Slow relaxation occurs in many physical and biological systems. "Creep" is an example from everyday life. When stretching a rubber band, for example, the recovery to its equilibrium length is not, as one might think, exponential: The relaxation is slow, in many cases logarithmic, and can still be observed after many hours. The form of the relaxation also depends on the duration of the stretchin...

Polypropylene is one of the most common, fastest growing and versatile thermoplastics currently used to produce tanks and chemical piping systems. Even at room temperature creep is considerable for polypropylene products. The creep behavior of strains, stresses, and displacement rates is investigated in a thick-walled cylinder made of polypropylene reinforced by functionally graded (FG) multi-w...

The damping behaviour of several vinyl polymers-poly(methy1 methacrylate) (PMMA), poly(viny1 chloride) (PVC), polystyrene (PS) and impact polystyrene (Psi)-was studied both as a funtion of temperature and strain amplitude. The measurements were performed from room temperature up to the glass transition temperature and shows amplitude dependence at frequencies of the order of 50 kHz. The data ar...

This study investigates the time-dependent long-term creep strain in a composite cylinder made of glass/vinylester with a unidirectional ply. The cylinder is subjected to an internal pressure and the boundary condition is free–free and acts as thermal insulation. The classical lamination theory (CLT) is used to derive the governing equations as a second-order equation to determine the radial, c...

When sufficient force is applied to a glassy polymer, it begins to deform through movement of the polymer chains. We used an optical photobleaching technique to quantitatively measure changes in molecular mobility during the active deformation of a polymer glass [poly(methyl methacrylate)]. Segmental mobility increases by up to a factor of 1000 during uniaxial tensile creep. Although the Eyring...

Within the framework of the path-integral approach we study the quantum vortex creep for the situation where both the Hall and the dissipative dynamics are simultaneously present. We calculate the relaxation rate and the crossover temperature separating the thermal activation and the quantum tunneling processes for anisotropic or multilayer superconductors. The results are compared with the ava...

spark plasma sintering (sps) method, as plasma activated sintering, is a method applicable for rapid sintering of metals and ceramics. owing to the advantage of rapid heating, the alumina ceramics obtained by sps have a grain size and density comparable to those of hot pressed ones. the increase of densification rate may be related to some difference in ion transport characteristics. this study...

the influence of flour content and immersion time in water on the creep behavior of composites made from high density polyethylene (hdpe) waste and mdf (medium density fiberboard) flour was investigated. mixing was carried out by a twin screw extruder and the sample was manufactured by flat hot press. firstly, the modulus of elasticity and bending strength of various mdf flour-polyethylene comp...

Bimaterial microcantilevers are used in numerous applications in microelectromechanical systems (MEMS) for thermal, mechanical, optical, tribological and biological functionalities. Unfortunately, the residual stress-induced curvature and combined effects of creep and stress relaxation in the thin film significantly compromises the performance of these structures. To fully understand the themom...

Dislocations in solids contribute to anelastic attenuation, relaxation of the shear modulus, transient creep, and steady state flow. These properties of the mantle may therefore be related. The glide and climb of dislocations appear to have the appropriate time constants to explain seismic wave attenuation and mantle viscosity, respectively. The dislocation density of the mantle depends on the ...