The present study investigated the effects of thermal aging, ultraviolet radiation (UV), and stress softening on the performance properties of rubber modified with Cloisite Na+ or Cloisite 20A. Tensile strength (TS), strain at break (SB), modulus, and the retention coefficient were measured before and after aging. Results showed that TS and SB decreased by about 50% after 7 days of aging for all tested samples due to the breakage of the chemical bonds between rubber and nanoparticles. The modulus at 300% elongation increased by 20%, 15%, and 7% after thermal aging for the unmodified sample, nanocomposites with Cloisite Na+, and Cloisite 20A, respectively. The shape retention coefficient of all samples was not affected by heat, except for the virgin rubber sample, which exhibited a decrease of about 15% under thermal aging. The virgin matrix and nanocomposites showed different values of aging coefficient during thermal aging and UV radiation. The dissipated energy of samples that were aged after stretching was slightly higher than that of samples that were aged after stretching due to the breakdown of the bonds within the nanocomposites. Loading-reloading energy results showed that the level of stress softening was lower when Mullins was applied after the aging of the samples. Differential scanning calorimetry results indicated a slight decrease in Tg1 in the aged and stretched samples and an increase in the temperature of the first endothermic peak due to the addition of nanofillers in the stretched and aged samples. Thermogravimetric analysis revealed that all tested samples exhibited similar thermograms, regardless of their state of stretching or aging. Scanning electron microscopy analysis showed that the fracture surface of the virgin unaged sample was rough with some holes, while it was flatter and less rough after aging.

Center of Polymer Systems Tomas Bata University in Zlin 760 01 Zlín Czech Republic

Faculty of Applied Chemistry Radom University 26 600 Radom Poland

Faculty of Chemistry Rzeszów University of Technology 35 959 Rzeszów Poland

See more in PubMed

Bokobza L. Natural rubber nanocomposites: A review. Nanomaterials. 2018;9:12. doi: 10.3390/nano9010012. PubMed DOI PMC

Sethulekshmi A.S., Saritha A., Joseph K. A comprehensive review on the recent advancements in natural rubber nanocomposites. Int. J. Biol. Macromol. 2022;194:819–842. doi: 10.1016/j.ijbiomac.2021.11.134. PubMed DOI

Sengupta R., Chakraborty S., Bandyopadhyay S.A., Dasgupta S., Mukhopadhyay R., Auddy K., Deuri A.S. A short review on rubber/clay nanocomposites with emphasis on mechanical properties. Polym. Eng. Sci. 2007;47:1956–1974. doi: 10.1002/pen.20921. DOI

Danafar F., Kalantari M. A review of natural rubber nanocomposites based on carbon nanotubes. J. Rubber Res. 2018;21:293–310. doi: 10.1007/BF03449176. DOI

Srivastava S.K., Mishra Y.K. Nanocarbon reinforced rubber nanocomposites: Detailed insights about mechanical, dynamical mechanical properties, payne, and mullin effects. Nanomaterials. 2018;8:945. doi: 10.3390/nano8110945. PubMed DOI PMC

Bhattacharya M., Maiti M., Bhowmick A.K. Influence of different nanofillers and their dispersion methods on the properties of natural rubber nanocomposites. Rubber Chem. Technol. 2008;81:782–808. doi: 10.5254/1.3548232. DOI

Archibong F.N., Orakwe L.C., Ogah O.A., Mbam S.O., Ajah S.A., Okechukwu M.E., Igberi C.O., Okafor K.J., Chima M.O., Ikelle I.I. Emerging progress in montmorillonite rubber/polymer nanocomposites: A review. J. Mater. Sci. 2023;58:2396–2429. doi: 10.1007/s10853-023-08173-4. DOI

Sayfo P., Pirityi D.Z., Pölöskei K. Characterization of graphene-rubber nanocomposites: A review. Mater. Today Chem. 2023;29:101397. doi: 10.1016/j.mtchem.2023.101397. DOI

Salehiyan R., Sinha Ray S. Rubber nanocomposites: Processing, Structure–Property Relationships, Applications, Challenges, and Future Trends. In: Sinha Ray S., editor. Processing of Polymer-Based Nanocomposites: Processing-Structure-Property-Performance Relationships. Volume 278. Springer; Cham, Switzerland: 2018. pp. 75–106. (Springer Series in Materials Science).

