Green TPUs from Prepolymer Mixtures Designed by Controlling the Chemical Structure of Flexible Segments

Abstract

This study concerns green thermoplastic polyurethanes (TPU) obtained by controlling the chemical structure of flexible segments. Two types of bio-based polyether polyols—poly(trimethylene glycol)s—with average molecular weights ca. 1000 and 2700 Da were used (PO3G1000 and PO3G2700, respectively). TPUs were prepared via a two-step method. Hard segments consisted of 4,4′-diphenylmethane diisocyanates and the bio-based 1,4-butanodiol (used as a chain extender and used to control the [NCO]/[OH] molar ratio). The impacts of the structure of flexible segments, the amount of each type of prepolymer, and the [NCO]/[OH] molar ratio on the chemical structure and selected properties of the TPUs were verified. By regulating the number of flexible segments of a given type, different selected properties of TPU materials were obtained. Thermal analysis confirmed the high thermal stability of the prepared materials and revealed that TPUs based on a higher amount of prepolymer synthesized from PO3G2700 have a tendency for cold crystallization. An increase in the amount of PO3G1000 at the flexible segments caused an increase in the tensile strength and decrease in the elongation at break. Melt flow index results demonstrated that the increase in the amount of prepolymer based on PO3G1000 resulted in TPUs favorable in terms of machining.

One-Shot Synthesis of Thermoplastic Polyurethane Based on Bio-Polyol (Polytrimethylene Ether Glycol) and Characterization of Micro-Phase Separation

“…Polyols constitute more than half of the total composition of the TPU and poly(ethylene glycol), poly(propylene glycol), poly(tetramethylene glycol) and poly(tetrahydrofuran) are commonly used polyether polyols, which are petrochemical-based. The synthesis of TPUs, including isocyanates, polyols, catalysts, and additives, and their application require abundant volatile organic compounds and emit hazardous pollutants that cause severe environmental pollution [ 6 , 7 ]. Since the application of TPU is increasingly extensive, decreasing the petrochemical monomers and energy required for polymerization and processing is becoming significant.…”

Synthesis and fabrication of biobased thermoplastic polyurethane filament for FDM 3D printing

“…The TPU is multiblock copolymers comprised of alternating SS and HS and so this segmented structure is the key feature of TPU molecular chain. 15,16 Due to thermodynamic incompatibility between the two structural units, the polymers undergo microphase separation resulting in hard segment (HS) domains dispersed in the soft segment (SS) matrix. TPU has a characteristic microphase separated structure due to the incompatibility of the hard and soft segments, with hard domains acting as the tie points for the flexible soft segment phase.…”

“…[18][19][20][21][22] This study is concerned with bio-based thermoplastic polyurethanes (TPU) obtained by using PO3G (Poly trimethylene Ether Glycol, SK Chemical), a bio-polyol made from fermented corn. PO3G is a 100% bio-based polyether polyol that can replace existing petro-based polyols and provides a 40% reduction in greenhouse gas emissions, 15 and has excellent biodegradability. Diisocyanates are widely used as raw materials for the production of TPUs formed by addition reactions.…”

“…Typically, TPUs are prepared from a dihydroxyl‐terminated precursor (polyol), an isocyanate and a low molecular weight diol or diamine chain extender. The TPU is multi‐block copolymers comprised of alternating SS and HS and so this segmented structure is the key feature of TPU molecular chain 15,16 . Due to thermodynamic incompatibility between the two structural units, the polymers undergo microphase separation resulting in hard segment (HS) domains dispersed in the soft segment (SS) matrix.…”

Segmented bio-based polyurethane composites containing powdered cellulose obtained from novel bio-based diisocyanate mixtures

“…The versatile chemical structure and properties of polyurethanes (PUs) and their composites have led to these materials finding a wide range of practical and different applications, such as in the automotive, medical devices or furniture industries (Głowińska and Datta 2016;Trache et al 2016). Polyurethane can be obtained by using bio-monomers, resulting in environmentally friendly polymers with high contents of green carbon and desirable properties (Głowińska and Datta 2015a;Pattamaprom et al 2020;Głowińska et al 2021;Kasprzyk et al 2021).…”