Electrospun Polylactide/Natural Rubber Fibers: Effect Natural Rubber Content on Fiber Morphology and Properties

Non-woven polylactide-natural rubber fiber materials with a rubber content of 5, 10 and 15 wt.% were obtained by electrospinning. The thermal, dynamic, and mechanical properties of the fibers were determined. It was shown that the average fiber diameter increased with adding of the NR content, while the linear and surface densities changed slightly. Using the differential scanning calorimetry, the thermal characteristics were obtained. It was found that the glass transition temperature of polylactide increased by 2–5 °C, and the melting temperature increased by 2–4 °C in the presence of natural rubber in the samples. By the method of electronic paramagnetic resonance at T = 50 and 70 °C it was determined that the mobility of the amorphous phase in PLA/NR fibers increased with the addition of NR. The adding of NR at a content of 15 wt.% increased the value of elongation at break by 3.5 times compared to pure PLA.

A statistical analysis on the influence of process and solution properties on centrifugally spun nanofiber morphology

Centrifugal spinning is a fast and safe nanofiber production technique and polyacrylonitrile (PAN) nanofibers have been widely studied for many applications including energy storage, filtration, sensors, and biomedical applications. Nanofiber morphology, specific surface area, porosity and average fiber diameter are important to determine the performance of nanofibers in these fields. In centrifugal spinning, nanofiber morphology and average fiber diameter are influenced by solution properties and process parameters including rotational speed, feeding rate, collector distance, and nozzle diameter. In this study, the effect of solution concentration, rotational speed, feeding rate, collector distance and nozzle diameter on average fiber diameter and fiber morphology were studied and statistical analysis was performed to determine the main factors. Optimum solution and process parameters were determined as well. Increased average fiber diameter was seen with increasing polymer concentration and nanofibers produced at 4000 rpm with the feeding rate of 60 ml/h had the lowest average fiber diameter for all studied nozzle sizes (0.3 mm, 0.5 mm and 0.8 mm). 8 wt. % PAN solution was centrifugally spun with the rotational speed of 4000 rpm, feeding rate of 60 ml/h, collector distance of 20 cm and nozzle diameter of 0.3 mm and bead free nanofibers with the average fiber diameter of 680 ± 87 nm was observed.

Polyvinyl Alcohol/Chitosan Single-Layered and Polyvinyl Alcohol/Chitosan/Eudragit RL100 Multi-layered Electrospun Nanofibers as an Ocular Matrix for the Controlled Release of Ofloxacin: an In Vitro and In Vivo Evaluation

A novel nanofiber insert was prepared with a modified electrospinning method to enhance the ocular residence time of ofloxacin (OFX) and to provide a sustained release pattern by covering hydrophilic polymers, chitosan/polyvinyl alcohol (CS/PVA) nanofibers, with a hydrophobic polymer, Eudragit RL100 in layers, and by glutaraldehyde (GA) cross-linking of CS-PVA nanofibers for the treatment of infectious conjunctivitis. The morphology of the prepared nanofibers was studied using scanning electron microscopy (SEM). The average fiber diameter was found to be 123 ± 23 nm for the single electrospun nanofiber with no cross-linking (OFX-O). The single nanofibers, cross-linked for 10 h with GA (OFX-OG), had an average fiber diameter of 159 ± 30 nm. The amount of OFX released from the nanofibers was measured in vitro and in vivo using UV spectroscopy and microbial assay methods against Staphylococcus aureus, respectively. The antimicrobial efficiency of OFX formulated in cross-linked and non-cross-linked nanofibers was affirmed by observing the inhibition zones of Staphylococcus aureus and Escherichia coli. In vivo studies using the OFX nanofibrous inserts on a rabbit eye confirmed a sustained release pattern for up to 96 h. It was found that the cross-linking of the nanofibers by GA vapor could reduce the burst release of OFX from OFX-loaded CS/PVA in one layer and multi-layered nanofibers. In vivo results showed that the AUC0–96 for the nanofibers was 9–20-folds higher compared to the OFX solution. This study thus demonstrates the potential of the nanofiber technology is being utilized to sustained drug release in ocular drug delivery systems.

Prediction and optimization of process parameters of electrospun polyacrylonitrile based on numerical simulation and response surface method

There is a strong coupling relationship between the process parameters of electrospun polyacrylonitrile (PAN) and its fiber diameter. By examining the mechanism of influence, the quality of electrospun products can be significantly improved and controlled. In this study, a novel idea for predicting and optimizing electrospun PAN process parameters was proposed. First, the control equation of the electrospun PAN was established based on the incompressible Navier–Stokes equation, and the volume force (generated via electric field force, gravity, and surface tension) and jet velocity during electrospinning were solved and analyzed via simulation software. Then, grey correlation analysis was used to calculate the correlation among the three process parameters (applied voltage, feed rate, and distance between the needle and collector) of the electrospun PAN, volume force, jet velocity, and average fiber diameter. Subsequently, the effect of simultaneous changes in multiple process parameters on the average fiber diameter was examined based on the response surface method, and a prediction model was established. Finally, the experimental results indicated that the model can predict the average fiber diameter when multiple process parameters are simultaneously changed. The model predicted the average fiber diameter with an error of only 0.28%, and the optimized minimum fiber average diameter was 235.3 nm (the applied voltage was 12 kV, the distance between the needle and collector was 15.6 cm, the feed rate was 0.37 mL/h). This study provides a theoretical basis for the on-line monitoring of the electrospun PAN.

