Theory Of Rubber Elasticity Research Articles

Eco-friendly property modulation of biobased gels of carboxymethyl cellulose-integrated poly(tertiary amine)s for the removal of azo-food dyes

Anionic polysaccharide-based gels enable the design of biobased materials with biochemical properties, non-toxic and natural origin. A new set of cationic gels was prepared from carboxymethylcellulose (CMC)-doped tertiary amino functional cationic monomers 2-(dimethylamino)ethyl methacrylate and N-(3-(dimethylamino)propyl) methacrylamide via the formation of semi-interpenetrated network (semi-IPN) at different polymerization temperatures, Tprep. A detailed understanding of the temperature-dependent synthesis and physicochemical response is required for the design of interpenetrating networks with CMC as an adsorbent that provides effective sources for the removal of azo-food dyes such as tartrazine and carmoisine from aqueous solutions. The variation of elasticity and swelling properties with respect to polymerization temperature was investigated. CMC-integration and polymerization temperature played a decisive role in the compressive elasticity. Incorporation of CMC into copolymer matrix led to a significant increase in elasticity of semi-IPNs, while mechanically weaker gels were obtained with increasing Tprep. Addition of CMC increased the swelling modulus of semi-IPNs formed at −18 °C by 2.6-fold. While the transparency changed depending on Tprep and microstructure, addition of CMC decreased the swelling rate of gels at all polymerization temperatures. The compressive modulus decreased with the swelling process in accordance with the Rubber elasticity theory. Semi-IPN gels showed stable swelling against pH-change in aqueous solutions and exhibited excellent pH-sensitivity significantly in low pH. A 4 to 12 fold decrease in maximum volume was observed by varying the pH between 2.1 and 9.8. The correlation between polymerization temperature and removal of azo-food dyes; tartrazine and carmoisine from contaminated wastewater with CMC-based gels was studied. Dynamic adsorption equilibrium was reached in 30 min, and tartrazine and carmoisine removal performances varied between 92.8 % and 98.4 %. respectively. The adsorption data for azo-dyes were evaluated by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Patterson, Sips, and Tooth isotherm models, but were best described by Langmuir and Redlich-Patterson models as they gave the highest correlation. Pseudo-first order, pseudo-second order, Elovich, Avrami kinetic and intra-particle diffusion models were investigated and dye adsorption was represented by pseudo-second-order model. After the adsorption process, semi-IPNs can easily be regenerated and effectively reused over five cycles. The study provided new insights towards the facile and sustainable synthesis of eco-friendly multifunctional CMC-based gels carrying tertiary amino groups for effective removal of azo-based food colorants.

Quantitative Macromolecular Modeling Assay of Biopolymer-Based Hydrogels

The rubber elasticity theory has been lengthily applied to several polymeric hydrogel substances and upgraded from idealistic models to consider imperfections in the polymer network. The theory relies solely on hyperelastic material models in order to provide a description of the elastic polymer network. While this is also applicable to polymer gels, such hydrogels are rather characterized by their water content and visco-elastic mechanical properties. In this work, we applied rubber elasticity constitutive models through hyperelastic parameter identification of hydrogels based on their stress–strain response to compression. We further performed swelling experiments and determined the intrinsic properties, i.e., density, of the specimens and their components. Additionally, we estimated their equilibrium swelling and employed it in the swelling-equilibrium theory in order to determine the polymer–solvent interaction parameter of each hydrogel with regard to cross-linking. Our results show that the average mesh size obtained from the rubber elasticity theory can be regarded as a concentration-dependent characteristic length of the hydrogel’s network and couples the non-linear elastic response to the specimens’ inherent visco-elasticity through hysteresis as a quantifier of energy dissipation under large deformation.

The Theories of Rubber Elasticity and the Goodness of Their Constitutive Stress–Strain Equations

One of the most important challenges in polymer science is a rigorous understanding of the molecular mechanisms of rubber elasticity by relating macroscopic deformation to molecular changes and deriving the constitutive stress–strain equation for the elastomeric network. The models developed from the last century to today describe many aspects of the physics of rubber elasticity; although these theories are successful, they are not complete. In this review we analyze the main theoretical and phenomenological models of rubber elasticity, including their assumptions, main characteristics, and stress–strain equations. Then, we compare the predictions of the theories to our experimental data of polydimethylsiloxane (PDMS) rubber, in order to highlight the goodness of the reviewed models. The nonaffine and phenomenological deformation models verify the experimental curves in tension and compression in the whole investigated deformation range λ≤2. On the contrary, the affine deformation hypothesis is rigorously verified only in the deformation range λ≤1.

