Premium
The splitting tendency of uniaxially‐oriented PET tapes investigated with nano‐indentation, nano‐scratch, differential scanning calorimetry, and X‐ray
Author(s) -
Sikder Arun Kumar,
Kleppinger Ralf,
Bashir Zahir,
Freudenschuss G.,
Fürst Herbert
Publication year - 2020
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.25500
Subject(s) - materials science , composite material , differential scanning calorimetry , indentation , nano , crystallinity , crystallite , scratch , physics , thermodynamics , metallurgy
Earlier, various additives werescreened to improve the weavability of poly(ethylene terephthalate) (PET) tape. For predicting the weavability, three tests had been used: tensile impact strength, fibrillar versus puckered fracture and an axial folding test. This paper shows the possibility of using a simple nano‐indentation method to decide on the splintering tendency of uniaxially‐oriented PET tapes, as a predictor for weavability. A plasticity index derived from the nano‐indentation correlated with PET tapes that were, or were not, weavable. Nano‐scratches applied parallel and perpendicular to the tape also showed differences that could be correlated to the splitting tendency. While investigating these tests methods, it was observed that pure uniaxially‐ oriented PET tape heat set at 140°C had a non‐splintering character even without additives, while polymeric additives were needed to resist splintering for the tape heat set at 240°C. Calorimetry showed no difference in heat‐of‐fusion implying identical crystallinity in the tapes heat set at 140°C and 240°C. However, X‐ray studies revealed that the crystallites in the tape heat set at 140°C were smaller/and or imperfect, and hence there were more lateral tie‐molecules that provided it the splitting resistance. Pure PET tape if heat set below 150°C may be a workable solution for weaving, thereby dispensing with the need for toughening additives.