---

The porosity of electrospun nanofibers web is a significant parameter affecting various areas of nanofibers applications. Thus, at first, the effect of most effective parameters, the concentration of polymer solution and flow rate, on the diameter of polyvinyl alcohol nanofibers, as a dissolving component, were investigated. Afterward, the hybrid web of polyamide 6/polyvinyl alcohol (PA/P) was prepared via a two-sided dual-nozzles electrospinning method. The morphology, diameter, pore size of nanofibers web and the effect of dissolving constituent were studied based on images of the scanning electron microscope. To measuring the porosity of nanofibrous webs, three practical and straightforward methods that have been proposed in the literature were utilized. It was observed that when one component was dissolved, the diameter of the resultant web was decreased, and the porosity has been reduced to about 70% based on the best selected method of porosity. Additionally, the average pore size of electrospun PA6 webs has been decreased about 30-58% relative to the original hybrid webs.

---

Aims: Nylon or polyamide is one of the most used and most important polymers used in the plastic and fiber industries of the world. For this reason, its use is less sensitive to the properties of its very poor biodegradability. Therefore, the aim of the present study was the biodegradability modification of synthetic polyamide 6 (pa6) fibers via in-situ melt blending with recycled poly (lactic) acid plastic food container flakes (r-PLA) during the melt spinning process.
Materials & Methods: In this experimental study, polyamide chips 6 in textile industry and Poly (Lactic) Acid Plastic Disposable Container Flakes were used. The weight loss, mechanical properties, and surface morphology variations of pure and modified fiber samples after soil burial test were analyzed for comprehensive biodegradability study of the modified fiber samples. Data were analyzed by One-Way Analysis of Variance.
Findings: The mechanical tests performed on Norris fiber showed successful production of blend fibers with the percentages of 5, 10, 20, 30, and 40 of the components of r-PLA and A 50% r-PLA fiber sample did not have acceptable mechanical properties. The changes of PA6/r-PLA blended fibers with a significant increase in r-PLA component in the PA6 substrate were significant.
Conclusion: The blend modified of PA6 and Poly (Lactic) recycled samples, with a composition containing from 5% to 40% of the dispersed recycled poly-lactic acid fraction have successfully melt spinning capability. By increasing the percentage of recycled poly lactic acid in the blended fibers, the mechanical properties show improvement in samples of 5% and 10% by weight and show reduction in higher percentages. Iincreasing the biodegradability of modified PA 6 fibers with increasing the r-PLA content is obviously confirmed.

---

Ti-6Al-4V alloy due to excellent mechanical properties mainly is used in the aerospace, automobile and biomedical industries. Electrical discharge machining (EDM) are used extensively for machining of this alloy. Due to the thermoelectric nature of this process, unwanted changes happen on machined surface such as development of residual stresses and the change in the corrosion resistance. The aim of this study is the experimental investigation of the effect of input parameters (discharge current and pulse on time) on the amount and distribution of residual stresses and corrosion resistance changes of the machined surface in EDM process of Ti-6Al-4V alloy. For this purpose, samples of Ti-6Al-4V alloy were machined by EDM process and residual stresses induced successive sparks in different setting (different discharge currents and pulses on time) were measured by nanoindentation method and SEM images of machined surface used to better assess of samples surface integrity. TOFL measurement method used to determine the corrosion resistance of the samples. Results indicate that at this process tensile stresses is formed on surface and mentioned stresses increase with depth initially and after reaching a maximum dropping out and eventually leads to pressure stress. By increasing pulse on time and discharge current, maximum tension residual stress only slightly increases and is near ultimate tensile strength of work piece material. Comparison of corrosion results indicated that the corrosion resistance of EDMed samples, was less than the not machined specimens.