Study of Shear and Extensional Viscosities of Biodegradable PBS/CO2 Solutions

Abstract

The purpose of this research is to study the pressure drop profiles of biodegradable polybutylene succinate (PBS)/CO2 solutions in a slit die and to measure the rheological properties of the solutions as a function of the blowing agent concentration. A slit die with four pressure transducers has been designed to describe the effects of shear rate, temperature, pressure, and gas content on the shear viscosity and extensional viscosity of the flowing PBS/CO2 solutions. The low shear rate viscosity of the pure polymer was measured using a cone and plate rheometer. Extensive experiments were conducted to investigate the polymer/gas solution viscosities at five different shear rates, three temperatures and five gas contents. Cross-Carreau model and generalized Arrhenius equation were used to describe the shear-viscosity behaviors of PBS/CO2 solutions. The extensional viscosity of solution was modeled based on Cogswell’s equation.

Measurement of the PVT property of PP/CO2 solution

“…The increased specific volume (i.e., increased free volume) causes an increase in the solubility and diffusivity [28]. The dissolved CO 2 causes a plasticization effect to reduce the viscosity of the polymer/gas mixtures and increase the chain mobility [36][37][38]. Also this increased specific volume decreases the surface tension of polymer [8].…”

Open‐Pore Biodegradable Foams Prepared via Gas Foaming and Microparticulate Templating

“…applied to a large class of biodegradable polymers ranging from synthetic polyesters [12][13][14][15][16][17][18] to natural materials such as thermoplastic proteins [19] and saccharides. [20] Although gas foaming allows fine control over the extension of the porous network of the foams, achievement of a high degree of open porosity (up to 100%) is often impaired by a combination of rheological and processing limitations that do not allow complete pore opening during foaming and lead to the formation of a closed external skin.…”

Combined Effects of Saturation Pressure and Gas Desorption on Foaming Characteristics of Microcellular Plastics

“…Material properties of microcellular plastics (MCPs) were reported by many researchers, which included tensile modulus [4,5] , fracture toughness [6] , fatigue [7] , and viscoelastic behavior [8] . The important factor that influences the mechanical properties of MCPs is the morphology of cells such as the cell size, shape, and density [9,10] . Figure 1 shows a schematic of the microcellular foaming process.…”