The Role of Diisocyanate Structure to Modify Properties of Segmented Polyurethanes

Abstract

Segmented thermoplastic polyurethanes (PU) were synthetized using a polycarbonatediol macrodiol as a flexible or soft segment with a molar mass of 2000 g/mol, and different diisocyanate molecules and 1,4-butanediol as a rigid or hard segment. The diisocyanate molecules employed are 3,3′-Dimethyl-4,4′-biphenyl diisocyanate (TODI), 4,4′-diphenylmethane diisocyanate (MDI), 4,4’-Methylenebis(phenyl isocyanate) 1-isocyanato-4- [(4-phenylisocyanate)methyl]benzene and 1-isocyanate-4-[(2-phenylisocyanate) methyl]benzene (ratio 1:1) (MDIi), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI). The polyurethanes obtained reveal a wide variation of microphase separation degree that is correlated with mechanical properties. Different techniques, such as DSC, DMA, and FTIR, have been used to determine flexible–rigid segment phase behavior. Mechanical properties, such as tensile properties, Shore D hardness, and “compression set”, have been determined. This work reveals that the structure of the hard segment is crucial to determine the degree of phase miscibility which affects the resulting mechanical properties, such as tensile properties, hardness, and “compression set”.

The Influence of Diisocyanate Structure on Thermal Stability of Thermoplastic Polyurethane Elastomers Based on Diphenylmethane-Derivative Chain Extender with Sulfur Atoms

“…The oligoester diols generally give materials of a higher tensile strength, harder and less stretchable than oligoether diols which are moreover more resistant to ultraviolet rays and oxidation. However, from the oligoether diols polymers exhibiting improved low-temperature properties and better resistance to high humidity conditions as well as attack by fungi and bacteria are synthesized [ 2 , 15 , 16 ]. As for the isocyanate component, it is well known that aromatic diisocyanates are used to obtain polymers of high tensile strength and modulus of elasticity, as well as thermal resistance [ 17 , 18 , 19 ].…”

Quantification Characterization of Hierarchical Structure of Polyurethane by Advanced AFM and X-ray Techniques

“…3,4 In contrast, the SS is typically composed of polyether or polyester polyol with molecular weights ranging from 1000 to 3000 g/mol. 5,6 These inherent structural characteristics of PU give rise to a wide range of versatile properties, making it a highly desirable material in various industries.…”

“…Specifically, the HS has a high glass-transition temperature ( T g ), which imparts rigidity to the material, while the SS has a lower T g , contributing to its elasticity. The HS is generated through the chemical reaction between isocyanate and small molecular diols. , In contrast, the SS is typically composed of polyether or polyester polyol with molecular weights ranging from 1000 to 3000 g/mol. , These inherent structural characteristics of PU give rise to a wide range of versatile properties, making it a highly desirable material in various industries.…”

Inserting urethane into 1,2,3‐triazole click‐cured solid propellant binder to form microphase separation and enhance mechanical and combustible performances

“…Notably, the excellent mechanical performance of the isocyanate curing system comes from its microphase separation structure. 30 Thus, we developed a triazole curing system near the position which the urethane structure was grafted at. We hypothesized that such a urethane structure can establish a micro-hard phase and bring no humidity influence on the curing system.…”

“…Furthermore, the GAP‐based triazole‐cured binder system suffers from uncontrollable reaction equivalent because the molecular chain contains many CH 2 N 3 side groups, 29 and the preformed rigid triazoles had great spatial occupancy which hindered the formation of nearby triazoles. Notably, the excellent mechanical performance of the isocyanate curing system comes from its microphase separation structure 30 …”