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Chicken feathers waste from poultry industry was incorporated in poly(lactic acid) matrix to obtain an environmental friendly biocomposite taking advantage of the unique properties of chicken feathers, such as low density, biodegradability and good thermal and acoustic properties, and of the biodegradability of the poly(lactic acid). The effect of manufacturing conditions on the final properties of the composite and on the matrix–fiber compatibility was studied. Optimal manufacturing conditions, in order to obtain the best mechanical results, were found at a temperature of 170–180℃ for a processing time of 5 min and a speed of mixing of 50 r/min. Young’s modulus was not very affected by the chicken feather’s content showing a maximal variation of less than 8%, indicating that is possible to include chicken feathers in a composite maintaining its stiffness. However, tensile strength and elongation decreased up to 58 and 12%, respectively, when chicken feather content was 25% because of the restraining effect of the fibers. Moreover, dimensional stability was negatively affected with the inclusion of chicken feathers. Infrared spectroscopy and scanning electron microscopy studies show that fiber–matrix interaction exists but it is weak. [ABSTRACT FROM AUTHOR]

Disposal of Chinese herbal residues (CHRs) during Chinese herbal medicine production and processing has become a problem that requires attention. In this study, CHRs were pretreated by steam explosion or pulverization and composites were prepared by mixing pretreated CHRs with polylactic acid. The mechanical properties of composites of CHRs pretreated by two different methods were compared, the main compositions of CHRs were analyzed, and the morphology of various CHRs and brittle fracture surfaces of composites were observed by scanning electron microscopy. The results show that the mechanical properties of the composites are closely related to the herbal species and pretreatment methods. The mechanical properties of CHR composites pretreated by steam explosion are superior to those pretreated by pulverization. Choosing CHRs with large fiber cell wall–lumen ratio, high lignin and cellulose contents, low contents of hetero cells and hemicellulose are helpful in making composites with good comprehensive performance. [ABSTRACT FROM AUTHOR]

Abstract: Over the last few years, intensive research has been devoted to the exploitation of “green products” based on natural resources for both matrices and as reinforcements in composite systems. The mechanical properties of reinforced biocomposites, such as flax/polylactic acid (PLA), are largely governed by interfacial properties between the two constituents apart from their intrinsic properties. Although many papers indirectly demonstrate the importance of optimising the interface between these two polymers, the exact nature of the interaction between the natural fibre and the polymeric matrix has not been clearly investigated on a fundamental level and is presently a major technological limitation of these materials. This work presents the first direct study of adhesion forces, by colloidal force microscopy, between smooth PLA films representing the polymer matrix, and a microbead of cellulose that mimic the cellulose material in flax fibres. Normalised adhesion force measurements have shown the importance of capillary forces when experiments were carried out under ambient conditions. Experiments, conducted under dry air, allowed for the deduction of the contribution of pure van der Waals forces, and our results, through the calculation of the Hamaker constant, show that these forces, for the PLA/cellulose/air system, were lower than those obtained for the cellulose/cellulose/air system and hence underlined the importance of optimising the interface among these materials. This study demonstrates the capacity of AFM to probe direct interactions in complex systems by adjusting the nature of the surface and the probe to mimic the materials in contact. Furthermore, the technique can be operated in a variety of environments, consistent with composite making and provides particular opportunity for testing and improving the properties of these new classes of composite materials. [Copyright &y& Elsevier]