Hejazi I., Sharif F., Garmabi H. Effect of material and processing parameters on mechanical properties of polypropylene/ethylene–propylene–diene–monomer/clay nanocomposites. Mater. Des. 2011;32:3803–3809. doi: 10.1016/j.matdes.2011.03.017. DOI

Bakar M., Przybyłek M., Białkowska A., Żurowski W., Hanulikova B., Stoček R. Effect of mixing conditions and montmorillonite content on the mechanical properties of a chloroprene rubber. Mech. Compos. Mater. 2021;57:387–400. doi: 10.1007/s11029-021-09962-1. DOI

Choudhury A., Bhowmick A.K., Soddemann M. Effect of organo-modified clay on accelerated aging resistance of hydrogenated nitrile rubber nanocomposites and their life time prediction. Polym. Degrad. Stab. 2010;95:2555–2562. doi: 10.1016/j.polymdegradstab.2010.07.032. DOI

Bellas R., Diez J., Rico M., Barral L., Ramirez C., Montero B. Accelerated ageing of styrene–butadiene rubber nanocomposites stabilized by phenolic antioxidant. Polym. Compos. 2014;35:334–343. doi: 10.1002/pc.22666. DOI

Chakraborty S., Kar S., Dasgupta S., Mukhopadhyay R., Chauhan N.P., Ameta S.C., Bandyopadhyay S. Effect of ozone, thermo, and thermo-oxidative aging on the physical property of styrene butadiene rubber-Organoclay nanocomposites. J. Elastom. Plast. 2010;42:443–452. doi: 10.1177/0095244310374226. DOI

Chen S., Yu H., Ren W., Zhang Y. Thermal degradation behavior of hydrogenated nitrile-butadiene rubber (HNBR)/clay nanocomposite and HNBR/clay/carbon nanotubes nanocomposites. Thermochim. Acta. 2009;491:103–108. doi: 10.1016/j.tca.2009.03.010. DOI

Bakar M., Przybyłek M., Białkowska A., Żurowski W., Hanulikova B., Masař M. Effect of Aging Conditions and Rubber Waste Content on the Mechanical Properties and Structure of Montmorillonite/Acrylonitrile Butadiene Rubber Nanocomposites. J. Macromol. Sci. B. 2021;60:553–570. doi: 10.1080/00222348.2021.1885115. DOI

Marković G., Marinović-Cincović M.S., Jovanović V., Samaržija-Jovanović S., Budinski-Simendić J. Gamma irradiation aging of NBR/CSM rubber nanocomposites. Compos. B Eng. 2012;43:609–615. doi: 10.1016/j.compositesb.2011.11.056. DOI

Pubellier P., Robin C. Molecular-Level Understanding of the Network Structural Changes of Thermo-oxidatively Aged Natural Rubber Nanocomposites. Macromolecules. 2023;56:4208–4218. doi: 10.1021/acs.macromol.3c00029. DOI

Mathew S., Varghese S., Joseph R. Degradation behaviour of natural rubber layered silicate nanocomposites. Prog. Rubber Plast. Recycl. Technol. 2013;29:1–20. doi: 10.1177/147776061302900101. DOI

Keloth Paduvilan J., Velayudhan P., Amanulla A., Joseph Maria H., Saiter-Fourcin A., Thomas S. Assessment of graphene oxide and nanoclay based hybrid filler in chlorobutyl-natural rubber blend for advanced gas barrier applications. Nanomaterials. 2021;11:1098. doi: 10.3390/nano11051098. PubMed DOI PMC

Hu H., Jia Z., Wang X. Aging mechanism of silicone rubber under thermal–tensile coupling effect. IEEE Trans. Dielectr. Electr. Insul. 2022;29:185–192. doi: 10.1109/TDEI.2022.3146543. DOI

