Blerina Kolgjini

Three-Phase Characterization of Uniaxially Stretched Linear Low-Density Polyethylene

This study comprises a detailed morphological study of cold-drawn polyethylene monofilaments by Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray measurements. The structure of the three-phase morphology of the linear low-density polyethylene monofilaments was investigated by combining these measurements. It was found that the most important structure variation was found in the intermediate or rigid amorphous phase, whereby the amounts of crystalline and amorphous phases were nearly constant and almost independent of the cold-draw ratio. The intermediate third phase contains gauche and transmolecules, and the amount of transmolecules was increased with the cold-draw ratio and was directly related to this cold-draw ratio. It was found that the two peaks in the Raman spectra, respectively, at 1303 and 1295 cm-1, can be correlated to the amount of gauche and transmolecules in the polyethylene monofilaments. A good and new insight into the three-phase morphology was obtained by combining the DSC and X-ray measurements with the amounts of trans- and gauche molecules from the Raman spectra analysis.

Influence of heat treatment on the bending behaviour of LLDPE monofilaments

Abstract It is known that artificial turf surfaces based on LLDPE monofilaments have the potential to replace natural turf surfaces used for several sport surfaces. Even though the production parameters have a strong influence on the behaviour of monofilaments and indirectly on the final product, the effect of heat treatment at different stages of the production lines is not studied in detail. Therefore, the influence of heat treatment during the production of monofilaments was investigated. This investigation includes a study of the mechanical properties such as tensile testing and bending behaviour and morphological analyses by employing DSC measurements. The results show that the applied heat treatment has a strong influence on the bending behaviour even though the classical studied morphology structures do not show significant changes. Heat treatment influences quite importantly the characteristics of the non-crystalline part of the monofilaments and results in better long-term properties, such as resilience, deformation recovery and fibrillation resistance.