Electrospun jets launched from polymeric bubbles

In this paper the launching of liquid polymer jetsfrom the apex of gas bubbles on thepolyvinylpyrrolidone in ethanol (PVP) solutionsurface due to an applied electrical potential isinvestigated. Jets of polymer launched from bubbleprovide an alternative method for electrospinningpolymer nanofibers that may be scalable forcommercial production. Bubbles were experimentallycreated on the surface of a polymer solution byforcing air through a syringe into the polymersolution. An electric potential was applied to thesolution to launch the jets. The polymer solutionconcentration was varied to determine the optimumconcentration. The semi-angle of the apex of bubblejust prior to jet launch was observed to be close to thetheoretical value of 49.3 degrees for a pendant drop

A New Image Analysis Based Method for Measuring Electrospun Nanofiber Diameter

In this paper, a new image analysis based method for electrospun nanofiber diameter measurement has been presented. The method was tested by a simulated image with known characteristics and a real web. Mean (M) and standard deviation (STD) of fiber diameter obtained using this method for the simulated image were 15.02 and 4.80 pixels respectively, compared to the true values of 15.35 and 4.47 pixels. For the real web, applying the method resulted in M and STD of 324 and 50.4 nm which are extremely close to the values of 319 and 42 nm obtained using manual method. The results show that this approach is successful in making fast, accurate automated measurements of electrospun fiber diameters

Effect of Dopant on the Nanostructured Morphology of Poly (1-naphthylamine) Synthesized by Template Free Method

The study reports some preliminary investigations on the template free synthesis of ascantlyinvestigated polyaniline (PANI) derivative—poly (1-naphthylamine) (PNA) by template free method in presence as well as absence of hydrochloric acid (HCl) (dopant), using ferric chloride as oxidant. The polymerization was carried out in alcoholic medium. Polymerization of 1-naphthylamine (NPA) was confirmed by the FT-IR as well as UV–visible studies. The morphology and size of PNA particles was strongly influenced by the presence and absence of acid which was confirmed by transmission electron microscopy (TEM) studies

Multi-response analysis in the material characterisation of electrospun poly (lactic acid)/halloysite nanotube composite fibres based on Taguchi design of experiments: fibre diameter, non-intercalation and nucleation effects

Poly (lactic acid) (PLA)/halloysite nanotube (HNT) composite fibres were prepared by using a simple and versatile electrospinning technique. The systematic approach via Taguchi design of experiments (DoE) was implemented to investigate factorial effects of applied voltage, feed rate of solution, collector distance and HNT concentration on the fibre diameter, HNT non-intercalation and nucleation effects. The HNT intercalation level, composite fibre morphology, their associated fibre diameter and thermal properties were evaluated by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), imaging analysis and differential scanning calorimetry (DSC), respectively. HNT non-intercalation phenomenon appears to be manifested as reflected by the minimal shift of XRD peaks for all electrospun PLA/HNT composite fibres. The smaller-fibre-diameter characteristic was found to be sequentially associated with the feed rate of solution, collector distance and applied voltage. The glass transition temperature (T g) and melting temperature (T m) are not highly affected by varying the material and electrospinning parameters. However, as the indicator of the nucleation effect, the crystallisation temperature (T c) of PLA/HNT composite fibres is predominantly impacted by HNT concentration and applied voltage. It is evident that HNT’s nucleating agent role is confirmed when embedded with HNTs to accelerate the cold crystallisation of composite fibres. Taguchi DoE method has been found to be an effective approach to statistically optimise critical parameters used in electrospinning in order to effectively tailor the resulting physical features and thermal properties of PLA/HNT composite fibres

DEFECT DIFFUSION MODELS FOR INTERNAL FRICTION PROCESSES IN POLYETHYLENE

Defect loops that encircle one chain in a polyethyene crystal are characterized in terms that are used to describe dislocation loops in metals. In a polyethylene crystal the defect loop which requires the least energy for creation belongs to the relatively unknown class of defects called dispirations. Dispirations can be thought of as defects in the helical symmetry of the polyethylene molecule in the crystal. The processes by which the diffusion of dispiration loops can contribute to relaxation processes in polyethylene are described

Chain unfolding in single crystals of ultralong alkane C390H782 and polyethylene: An atomic force microscopy study

Ultralong alkanes (CnH2n+2, n > 150) are generally considered as the most appropriate model for polyethylene, PE, and studies of these compounds can shed light on fine structural features of polymer crystals and the mechanisms of polymer crystallization. High-temperature atomic force microscopy was applied for comparative studies of solution-grown single crystals of C390H782 (the longest available alkane) and PE. While the structures of single crystals of C390H782 and PE are similar, the details of their thermal behavior are quite different. The structural transitions in C390H782 crystals follow the typical oligomer-type integral chain-folding scheme. Upon annealing, the alkane crystal undergoes a complete series of transformations corresponding to stepwise unfolding from the folded-in-five conformation toward the fully extended-chain crystal. The chain unfolding in PE crystals is a continuous and slower process. The morphological evolution of single crystals on heating is found to be dependent on the presence of solvent traces. Melting of the alkane crystals on graphite is accompanied by spreading of the alkane onto the substrate leading to the formation of a thin epitaxial layer. The complete melting of this film occurs at 185 °C, i.e. approximately 55 °C above the melting point of the bulk material.SCOPUS: ar.jinfo:eu-repo/semantics/publishe