Papers by Keyword: Rheological Behavior

Abstract: This paper describes the process of fabricating porous carbon preform by casting the camphene based charcoal slurry. Five kinds of slurry with different solid content varied from 20vol% to 40vol% has been prepared, we have studied the rheological behavior of slurries and the sublimation behavior of casted bodies. Porous carbon preform with negligible linear shrinkage (<0.6%), high porosity (>67vol%) and interconnected pore structure has prepared.

Abstract: In PIM process, the molding stage is a critical step for the fabrication of sound parts without cracks and distortions. So, this step requires specific rheological behavior. Rheological analysis can be made to quantify the stability of the PIM feedstock during molding process. In this study, an experimental rheological study has been performed to evaluate the influence of palm stearin on the rheological behavior and stability of Inconel 718 powder injection molding (PIM) feedstock. The effects of shear rate and temperature were investigated via capillary rheometer method. The viscosity and shear rate of the feedstock were measured at various range of temperature and shear rate across the L/D = 1 capillary rheometer. The results show that the formulation binder system PSPE 7030 is the best feedstock to be injection molded because it has moderate value of flow sensitivity index, lower value for flow activation energy and higher value for mold ability index. Besides that, the increasing of PS content in the binder system has found reduce viscosity and value of flow activation energy and increase value of mold ability index of feedstock.

Abstract: The rheological behavior of slurry of foam cushion packaging based on fiber and starch was analyzed using digital viscosity meter. Meanwhile the response relationship of viscosity to time, shear rate to shear stress, and viscosity to temperature were also measured. The results showed that the slurry is a kind of non-newtonian fluid with the character of shear thinning. With the increasing of shear rate, apparent viscosity of system keeps in decreasing till the steady state finally. With temperature rising, plastic viscosity and yield strength of slurry will be smaller susceptibly. At last, Casson-Model was chose for the matching of plastic viscosity and yield strength.

Abstract: Alginate fibers were prepared by extruding a concentrated sodium alginate solution into calcium chloride coagulation bath. The rheological behavior of different concentrations of sodium alginate solutions were investigated to evaluate the spinnability. The effect of dope concentration on the morphologies and mechanical properties of resulting alginate fibers were examined. The results showed that sodium alginate solutions were pseudoplastic fluid and had good spinnability with concentration ranging in 1.5%-3.5%. Moreover, the morphology of obtained fibers became smoother with increasing sodium alginate concentrations. When the sodium alginate concentration was 3.5%, the tensile strength and elongation at break of alginate fibers reach to 13.6±1.2 cN/tex and 8±0.5%, respectively.

Abstract: The effect of ageing time on the macromolecular composition and conformation on intermolecular entanglement and crosslinking was investigated for a water-soluble, hydrophobically associating polymer (WSHAP), by steady-flow and oscillatory experiments at reservoir temperature (65 °C). The measurement of rheological properties was carried out with changing sample properties such as shear stress, shear rate and storage time. Moreover, for the investigated samples, the mathematical interpretation of relationship between the modulus G and the shear rate γ according to the Ostwald de Waele (power law) model, was carried out. Energy of viscous flow (E_a) has also been determined and discussed.

Abstract: The curing reaction of the bismaleimide resin system was analyzed by FT-IR spectroscopy and differential scanning calorimetry, and the curing reaction kinetics parameters were characterized. Otherwise the rheological behavior of the bismaleimide resin was studied through tracking the changes of the resin viscosity with reaction temperature and time by using a rotatory viscometer. The rheologic dynamic equation and dynamic index of the resin were also established under the condition of constant temperature.The result showed that the bismaleimide resin system was a typical thermosetting resin. This research will help to optimize the molding process parameters of the bismaleimide resin.

Abstract: A real-time die swell data gathering system was developed based on laser diameter gauge in order to measure the die swell of the viscoelastic materials. Software of the system is compiled by C language. Data gathering, date display, data saving and date analysis were realized. Experimental procedures were established, by which the die swell can be acquired. The laser gauge is put 5cm under the die of self-developed multi-function and all-electric rheometer (MAR) to measure the diameter of the extrudate. The rheological behaviors of the PP/PS blends are tested. The change laws of the melt die swell ratio in the condition of different frequency and amplitude were obtained. Compared with the steady-state extrusion, after introducing vibration force field, the melt die swell ratio decreases obviously. The die swell ratio of the blends decrease in fluctuation state with the increase of the frequency; while decreases gradually with the increase of the amplitude. In addition, with the die length-diameter ratio increases, die swell ratio of the blends decreases gradually.

Abstract: The rheological behavior and extrudate swell of polypropylene (PP)/silicon carbide (SiC) composites were investigated. Polypropylene-grafted-maleic anhydride (PP-g-MA) was introduced into blending system as a compatibilizer. The effect of silicon carbide loading and surface modification on the rheological behavior of PP/SiC composites were studied using a capillary rheometer and SEM analysis. The results showed that the composites exhibit pseudoplastic behavior as the shear stress and extrudate swell increased with increasing shear rate, while shear viscosity decreased. Moreover, an increasing elongation rate leads to reduce elongation viscosity. The addition of PP-g-MA in PP/SiC composites has significantly decreased the apparent shear stress, apparent shear viscosity and percentage of extrudate swell.

Abstract: Macrocyclic aryl ester dimer has been synthesized from o-phthaloyl dichloride with bisphenol A under pseudo high dilution conditions via interfacial polycondensation. The rheological behaviors during ring-opening polymerization of cyclic ester dimer at different experiment conditions have been investigated. The results show that it exists initial stage in the ROP reaction and the viscosity is lower than 10Pa·S in the initial period. The length of the initial stage can be controlled by the experiment conditions and the viscosity increases dramatically after the initial stage.

Abstract: Poly hexamethylene adipamide (PA66) nanocomposite fibers were prepared by using PA66 and polyhedral oligomeric silsesquioxanc (POSS). Rheological behavior, mechanical and thermal properties were characterized. Rheological study showed that a small amount of POSS can improve the flowing property and reduce PA66 viscosity. The onset decomposition temperature was improved with the addition of POSS as indicated by TGA analysis. Nearly all the mechanical properties were found to be increased with the adding of POSS. However, it was seen that higher POSS loading would not improve fiber performance due to serious of agglomeration.