The aim of this study was to evaluate the effect of reinforcing polyaromatic polyamide (aramid) fibers with various orientations on the flexural properties of denture base resin. Aramid fibers with four orientations of unidirectional, woven, non-woven and paper-type were pre-impregnated and placed at the bottom of a specimen mold. Heat-polymerized denture base resin was packed over the fibers and polymerized. A three-point bending test was performed using a universal testing machine at a crosshead speed of 5 mm/min. The flexural strengths and flexural moduli of the unidirectional and woven groups were significantly higher than those of the control and other experimental groups. For the flexural moduli, all experimental groups showed significantly higher reinforcing effects than the control group. In conclusion, the unidirectional group located perpendicular to the direction of the load was most effective in reinforcing the denture base resin, followed by the woven group.

The effects of ultraviolet (UV) radiation on the properties of the biodegradable polymer, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-HHx), were evaluated. Photodegradation was followed by changes in molecular weight, crystallinity, morphology, and thermal properties. PHB-HHx undergoes both chain scission and crosslinking reactions upon UV irradiation. The crystallinity of PHB-HHx was higher during UV-photodegradation. scanning electron microscopy (SEM) micrographs of the PHB-HHx surface before and after UV exposure show that the photodegradation occurred via bulk erosion, not surface erosion. IR spectra showed that both the crystalline and amorphous portions of PHB-HHx were photodegraded through a Norrish type I reaction.

For the first time, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) nanofibrous membrane has been fabricated via electrospinning method. To improve the electrospinnability and reduce the diameter of fibers, the solvent and salt additives were used that affected on the parameters including such as the viscosity and the conductivity of the electrospinning solution for poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). Since the additional salts should be removed, it could be inferred that the co-solvent system was predominant to prepare the nanofibrous poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) membrane. This biodegradable nanofibrous poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) membrane has a great potential to be used in the various application fields such as tissue engineering, implants, packaging materials, agriculture, and so on.

No abstract

No abstract