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Biodegradable poly(butylene succinate) (PBS)/Alfa fiber biocomposites were prepared through the compression molding method. Scanning electron microscopy images were acquired to assess the effects of reinforcement and homogenization of mixtures and to determine the characteristics of the microstructure. The rheological properties, melting, and crystallization behavior of neat PBS and its biocomposites were investigated. Regarding the thermal properties, it was observed that the presence of Alfa fibers facilitates the crystallization of the PBS matrix, which suggests that Alfa cellulose fiber acts as a nucleating agent. The rheological analysis suggests that the biocomposites show a better dynamic behavior with the addition of Alfa fibers. Indeed, the incorporation of fibers increased the complex modulus and complex viscosity of the composites. Also, increasing the percentage of fibers in the matrix induces percolation, the shift and change in the slope of Cole–Cole curve of the PBS/Alfa fiber composite compared to that of neat PBS indicate that the PBS microstructure has changed with the addition of fibers. Moreover, the improvement of biocomposites properties is believed to be largely attributable to the homogeneous dispersion of the Alfa fibers within the polymer matrix and also to the strong interfacial interactions between the two constituents.

Effects of annealing temperature (Ta: 80-140°C) and time (ta: 3-30 h) on the crystalline phase transition in poly(lactic acid) (PLA) were studied by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). In the DSC curves, the sample annealed at Ta=80°C with time interval (ta: 10-30 h) demonstrates a peculiarly small exothermal peak (Texo) around 130°C, just prior to the melting point, corresponding to the disorder-to-order ('-to-) phase transition, while the sample annealed at temperature (Ta: 90-110°C) shows a double melting behavior considered as the '- phase transition. At Ta>110°C, the ′ -form of PLA was found to transform into the  one during the annealing process. The '-phase transition around 100°C (Ta: 90-110°C), determined from the two melting peaks (Tm1 and Tm2) as function of Ta at different times ta, shows a good correlation with the substantial increase in the crystallinity rate (Xc) with a maximum of 32% at Ta=120°C. Towards low temperatures, the glass modulus Eg reported by DMA thermograms, shows an important increase (30 000 MPa) at Ta=80°C for ta=3 h, due to the nucleation density extremely high in low PLA materials crystallization. After a sharp drop to 3 600 MPa at Ta=110°C, a marked improvement of Eg (15 900 MPa) is observed around Ta=120°C for all samples, regardless of time ta, temperature region where PLA is usually molded in the industrial melt processing. This interesting effect (improvement of Eg in range Ta=100-120°C) can be correlated with the grow of crystallinity in the same domain of Ta, and the '- phase transition Ta (Ta: 90-110 °C) determinate by the double Tm melting DSC peak, which is confirmed by the increase of Tg for Ta=90-110°C.