Effect of diisocyanate structure on viscoelastic, thermal, mechanical and electrical properties of cast polyurethanes

Abstract

SynopsisStructure property relationship of four different diisocyanates is studied in detail. The isocyanates selected are TDI, MDI Crude, HDI, and IPDI. Physical properties such as mechanical, dynamic mechanical, electrical, and thermal are studied. Dynamic mechanical analyses are based on the compound resonance principle. Among all, IPDI-based polymer showed mediocre trend and TDI-based polymer showed best properties.

Morphological features and thermal and mechanical response in segmented polyurethane elastomers based on mixtures of isocyanates

“…This is due to the substitution of DBDI by MDI. Previous work has also shown a tendency for the polymer network ordination and crystallinity to decrease 3,4 (Figures 6 and 7).…”

“…The difference in crystallinity associated with DBDI and MDI was previously evidenced and ascribed to the flexibility of the hard segments, which is characteristic to the DBDI segments and absent in the MDI hard segments. 9 With regard to the roughness order, it is evident that the crosssections of the materials SPU 4 , SPU 5 and SPU 1 (in which the two diisocyanates are mixed together in a random manner through the one-stage prepolymer synthesis route) are smoother than those obtained by the two-stage prepolymer polyaddition procedures. This is not only due to crystallinity as long as this parameter is the largest for the material SPU 4 , but not in the case of polymer SPU 2 .…”

“…9 With regard to the roughness order, it is evident that the crosssections of the materials SPU 4 , SPU 5 and SPU 1 (in which the two diisocyanates are mixed together in a random manner through the one-stage prepolymer synthesis route) are smoother than those obtained by the two-stage prepolymer polyaddition procedures. This is not only due to crystallinity as long as this parameter is the largest for the material SPU 4 , but not in the case of polymer SPU 2 . Taking into account the morphology model of the hard segment phase dispersed into the soft segment phase, 14 our assumption is that the domains of the soft segment crystals (if present) joined by hard segment matrices are small and dense in the SPUs obtained by the one-step prepolymer route, whereas they are bulky and rare in the SPUs obtained by the two-step prepolymer techniques.…”

“…(a) SPUs derived from a single diisocyanate (SPU 4 After 30 min of mixing, the remaining synthesis steps-chain extension, cure and postcure process-were performed as in case of point (A). The synthesis of the SPU 3 polymer also involved a two-step prepolymer synthesis similar to material SPU 2 , with the only difference being that the first introduced isocyanate was 0.1 mol of MDI, followed by dissolution of 0.1 mol of DBDI in the prepolymer.…”

High Performance Polyurethane Elastomers Using New Cyclaliphatic Diisocyanate

“…For the light stable applications, aliphatic diisocyanates, such as dicyclohexyl methane -4, 4′-diisocyanate (H 12 MDI) 4) , isophorone diisocyanate (IPDI) 5) , hexamethylene diisocyanate (HDI) 6) , 2,5(2,6)-bis(isocyanatomethyl)bicyclo [2.2.1] heptane (NBDI TM ) 6) and 1,3-bis (isocyanatemethyle) cyclo-expected that 1,4-H 6 XDI is applicable to various polyurethane products such as thermoplastic polyurethane elastomer (TPU) 8,9,10,11,18) , thermosetting polyurethane elastomer (TSU) 8,9,[12][13][14] , polyurethane solution 8,15) , polyisocyanate hardener 16) , polyurethane dispersion (PUD) 15,17) and flexible polyurethane foam 8,18) . This paper will report superior properties of polyurethane elastomers based on 1,4-H 6 XDI, in particular, mechanical and thermal properties using rheological technique.…”