Gelation of PU elastomers: rheological characterization for liquid additive manufacturing

AbstractPolyurethane (PU) is a versatile polymer with many applications in a wide range of products. A novel 3D printing technology called liquid additive manufacturing (LAM) extended its possibilities by generating PU elastomers with gradient properties in continuous processing. LAM, being a relatively new technique, has not been extensively researched, particularly in terms of the curing behavior of the liquid resin. In this work, we investigated the effect of composition on gelation time tGP as measured by time-resolved mechanical spectroscopy (TRMS) and analyzed using the Winter–Chambon criterion with the assistance of the IRIS software. This method is more accurate than the previous approach, which involved time sweeps with a constant frequency. It was found that the gel time tGP first decreased and then increased with increasing polyol ratio, ranging from 231 to 378 min. Furthermore, the crosslink densities of the different PU elastomers measured from the rheological and tensile tests were calculated and compared based on the theory of rubber elasticity. The crosslink density decreased with an increasing polyol ratio in both methods. However, the crosslink density values obtained from the rheological measurements were higher than those from the tensile tests. These findings demonstrate that adjusting the polyol ratio is an effective means of achieving gradient properties. The composition effects we measured offer valuable insights for the design of LAM–PU elastomers.

2D fibrillar osteoid niche mimicry through inclusion of visco-elastic and topographical cues in gelatin-based networks

Given the clinical need for osteoregenerative materials incorporating controlled biomimetic and biophysical cues, a novel highly-substituted norbornene-modified gelatin was developed enabling thiol-ene crosslinking exploiting thiolated gelatin as cell-interactive crosslinker. Comparing the number of physical crosslinks, the degree of hydrolytic degradation upon modification, the network density and the chemical crosslinking type, the osteogenic effect of visco-elastic and topographical properties was evaluated. This novel network outperformed conventional gelatin-based networks in terms of osteogenesis induction, as evidenced in 2D dental pulp stem cell seeding assays, resulting from the presentation of both a local (substrate elasticity, 25–40 kPa) and a bulk (compressive modulus, 25–45 kPa) osteogenic substrate modulus in combination with adequate fibrillar cell adhesion spacing to optimally transfer traction forces from the fibrillar ECM (as evidenced by mesh size determination with the rubber elasticity theory) and resulting in a 1.7-fold increase in calcium production (compared to the gold standard gelatin methacryloyl (GelMA)).

Quasiperiodic graph model of rubber elasticity in double-network gels undergoing mechanochemical coupling

Purpose The purpose of this paper is to study the mechanochemical effect and self-growth mechanism of double-network (DN) gel and to provide a quasiperiodic model for rubber elasticity. Design/methodology/approach The chemical reaction kinetics is used to identify the mechanochemical transition probability of host brittle network and to explore the mechanical behavior of endosymbiont ductile network. A quasiperiodic model is proposed to characterize the cooperative coupling of host–endosymbiont networks using the Penrose tiling of a 2 × 2 matrix. Moreover, a free-energy model is formulated to explore the constitutive stress–strain relationship for the DN gel based on the rubber elasticity theory and Gent model. Findings In this study, a quasiperiodic graph model has been developed to describe the cooperative interaction between brittle and ductile networks, which undergo the mechanochemical coupling and mechanical stretching behaviors, respectively. The quasiperiodic Penrose tiling determines the mechanochemistry and self-growth effect of DNs. Originality/value It is expected to formulate a quasiperiodic graph model of host–guest interaction between two networks to explore the working principle of mechanical and self-growing behavior in DN hydrogels, undergoing complex mechanochemical effect. The effectiveness of the proposed model is verified using both finite element analysis and experimental results of DN gels reported in literature.

Investigation of the Effect of Swelling on the Diffusion Properties of Polyethylene Glycol Hydrogel for Wound Healing Applications.

