الفهرس 
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Abstract
This thesis presents study on the optical, mechanical and thermal information for PGC (PGA/PCL( copolymer absorbable surgical suture material. It is USP 5/0 in size manufactured by Ethicon with the trade name Monocryl, which commonly used to close the tissues having large elongation capability such as skin. This suture is copolymer consists of polyglycolic acid PGA/polycaprolactone PCL (Poliglecaprone, PGC) The obtained information will provide useful quantitative data for the future design of sutures and may assist surgeons in their optimum selection of sutures for specific surgical and medical application. Two- and multiple- beam interferometric techniques were used to determinate the opto-mechanical and some structural properties of PGC absorbable surgical suture. In addition to provide accurate studying XRD technique was used to measure the degree of crystallinity of sutures material and investigate the variation in its structure after different degradation periods. A general introduction is given with a review of the previous work dedicated to the investigation of surgical suture material. Moreover, this chapter also introduces the description of the set-up and theoretical considerations of the interferometric techniques used in this work. The Poliglecaprone (PGC) PGA/PCL absorbable surgical suture samples were thermally treated by two different processes. The first method is the direct heat exposure, from 20 to 38°C, in the surrounding medium and the other is the annealing process at temperatures ranged from 65°C, 80°C, 100°C, 120°C and 140°C, for two different duration periods 60 and 120 min. The refractive indices and the birefringence of thermally treated PGA/PCL sutures were measured using multiple-beam Fizeau fringes in transmission. The changes of the molecular orientation distributions across the suture cross-sections (birefringence profiles) were studied for different annealing conditions. The activation energy in the two heating processes was calculated using Arrhenius equation. Also, the dispersion parameters, dispersion energies and Verdet constant were determined. The mechanical and physical properties of the suture materials are important for all function of suture and proper suture selection. A suture fibre-drawing device was designed and calibrated to be attached with the interferometric techniques to investigate the effect of mechanical stretching process on the structural properties of PGA/PCL copolymer suture material. Multiple-beam interferometric technique of the Fizeau type, in transmission, was used to investigate the optical properties of PGA/PCL copolymer suture materials. Different values of stresses were applied by utilizing the mechanical-drawing device. The influence of the applied stresses on the physical and structure properties was studied. The stress-strain curve and from which Young’s modulus was estimated to be (593.02 MPa). The Poosion ratio, the elastic shear modulus, T and the compressability, χ, the average work per chain, optical orientation factor, refractive indices, refractive index and birefringence profiles were determined for the PGA/PCL sutures at different values of applied stresses. The compatibility of the obtained stress-strain curve of the tested fibre with that previously obtained for soft tissues was discussed. Polymer biodegradation depends not only on the origin of the polymer but also on its chemical structure and the environmental degrading conditions. In-vitro degradation was performed to PGA/PCL copolymer suture by immersing it in phosphate buffered saline (PBS, pH 7.4) under static conditions at temperature of 37oC over a period of 10 days. The mechanical and optical properties of the degraded suture were investigated each 2 days. XRD technique was used to measure degree of crystallinity and crystalline size of PGA/PCL copolymer sutures material and investigate the variation in its structure after different degradation time. Mach-Zehnder interferometer was used to determine the refractive indices and birefringence of the suture samples at the same periods of degradation time. The results of the birefringence take the same behavior the degree of crystallinity which confirms the degradation process. The mechanical properties such as; Young’s modulus, E, the elastic shear modulus, T and the compressability, χ were investigated by using the designed mechanical drawing device attached to Mach-Zehnder interferometer.