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In this study, nylon 66 industrial fabrics (used in the conveyor belts) were exposed artificially to the accelerated ultraviolet rays and the degradation mechanism was evaluated using spectral, thermal, and morphological analyses. The fabric samples were exposed to six different exposure times in a UV chamber and tensile tests were carried out in the main and bias (45°) directions. The results showed that the shear modulus was reduced in the early stages covering 4 h of the UV radiation because of the linkages breakage and the increase in the amorphous regions. However, after this early stage, the shear modulus started to increase. The Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) analysis, and X-ray photoelectron spectroscopy (XPS) study were also performed to evaluate the surface morphology and the degradation mechanism of the nylon 66 fibers after UV illumination. The results also revealed that the formation of new links by free radicals caused the change in the bond wavelengths. Furthermore, it was found that there was an interesting mechanism for the UV degradation of nylon 66 fabrics at different exposure times, as confirmed by the results obtained regarding the mechanical properties of the samples. The results of this study can be, therefore, helpful for the industrial application of nylon 66 woven conveyor belts exposed to solar UV radiation.

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Polylactide/polycaprolactone asymmetric membranes for guided bone regeneration DOI 10.1515/epoly-2016-0138 e-Polymers 2016; 16(5): 351-358 Full length article: Biodegradable polymer membranes were fabricated by a combination of electrospinning and freeze-drying. Those asymmetric membranes possess favorable mechanical properties and are biocompatible. The differentiated porosity should on one side prevent soft tissue growth and on the other be a suitable scaffold for bone cells growth. Full length article: Esophageal prostheses and scaffolds should have the appropriate mechanical and strain properties in the longitudinal and circumferential directions. A novel bi-layered esophageal prosthesis was produced using knitted tubular silk fabric and coating of polyurethane.

Polyurethane (PU) nanofibres are widely used in tissue engineering of elastic tissues such as tendon and ligament, vascular and arterial grafts etc. Alignment of the PU nanofibres is also a desirable property of some tissues to mimic the morphology of the extracellular matrix. Elasthane™ 55D nanofibres were produced using a common electrospinning method and a rotating drum to collect the aligned fibres. Four flow rates and five collector speeds were investigated for their effects on nanofibres alignment and diameter. Field emission scanning electron microscopy (FESEM) images of nanofibrous webs were captured, and the diameter and alignment of the nanofibres were measured. Finally, stem cells from human exfoliated deciduous tooth (SHED) were seeded on the surface of the PU nanofibres to investigate the cell-scaffold interaction. Statistical results showed that the flow rate had a significant effect on the fibres diameter. Enhancing the flow rate led to increasing the diameter of the PU nanofibres. The results showed that the fibres alignment index was promoted by increasing the rotating speed of the collector. In addition, the morphological observation of SEM images indicated that cells grew in the alignment direction of the nanofibres. The results of this study can be applicable to produce and control the aligned PU nanofibres for specific applications such as vascular grafts, esophagus prosthesis, arterial grafts and tissue engineering of tendon and ligament.