The present research work aims to comprehensively analyze the effect of swelling of polyethylene glycol (PEG) hydrogel on its diffusion properties for wound healing applications. For this study, a computational model based on three fundamental theories namely, equilibrium swelling theory, rubber elasticity theory and free volume theory has been implemented to determine the diffusion parameters of PEG hydrogel having a molecular weight of 20,000 g/mol. The diffusion of two plant metabolites with inherent antimicrobial activity namely, Cinnamaldehyde and Curcumin and two synthetic antimicrobial drugs namely, Amphotericin B and Vancomycin has been simulated. The results demonstrate that the proposed theoretical framework is capable of predicting the alterations occurring in the diffusion characteristics due to the swelling of PEG hydrogel. The diffusion coefficient of the solute is found to increase with the volumetric swelling ratio (Qv), owing to the wider mesh size of the hydrogel matrix. The diffusion time of the therapeutic compounds is observed to be in the range of 2.40 - 8.30 h.Clinical Relevance- The modelling approach employed in this study will be clinically relevant for designing hydrogel drug delivery systems capable of accelerating the treatment of the infected wounds.

Influence of solvent quality on the swelling and deswelling and the shear modulus of semi-dilute solution cross-linked poly(vinyl acetate) gels.

We systematically examine the influence of varying temperature (T) over a large range in model poly(vinyl acetate) gels swollen in isopropyl alcohol. The theta temperature Θ, at which the second virial coefficient A2 vanishes, is found to be equal to within numerical uncertainty to the corresponding high molecular mass polymer solution value without cross-links, and we quantify the swelling and deswelling of our model gels relative to their size at T = Θ, as customary for individual flexible polymer chains in solutions. We also quantify the "solvent quality" dependence of the shear modulus G relative to G(T = Θ) and compare to the hydrogel swelling factor, α. We find that all our network swelling and deswelling data can be reduced to a scaling equation of the same general form as derived from renormalization group theory for flexible linear polymer chains in solutions so that it is not necessary to invoke either the Flory-Huggins mean field theory or the Flory-Rehner hypothesis that the elastic and mixing contributions to the free energy of network swelling are separable to describe our data. We also find that changes of G relative to G(T = Θ) are directly related to α. At the same time, we find that classical rubber elasticity theory describes many aspects of these semi-dilute solution cross-linked networks, regardless of the solvent quality, although the prefactor clearly reflects the existence of network defects whose concentration depends on the initial polymer concentration of the polymer solution from which the networks were synthesized.

Statistical field theory for nonlinear elasticity of polymer networks with excluded volume interactions.

Polymer networks formed by cross linking flexible polymer chains are ubiquitous in many natural and synthetic soft-matter systems. Current micromechanics models generally do not account for excluded volume interactions except, for instance, through imposing a phenomenological incompressibility constraint at the continuum scale. This work aims to examine the role of excluded volume interactions on the mechanical response. The approach is based on the framework of the self-consistent statistical field theory of polymers, which provides an efficient mesoscale approach that enables the accounting of excluded volume effects without the expense of large-scale molecular modeling. A mesoscale representative volume element is populated with multiple interacting chains, and the macroscale nonlinear elastic deformation is imposed by mapping the end-to-end vectors of the chains by this deformation. In the absence of excluded volume interactions, it recovers the closed-form results of the classical theory of rubber elasticity. With excluded volume interactions, the model is solved numerically in three dimensions using a finite element method to obtain the energy, stresses, and linearized moduli under imposed macroscale deformation. Highlights of the numerical study include: (i) the linearized Poisson's ratio is very close to the incompressible limit without a phenomenological imposition of incompressibility; (ii) despite the harmonic Gaussian chain as a starting point, there is an emergent strain-softening and strain-stiffening response that is characteristic of real polymer networks, driven by the interplay between the entropy and the excluded volume interactions; and (iii) the emergence of a deformation-sensitive localization instability at large excluded volumes.

Volumetric Printing of Thiol-Ene Photo-Cross-Linkable Poly(ε-caprolactone): A Tunable Material Platform Serving Biomedical Applications.

Current thoroughly described biodegradable and cross-linkable polymers mainly rely on acrylate cross-linking. However, despite the swift cross-linking kinetics of acrylates, the concomitant brittleness of the resulting materials limits their applicability. Here, photo-cross-linkable poly(ε-caprolactone)networks through orthogonal thiol-ene chemistry are introduced. The step-growth polymerized networks are tunable, predictable by means of the rubber elasticity theory and it is shown that their mechanical properties are significantly improved over their acrylate cross-linked counterparts. Tunability is introduced to the materials, by altering Mc (or the molar mass between cross-links), and its effect on the thermal properties, mechanical strength and degradability of the materials is evaluated. Moreover, excellent volumetric printability is illustrated and the smallest features obtained via volumetric 3D-printing to date are reported, for thiol-ene systems. Finally, by means of in vitro and in vivo characterization of 3D-printed constructs, it is illustrated that the volumetrically 3D-printed materials are biocompatible. This combination of mechanical stability, tunability, biocompatibility, and rapid fabrication by volumetric 3D-printing charts a new path toward bedside manufacturing of biodegradable patient-specific implants.

