Laser-Marking Mechanism of Thermoplastic Polyurethane/Bi₂O₃ Composites

Abstract

Using bismuth oxide (Bi2O3) as a laser-marking additive and thermoplastic polyurethane (TPU) as the matrix, TPU/Bi2O3 composite materials were prepared by melt blending in a torque rheometer. The sheet samples prepared from the TPU/Bi2O3 composites were treated in air by scanning with a neodymium-doped yttrium aluminum garnet (Nd: YAG) pulsed laser beam at a wavelength of 1064 nm. Compared with the pure TPU sample, the laser-marked composite samples exhibited differences in marking contrast as the Bi2O3 content increased from 0.1% to 1.0% based on stereomicroscope analysis. Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, thermogravimetry analysis, and X-ray diffraction were used to characterize the laser-marked surface material of the composite samples. Furthermore, a mechanism for the laser-effected darkening of the TPU/Bi2O3 composites was proposed. The results herein indicated that the addition of the Bi2O3 laser-sensitive additive to TPU resulted in laser darkening of the TPU/Bi2O3 composites. The marking contrast and visual appearance of the surface of the TPU/Bi2O3 composites after laser irradiation was due to a synergistic effect consisting of carbonization via TPU pyrolysis and reduction of Bi2O3 to black bismuth metal.

Direct Semiconductor Laser Writing of Few‐Layer Graphene Polyhedra Networks for Flexible Solid‐State Supercapacitor

“…As an example, Kaner and co-workers demonstrated a simple DLW approach for fabrication of graphene-based supercapacitor arrays with the household DVD appliance. [6] Given that the wavelength of our semiconductor lasers (1.06 µm) is only one tenth of the widely used CO 2 cutting lasers (10.6 µm) for PI ablation and more close to the intrinsic absorption edge of PI, [7] we conceived the designing and assembling of flexible solid state supercapacitors with our laser irradiated PI as electrodes by DLW method. [4,5] Recently, we have reported a semiconductor light emitting diode-pumped neodymium-doped yttrium aluminum garnet (Nd:YAG) laser DLW approach to pattern the hybrid thermoplastic elastomer flakes with the logotypes of amorphous carbon.…”

Effective Control of Laser‐Induced Carbonization Using Low‐Density Polyethylene/Polystyrene Multilayered Structure via Nanolayer Coextrusion

“…Laser marking is a new type of surface patterning. It uses the high energy of a laser to carbonize or foam the surface of a polymer . As a result, a mark is obtained with a large color difference from the polymer.…”

“…In addition, some common polymers such as polyethylene (PE), polypropylene (PP), and thermoplastic polyurethane are insensitive to the laser energy and form a fuzzy laser mark. Therefore, laser‐sensitive additives would need to be used to improve the laser‐marking properties of the polymer matrix, such as diantimony trioxide (Sb 2 O 3 ), mica, bismuth oxychloride (BiOCl), bismuth oxide (Bi 2 O 3 ), stannic oxide (SnO 2 ), and titanium dioxide (TiO 2 ) …”

“…However, the degree of carbonization cannot be effectively controlled, and the sharpness of the pattern depends on the addition of the laser‐sensitive additives. The addition of laser‐sensitive additives will introduce some new problems such as the effect of the degree of dispersion on the uniformity of the pattern, the effect of the type of the laser‐sensitive additives on the strength and color of the polymer matrix, and the effect of the toxicity of the laser‐sensitive additives on the polymer matrix . In addition, environmental and cost issues can also limit their applications.…”

“…The addition of laser-sensitive additives will introduce some new problems such as the effect of the degree of dispersion on the uniformity of the pattern, the effect of the type of the laser-sensitive additives on the strength and color of the polymer matrix, and the effect of the toxicity of the laser-sensitive additives on the polymer matrix. [7,22] In addition, environmental and cost issues can also limit their applications. Therefore, it is extremely important to improve the laser-marking properties of a polymer matrix without adding laser-sensitive additives.…”