Abstract

In this study, at first, thin films of poly(3‐hydroxybutyrate‐co−3‐hydroxyvalerate) (PHBV) nanocomposites were prepared by adding 1–3 wt % grafted halloysite nanotubes (G‐HNTs). Jute‐PHBV bio‐nanocomposites were then fabricated using these films and chemically treated jute fibers in a compression mold machine. The effect of treatment and modification on jute fiber and halloysite nanotubes (HNTs), and the change in their morphology was investigated using Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM). Flexural and thermomechanical properties were determined using a three‐point bend test and dynamic mechanical analysis (DMA). The results showed separation of fiber bundles with rough fiber surfaces, and grafting of silane coupling agents on fibers and HNTs after the chemical treatment. As a result, a strong bonding was established between the PHBV, G‐HNTs and jute fibers that lead to significant improvements in flexural and thermomechanical properties of jute‐PHBV bio‐nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43994.

Forcespinning technique was used to fabricate sub-micron size polycaprolactone (PCL) fibers. Forcespinning method uses centrifugal forces for the generation of fibers unlike the electrospinning method which uses electrostatic force. PCL has been extensively used as scaffolds for cell regeneration, substrates for tissue engineering and in drug delivery systems. The aim of this study is to qualitatively analyze the force spun fiber mats and investigate the effect of the spinneret rotational speed on the fiber morphology, thermal and mechanical properties. The extracted fibers were characterized by scanning electron microscopy differential scanning calorimetry, tensile testing and dynamic mechanical analysis. The results showed that higher rotational speeds produced uniform fibers with less number of beads. The crystallinity of the fibers decreased with increase in rotational speeds. The Young’s modulus of the forcespun fibers was found to be in the range of 3.5 to 6 MPa. Storage and loss moduli decreased with the increase in the fiber diameter. The fibers collected at farther distance from spinneret exhibited optimal mechanical properties compared to the fibers collected at shorter distances. This study will aid in extracting fibers with uniform geometries and lower beads to achieve the desired nanofiber drug release properties.

We implemented molecular dynamics simulations to study the effect of single-walled carbon nanotube (SWCNT) and carboxylic (-COOH) functionalized SWCNT on the crosslinking and interfacial behavior of Epon 862 nanocomposite. Results showed that the introduction of control SWCNT in the Epon system reduced the crosslinking by 8-12% in comparison to control system (without CNT). The molecules of Epon 862 and Epikure-W changed their conformation and aligned themselves in the direction parallel to the surface wrapping the nanotubes. Also, no interfacial bonding was found between the polymer and SWCNT. However, the introduction of the-COOH functional groups on the surface of SWCNT lead to increase in crosslinking and resulted in a strong bond formation between the polymer and nanotube interphase. A significant increase in energy was found in Epon/COOH-SWCNT systems that lead to an increase of 33% in interfacial strength in comparison to Epon/SWCNT counterpart. The pullout simulations of Epon/SWCNT samples showed separation at the interphase with no polymer atoms attached to CNT. In contrast, bond stretching and breakage were observed in the polymer chain, whereas, a strong interphase was observed in Epon/COOH-SWCNT samples. This study reveals the nanolevel interactions between the nanotubes and polymers which otherwise not possible through experimental techniques, and lead to cognize that the functionalization of SWCNT with-COOH groups can establish a strong network with the epoxy chain and significantly enhance the interfacial properties particularly for applications where the interphase is critical.

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