Dissipative Behaviour Analysis of Reprocessed Polyethylene Terephthalate using Digital Image Correlation and Updated Finite Element Analysis

Abstract

Polyethylene terephthalate (PET) is a semi-crystalline polyester that is usually processed by conventional methods. However, the degradation of this polyester during the melting process impacts its macroscopic behaviour, which is particularly true for recycled PET that is subjected to multiple processes at the melting temperature by extrusion, injection-moulding or pelletizing. In this work, the impact of reprocessing on the mechanical properties of PET is studied. This approach requires exploring the influence of implementation on both its own mechanical performance factor and on the damage linked to the striction problem. An experimental protocol was developed to study large strain responses through a set of sequenced and instrumented uniaxial traction tests based on the standard ISO-5272-1-A and hourglass geometries. Updated finite element simulations were coupled with digital image correlation, thereby providing access to the parameters of a phenomenological model. This coupled approach enables researchers to understand both the complex shape of the stress-strain curve and the well-known dilatant mechanism that is observed during uniaxial deformation.

Impact of Titanium Dioxide in the Mechanical Recycling of Post-Consumer Polyethylene Terephthalate Bottle Waste: Tensile and Fracture Behavior

“…During testing, visual observations revealed that the first stress drop were ascribed to the formation of multiple micro-shear bands over the whole slender section length, while the second stress drop corresponded to necking inception, as shown in Figure 5b. This behavior has already been reported in the literature for oriented glassy PET fibers as well as for rPET [45,46] and ascribed to the chain ability to be highly oriented as well as stretched upon tensile loading in order to initiate neck formation. Accordingly, the post-yielding behavior of physically aged rPET-T material can be plausibly explained as follows.…”

Strain Localisation in iPP/MWCNT Nanocomposites Using Digital Image Correlation

“…The scale factor or magnification ( k ), which depends on the focal lens and the distance between the camera and object, was fixed to 32 µm per pixel. This scale factor constitutes a compromise between a necessary spatial resolution for the local strain measurements and the limitation of the perspective errors associated to the out‐of‐plane displacement .…”

“…The scale factor or magnification (k), which depends on the focal lens and the distance between the camera and object, was fixed to 32 μm per pixel. This scale factor constitutes a compromise between a necessary spatial resolution for the local strain measurements and the limitation of the perspective errors associated to the out-of-plane displacement [28]. As far as local analysis is concerned, expected samples were machined with a curved profile so that the neck initiation takes place within the observation field of the camera (Figure 5a).…”

A new methodology for the mechanical behavior analysis of polyvinyl chloride and recycled polyethylene terephthalate foams: Finite element model updating using mechanical field measurements

“…The crosshead speed was set for each specimen to obtain a strain rate of 1.1 × 10 −2 s −1 . The evaluation of the in-plane strain tensors on each observed face of the sample by DIC technique was performed with a home-developed software called ‘CinEMA’ 22 which enabled the calculation of the different apparent elastic modulus and transverse contraction coefficients. The evaluation of the strain tensor at the sample surface is based on local least-squares adjustment, using a linear fit of the displacement field around the considered point contained in the suitable gauge length.…”

“…As a viable solution, interpreting these tests requires numerical finite element modeling. This paper aims to determine, by a finite element model updating (FEMU) method, [20][21][22] the intrinsic elastic parameters of two types of foams: a regular PVC and a rPET, both having a density of 80 kg/m 3 , in order to study the potential substitution of the former with the latter, thus providing a more environmentally friendly and sustainable alternative.…”