A theoretical model for the prediction of tensile strengths of particulatefilled polymers is proposed. According to this model each particle is divided into an infinite number of coaxial cylinders and by applying Cox's theory the mean stress developed in each section of the particle may be calculated. Further a modified rule of mixtures was applied where the degree of adhesion between matrix material and filler particles as well as the degradation of the mechanical behaviour of the matrix due to the existence of the particles is taken into account. Therefore, when tensile strengths of polymer and particles are known, tensile strength of the filled polymer corresponding to specific values of degree of adhesion as well as of the matrix degradation can be estimated by the model. Finally, the model was successfully applied to a series of published data.

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SynopsisGel permeation chromatography (GPC) calibration curves log hydrodynamic volume versus elution volumes were obtained from a series of single and mixed eluents for polystyrene on inorganic carriers. The observed calibration shifts were interpreted as a result of adsorption and partition effects on elution volume V,. Secondary contributions to the separation mechanism can be qualitatively described by means of thermodynamic relations from liquid adsorption (LSC) and liquid partition (LLC) chromatography using the solubility parameters of the eluents. The universal calibration procedure based on the hydrodynamic volume of the coils is directly applicable only for systems in which adsorption and partition is approximately the same.

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The aim of this work was to evaluate the effects of incorporating thrombin in arabinogalactan (AG)/β-glucan (BG)-based carriers. The products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy techniques. Results, especially deconvoluted XRPD patterns indicated creation of new phases and potential complex formation. Results also highlighted that the AG carrier leads to higher residual thrombin-specific activity, while the in vivo haemostatic effect was enhanced when insoluble BG was present in the matrix. Our results confirm that thrombin can be successfully added to the carriers and that these materials are promising alternatives to standard vehicles.

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The rheological properties of water soluble cellulose derivatives (hydroxypropylcellulose, modified hydroxyethylcellulose) and gelatin aqueous solutions in a system with ionic surfactant were studied. The viscosity maximum was found in the region of critical micellar concentration (CMC) of the surfactant as a result of micelle formation. An increase of the CMC value with increasing molecular weight was observed and a decrease of this value for the hydrophobically modified polymer solution was found compared to the CMC value of the surfactant aqueous solution. A slight viscosity maximum was also found in gelatin systems with cationic and anionic surfactant. The viscosity increase (cross bonding) of gelatin aqueous solutions is more affected by a cationic surfactant than by an anionic one. pH measurements on gelatin systems indicate that the minimal viscosity is reached in the region of the isoelectric point.