10.1007/s10163-019-00862-0. DOI

Salleh S.Z., Hanafi I., Zulkifli A. Study on the effect of virgin and recycled chloroprene rubber (vCR and rCR) on the properties of natural rubber/chloroprene rubber (NR/CR) blends. J. Polym. Eng. 2013;33:803–811. doi: 10.1515/polyeng-2013-0127. DOI

Naba K.D., Tripathy D.K. Miscibility studies in blends of bromobutyl rubber and natural rubber. J. Elastomers Plast. 1993;25:158–179.

Kruzelak J., Sykora R., Hudec I. Sulfur and peroxide vulcanisation of rubber compounds-overview. Chem. Pap. 2016;70:1533–1555. doi: 10.1515/chempap-2016-0093. DOI

Babu R.R., Shibulal G.S., Chandra A.K., Naskar K. Compounding and vulcanization. In: Visakh P., Thomas S., Chandra A., Mathew A., editors. Advances in Elastomers I. Advanced Structured Materials. Volume 11. Springer; Berlin/Heidelberg, Germany: 2013. pp. 83–138.

Akiba M., Hashim A.S. Vulcanization and crosslinking in elastomers. Prog. Polym. Sci. 1997;22:475–521. doi: 10.1016/S0079-6700(96)00015-9. DOI

Mallon P.E., McGill W.J., Shillington D.P. A DSC study of the crosslinking of polychloroprene with ZnO and MgO. J. Appl. Polym. Sci. 1995;55:705–721. doi: 10.1002/app.1995.070550507. DOI

Vukov R. Zinc oxide cross-linking chemistry of halobutyl elastomers—A model compound approach. Rubber Chem. Technol. 1984;57:284–290. doi: 10.5254/1.3536008. DOI

Kuntz I., Zapp R.L., Pancirov R.J. The chemistry of the zinc oxide cure of halobutyl. Rubber Chem. Technol. 1984;57:813–825. doi: 10.5254/1.3536036. DOI

Pöschl M., Sathi S.G., Stoček R., Kratina O. Rheometer evidence for the co-curing effect of a bismaleimide in conjunction with the accelerated-sulfur on natural rubber/chloroprene rubber blends. Polymers. 2021;13:1510. doi: 10.3390/polym13091510. PubMed DOI PMC

Ahmed K., Nizami S.S., Raza N.Z., Shirin K. Cure characteristics, mechanical and swelling properties of marble sludge filled EPDM modified chloroprene rubber blends. Adv. Mater. Phys. Chem. 2012;2:90–97. doi: 10.4236/ampc.2012.22016. DOI

Sathi S.G., Jang J.Y., Yu H.C., Huh Y.I., Nah C. Cure characteristics and physico-mechanical properties of a conventional sulfur-cured natural rubber with a novel anti-reversion agent. J. Polym. Res. 2016;23:237–248.

Sathi S.G., Stoček R., Kratina O. Reversion free high-temperature vulcanization of cis-polybutadiene rubber with the accelerated-sulfur system. Express Polym. Lett. 2020;14:838–847.

Sathi S.G., Harea E., Machů A., Stoček R. Facilitating high-temperature curing of natural rubber with a conventional accelerated-sulfur system using a synergistic combination of bismaleimides. Express Polym. Lett. 2021;15:16–27. doi: 10.3144/expresspolymlett.2021.3. DOI

Desai H., Hendrikse K.G., Woolard C.D. Vulcanization of polychloroprene rubber. I. A revised cationic mechanism for ZnO crosslinking. J. Appl. Polym. Sci. 2007;105:865–876. doi: 10.1002/app.23904. DOI

Berry K., Liu M., Chakraborty K., Pullan N., West A., Sammon C., Topham P.D. Mechanism for cross-linking polychloroprene with ethylene thiourea and zinc oxide. Rubber Chem. Technol. 2015;88:80–97. doi: 10.5254/rct.14.85986. DOI

Sathi S.G., Jang J.Y., Jeong K.U., Nah C. Thermally stable bromobutyl rubber with a high crosslinking density based on a 4,4′ bismaleimidodiphenylmethane curing agent. J. Appl. Polym. Sci. 2016;133:44092. doi: 10.1002/app.44092. DOI

Sathi S.G., Jeon J., Won J., Nah C. Enhancing the efficiency of zinc oxide vulcanization in brominated poly (isobutylene-co-isoprene) rubber using structurally different bismaleimides. J. Polym. Res. 2018;25:108–121. doi: 10.1007/s10965-018-1512-8. DOI

Sathi S.G., Jang J.Y., Jeong K.U., Nah C. Synergistic effect of 4,4′-bis(maleimido) diphenylmethane and zinc oxide on the vulcanization behavior and thermo-mechanical properties of chlorinated isobutylene–isoprene rubber. Polym. Adv. Technol. 2017;28:742–753.