Preparation and properties of segmented thermoplastic polyurethane elastomers with two different soft segments

Abstract

Thermoplastic polyurethane elastomers were prepared from 4,4-diphenylmethane diisocyanate (MDI)/1,4-butanediol (BD)/poly(propylene glycol) (PPG) and MDI/BD/poly(oxytetramethylene glycol) (PTMG). The MDI/BD-based hard-segment content of polyurethane prepared in this study was of 39 -65 wt %. These polyurethane elastomers had a constant soft-segment molecular weight (M n , 2000), but a variable hard-segment block length (n, 3.0 -10.1; M n , 1020 -3434). The effects of the hardsegment content on the thermal properties and elastic behavior were investigated. These properties of the PPG-based MPP samples and the PTMG-based MPT samples were compared. The polyurethane prepared in this study had a hard-segment crystalline melting temperature in the range of 185.5-236.5°C. With increasing hard-segment content, the dynamic storage modulus and glass transition temperature increased in both the MPP and MPT samples. The permanent set (%) increased with increasing hard-segment content and successive maximum elongation. The permanent set (%) of the MPP samples was higher than that of MPT samples at the same hard-segment content. The value of K (area of the hydrogen-bonded carbonyl group/area of the free carbonyl group) increased with increasing hard-segment content in both the MPP and MPT samples, and the K value of the MPT samples was higher than that of the MPP samples at the same hard-segment content.

Polyurethanes with Narrow‐ and Polydisperse Hard Segment Distributions

“…The studied copolymers with HS consisting of MDI-6T6-MDI (n ¼ 1) were thus relatively thermally stable. The modulus for the PD HS copolymers decreased in the same temperature range at a rate of 0.6% per 8C (Table 3) S31 S10 160 c) 0.6 231 -a) HS repeat length, ND, and PD; b) Not measurable; c) Data from ref [12,13] and by assuming G( ¼ E(/3. DG 0 value was quite low and was probably an effect of a uniform 6T6 being used as an extender instead of a randomly distributed 6T6.…”

“…First, a soft segment (SS) prepolymer, end-capped with diisocyanate is prepared with excess diisocyanate. [11][12][13] This prepolymer is subsequently extended with an extender and possibly also additional diisocyanate. For thermoplastic elastomer applications, the diisocyanate, MDI 4,4 0 methylenebis(phenyl isocyanate) is often used, and in order to obtain copolymers with good low temperature properties, poly(propylene oxide) (PPO) is generally employed since PPO is noncrystalline.…”

“…[12] If additional MDI is added together with the diamine, the HS length distribution becomes random. [13] Generally, the melting temperature of the HSs increases rather significantly as their length increases. [4,12,13] However, the melting temperature is also dependant on the SS concentration.…”

“…[13] Generally, the melting temperature of the HSs increases rather significantly as their length increases. [4,12,13] However, the melting temperature is also dependant on the SS concentration. The SSs act as a solvent for the HS and the effect on the melting temperature depression thus depends on the SS content as well as on the miscibility of the segments.…”

In Based on Amino Acid Compounds Synthesis of New Poly(Ester-Imide)s and Poly(Imide-Urethane)s Derivatives

“…The soft parts are normally composed of polyesters or polyethers with high molecular weight which have high flexibility at room temperature and highly affect the properties of the polymer. The hard parts are composed of di-isocyanate and diol with low molecular weight 27 . Thermostable polyurethanes have numerous properties which result in their wide applications in manufacturing decorative and structural materials, flexible foams for mattress and pillow, rigid foams for insulation, solid or micro foams for dyeing tools, painting rollers, hydraulic stamps, and oil-resistant elastomers.…”