Rheology product testing

Quality Control and Testing. Control of inks is done by examining their color strength, hue, tack, rheology, drying rate, stabiHty, and product resistance. Elaborate control equipment and laboratory testing procedures are employed to test the finished inks. Weather-Ometers,... 

Despite their flaws, batch processes have stood the test of time for a number of reasons, the most important of which is the flexibihty it brings to the manufacturer in terms of the range of products that the plant can produce, the feedstocks used to produce them, and the speed at which they can be brought to market with very limited information on physical properties, reaction kinetics, and so on (very few, if any, Michelin-starred chefs have ever measured the rheology or kinetics of their latest culinary creation). This flexibility, however, has a price which comes in the form of lower efficiencies in terms of production, energy, labor, and so on, and ultimately efficiency equates to cost However, one should never underestimate the pull of flexibility particularly, as discussed earlier in the examples of fermentation, where control of important parameters is difficult to achieve. 

D Miller, EM Wiener, A Turowski, C Thunig, H Hoffmann. O/W emulsions for cosmetic products stabilized by alkyl phosphates rheology and storage tests. Colloids Surfaces A Physicochem Eng Aspects 152(1-2) 155-160, 1999. 

Quality Control. In controlling the quality of production propellants, it is necessary to conduct various rheological tests on propellant samples in the laboratory. 

An in vitro release rate can reflect the combined effect of several physical and chemical parameters, including solubility and particle size of the active ingredient and rheological properties of the dosage form. In most cases, in vitro release rate is a useful test to assess product sameness between prechange and postchange products. However, there may be instances where it is not suitable for this purpose. In such cases, other physical and chemical tests to be used as measures of sameness should be proposed and discussed with the Agency. With any test, the metrics and statistical approaches to documentation of sameness in quality attributes should be considered. 

The two methods described herein are inherently different in that one is a traditional initial velocity assay that attempts to quantitatively measure rates of product formation (see Basic Protocol 1), whereas the other correlates the activity of an enzyme preparation with its ability to change the rheological properties (i.e., viscosity) of a substrate solution (see Basic Protocol 2). For both assays, it is presumed that the analyst is using soluble substrate and enzyme preparations, appropriate buffer systems, and a method to control the reaction mixture temperature. The ultimate goal of both assays is the same to obtain a quantitative estimate of the PGase activity of a test solution. 

This volume provides an overview of polymer characterization test methods. The methods and instrumentation described represent modern analytical techniques useful to researchers, product development specialists, and quality control experts in polymer synthesis and manufacturing. Engineers, polymer scientists and technicians will find this volume useful in selecting approaches and techniques applicable to characterizing molecular, compositional, rheological, and thermodynamic properties of elastomers and plastics. 

Corn stover, a well-known example of lignocellulosic biomass, is a potential renewable feed for bioethanol production. Dilute sulfuric acid pretreatment removes hemicellulose and makes the cellulose more susceptible to bacterial digestion. The rheologic properties of corn stover pretreated in such a manner were studied. The Power Law parameters were sensitive to corn stover suspension concentration becoming more non-Newtonian with slope n, ranging from 0.92 to 0.05 between 5 and 30% solids. The Casson and the Power Law models described the experimental data with correlation coefficients ranging from 0.90 to 0.99 and 0.85 to 0.99, respectively. The yield stress predicted by direct data extrapolation and by the Herschel-Bulkley model was similar for each concentration of corn stover tested. 

Many different test methods are used to measure the reactivity or cure rate of the epoxy adhesive. Some of these, such as working life or pot life, are very practical and are used to plan the production process. Others, such as exotherm, are used to determine reaction kinetics. Still others are used to characterize the epoxy network as it cures for the purposes of determining the degree of crosslinking and the rheological properties of the curing adhesive. 

Large deformation tests, in which a solid sample is strained to well beyond its linear limit, and often to fracture, are designed to obtain a quantitative measure of a product s functionality in end use. Many large deformation tests are empirical or imitative, and do not yield fundamental rheological or fracture data. However, such tests can, with some materials, be set up and performed in such a way that fundamental information is obtained (McCarthy, 1987). 

---