Photoelastic characterization of shear-bands in mechanically stretched polymeric fibers.

In this work, the shear bands formed during the stretching of isotactic polypropylene fibers are studied. The digital photoelasticity technique is applied to provide full-field visualization of the stress of the shear bands regions. The mechanical testing device is modified to be suitable for mechanical measurements. The effect of different parameters, that is, the stretching rates and the ambient temperature on the formation of shear bands is investigated. Finally, the influence of heating pre-existed shear bands is studied. Photoelastic patterns of the shear bands at these conditions are included for illustration.

Phase estimation for investigating the optical and mechanical properties of Monocryl suture for soft tissue approximation and ligation.

Monocryl is a bio-absorbable suture composed of a polyglycolide and poly-epsiloncaprolactone copolymer material and is considered a promising candidate for soft tissues approximation. Consequently, the physical, mechanical, and morphological properties are essential for the surgeons to select the suitable suture for their surgical perform. In this article, Mach Zehnder interferometer equipped with a mechanical drawing device are used for evaluating the mechanical properties and a better understanding of how the Monocryl suture reacts to loading. The two-dimensional fast Fourier transform is applied to extract the phase from the captured interference microinterferograms at different draw ratios. The extracted phase helps to determine some opto-mechanical and structural properties of Monocryle suture. Quantitative structure-activity relationships model is employed for investigating the biological activity of the tested suture. The stress-strain behavior of Monocryl suture has a J-shaped behavior which compatible with the behavior of the soft tissues. The molecular electrostatic potential maps showed that Monocryl model structure is proved to be electrophilic interplays.

FECO fringes for investigating the effect of grafting process on the dispersion properties of polyamaide-6 fibers.

Polyamide-6 fiber was modified by grafting it with poly(methyl methacrylate) PMMA polymer. The grafting process is widely used in industry to introduce new properties and overcome some obstacles, for instance, in storing energy applications. Multiple-beam interference techniques are very precise techniques to characterize the different properties of polymeric fibers. Fringes of equal chromatic order FECO technique was used to study the effect of grafting process on the dispersion properties of polyamides fibers. A mechanical drawing device was attached to the FECO system to evaluate the mechanical deformation impact on the samples and on their dispersion properties. The dispersion properties were evaluated by measuring their refractive indices, Cauchy's constants, average excitation energy, dispersion energy, lattice energy, interband oscillator wavelength, static dielectric constant, and Abbe's dispersion number. The results show that grafting polyamide-6 with PMMA produced a new material with a different structure and different dispersion properties. Microinterferograms, graphs and tables were given for illustrations.

Fractographic characterization of isotactic polypropylene fibers.

In this article we present an opto-thermo-mechanical characterization of isotactic polypropylene monofilament during failure by fracture. The digital photoelasticity, the two-beam Pluta polarising interference microscope and the computed tomography are used to provide quantitative data and visual models of the fracture regions of isotactic polypropylene fibers suffering failure by fracture at different thermal and mechanical conditions. Birefringence values and the intrinsic stress-anisotropy are measured at the fracture surface. 3D models of the fracture regions are reconstructed. Photoelastic patterns and two-beam interferograms are included for illustration.

Characterization of the mechanical and structural properties of PGA/TMC copolymer for cardiac tissue engineering.

Recently, scientific research has confirmed that a single polymer material cannot meet the ambitions of all surgical requirements. Thus, combinations of different types of polymeric materials are used in order to manufacture different suture materials. A copolymer of Polyglycolide (PGA) and trimethylene carbonate (TMC) is one of the simplest bioabsorbable monofilament sutures. The optical properties of PGA/TMC copolymer surgical suture were investigated by using multiple-beam interferometric of Fizeau type. The mechanical properties were measured by a suture-drawing apparatus attached to the multiple-beam interferometric system. The refractive indices, stress-strain curve, elastic shear modulus, Young's modulus and crosslink density were investigated for the PGA/TMC surgical suture at various draw ratios. The biological activities were conducted by Quantitative Structure Activity Relationships (QSAR) descriptors. Molecular Electrostatic Potential (MESP) maps were used to describe the reactivity and functional active sites for the given molecule. The behavior of stress-strain curve confirms the compatibility of the suture with the sternum which proves that this suture is a good candidate for cardiac operations. RESEARCH HIGHLIGHTS: Fizeau fringes is accurate in characterizing properties of PGA/TMC surgical suture. The biological activities were conducted by (QSAR) descriptors. The compatibility measurements lead to it is a good candidate for cardiac operations.

The influence of grafting process on the optical, geometrical, and structural parameters of nylon-6 fibers.

Mach-Zehnder interferometer technique is utilized to study the impact of grafting of the nylon-6 fibers with poly (methyl methacrylate) (PMMA) polymer on the optical, geometrical, and structural properties. He-Ne laser diffraction technique is applied to study the changes in the fiber thickness of two samples (nylon-6 blank and nylon-6 grafted with PMMA) at different positions along the fiber length. The geometrical parameters are investigated by determining the cross-sectional shape of the two samples. The results of the interferometric and the diffraction techniques show that there is no variation in the thickness of nylon-6 fiber but variations in the thickness of the grafted nylon-6 fiber are obvious. The optical and physical properties along the axis of these fibers are characterized by measuring their refractive indices, birefringence, polarizability per unit volume, dielectric constant, surface reflectivity and the refractive index profile. The results show that PMMA polymer changed the optical, geometrical, and structural properties of the nylon-6 blank fiber. Microinterferograms are given for illustrations.