Kong Y., Chen X., Li Z., Li G., Huang Y. Evolution of crosslinking structure in vulcanized natural rubber during thermal aging in the presence of a constant compressive stress. Polym. Degrad. Stab. 2023;217:11051. doi: 10.1016/j.polymdegradstab.2023.110513. DOI

Zheng W., Zhao X., Li Q., Chan T.W., Zhang L., Wu S. Compressive stress relaxation modeling of butadiene rubber under thermo-oxidative aging. J. Appl. Polym. Sci. 2017;134:44630. doi: 10.1002/app.44630. DOI

Li C., Ding Y., Yang Z., Yuan Z., Ye L. Compressive stress-thermo oxidative ageing behaviour and mechanism of EPDM rubber gaskets for sealing resilience assessment. Polym. Test. 2020;84:106366. doi: 10.1016/j.polymertesting.2020.106366. DOI

Peng Q., Zhu Z., Jiang C., Jiang H. Effect of stress relaxation on accelerated physical aging of hydrogenated nitrile butadiene rubber using time-temperature-strain superposition principle. Adv. Ind. Eng. Polym. Res. 2019;2:61–68. doi: 10.1016/j.aiepr.2019.03.002. DOI

Lou W., Xie C., Guan X. Coupled effects of temperature and compressive strain on aging of silicone rubber foam. Polym. Degrad. Stab. 2022;195:109810. doi: 10.1016/j.polymdegradstab.2021.109810. DOI

Ahagon A., Kirino Y. Aging of black filled rubber under deformation. Rubber Chem. Technol. 2006;79:641–652. doi: 10.5254/1.3547958. DOI

Quang N.T., Hung D.V., Chuong B., Le T.T. Mullins Effect and Crack Growth in Natural Rubber Vulcanizates during Heat Aging and Cyclic Loading. Eng. Technol. Sustain. Dev. 2021;31:061–067.

Kittur M.I., Andriyana A., Ang B.C., Ch’ng S.Y., Verron E. Inelastic response of thermo-oxidatively aged carbon black filled polychloroprene rubber. Part II: Mullins effect. Polym. Degrad. Stab. 2022;204:110120. doi: 10.1016/j.polymdegradstab.2022.110120. DOI

Diani J., Brieu M., Vacherand J.M. A damage directional constitutive model for Mullins effect with permanent set and induced anisotropy. Eur. J. Mech. A Solids. 2006;25:483–496. doi: 10.1016/j.euromechsol.2005.09.011. DOI

Dargazany R., Itskov M. A network evolution model for the anisotropic Mullins effect in carbon black filled rubbers. Int. J. Solids Struct. 2009;46:2967–2977. doi: 10.1016/j.ijsolstr.2009.03.022. DOI

Zhu P., Zhong Z. Constitutive modelling for the mullins effect with permanent set and induced anisotropy in particle-filled rubbers. Appl. Math. Model. 2021;97:19–35. doi: 10.1016/j.apm.2021.03.031. DOI

Anssari-Benam A., Akbari R., Dargazany R. Extending the theory of pseudo-elasticity to capture the permanent set and the induced anisotropy in the Mullins effect. Int. J. Non-Linear Mech. 2023;156:104500. doi: 10.1016/j.ijnonlinmec.2023.104500. DOI

Chu H., Lin J., Lei D., Qian J., Xiao R. A network evolution model for recovery of the Mullins effect in filled rubbers. Int. J. Appl. Mech. 2020;12:2050108. doi: 10.1142/S1758825120501082. DOI

Merckel Y., Diani J., Brieu M., Caillard J. Constitutive modeling of the anisotropic behavior of Mullins softened filled rubbers. Mech. Mater. 2013;57:30–41. doi: 10.1016/j.mechmat.2012.10.010. DOI

Fazekas B., Goda T.J. Constitutive modelling of rubbers: Mullins effect, residual strain, time-temperature dependence. Int. J. Mech. Sci. 2021;210:106735. doi: 10.1016/j.ijmecsci.2021.106735. DOI

Białkowska A., Przybyłek M., Sola-Wdowska M., Masař M., Bakar M. Mechanical properties and Mullins effect in rubber reinforced by montmorillonite. Bull. Pol. Acad. Sci. Tech. Sci. 2023;71:e147059. doi: 10.24425/bpasts.2023.147059. DOI

Rubber—Measurement of Vulcanization Characteristics with the Oscillating Disc Curemeter. International Organization for Standardization; Geneva, Switzerland: 1994.

