Mark-Houwink Parameters for Aqueous-Soluble Biopolymers. Temperature effect

R. POSTEMSKI, D. ARELLANO, M. ESCUDERO, R. COLLA, S. PICCO, M. MASUELLI

Buenos Aires

Workshop; II Workshop on Bio-degradable Polymers and Biocomposites III Workshop BIOPURFIL, Bio-based Polyurethane Composites with Natural Fillers; 2015

II Workshop on Bio-degradable Polymers and Biocomposites III Workshop BIOPURFIL, Bio-based Polyurethane Composites with Natural Fillers

The intrinsic viscosity measurements used to calculate the Mark-Houwink (M-H) parameters are generally performed for different molecular weights at a constant temperature, with the standard value of this temperature being 25°C, or else 37°C in the case of mammalian proteins, or else under theta conditions for polymers and biopolymers. In the polymer industry, polysaccharides and proteins must circulate through pipes during transport processes where pumps have a very high-energy expenditure and where temperatures must be greatly increased, and at this point calculation of the Mark-Houwink parameters becomes important. The M-H parameters are calculated at standardized temperatures and in many cases, these are not useful because of the errors they carry, and it then becomes very difficult to calculate the molecular weight. It is therefore necessary to know the change in molecular weight as evidence of a change in the product obtained, as this may create a need to halt the production process, transport, or extrusion. The basic criterion is that the molecular weight does not change with temperature, or at least within one discrete range of temperatures, but that there is hydrodynamic change (intrinsic viscosity). The method is simple and requires iterative mathematical processing and measurement of intrinsic viscosity at different temperatures.