Preparation of fluorescent thermoplastic polyurethane microcellular foam films blown by supercritical CO₂

Abstract

In this study, the microcellular thermoplastic polyurethane foam with excellent fluorescent performance and a density of about 0.32 g/cm 3 was prepared using solid-state foaming technology. The micro-sized green fluorescent pigment not only endowed thermoplastic polyurethane film with color, but also acted as nucleating agent to influence the cell morphology of thermoplastic polyurethane foam. Laser scanning confocal microscopy testing demonstrated that the characteristic excitation and emission peaks were observed in thermoplastic polyurethane/fluorescent pigment films and foams at 465 and 510 nm, respectively. It is found that the specific intensity of the characteristic emission peak was higher than that of the unfoamed counterpart, resulting from the formation of skin-core structure in thermoplastic polyurethane foam. By adjusting the thickness of unfoamed skin layer, the fluorescent performance of thermoplastic polyurethane / fluorescent pigment foam could be optimized.

Increasing cell density/decreasing cell size to produce microcellular and nanocellular thermoplastic foams: A review

“…Then, the single-phase mixture of polymer/gas is formed by mixing process (e.g. by rotation of the screw in extrusion or injection process 19–21 ) or by diffusion of the gas into the polymer (e.g. batch foaming process 22,23 ) The cell nucleation as the next stage occurs due to a thermodynamic instability.…”

Preparation of Microcellular Foams by Supercritical Carbon Dioxide: A Case Study of Thermoplastic Polyurethane 70A

“…Wang et al used two foaming routes according to the foaming temperature to fabricate structurally tunable TPU foams with improved mechanical properties [13]. Wang et al designed a microcellular TPU foam with excellent fluorescent performance for decorative purpose using fluorescent pigment as the additive [14]. Jiang et al prepared TPU foam sheets using a mold foaming process and investigated the foaming behavior at different foaming temperatures [15].…”

Foaming of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Supercritical Carbon Dioxide: Foaming Performance and Crystallization Behavior

“…One key strategy is to construct cellular morphology in the polymer matrix. Over the past 10 years, supercritical carbon dioxide (scCO 2 ) has received considerable attention as a foaming agent for polymeric foams − owing to its nontoxicity and nonflammability. − It is well known that the foaming behavior of semicrystalline polymers is much more complicated than that of amorphous polymers on account of the existence of crystals . The existing crystal regions not only decrease the CO 2 solubility in the matrix but also influence cell nucleation and cell growth.…”