Rubber, Vulcanized or Thermoplastic—Accelerated Ageing and Heat-Resistance Tests. International Organization for Standardization; Geneva, Switzerland: 2000.

Rubber, Vulcanized or Thermoplastic—Determination of Tensile Stress-Strain Properties. International Organization for Standardization; Geneva, Switzerland: 2007.

Rubber, Vulcanized or Thermoplastic—Determination of Compression Set at Ambient, Elevated or Low Temperatures. International Organization for Standardization; Geneva, Switzerland: 1998.

Tan J.H., Chen C.L., Wu J.Y., He R., Liu Y.W. The effect of UV radiation ageing on the structure, mechanical and gas permeability performances of ethylene–propylene–diene rubber. J. Polym. Res. 2021;28:81. doi: 10.1007/s10965-021-02447-8. DOI

Wang S., Xu J., Li H., Liu J., Zhou C. The effect of thermal aging on the mechanical properties of ethylene propylene diene monomer charge coating. Mech. Time-Depend. Mat. 2022;28:321–336. doi: 10.1007/s11043-022-09557-w. DOI

Mishra S., Shimpi N.G., Mali A.D. Effect of surface modified montmorillonite on photo-oxidative degradation of silicone rubber composites. Macromol. Res. 2013;21:466–473. doi: 10.1007/s13233-013-1035-4. DOI

Ogden R.W., Roxburgh D.G. A pseudo–elastic model for the Mullins effect in filled rubber. Proc. R. Soc. London. Ser. A Math. Phys. Eng. Sci. 1999;455:2861–2877. doi: 10.1098/rspa.1999.0431. DOI

Pan Y., Zhong Z. Modeling the Mullins effect of rubber-like materials. Int. J. Damage Mech. 2017;26:933–948. doi: 10.1177/1056789516635728. DOI

Sasikumar K., Manoj N.R., Mukundan T., Khastgir D. Hysteretic damping in XNBR–MWNT nanocomposites at low and high compressive strains. Compos. Part B-Eng. 2016;92:74–83. doi: 10.1016/j.compositesb.2015.04.005. DOI

Diani J., Fayolle B., Gilormini P.A. review on the Mullins effect. Eur. Polym. J. 2009;45:601–612. doi: 10.1016/j.eurpolymj.2008.11.017. DOI

Krpovic S., Dam-Johansen K., Skov A.L. Importance of Mullins effect in commercial silicone elastomer formulations for soft robotics. J. Appl. Polym. Sci. 2021;138:50380. doi: 10.1002/app.50380. DOI

Ma C., Ji T., Robertson C.G., Rajeshbabu R., Zhu J., Dong Y. Molecular insight into the Mullins effect: Irreversible disentanglement of polymer chains revealed by molecular dynamics simulations. Phys. Chem. Chem. Phys. 2017;19:19468–19477. doi: 10.1039/C7CP01142C. PubMed DOI

Fu W., Wang L., Huang J., Liu C., Peng W., Xiao W., Li S. Mechanical properties and Mullins effect in natural rubber reinforced by grafted carbon black. Adv. Polym. Technol. 2019;2019:4523696. doi: 10.1155/2019/4523696. DOI

Song Y., Yang R., Du M., Shi X., Zheng Q. Rigid nanoparticles promote the softening of rubber phase in filled vulcanizates. Polymer. 2019;177:131–138. doi: 10.1016/j.polymer.2019.06.003. DOI

