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1. Rubber that lasts longer

   https://doi.org/10.1038/s41893-025-01549-1  

   Craig, Stephen L; Rubinstein, Michael (May 2025, Nature Sustainability)
2. The Nonlinear Viscoelastic Response of Suspensions of Vacuous Bubbles in Rubber: I — Gaussian Rubber with Constant Viscosity

   https://doi.org/10.1007/s10659-021-09868-y  

   Shrimali, Bhavesh; Ghosh, Kamalendu; Lopez-Pamies, Oscar (January 2022, Journal of Elasticity)
3. Necking and drawing of rubber–plastic bilayer laminates

   https://doi.org/10.1039/C8SM00684A  

   Ramachandran, Rahul G.; Hariharakrishnan, S.; Fortunato, Ronald; Abramowitch, Steven D.; Maiti, Spandan; Velankar, Sachin S. (January 2018, Soft Matter)

   We examine the stretching behavior of rubber–plastic composites composed of a layer of styrene–ethylene/propylene–styrene (SEPS) rubber, bonded to a layer of linear low density polyethylene (LLDPE) plastic. Dog-bone shaped samples of rubber, plastic, and rubber–plastic bilayers with rubber : plastic thickness ratio in the range of 1.2–9 were subjected to uniaxial tension tests. The degree of inhomogeneity of deformation was quantified by digital image correlation analysis of video recordings of these tests. In tension, the SEPS layer showed homogeneous deformation, whereas the LLDPE layer showed necking followed by stable drawing owing to its elastoplastic deformation behavior and post-yield strain hardening. Bilayer laminates showed behavior intermediate between the plastic and the rubber, with the degree of necking and drawing reducing as the rubber : plastic ratio increased. A simple model was developed in which the force in the bilayer was taken as the sum of forces in the plastic and the rubber layers measured independently. By applying a mechanical energy balance to this model, the changes in bilayer necking behavior with rubber thickness could be predicted qualitatively. 

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4. Multiscale stress deconcentration amplifies fatigue resistance of rubber

   https://doi.org/10.1038/s41586-023-06782-2  

   Steck, Jason; Kim, Junsoo; Kutsovsky, Yakov; Suo, Zhigang (December 2023, Nature)

   Rubbers reinforced with rigid particles are used in high-volume applications, including tyres, dampers, belts and hoses1. Many applications require high modulus to resist excessive deformation and high fatigue threshold to resist crack growth under cyclic load. The particles are known to greatly increase modulus but not fatigue threshold. For example, adding carbon particles to natural rubber increases its modulus by one to two orders of magnitude1,2,3, but its fatigue threshold, reinforced or not, has remained approximately 100 J m−2 for decades4,5,6,7. Here we amplify the fatigue threshold of particle-reinforced rubbers by multiscale stress deconcentration. We synthesize a rubber in which highly entangled long polymers strongly adhere with rigid particles. At a crack tip, stress deconcentrates across two length scales: first through polymers and then through particles. This rubber achieves a fatigue threshold of approximately 1,000 J m−2. Mounts and grippers made of this rubber bear high loads and resist crack growth over repeated operation. Multiscale stress deconcentration expands the space of materials properties, opening doors to curtailing polymer pollution and building high-performance soft machines. 

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5. Direct ink writing of piezoresistive isoprene rubber nanocomposites

   https://doi.org/10.1002/pc.29535  

   Banks, James D; Emami, Anahita (July 2025, Polymer Composites)

   Abstract Despite the growing interest in flexible electronics and wearable sensors, research in piezoresistive polymer nanocomposites has stagnated in consideration of the polymer matrices, particularly in additive manufacturing (AM) applications. This research focuses on using a low‐molecular isoprene rubber (IR) as a matrix filled with carbonaceous nanoparticles conductive carbon black (CCB) and carbon nanotubes (CNT) to create piezoresistive sensors printed via direct ink writing (DIW). Using IR as a matrix not only provides an avenue for an alternate sensor matrix, but also offers a distinct advantage for retrofit sensor applications to other diene rubber substrates due to both the feedstock and substrate possessing the same vulcanization mechanism. Thereby, the rheological, mechanical, and piezoresistive properties of the IR nanocomposites are fully investigated, with emphasis on non‐ambient conditions (temperature and durability). In this work it is shown that while CCB exhibits a lower gauge factor (between 1.5 and 8) across all strain rates, strain ranges, and temperatures when compared to CNT compounds (gauge factors between 1.5 and 260), CCB compounds possess better linearity, less temperature deviation, and overall better performance under cyclic loading conditions. This is followed by demonstrations for real‐world applications, including the direct‐to‐product printing of a CCB strain gauge on a chloroprene rubber substrate. HighlightsAM via DIW of piezoresistive isoprene sensors filled with conductive CB and multi‐wall carbon nanotubes.Printed samples capable of achieving tensile strength >3.5 MPa.CB sensors showed less sensitivity, but better durability and repeatability compared to carbon nanotube filled sensors.Piezoresistive isoprene strain gauge printed on chloroprene substrate with direct adhesion. 

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