2.5. Investigation of flow properties
The flow properties of PLA and its bio-composites were
investigated by means of a capillary rheometer (Rosand
RH2000). A Flowmaster software was used to analyze
the rheological data of PLA and wood fibers reinforced
PLA bio-composites. The residence time of the sample
was maintained 1 min in the barrel with the temperature
of 180 C. The experiments were conducted at different
shear rates. The apparent shear rate ( _caÞ and shear stress
(swÞ can be calculated from the Eqs. (1) and (2). The equations
are as follows (Abraham and George, 2007; Awal and
Sain, 2011; Ku and Lin, 2005):