Studies regarding biodegradable nanocomposites to be used as orthopedics devices have been intensified. This work aims to investigate the influence of ND dispersion on thermal and mechanical properties of a biocomposite of poly(3-hydroxybutyrate) (P(3HB)) reinforced with nanodiamonds (ND) intended to be used as orthopedics devices, with advantages as biodegradability. In order to improve its dispersion, P(3HB) has encapsulated ND in three different mass ratios: P(3HB):ND(16:1), (12:1) and (8:1). However, for all formulations, NDs are presented as agglomerates, in different intensities. In order to relate the distribution of ND within the polymer matrix and biocomposite properties, TGA, DSC, and DMA analysis were done. The formulation with higher content of ND, P(3HB):ND(8:1), presents larger aggregates; thus, decreasing its properties. With smaller and more distributed agglomerates, the 12:1 ratio composite displayed superior storage modulus and glass transition temperature, probably due to better polymer chain restriction.

Several studies of biodegradable polymers and copolymers have been carried for different applications in the biomedical area. This current study aims to develop a biocomposite to be used as an orthopedic device, using poly(3-hydroxybutyrate-co-3-hydroxyvalerate) P(HB-HV), a biodegradable copolymer, with 94%HB and 6%HV, as matrix; and nanodiamonds (ND) with primary grains of 4-6nm, as reinforcement. The nanodiamonds were previously encapsulated by P(HB-HV) and specimens were prepared using a hydraulic press and injection molding machine, in order to evaluate which method presents a better performance. Thermal and mechanical analyses were done to compare their behavior. The biocomposite and pure P(HB-HV) samples were analyzed by flexural testing, nanoidentation, DMA, XRD, TGA. The distribution of nanodiamonds on the specimen fracture surface were investigated by SEM. The SEM micrographs allowed us to concluded that the encapsulation of nanodiamonds by P(HB-HV) was successfully performed, promoting a better interface and distribution in the polymeric matrix. The presence of ND in the polymeric matrix decreased the P(HB-HV) crystallinity, inhibiting the crystallite growth. The mechanical properties obtained from flexural test, nanoidentation and DMA of the injection-molded specimens were superior to compression-molded, due to its homogeneous and continuous structure. In vitro analysis was performed to evaluate the samples cytoxicity.

Ramie (Boehmeria nivea) fiber is one of several lignocellulosic fibers with superior strength, but the least investigated, particularly as reinforcement in strong, tough polymeric composites. This paper presents mechanical properties for polyester reinforced with aligned ramie fibers up to 30% by volume. It was found that adding 30 vol% of ramie fibers increases the flexural strength of polyester about three times (212 ± 12 MPa vs. 63 ± 7 MPa) and tensile strength by a factor of two (89 ± 9 MPa vs. 53 ± 3 MPa). Polyester-ramie fiber composites also displayed a significant improvement in toughness. The impact energy values, as measured by Charpy and Izod impact tests, increased nearly two orders of magnitude for 30 vol% ramie fiber composite as compared to neat polyester. Additionally, fractographic studies revealed reasonable wetting of fibers by the polyester resin, and FTIR analysis confirmed a hydrophilic nature of ramie fibers. In spite of weak adhesion between hydrophilic fibers and hydrophobic matrix, composites of improved strength and toughness were demonstrated in this study. Limited fiber-matrix adhesion was reflected in preferential longitudinal propagation of cracks along the fiber/polyester interfaces, indicating also that most of the fracture area is associated with the fiber surface.