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.
Three different techniques are used for visualization the failure by fracture of isotactic polypropylene fibers. Systematic discussion of fracture mechanism is given. It concluded that the fiber core layers would fail before their outer layers.
In this article, we used the opto‐mechanical stress testing‐device to stretch a monofilament of isotactic Polypropylene, iPP, fibers. This device was used to obtain the mechanical behavior of these ...fibers by measuring the complete stress–strain curves at different stretching conditions. Using this device, the different regions of iPP fiber where the mechanical deformation takes place was characterized, including the necking region and fracture initiation process. The obtained mechanical behavior of iPP fibers was correlated to the variations of different optical parameters by attaching the device with the Pluta polarizing interference microscope. This microscope and the stress device allowed us to simultaneously measure the optical parameters and stress–strain data during stretching process at different stretching speeds. These data provide us with comprehensive information on the opto‐mechanical behavior of polymeric fibers. Interferograms are included for illustration.
The opto‐mechanical stress testing‐device was used to stretch a monofilament of, iPP, fibers. The mechanical deformation takes place was characterized, including the necking region and fracture initiation process at different stretching speeds.
A multi-mode opto-thermo-mechanical stretching system was modified to study the changes in the 3D of optical and structural properties of stretched fibre along its axis. The structural deformation of ...isotactic Polypropylene, (iPP), fibres was studied at different draw ratios. The modified system coupled with Pluta polarising interference microscope was used to determine the variation of the birefringence in three dimensions during stretching process. Using this modified system, the multi-necking was detected. Subfringe analysis technique was used to determine the phase distribution of the obtained microinterferograms, which were given for illustration.
The interference fringes formed in an air wedge and those based on the theory of two-beam interference such as the Pluta microscope and Michelson interferometer are utilized for estimating the ...thickness and/or refractive index of transparent polypropylene thin films. The theories of the methods are presented, and their applications to measurement of film thickness and refractive index are given. The accuracy of the measured film thickness and refractive index is calculated. The three interference methods proved that they could be transformed into valuable technological tools. The study established that, estimation of the thickness of thin films by the air wedge interference method is more simple and more accurate than the others. Films not more than 50 μm thickness are recommended in the Pluta interference microscope.
The core–cladding refractive index difference
Δn and the index gradient profile parameter
α of the graded index (GR-IN) optical fibre has been determined. The curve representing the real path, in the ...core region, due to refraction of the beam and the change in the exit wavefront are considered. Multiple-beam Fizeau fringes and two-beam interference Pluta polarizing microscope, are used for this investigation. A new method, based on a derived mathematical expression, is used with a prepared computer program to estimate the fringe shift inside GR-IN of the fibre core. The estimated and experimental values of the fringe shift, along the core radius, are used to obtain the refractive index profile of the optical fibre. A comparison between the new method and a previous model considering the refraction has been shown. Microinterferograms are given for illustrations.
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