Manufacturing of composite materials is usually accompanied with residual stresses.These stresses should be evaluated and assessed.To this end,a micromechanical model for periodic material whose temperature dependent ...Manufacturing of composite materials is usually accompanied with residual stresses.These stresses should be evaluated and assessed.To this end,a micromechanical model for periodic material whose temperature dependent constituents behave as thermorheologically complex materials(TCM)has been developed.This model,referred as the high fidelity generalized method of cells(HFGMC),takes into account the detailed interaction between the fiber and resin,their volume ratios,the fibers distribution and their waviness.This model is linked,in conjunction with a special UMAT subroutine,to the ABAQUS finite element code for prediction of the response of thermoviscoelastic composite structures during cool down process.The present investigation shows the effect of the cool down rate on the residual stress developed in the composite cylindrical structures.展开更多
A variety of linear and 3-arm star polyethylene （PE） model polymers covering a wide range of molecular weight are synthesized by the living polymerization of butadiene and the subsequent hydrogenation. Several rheol...A variety of linear and 3-arm star polyethylene （PE） model polymers covering a wide range of molecular weight are synthesized by the living polymerization of butadiene and the subsequent hydrogenation. Several rheological parameters of these model linear and 3-arm star PE samples are analyzed for detecting the long chain branching （LCB） structure. It is found that the analyses based on zero shear viscosity, vGP plot and flow activation energy are very sensitive to the 3-arm star PEs. The information on the presence of LCB can be obtained with these methods even for low molecular weight samples, which can not be determined by GPC-MALLS. However the information about the LCB structure can not be obtained by the rheological methods alone.展开更多
While supramolecular hydrogels have received growing interest due to their unique dynamic features,their relatively weak mechanical properties have largely limited their biomedical applications.In this study,we propos...While supramolecular hydrogels have received growing interest due to their unique dynamic features,their relatively weak mechanical properties have largely limited their biomedical applications.In this study,we propose and demonstrate a strategy to reinforce the mechanical properties of supramolecular hydrogel by introducing polymeric multiple-unit linker(PMUL),which incorporates multiple supramolecular units into a polymeric backbone to crosslink supramolecular hydrogel.We demonstrated that PMUL can effectively improve the kinetic stability of supramolecular crosslinkers through multiple-unit interaction in a DNA supramolecular hydrogel model system,thus leading to higher mechanical strength.Meanwhile,the dynamic features of the supramolecular hydrogels have been well preserved,including shear-thinning,self-healing properties,and reversible thermal responsiveness.This strategy offers a simple but effective way for mechanical reinforcement of supramolecular hydrogels to construct novel biomaterials.展开更多
We study the continuous dependence on coefficients of solutions of the nonlinear nonhomogeneous Fourier boundary value problems involving the p(x)-Laplace operator.
文摘Manufacturing of composite materials is usually accompanied with residual stresses.These stresses should be evaluated and assessed.To this end,a micromechanical model for periodic material whose temperature dependent constituents behave as thermorheologically complex materials(TCM)has been developed.This model,referred as the high fidelity generalized method of cells(HFGMC),takes into account the detailed interaction between the fiber and resin,their volume ratios,the fibers distribution and their waviness.This model is linked,in conjunction with a special UMAT subroutine,to the ABAQUS finite element code for prediction of the response of thermoviscoelastic composite structures during cool down process.The present investigation shows the effect of the cool down rate on the residual stress developed in the composite cylindrical structures.
文摘A variety of linear and 3-arm star polyethylene （PE） model polymers covering a wide range of molecular weight are synthesized by the living polymerization of butadiene and the subsequent hydrogenation. Several rheological parameters of these model linear and 3-arm star PE samples are analyzed for detecting the long chain branching （LCB） structure. It is found that the analyses based on zero shear viscosity, vGP plot and flow activation energy are very sensitive to the 3-arm star PEs. The information on the presence of LCB can be obtained with these methods even for low molecular weight samples, which can not be determined by GPC-MALLS. However the information about the LCB structure can not be obtained by the rheological methods alone.
基金supported by the National Natural Science Foundation of China(grant nos.21890731,21821001,21534007,21971248,and 21890730)the National Basic Research Plan of China(grant no.2018YFA0208900)the Institute of Chemistry CAS(grant no.C220200701).
文摘While supramolecular hydrogels have received growing interest due to their unique dynamic features,their relatively weak mechanical properties have largely limited their biomedical applications.In this study,we propose and demonstrate a strategy to reinforce the mechanical properties of supramolecular hydrogel by introducing polymeric multiple-unit linker(PMUL),which incorporates multiple supramolecular units into a polymeric backbone to crosslink supramolecular hydrogel.We demonstrated that PMUL can effectively improve the kinetic stability of supramolecular crosslinkers through multiple-unit interaction in a DNA supramolecular hydrogel model system,thus leading to higher mechanical strength.Meanwhile,the dynamic features of the supramolecular hydrogels have been well preserved,including shear-thinning,self-healing properties,and reversible thermal responsiveness.This strategy offers a simple but effective way for mechanical reinforcement of supramolecular hydrogels to construct novel biomaterials.
文摘We study the continuous dependence on coefficients of solutions of the nonlinear nonhomogeneous Fourier boundary value problems involving the p(x)-Laplace operator.
