Starch and microbial exo-polysaccharides produced by prokaryotes (i.e. Eubacteria and Archaebacteria) and eukaryotes (i.e. phytoplankton, fungi, and algae) are recognized as a permanent source of biopolymers for the packaging industry. However, the unsuitable mechanical properties for thermoplastic applications and/or high cost of production have restricted their generalized use. Fungal isolates of the genus Ophiostoma are able to produce exo-polysaccharides or protein-like compounds in a medium containing starch as the substrate. Various analytical techniques were used as an approach to investigate the interaction between starch and the fungal extracellular metabolites and the effect of the molecular-structural modifications on the functional properties of the materials. Native starches were used as control in all experiments. Analyses performed by dynamic mechanical thermal analysis (DMTA), which provides information related to the viscoelastic properties, showed that the storage modulus (E') increased substantially after the modification of the starch showing a process of chain stiffness. The determination of the glass transition temperature (Tg) by tan  and loss modulus (E'') peaks showed various thermal transitions indicating a complex molecular aggregation due to the potential presence of dissimilar amorphous polymers. Experiments performed in DSC confirmed the presence of the various thermal transitions associated to the Tg of these materials. The first derivative of mass loss with respect to temperature during the thermogravimetric (TG) analysis was slightly lower compared with native starches (at ~630 and 650°C). However, modified starches can withstand high temperatures showing residues up to 20% at 1000°C. Studies on the characterization of the flow properties of the polymers by capillary rheology showed in both samples a shear thinning behavior. The double logarithmic plot of the shear rate vs. shear viscosity produced a straight line and in consequence a power law equation was used to describe the rheological behavior ( = K'n). The results showed that in order to achieve the same shear rate (') in both samples (modified and native starches) it is necessary to apply a higher shear stress () in the fungal treated materials. As a result, the consistency power law index (n) decreased and the consistency value increased (K). The practical consequence is that the melting point of these polysaccharides shifted to higher temperatures. By using various analytical techniques (including chromatography, spectroscopy, spectrometry) it was found that these phenomena may be due to the interaction of starch with protein-like or exo-polysaccharides or both which may influence the viscosity, bind adjacent molecules (i.e. network-like) and restrict the molecular motion. Evidences of the presence of pendant groups attached to high molecular weight compounds were also found. This information will give guidance to further structural studies and it is intended to pave the way for a variety of industrial applications.

Starch and microbial exo-polysaccharides produced by prokaryotes (i.e. Eubacteria and Archaebacteria) and eukaryotes (i.e. phytoplankton, fungi, and algae) are recognized as a permanent source of biopolymers for the packaging industry. However, the unsuitable mechanical properties for thermoplastic applications and/or high cost of production have restricted their generalized use. Fungal isolates of the genus Ophiostoma are able to produce exo-polysaccharides or protein-like compounds in a medium containing starch as the substrate. Various analytical techniques were used as an approach to investigate the interaction between starch and the fungal extracellular metabolites and the effect of the molecular-structural modifications on the functional properties of the materials. Native starches were used as control in all experiments. Analyses performed by dynamic mechanical thermal analysis (DMTA), which provides information related to the viscoelastic properties, showed that the storage modulus (E') increased substantially after the modification of the starch showing a process of chain stiffness. The determination of the glass transition temperature (Tg) by tan  and loss modulus (E'') peaks showed various thermal transitions indicating a complex molecular aggregation due to the potential presence of dissimilar amorphous polymers. Experiments performed in DSC confirmed the presence of the various thermal transitions associated to the Tg of these materials. The first derivative of mass loss with respect to temperature during the thermogravimetric (TG) analysis was slightly lower compared with native starches (at ~630 and 650°C). However, modified starches can withstand high temperatures showing residues up to 20% at 1000°C. Studies on the characterization of the flow properties of the polymers by capillary rheology showed in both samples a shear thinning behavior. The double logarithmic plot of the shear rate vs. shear viscosity produced a straight line and in consequence a power law equation was used to describe the rheological behavior ( = K'n). The results showed that in order to achieve the same shear rate (') in both samples (modified and native starches) it is necessary to apply a higher shear stress () in the fungal treated materials. As a result, the consistency power law index (n) decreased and the consistency value increased (K). The practical consequence is that the melting point of these polysaccharides shifted to higher temperatures. By using various analytical techniques (including chromatography, spectroscopy, spectrometry) it was found that these phenomena may be due to the interaction of starch with protein-like or exo-polysaccharides or both which may influence the viscosity, bind adjacent molecules (i.e. network-like) and restrict the molecular motion. Evidences of the presence of pendant groups attached to high molecular weight compounds were also found. This information will give guidance to further structural studies and it is intended to pave the way for a variety of industrial applications.

The effects of coating formulation on thermal characteristics of coating layers were systematically studied for xerographic toner fusion on coated papers. Model coatings were formulated using three types of ground calcium carbonate and one kaolin pigments, each mixed with 6, 10, 18, and 25 pph of styrene butadiene latex binder. Porosity was found to be a key parameter for coating thermal conductivity adjustment, and was determined by the latex concentration. The particle size distribution and morphology of pigments also affect the overall thermal characteristics of coating layers. Print qualities on model coated papers were evaluated by print gloss measurement, toner adhesion test, and pair-wise visual ranking, and it was proved that print gloss is reduced with increasing bulk thermal conductivity of coating layers. The coating layer consisted of Covercarb HP pigment and 10 pph of latex was found to have the best performance in the three print quality evaluation tests.

The effects of coating formulation on thermal characteristics of coating layers were systematically studied for xerographic toner fusion on coated papers. Model coatings were formulated using three types of ground calcium carbonate and one kaolin pigments, each mixed with 6, 10, 18, and 25 pph of styrene butadiene latex binder. Porosity was found to be a key parameter for coating thermal conductivity adjustment, and was determined by the latex concentration. The particle size distribution and morphology of pigments also affect the overall thermal characteristics of coating layers. Print qualities on model coated papers were evaluated by print gloss measurement, toner adhesion test, and pair-wise visual ranking, and it was proved that print gloss is reduced with increasing bulk thermal conductivity of coating layers. The coating layer consisted of Covercarb HP pigment and 10 pph of latex was found to have the best performance in the three print quality evaluation tests.