The purpose of this study was to mathematically characterize the effects of defined experimental parameters (probe speed and the ratio of the probe diameter to the diameter of sample container) on the textural/mechanical properties of model gel systems. In addition, this study examined the applicability of dimensional analysis for the rheological interpretation of textural data in terms of shear stress and rate of shear. Aqueous gels (pH 7) were prepared containing 15% w/w @entity57405 and @entity4280 ( @entity12468 ) (0, 3, 6, or 9% w/w). Texture profile analysis (TPA) was performed using a Stable Micro Systems texture analyzer (model TA-XT 2; Surrey, UK) in which an analytical probe was twice compressed into each formulation to a defined depth (15 mm) and at defined rates (1, 3, 5, 8, and 10 mm s(-1)), allowing a delay period (15 s) between the end of the first and beginning of the second compressions. Flow rheograms were performed using a Carri-Med CSL(2)-100 rheometer (TA Instruments, Surrey, UK) with parallel plate geometry under controlled shearing stresses at 20.0 degrees +/- 0.1 degrees C. All formulations exhibited @entity450 with no thixotropy. Increasing concentrations of @entity12468 significantly @entity3358 , compressibility, adhesiveness, and consistency. Increased @entity3358 , compressibility, and consistency were ascribed to enhanced polymeric entanglements, thereby increasing the resistance to deformation. Increasing probe speed @entity3358 in a linear manner, because of the effects of probe speed on probe displacement and surface area. The relationship between formulation @entity3358 was linear and was dependent on probe speed. Furthermore, the proportionality constant (gel strength) increased as a function of @entity12468 concentration. The relationship between formulation @entity3358 and diameter ratio was biphasic and was statistically defined by two linear relationships relating to diameter ratios from 0 to 0.4 and from 0.4 to 0.563. The dramatically increased @entity3358 , associated with diameter ratios in excess of 0.4, was accredited to boundary effects, that is, the effect of the container wall on product flow. Using dimensional analysis, the @entity3358 in TPA were mathematically transformed into corresponding rheological parameters, namely shearing stress and rate of shear, thereby allowing the application of the power law (eta = kgamma(n)) to textural data. Importantly, the consistencies (k) of the formulations, calculated using transformed textural data, were statistically similar to those obtained using flow rheometry. In conclusion, this study has, firstly, characterized the relationships between textural data and two key instrumental parameters in TPA and, secondly, described a method by which rheological information may be derived using this technique. This will enable a greater application of TPA for the rheological characterization of pharmaceutical gels and, in addition, will enable efficient interpretation of textural data under different experimental parameters.

Examination of the flow rheological and textural properties of polymer gels composed of @entity57405 and XXXX : rheological and mathematical interpretation of textural parameters.

@entity3358 :: ('MESH:D018804', 'Disease') :: ['increased formulation hardness', 'hardness', 'hardness and probe displacement'] @entity12468 :: ('CHEBI:53245', 'Chemical') :: ['PVP'] @entity450 :: ('MESH:D006940', 'Disease') :: ['pseudoplastic flow'] @entity4280 :: ('MESH:D011205', 'Chemical') :: ['poly(vinylpyrrolidone)'] @entity57405 :: ('MESH:C506726', 'Chemical') :: ['poly(methylvinylether-co-maleic anhydride)']
@entity4280 :: (MESH:D011205,Chemical) :: ['poly(vinylpyrrolidone)']
