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Sodium alginate is a very popular thickening agent used in food, pharmaceutical and textile industry. It is also used in different biomedical applications and wound dressings due to its biocompatible properties. In this study, however, this biopolymer was electrospun from aqueous solution by combining a small portion of polyethylene oxide (PEO) as carrying polymer. In the spinning solution, 70:30 Na-alginate/PEO of total 4.0 wt.% was used to obtain bead-free nanofibres from electrospinning. To provide insolubility and antibacterial properties, these fibres were then chemically modified by treating with CaCl2 and AgNO3 in ethanol absolute solution. During chemical treatment process, 1.0 and 5.0 wt.% of CaCl2, and 0.5 and 1.0 wt.% of AgNO3 were used. The nanofibres structure and morphology were investigated by Field Gun Emission Scanning Electron Microscope (SEM), Energy Dispersion X-ray (EDX), and Fourier Transform Infrared Spectroscopy (FTIR). The results prove that silver-loaded antibacterial alginate nanofibres have been successfully produced. Key words: electrospinning; sodium alginate; poly(ethylene oxide); anti-bacterial; nanofibres

Electrospun nanofibers have large surface area, high porosity, and controllable orientation while conventional microfibers have appropriate mechanical properties such as stiffness, strength, and elasticity. Therefore, the combination of nanofibers and microfibers can provide building elements to engineer biomimetic scaffolds for tissue engineering. In this study, a core–shell structured fibrous structure with controllable surface topography is created by electrospinning polycaprolactone (PCL) nanofibers onto polyglycolic acid (PGA) microfibers. The surface morphology, surface wettability, and mechanical properties of the resultant core–shell structure are characterized. FE-SEM images reveal that the orientation of PCL nanofibers on the yarn surface can be tuned by a fiber collector and rotating disks. Benefiting from the introduction of a shell of aligned PCL nanofibers on the core of PGA yarn, the uniaxially aligned PCL nanofiber–covered yarns (A-PCLs) exhibit higher hydrophilicity, porosity, and mechanical properties than the core PGA yarns. Moreover, A-PCLs promote the adhesion and proliferation of BALB/3T3 (mouse embryonic fibroblast cell line), and guide cell growth along the biotopographic cues of the PCL nanofibers with controllable alignment. The developed core–shell yarn having both the desired surface topography of PCL nanofibers and mechanical properties of PGA microfibers demonstrates great potential in constructing various tissue scaffolds.

Three-dimensional (3D) shell-structured PLA/Flax biocomposites were fabricated using a novel method incorporating the 3D nonwoven web-forming process. PLA and flax fibers were blended in the fiber opening stage and converted to webs on the 3D mold using the air-laying principle. The 3D webs were then consolidated by through-air thermal bonding. The compression molding technique was used finally to convert the 3D webs to the biocomposites. The relationship between the main process parameters and the properties of the biocomposites was investigated. The results show that with increasing flax fiber content, the crush failure load, total energy absorption, specific energy absorption, and crush efficiency increased. The crushing properties decreased with increased molding temperature, but the crushing properties are not significantly affected by the molding time. The physical properties of 3D biocomposites were also evaluated and the appropriate processing parameters for 3D biocomposites were established. POLYM. COMPOS., 35:1244–1252, 2014. © 2013 Society of Plastics Engineers

Flax fiber reinforced polylactic acid (PLA) biocomposites were made using a new technique incorporating an air-laying nonwoven process. Flax and PLA fibers were blended and converted to fiber webs in the air-laying process. Composite prepregs were then made from the fiber webs. The prepregs were finally converted to composites by compression molding. The relationship between the main process variables and the properties of the biocomposite was investigated. It was found that with increasing flax content, the mechanical properties increased. The maximum tensile strength of 80.3 MPa, flexural strength of 138.5 MPa, tensile modulus of 9.9 GPa and flexural modulus of 7.9 GPa were achieved. As the molding temperature and molding time increased, the mechanical properties decreased. The thermal and morphological properties of the biocomposites were also studied. The appropriate processing parameters for the biocomposites were established for different fiber contents.

Delamination is the most common failure mode in laminated compositesdue to the reduced strength in the through-the-thickness direction. Air-jettexturing was used to produce bulk and loops in the yarn which providesmore surface contact between the fibres and the resin. The development ofcore-and-effect textured glass yarns and the effect of texturing parameterswere presented in the previous paper. This paper describes the effect oftexturing on the mechanical properties including tensile properties, flexureproperties, inter-laminar shear strength (ILSS) and fracture toughness(Mode I) of glass laminated composites. The composites of plain and twillweave fabrics were developed from both the textured and non-texturedyarns. It was observed that the tensile properties decreased and theflexure properties remained unchanged after texturing. However,significant improvement was observed in inter-laminar shear strength andthe Mode I fracture toughness of the composites after texturing. Thebulkier, loopy structure of the textured yarn provided more surface contactbetween the fibre and the resin and significantly improved the bondingstrength

Highly porous polylactide (PLA) microfibers with the diameter of about 14 µm are prepared by melt-spinning and stretching core–sheath PLA fibers (CSF) and sequent treatment of ethyl acetate. The resultant pores are regular and elliptical. The average values of length of major axis and minor axis of elliptical pores are around 1 and 0.5 μm, respectively. This new and facile method can prepare porous PLA fibers on industrial scale, and nearly overcome all the shortcomings of melt-spinning and stretching method. In addition, highly porous structure in partially oriented poly(l-lactide) yarn (POY) can be also formed by treating POY using ethyl acetate. The obtained pores are irregular. In addition, the formation mechanism of pore structure in CSF is different with the one in POY. The former is the separation of row-nucleated lamellae induced by stretching while the latter is swelling and subsequent solvent-induced crystallization. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45860.