Impact of Electron Beam Irradiation on Thermoplastic Polyurethanes Unraveled by Thermal Field-Flow Fractionation

Abstract

The impact of electron beam irradiation on thermoplastic polyurethane material was studied for both an aliphatic and an aromatic polyurethane with equal amount of hard and soft segments. Irradiation doses up to 300 kGy at room temperature and at 100 °C were applied. Changes in chemical structure, molar mass and size were assessed using infrared spectroscopy, differential scanning calorimetry, size exclusion chromatography and thermal field flow fractionation. Material alterations were correlated with trends regarding to degradation, crosslinking or branching changes. Thereby, limits of characterization by size exclusion chromatography are addressed and amended by thermal field-flow fractionation studies. In addition, a thermophoretic analysis has been carried out complementary to the portfolio of analytical methods applied in this work.

Electron Beam-Mediated Cross-Linking of Blown Film-Extruded Biodegradable PGA/PBAT Blends toward High Toughness and Low Oxygen Permeation

“…These are attributed to the degradation of the esters along the polymer chain backbone and indicate the formation of oxidatively degraded chain scission with terminal carboxylic acids and anhydrides (see Scheme ). This follows previously observed degradation above 250 kGy EBT of other polymers. − The FTIR spectra of the white regions of the films treated at 450 kGy or the other areas of the films treated with 400 and 450 kGy do not show any degradation. This is presumably because after significant irradiation of the film at higher dosages, sufficient scission, cross-linking, and degradation occur on the polymer surface.…”

“…(See Scheme 1) This follows previously observed degradation above 250 kGy EBT of other polymers. [29][30][31] The FTIR spectra of the white regions of the films treated at 450 kGy or the other areas of the films treated with 400 and 450 kGy do not show any degradation. This is presumably because after significant irradiation of the film at higher dosages, sufficient scission, crosslinking, and degradation occurs on the polymer surface.…”

Preparation of Isotropic Branched LCP Films via a Dynamic Rotating Die: Relationship among Orientation, Mechanical Properties, and Microstructure

“…The infrared spectra of neat LCP and ADR 4468, as well as ADR-modified LCP, are depicted in Figure 3; the peak at 907 cm −1 in ADR 4468 corresponds to the characteristic peak of the epoxy group, 30,31 which is not observed on the branched LCP due to significant amount of methylene produced from the ring-opening reaction of epoxy groups, and absorption peaks of the C−H asymmetric stretching vibration (2920 cm −1 ) and symmetric stretching vibration (2850 cm −1 ) for methylene groups appear on the modified LCP. 32 These methylene peaks are also more pronounced on ADR 4468 but not obvious on neat LCP. In conclusion, LCP successfully reacted with ADR 4468, and the epoxy groups were completely consumed.…”

Increasing Bending Strength of Polycarbonate Reinforced by Carbon Fiber Irradiated by Electron Beam

“…It follows that low-voltage electron beam irradiation (HLEBI) has been used to improve the mechanical properties of numerous materials [2,[28][29][30][31][32][33][34][35][36][37][38]. For the PC macromolecule, HLEBI generates dangling bonds at bonding sites with the lowest dissociation energies, as shown in Figure 1.…”

“…Since the CF is activated with HLEBI, charge transfer is expected to occur in the PC at the interface generating strong bonds with CF, preventing CF pull-out and ply delamination. Studies on electron beam treatment for recyclable TP polymers without CF are few in number [2,[28][29][30] but include those on PC [2], polyurethane (PU) [28,29], and polypropylene (PP) blends [30]. For CFRTP PP, tensile strength and Young's modulus were increased with an EB dose from 100 to 400 kGy [31] while, for TP PEEK (polyetheretherketone) CFRP specimens, impact strength was increased by 56% at a low accumulative probability, indicating increased reliability and safety by the possibility of strengthening the weakest samples in the data [32].…”