Quantitative structure-property relationships of thermoset pea protein gels with ethanol, shear, and sub-zero temperature pretreatments

Pea protein is often processed to alter the protein's native structure, enhancing desirable textures in meat and dairy analog products. Cold denaturation is a universal phenomenon in protein that exposes hydrophobic amino acids, though little information exists about this in food science research. In this work, ethanol, shear forces, and low temperatures were used to modify the structure of commercial pea protein isolate, and impacts on gelation are characterized. Treatment at −10 °C in ethanol with applied shear forces led to gels with the lowest tan δ values during temperature ramps and frequency sweeps. A quantitative structure-property relationship (QSPR) method found that hydrogen bonding can be derived from secondary structure (R 2 = 0.960), and hydrogen bonding correlated with the temperature dependence of G′ during cooling in treatments. This work suggests cold denaturation forms hydrophobically bound gels that may aid in replacing fatty textures, and a QSPR framework aids in interpreting rheological data. • Ethanol, shear forces, and low-temperature treatment increase pea protein gel strength. • The number of hydrogen bonds can be estimated from protein secondary structure resulting from FTIR. • Hydrogen bonding correlates to the degree of stiffening during gelation. • Hydrogen bonding correlates to the number of crosslinks estimated using rubber elasticity theory. • Cold denaturation facilitates the design of new cold processing methods to enhance functionality of proteins.

Correlation between effective charge density and crosslinking efficiency of dicarboxylic acid containing highly anionic networks

By investigating the relationship between the swelling and deformation properties, an attempt was made to establish a correlation between microstructure and charge density of anionic polyacrylamide/itaconic acid (PAAm/ITA) hydrogels. The effective charge density of network dominated the microstructure of PAAm/ITA hydrogels. The porosity of anionic hydrogels increased with addition of diprotic ITA, and resulting microstructure determined the swollen state deformation. Based on effective charge density, the swelling gradually increased and maximum swelling was achieved with 14% ITA, while there was a 24-fold increase in gel volume relative to homopolymer network. The relationship between elasticity and crosslinking density was explained using Rubber elasticity theory on deformation behavior. A variety of factors that affect swelling and elasticity was explored such as effective charge density, crosslink density of anionic network as well as pH of solution and surfactant type. The equilibrium volume swelling ratio in water scales with network charge density by the relation φV ∝ feff1.17, while the dependence of reduced modulus with equilibrium gel volume was found to be Gr≈(φV)−0.28 indicating that equilibrium swollen PAAm/ITA hydrogels are in Gaussian regime. An empirical relationship has been found implying that by varying amount of ITA, the crosslinked structure and crosslinking density can be effectively controlled. PAAm/ITA hydrogels showed good reversible characteristics during repeated oscillations between pH 11.2 and 2.1, which is important for controlled drug delivery system. Rapid water penetration of PAAm/ITA hydrogels with internal morphology and high swelling resulting from the presence of ITA revealed internal adsorption sites for methyl violet and methylene blue. The adsorption kinetics followed a pseudo-second order and showed a two-stage intra-particle diffusion model. The results will contribute to the determination of correlation between anionic structure and properties for efficient and economical design of anionic materials for specific uses and industrial scale-up.

Undirected graphical model of adjacency matrix for dynamic elasticity in polyelectrolyte hydrogels

Molecular network plays a critical role in determining dynamic elasticity of soft condensed polymers, e.g., their varied cross-linking densities and end-to-end distances with changed Young's moduli. Although it has been studied for decades, the coupling relationship between vertices and edges of molecular networks is not well understood, mainly because the degree of the crosslinking points and asymmetry molecular networks have not been considered in the previously models. In this study, a graph theory was employed to formulate an undirected graphical model and describe the coupling between vertices and edges in molecular networks, based on which the dynamic elasticity of polyelectrolyte hydrogel was modeled. From the Kirchhoff graph theory and bead-spring model, the coupling relationship between vertices and edges was obtained using end-to-end distance and viscosity parameters. Combining the Watts–Strogatz model and kinetic probability, the coupling between vertices and edges for the polyelectrolyte network was studied. Furthermore, an adjacency matrix with eigenvalue, number of vertices and mean degree was proposed to formulate constitutive relationships including dynamic elasticity and stress-strain, according to rubber elasticity theory and Mooney-Rivlin model, respectively. The linking between the vertices and edges determines the network structure and dynamic elasticity of the polyelectrolyte hydrogel. Based on the graph theory, the vertices and edges are encoded by adjacency matrix, which is proposed to describe the dynamic elasticity of symmetric and asymmetric network structures using the crosslinking density and end-to-end distance. Finally, effectiveness of the undirected graphical model was verified using both finite element analysis and experimental results of polyelectrolyte hydrogels reported in literature.

