Energy dissipation in stretching filled rubbers

Abstract

SynopsisEnergy expended irreversibly in stretching filled rubbers is calculated for a simple two-phase series model: a soft phase resembling the corresponding unfilled rubber and a hard phase in series with the soft phase. It is assumed that the Iubber is initially wholly in the hard state and that it changes progressively into the softened state on stretching, as proposed by Mullins and Tobin. For a wide range of model parameters, the dissipation of mechanical energy is predicted to rise to about 40% of the input energy at large strains. This predicted behavior is in reasonably good agreement with observations of extra energy dissipat,ion in carbon black-filled rubbers, in comparison with corresponding unfilled rubbers, suggesting that the proposed mechanism of hysteresis by phase transformation is valid. A method of combining energy losses from two simultaneous dissipative processes is also proposed.

Thermo-responsive properties of metallo-supramolecular block copolymer micellar hydrogels

“…This proportion is known as the hysteresis loss and is given, with respect to the strain energy, by the area under the stress-strain loop. 22 In essence, the rheological response of the investigated hydrogel is consistent with the thermo-responsive behaviour of poly(N-isopropylacrylamide) chains in aqueous solution. Below the LCST, favourable interactions allow the dissolution of the polymer in water via hydrogen bonding.…”

Metal–Ligand Complexes as Dynamic Sacrificial Bonds in Elastic Polymers

“…Rubbers employed in technical applications, such as gaskets, seals, hoses, belts, tires, and others, are generally prepared by chemical cross-linking of polymers having a low glass transition temperature. − The originally (highly) viscous base polymer is usually compounded with the cross-linking agent(s) and additives such as processing aids, reinforcing fillers, pigments, and additives before it is converted into a cross-linked (vulcanized) polymer network with tangible strength and elasticity, usually via the thermally induced formation of covalent bonds between the polymer chains. , Besides the choice of the base polymer, and the nature and content of the curing system, the desired profile with respect to thermomechanical properties, damping characteristics, stress–strain behavior, and stability under a given set of conditions is generally achieved via formulation, that is, in the process of rubber compounding . The past decades have seen many developments that aim at improving specific aspects of the mechanical properties, notably through the incorporation of various fillers. − A particularly effective reinforcement is achieved with filler particles of sub-micrometer size that are uniformly dispersed in the continuous polymer phase. − When these conditions are met, a significant increase in stiffness and ultimate tensile strength can be achieved with only a minimal sacrifice in the form of reduced elasticity . Common fillers include carbon black (CB) and silica, ,− cross-linked polystyrene particles, carbon nanotubes, ,, graphene, − nanoclay, − and cellulose nanocrystals. − …”

“…While previous efforts to modify elastomers through the introduction of non-covalent interactions have mainly been motivated by the goal to increase the stiffness and strength, ,,,− we sought to exploit reversible metal–ligand interactions as dynamic cross-links that can act as sacrificial bonds, dissipate excessive energy, and furnish an effective reinforcement without negatively impacting other properties (Figure ). To render our study not only fundamentally but also technologically relevant, we targeted chemistries that are compatible with materials and processes used in current products.…”

Silica Nanoparticle Reinforced Composites as Transparent Elastomeric Damping Materials

“…It is well-known that the mechanical properties of rubber can be significantly improved by filler-filling, which is the reason why filler-filled rubbers are widely used. In addition, the mechanical properties of filler-filled rubbers can be designed to meet the required properties by changing the type, filling amount, and properties of the filler. , Many studies have been performed on the toughness of filler-filled rubbers, and it is considered that bound rubber with a high elastic modulus and its network structure, in which polymer chains are adsorbed on the filler surface, play an important role. − The mechanical properties derived from the presence of filler aggregates, such as the Mullins effect and the Payne effect, which are characteristic phenomena of filler-filled rubbers, have also been discussed from various perspectives. ,− However, although many researchers have proposed theories on the reinforcement mechanism of filler-filled rubbers, the mechanism is not completely understood. The presence of multiple additives (dispersants, plasticizers, vulcanizing agents, etc.)…”