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Biodegradable polymers play a significant role in medical applications, especially internal devices because they can be broken down and absorbed into the body without producing harmful degradation products. In this study, biodegradable polylactic acid (PLA)-polyhydroxyalkanoate (PHA)-based nanocomposites with various PHA and nano-hydroxyapatite (nHAp) contents were prepared using solution casting method. Mechanical properties, microstructure, thermal stability, thermal properties, and in vitro degradation of the PLA-PHA-based composites were investigated. PLA-20PHA/5nHAp was shown to give the desired properties so it was selected to investigate electrospinnability at different applied high voltages. PLA-20PHA/5nHAp composite shows the highest improvement of tensile strength at 36.6 ± 0.7 MPa, while PLA-20PHA/10nHAp composite shows the highest thermal stability and in vitro degradation at 7.55% of weight loss after 56 days of immersion in PBS solution. The addition of PHA in PLA-PHA-based nanocomposites improved elongation at break, compared to the composite without PHA. PLA-20PHA/5nHAp solution was successfully fabricated into fibers by electrospinning. All obtained fibers showed smooth and continuous fibers without beads with diameters of 3.7 ± 0.9, 3.5 ± 1.2, and 2.1 ± 0.7 µm at applied high voltages of 15, 20, and 25 kV, respectively.

This work aims to enhance the mechanical properties, oil resistance, and thermal properties of acrylonitrile butadiene rubber (NBR) by using the Nile tilapia fish scales as a filler and using bis(triethoxysilylpropyl)tetrasulfide (TESPT) as a coupling agent (CA). The prepared fish scale particles (FSp) are B-type hydroxyapatite and the particle shape is rod-like. The filled NBR with FSp at 10 phr increased tensile strength up to 180% (4.56 ± 0.48 MPa), reduced oil absorption up to 155%, and increased the decomposition temperature up to 4 °C, relative to the unfilled NBR. The addition of CA into filled NBR with FSp at 10 phr increased tensile strength up to 123% (5.62 ± 0.42 MPa) and percentage of elongation at break up to 122% relative to the filled NBR with FSp at 10 phr. This work demonstrated that the prepared FSp from the Nile tilapia fish scales can be used as a reinforcement filler to enhance the NBR properties for use in many high-performance applications.

Nano-hydroxyapatite (nHAp) as a bio-filler used in PLA composites was prepared from fish by acid deproteinization (1DP) and a combination of acid-alkali deproteinization (2DP) followed by alkali heat treatment. Moreover, the PLA/nHAp composite films were developed using solution casting method. The mechanical and thermal properties of the PLA composite films with nHAp from different steps deproteinization and contents were compared. The physical properties analysis confirmed that the nHAp can be prepared from fish scales using both steps deproteinization. 1DP-nHAp showed higher surface area and lower crystallinity than 2DP-nHAp. This gave advantage of 1DP-nHAp for use as filler. PLA composite with 1DP-nHAp gave tensile strength of 66.41 ± 3.63 MPa and Young's modulus of 2.65 ± 0.05 GPa which were higher than 2DP-nHAp at the same content. The addition of 5 phr 1DP-nHAp into PLA significantly improved the tensile strength and Young's modulus. PLA composite solution with 1DP-nHAp at 5 phr showed electrospinnability by giving continuous fibers without beads.