Development and characterisation of novel electrospun polylactic acid/tubular clay nanocomposites

A novel material formulation method of polylactic acid /tubular clay nanocomposites via electrospinning was introduced and the important processing parameters such as solution concentration, clay loading, material feed rate were particularly investigated. The hybrid fibre diameter, the clay dispersability and the thermal properties of such nanocomposites were then characterised by using the scanning electron microscopy, wide-angle X-ray diffraction and differential scanning calorimetry, respectively, to establish a fundamental structure–property relationship for the future application

The effect of graphene oxide (GO) nanoparticles on the processing of epoxy/glass fiber composites using resin infusion

In this paper, the effects of graphene oxide (GO) nanoparticles on glass fiber composite processing by incorporating them into epoxy resin were investigated. GO was synthesized from graphite powder and was mixed with epoxy resin. Three different GO contents of 0.05, 0.1, and 0.2 wt% were used. Epoxy/GO samples were tested for rheology and cure kinetics to evaluate the effects of GO content on important resin infusion processing parameters. The results show that adding GO to neat epoxy resin increased the viscosity and affected the resin cure reaction by reducing the resin gel time. After that, glass fiber composites were prepared using the resin infusion process. Samples with 0.2 wt% GO result in very slow resin infiltration time with premature resin gelation. A 30 % increase in flexural strength and a 21 % increase in flexural modulus are manifested by adding GO as the secondary reinforcement to glass fiber composites

Polylactic acid (PLA) biocomposites reinforced with coir fibres: Evaluation of mechanical performance and multifunctional properties

The effects of fibre content (5-30 wt%) and fibre treatment on surface morphology, tensile, flexural, thermal and biodegradable properties of polylactic acid (PLA)/coir fibre biocomposites were evaluated via scanning electron microscopy (SEM), mechanical testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and soil burial method. Similar decreasing trends were found for tensile and flexural strengths with higher strength values obtained for PLA/treated coir fibre biocomposites. 20 wt% treated coir fibres were determined to achieve optimum tensile and flexural strengths of biocomposites. Regardless of fibre treatment, the thermal stability of biocomposites is worsened with increasing the fibre content. The decreased cold crystallisation temperatures of biocomposites further confirms the effective nucleating agent role of coir fibres. The biocomposites undergo much faster degradation than PLA, with the maximum weight loss of 34.9% in treated fibre biocomposites relative to 18% in PLA after 18-day burial, arising from the hydrophilic nature of coir fibres

Tetracycline hydrochloride (TCH)-loaded drug carrier based on PLA:PCL nanofibre mats: experimental characterisation and release kinetics modelling

The experimental characterisation of electrospun poly(lactic acid) (PLA): poly(e-caprolactone) (PCL) as drug carriers, at five blend ratios from 1:0, 3:1, 1:1, 1:3 and 0:1, was holistically investigated in terms of their morphological structures, crystallinity levels and thermal properties. A widely used antibiotic tetracycline hydrochloride (TCH) was loaded to prepared fibrous mats at TCH concentrations of 1 and 5 wt%. The additional TCH into PLA: PCL better facilitates the reduction of fibre diameter than polymer blends. Increasing the TCH concentration from 1 to 5 wt% was found to result in only a modest decrease in the crystallinity level, but a significant increase in the crystallisation temperature (Tc) for PLA within PLA: PCL blends. The infrared spectra of fibre mats confirm the successful TCH encapsulation into fibrous networks. The first order and Zeng models for drug release kinetics were in better agreement with experimental release data, indicating the release acceleration of TCH with increasing its concentration. In a typical case of PLA: PCL (1:1) loaded with 5 wt% TCH, the fibre mats apparently demonstrate more wrinkled and floppy structures and increased fibre diameters and decreased inter-fibrous spaces after 7-day in vitro fibre degradation, as opposed to those obtained after 3-h degradation

Phase transformations and crystallization kinetics in electrospun TiO2 nanofibers in air and argon atmospheres

The effects of atmospheric air and argon environments on thermal-induced phase transformations in electrospun TiO2 nanofibers have been investigated in situ using synchrotron radiation diffraction. Diffraction results showed that the as-synthesized TiO2 nanofibers were initially amorphous, but crystallized to form anatase and rutile after thermal annealing in air or argon at elevated temperatures. The crystallization temperature of anatase was delayed by 100 °C in argon relative to in air, and the transformation of anatase into rutile occurs faster in argon atmosphere than in air due to the formation of oxygen vacancies. Non-linear strains formed in both polymorphs and the substantial elevation of rutile thermal expansion pointed to strain anisotropy in the rutile phase and the concomitant fibre breakage

Effect of surface functionalization of halloysite nanotubes on synthesis and thermal properties of poly(ε-caprolactone)

In this work, halloysite nanotubes (HNTs) and functionalized HNTs–APTES (aminopropyltriethoxysilane) in concentrations 0.5, 1 and 2.5 wt% were used as nanofillers in the synthesis of poly(ε-caprolactone) (PCL) nanocomposites via the in situ ring-opening polymerization of ε-caprolactone (CL). The successful functionalization of HNTs was confirmed with X-ray photoelectron spectroscopy. The effects of HNTs and HNTs–APTES on the polymerization procedure and on the thermal properties of PCL were studied in detail. It was found that both nanofillers reduced the M¯ n values of the resulting nanocomposites, with the unfunctionalized one reducing it in a higher extent, while SEM micrographs indicated satisfactory dispersion in the PCL matrix. The crystallization study under isothermal and dynamic conditions revealed the nucleating effect of the nanotubes. The functionalization of nanotubes enabled even faster rates and attributed higher nucleation activity as a result of better dispersion and the formation of a strong interface between the filler and the matrix. An in-depth kinetic analysis was performed based on the data from crystallization procedures. PLOM images confirmed the effectiveness of both fillers as heterogeneous nucleation agents. Finally, from TGA analysis, it was found that HNTs did not affect the thermal stability of PCL while for HNTs–APTES, a small decrease in Tmax was observed, of about 5 °C for all filler contents.</p