Enhancing melt strength and crystallization kinetics in polylactide: Influence of chain topology.

The generation of long-chain branches (LCB) in biobased and biodegradable polylactide (PLA) by adding different amounts of a chain extender is studied. The rheological and calorimetric behavior have been used to determine the effect of LCB presence and their topology on PLA melt strength and crystallization behavior. Rheological modeling of linear and non-linear viscoelastic shear and extensional properties identified several possible branched structures.

Rheology and Tack Properties of Biodegradable Isodimorphic Poly(butylene succinate)--Poly(ε-caprolactone) Random Copolyesters and Their Potential Use as Adhesives.

The sole effect of the microstructure of biodegradable isodimorphic poly(butylene succinate)--poly(ε-caprolactone) random copolyesters on their rheological properties is investigated. To avoid the effect of molecular weight and temperature, two rheological procedures are considered: the activation energy of flow, , and the phase angle versus complex modulus plots. An unexpected variation of both parameters with copolyester composition is observed, with respective maximum and minimum values for the 50/50 composition.

Effect of sugar addition on glass transition temperatures of cassava starch with low to intermediate moisture contents.

This work studies how sucrose (S) addition modifies the thermal properties of cassava starch (CS). Neat CS and CS-S blends with 4, 6 and 8% sugar contents (CS-S-4%, CS-S-6% and CS-S-8%) were prepared and analyzed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA), in a wide range of moisture levels (2-20%). In equilibrated samples with moisture contents lower than 10%, twoendothermic steps were observed during first DSC heating scans and two corresponding relaxation maxima in tan δ were detected by DMTA.

Glass transitions and physical aging of cassava starch - corn oil blends.

Glass transition temperatures and physical aging of amorphous cassava starch and their blends with corn oil were assessed by differential scanning calorimetry (DSC). Two enthalpic relaxation endotherms, well separated in temperature values, were exhibited by neat amorphous cassava starch with 10.6% moisture content, evidencing two amorphous regions within the starch with different degrees of mobility.

Anti-plasticization of cassava starch by complexing fatty acids.

The effect of adding 1-8% amylose complexing fatty acids (CFA), such as linoleic and oleic acids, on the glass transition temperature (Tg) of cassava starch (CS) with moisture content varying from 5 to 35% (dry basis) was studied. The main relaxation temperature (Tα), associated with the glass transition temperature of the samples (Tg), was determined by dynamic-mechanical-thermal analysis. The plasticizing behavior of water in the blends was evidenced by a decrease of Tα values with moisture content.