Structure-property relationships of Kaolin-nanocomposite beads decorated with tertiary amines: Influence of shape on network elasticity and multi-responsivity

Aluminosilicate mineral Kaolin-loaded nanocomposite beads containing cationic 2-(dimethylamino)ethyl methacrylate (DMAEMA) and thermoresponsive N-isopropylacrylamide (NIPA) have been successfully synthesized by combined method of dropwise freezing into cryogenic liquid and sedimentation cryogelation. Hertzian elasticity, thermal stability, and responsive-swelling properties were investigated. The nanocomposite gels exhibited better mechanical properties and thermal stability than neat copolymer gels. The stress and displacement distribution on surface of Kaolin-loaded nanocomposite beads were evaluated with classical Hertz theory, and the results were compared with the results obtained from Rubber elasticity theory. The scaling relationship for contact stress and surface displacement was obtained assuming Hertz's small contact area, and the compression force was scaled with displacement with an exponent of 1.34 ± 0.08. The elastic properties directly attributed to effective potential showed that Hertz potential is valid for small deformations and the elastic modulus decreased with the swollen bead diameter. Addition of Kaolin and NIPA to PDMAEMA-based network has opposite effect on the mechanical properties. The elastic modulus increased, but the swelling ratio decreased with addition of Kaolin. The opposite behavior was observed when NIPA was added, the swelling increased and the mechanical properties weakened. All gels showed significant temperature sensitivity as a result of combination of PDMAEMA and PNIPA, while the swelling was higher at acidic pH than alkaline pH. An overshooting effect attributed to the dynamic conformational changes of tertiary amine of DMAEMA was observed during swelling in pH 3.6. The increase in network density of nanocomposite gel with addition of Kaolin leads to slower relaxation of molecules, and water absorption tends to become relaxation-controlled. An increase in diffusion exponent is observed as diffusion changes from Fickian to non-Fickian. Influence of single salts; NaCl, KCl and K2CO3 on swelling of nanocomposites was investigated. The swelling of Kaolin-loaded nanocomposites decreased with increasing ionic strength, and a “salting-out” effect was observed. The use of naturally occurring nanoscale particles in such structural material design is an important method for biomedical applications and separation technology.

Self-consistent fractal geometry in polyampholyte hydrogels undergoing exchange and correlation charge-density

Polyampholyte (PA) hydrogels are incorporated of many internally charged polymer chains, which play an important role to influence the fractal networks and dynamic elasticity of the PA hydrogels owing to their different exchange and correlation charge-densities. Many properties of the PA hydrogels, such as mechanical strength and deformation, are significantly dependent on their fractal networks. However, working principles of chemo-mechanical coupling between the fractal networks and the elasticity of PA hydrogels have not been fully understood. In this study, a self-consistent fractal geometry model integrated with a complex function is proposed to understand the constitutive relationship between dynamic networks and tailorable mechanics in the PA hydrogels. The newly developed model is uniquely incorporated with the mechanochemistry, and describes the chemical polarization reactions of charged networks and their mechanical behaviors using complex fractal functions. Based on the rubber elasticity theory, constitutive stress–strain relationships of fractal networks have been described using their elastic, conformational, repulsive and polarization free-energy functions. Finally, effectiveness of the proposed model has been verified using both finite element analysis and experimental results of the PA hydrogels reported in literature.

