The rheological properties of three biodegradable partially crystalline alipathic polyesters—poly ε carolactone (PCL), polylactic acid (PLA), and polyhydroxybutyrate‐co‐hydroxyvalerate (PHBV)—were investigated. Low shear viscosity (η), first normal stress difference (N1), and dynamic properties (G′ and G″), were measured for each polymer using rotational instruments. High shear viscosity data was obtained using a capillary rheometer. Gel permeation chromatography indicates that both PLA and PHBV undergo degradation during processing. Thermal degradation rate constants for PLA and PHBV were determined from the time‐sweep data. Data indicates that material functions are proportional to the molecular weight for PCL and PLA samples, and directly related to the HV content in the PHBV samples. The relaxation spectra were calculated from the G′ and G″ data using the regularization method and the applicability of the nonlinear Wagner equation was checked on these materials. Results are discussed in terms of variations in the molecular characteristics on rheological properties and their possible influence on the processability.

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The small amplitude rheological properties of doughs of different compositions were measured using a dynamic rheometer. In the first study, the effect of water, flour, and added gluten on the dynamic properties was investigated. Frequency sweep was carried out in the range of 0. 1 to 100 s−1 at an applied strain of 0. 1%. Storage (G') and loss (G”) moduli for each composition were recorded. The storage modulus versus frequency plots were a series of parallel curves indicating that the moisture‐to‐flour ratio was the most important parameter. The loss modulus versus frequency plot showed a falling‐off after a frequency of 40 s−1. A plot of tan δ versus frequency indicated a more elastic dough at shorter time

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