Khajehsaeid K. Development of a network alteration theory for the Mullins-softening of filled elastomers based on the morphology of filler–chain interactions. Int. J. Solids Struct. 2016;80:158–167. doi: 10.1016/j.ijsolstr.2015.10.032. DOI

Qian M., Zou B., Chen Z., Huang W., Wang X., Tang B., Liu Q., Zhu Y. The influence of filler size and crosslinking degree of polymers on Mullins effect in filled NR/BR composites. Polymers. 2021;13:2284. doi: 10.3390/polym13142284. PubMed DOI PMC

Marckmann G., Verron E., Gornet L., Chagnon G., Charrier P., Fort P. A theory of network alteration for the Mullins effect. J. Mech. Phys. Solids. 2002;50:2011–2028. doi: 10.1016/S0022-5096(01)00136-3. DOI

Kittur M.I., Andriyana A., Ang B.C., Ch’ng S.Y., Verron E. Inelastic response of thermo-oxidatively aged carbon black filled polychloroprene rubber. Part I: Viscoelasticity. Polym. Degrad. Stab. 2022;205:110118. doi: 10.1016/j.polymdegradstab.2022.110118. DOI

Bouaziz R., Ahose K.D., Lejeunes S., Eyheramendy D., Sosson F. Characterization and modeling of filled rubber submitted to thermal aging. Int. J. Solids Struct. 2019;169:122–140. doi: 10.1016/j.ijsolstr.2019.04.013. DOI

Li Z., Xu H., Xia X., Song Y., Zheng Q. Energy dissipation accompanying Mullins effect of nitrile butadiene rubber/carbon black nanocomposites. Polymer. 2019;171:106–114. doi: 10.1016/j.polymer.2019.03.043. DOI

Bokobza L. Elastomer nanocomposites: Effect of filler–matrix and filler–filler interactions. Polymers. 2023;15:2900. doi: 10.3390/polym15132900. PubMed DOI PMC

Merckel Y., Diani J., Brieu M., Gilormini P., Caillard J. Characterization of the Mullins effect of carbon-black filled rubbers. Rubber Chem. Technol. 2011;84:402–414. doi: 10.5254/1.3592294. DOI

Castaño-Rivera P., Calle-Holguín I., Castaño J., Cabrera-Barjas G., Galvez-Garrido K., Troncoso-Ortega E. Enhancement of chloroprene/natural/butadiene rubber nanocomposite properties using organoclays and their combination with carbon black as fillers. Polymers. 2021;13:1085. doi: 10.3390/polym13071085. PubMed DOI PMC

Carli L.N., Roncato C.R., Zanchet A., Mauler R.S., Giovanela M., Brandalise R.N., Crespo J.S. Characterization of natural rubber nanocomposites filled with organoclay as a substitute for silica obtained by the conventional two-roll mill method. Appl. Clay Sci. 2011;52:56–61. doi: 10.1016/j.clay.2011.01.029. DOI

Li H., Wang L., Song G., Gu Z.H., Li P., Zhang C.H., Gao L. Study of NBR/PVC/oMMT nanocomposites prepared by mechanical blending. Iran. Polym. J. 2010;19:39–46.

Corby M., De Focatiis D.S. Reversibility of the Mullins effect for extending the life of rubber components. Plast. Rubber Compos. 2019;48:24–31. doi: 10.1080/14658011.2018.1443384. DOI

Denora I., Marano C. Stretch-induced softening in filled elastomers: A review on Mullins effect related anisotropy and thermally induced recovery. Polym. Test. 2024;133:108399. doi: 10.1016/j.polymertesting.2024.108399. DOI

Dargazany R., Itskov M. Constitutive modeling of the Mullins effect and cyclic stress softening in filled elastomers. Phys. Rev. E. 2013;88:012602. doi: 10.1103/PhysRevE.88.012602. PubMed DOI

Gao J., Yang X., Huang L., Suo Y. Experimental study on mechanical properties of aramid fibres reinforced natural rubber/SBR composite for large deformation–quasi-static mechanical properties. Plast. Rubber Compos. 2018;47:381–390. doi: 10.1080/14658011.2018.1514480. DOI