Non-Euclidean geometry model for chemo-mechanical coupling in self-assembled polymers towards dynamic elasticity

Self-assembly plays a fundamental role to determine thermodynamic properties of polymer systems, e.g., resulting in the formation of dynamically cross-linked networks with varied elasticity. However, the working principle of chemo-mechanical coupling between the self-assembly and elasticity of polymers is complex and has not been well understood. In this study, a non-Euclidean geometry model incorporating thermodynamics of microphase separation is proposed to understand the chemo-mechanical coupling in self-assembled triblock polymers. The thermodynamic separation of microphases, which is resulted from the self-assembly of polymeric molecules, is formulated using a non-Euclidean geometry equation, of which the geometrical parameters are applied to characterize the topologies of self-assembled and cross-linked networks. The non-Euclidean geometry model is further employed to describe chemo-mechanical coupling between the self-assembled network and dynamic elasticity of the triblock polymers, based on the rubber elasticity theory. Effectiveness of the proposed model is verified using both finite-element analysis and experimental results reported in literature. This study provides a new geometrical approach to understand the mechanochemistry and thermodynamics of self-assembled block polymers.

Recent Studies on Degradation Mechanism of Rubber Vulcanizates by Chemorheology

Abstract A critical discussion is presented of the influence of chemical degradation mechanisms on the mechanical properties, especially stress relaxation, of vulcanized rubber. The response of the vulcanizate is interpreted in terms of the kinetic theory of rubber elasticity. Different chemical mechanisms are explored. The influence of diluent is interpreted in terms of the kinetic theory of rubber elasticity. Different chemical mechanisms are explored. The influence of diluent is considered. Comparisons are made to experiments on polyisoprenes and polyurethanes.

Determination of the molecular weight between cross‐links for different ambers: Viscoelastic measurements of the rubbery plateau*

AbstractWhile much is known about the chemistry of amber, there are, to our knowledge, no quantitative estimates of the molecular weight between cross‐links or quantitative estimates of the amount of cross‐linking. In the present study we provide new data that advances our understanding of ancient ambers through an investigation of the network structure based on measurements of the rubbery modulus. Then, using rubber elasticity theory, we provide semiquantitative insights into the network structure. The work provides direct mechanical evidence of the chemically cross‐linked structure of a Burmese amber, a Dominican amber, a Fushun amber, and two Baltic ambers by quantifying the molecular weight between cross‐links . The values of of the studied ambers ranges from 1800 to 3000 g/mol, and the number of monomers between two cross‐link junctions is estimated to be between 6 and 10.

Recent Progress in Biopolymer-Based Hydrogel Materials for Biomedical Applications.

Hydrogels from biopolymers are readily synthesized, can possess various characteristics for different applications, and have been widely used in biomedicine to help with patient treatments and outcomes. Polysaccharides, polypeptides, and nucleic acids can be produced into hydrogels, each for unique purposes depending on their qualities. Examples of polypeptide hydrogels include collagen, gelatin, and elastin, and polysaccharide hydrogels include alginate, cellulose, and glycosaminoglycan. Many different theories have been formulated to research hydrogels, which include Flory-Rehner theory, Rubber Elasticity Theory, and the calculation of porosity and pore size. All these theories take into consideration enthalpy, entropy, and other thermodynamic variables so that the structure and pore sizes of hydrogels can be formulated. Hydrogels can be fabricated in a straightforward process using a homogeneous mixture of different chemicals, depending on the intended purpose of the gel. Different types of hydrogels exist which include pH-sensitive gels, thermogels, electro-sensitive gels, and light-sensitive gels and each has its unique biomedical applications including structural capabilities, regenerative repair, or drug delivery. Major biopolymer-based hydrogels used for cell delivery include encapsulated skeletal muscle cells, osteochondral muscle cells, and stem cells being delivered to desired locations for tissue regeneration. Some examples of hydrogels used for drug and biomolecule delivery include insulin encapsulated hydrogels and hydrogels that encompass cancer drugs for desired controlled release. This review summarizes these newly developed biopolymer-based hydrogel materials that have been mainly made since 2015 and have shown to work and present more avenues for advanced medical applications.

Material and Product Development for Carbon Neutrality

In recent years, the promotion of carbon neutrality has been required all over the world. We are implementing various initiatives that will lead to the reduction of CO2 emissions. Weight reduction of automobile parts is also one of the efforts to reduce CO2. Not only improving fuel efficiency but also reducing the amount of materials used, weight reduction leads to reduction of CO2 emissions.This paper introduces an example of weight reduction by developing a high-stiffness rubber material for an air cleaner hose. The important functions required for an air cleaner hose are negative pressure resistance, assembly performance, and sealing performance. In order to reduce the weight while maintaining these functions, it was necessary to develop a highly stiffness material with low temperature dependence of stiffness. In the development, we developed a new high-stiffness rubber material with low temperature dependence by using the rubber elasticity theory.