Acoustical absorptive properties of meltblown nonwovens for textile machinery

Noise pollution is one of the harmful physical sources in the textile industry, which is among those industries that are faced with noise exposure problems. The results of environmental sound measurements at modern textile mills have shown that the sound pressure level varied from 95 to 130 dB, where the highest sound pressure level was at weaving machines. Textile insulation materials can be fitted in order to decrease sound pollution at a low cost. The objective of this work is to design a sound absorber that can be fixed to the body of the machines, at the point of the noise generation, to reduce noise pollution. Poly(lactic acid) (PLA), which is an environmentally friendly material, was used to produce different samples of meltblown nonwoven absorbers to be used for damping the noise of textile machinery. PLA meltblown nonwoven fabric with the areal density of 16.7 g/m2, average fiber diameter of 1.1 µm, mean pore diameter of 9.8 µm and thickness of 0.27 mm exhibited significant sound absorption. The sample with the smallest average fiber diameter among those investigated had the highest damping effect: 23.95, 41.29 and 29.32 dBA at frequencies of 400, 1000 and 1500 Hz, respectively. Our goal is to have a practical tool that accurately evaluates the absorber sound damping under the actual running conditions of the textile machinery. The design of the absorber from one layer of the PLA meltblown nonwoven over a rigid polyurethane foam sheet had an excellent sound absorption property.

Poly(ε-Caprolactone)/Poly(Glycerol Sebacate) Composite Nanofibers Incorporating Hydroxyapatite Nanoparticles and Simvastatin for Bone Tissue Regeneration and Drug Delivery Applications

Herein, we report a drug eluting scaffold composed of a composite nanofibers of poly(ε-caprolactone) (PCL) and poly(glycerol sebacate) (PGS) loaded with Hydroxyapatite nanoparticles (HANPs) and simvastatin (SIM) mimicking the bone extracellular matrix (ECM) to improve bone cell proliferation and regeneration process. Indeed, the addition of PGS results in a slight increase in the average fiber diameter compared to PCL. However, the presence of HANPs in the composite nanofibers induced a greater fiber diameter distribution, without significantly changing the average fiber diameter. The in vitro drug release result revealed that the sustained release of SIM from the composite nanofiber obeying the Korsemeyer–Peppas and Kpocha models revealing a non-Fickian diffusion mechanism and the release mechanism follows diffusion rather than polymer erosion. Biomineralization assessment of the nanofibers was carried out in simulated body fluid (SBF). SEM and EDS analysis confirmed nucleation of the hydroxyapatite layer on the surface of the composite nanofibers mimicking the natural apatite layer. Moreover, in vitro studies revealed that the PCL-PGS-HA displayed better cell proliferation and adhesion compared to the control sample, hence improving the regeneration process. This suggests that the fabricated PCL-PGS-HA could be a promising future scaffold for control drug delivery and bone tissue regeneration application.

237 Evaluation of fleece and fiber characteristics of ultrafine Paco-Vicunas farmed in Missouri

Data recordings of animal breeding, fleece production, and fiber characteristics in an ultrafine Paco-Vicuna herd farmed at Victory Farm, Missouri were analyzed. A selective mating strategy was applied while establishing an ultrafine fleece growing Paco-Vicuna herd on the ranch over 12 years. The herd size was expanded from five males and one dozen breeding females in 2009 to more than 200 heads in 2016. All animals were recorded for sires, dams, and registered pedigree, birth weight, weaning weight, shearing weight, and fleece weight. Mid-side flank fleece samples were measured for Optical Fiber Diameter Analyser (OFDA) fiber characteristics, including mean fiber diameter, length, and fiber curvature. Live weight, fleece weight, and fiber characteristics were analyzed using SAS® GLM procedures. Mean birth weight, weaning weight, mixed age shearing weight, fleece weight, fiber diameter, coefficient of fiber diameter variation, fiber length, and fiber curvature were 6.82 kg, 25.27 kg, 48.84 kg, 0.85 kg, 16.6 µm, 25.2%, 64.6 mm and 56.9 degree /mm, respectively. The average fiber diameter of herd was 18.3 µm at 2009 clip, which was gradually but significantly (P < 0.05) reduced yearly to 16.4 µm at 2019 clip. In addition, the finest 25 percent of the herd’s fleeces were tested and found to have an average fiber diameter of 14 micron, which was within vicuna fleece fiber diameter ranges. These measures did not significantly increase with ages. Heritability estimates for the fleece weight and fiber diameter, length, and curvature were 0.40, 0.65, 0.29, and 0.50, respectively. The average fiber diameter measurements of Paco-Vicuna herd at Victory Farm were significantly (P < 0.01) finer than the comparable camelid herds in the country. This study found that strict selective breeding is effective for genetic gains in ultrafine fiber diameter and fleece quality in Paco-Vicunas.

The Design and Implementation of a Disk Electrospinning Device

The electrospinning procedure is a relatively simple and fast way of producing polymer fibers with diameters in the micrometer range. The one needle setup is commonly used due to its flexible design and effectiveness; however, this procedure has one major shortcoming; it has low productivity. The disk electrospinning design presented here combines the advantages of the corona and needleless electrospinning setups, namely the small solution surface area and high productivity. We used 33 wt% polyvinylpyrrolidone (PVP) solution to produce PVP fibers with the new design. The average fiber diameter of the produced PVP fibers was d = 446±116 nm, which is ~25 % larger compared to fibers produced with the one needle method.