Investigation of Thermoplastic Polyurethanes Synthesized via Two Different Prepolymers

Abstract

The man aim of this work was to investigate the effect of the molecular weight of polyols, mixture of prepolymers, and [NCO]/[OH] molar ratio used during the prepolymer chain extending step on the chemical structure, thermomechanical and mechanical properties, and thermal stability of thermoplastic poly(ether-urethane)s In this work thermoplastic poly(etherurethane)s were synthesized by using polyols with a various molecular weight, 4,4′-diphenylmethane diisocyanate and biobased glycol. Materials were obtained by a two-step method. The tests were carried out for polyurethanes obtained from a mixture of prepolymers and for reference samples. In the case of materials obtained with using mixture of prepolymers, the ratio of both prepolymers was determined on 50/50 weight percent. Soft segments of materials prepared with using mixture consist of two different polyols. The chemical structure was analyzed using FTIR spectroscopy. The Gaussian deconvolution technique was used to study the hydrogen bonding as well as to decompose carbonyl region of three peaks in various TPUs. The thermal degradation behavior was investigated by using thermogravimetric analysis at heating rates of 10 °C/ min. It was confirmed that the mixture of prepolymers has an effect of the degree of phase separation, thermal stability and selected properties of synthesized thermoplastic poly(ether-urethane)s.

Green thermoplastic poly(ether-urethane)s - synthesis, chemical structure and selected properties investigation

“…1065 cm -1 ) is assigned to the hydrogen bonding interaction between C-O-C and N-H groups [12]. The chemical structure of all obtained materials is similar, and the small shifts at the wave numbers are caused by the content of hard segments [9].…”

“…Calculation method based on the amounts of free carbonyl bonded and H-bonded in amorphous and ordered regions. After the deconvolution of spectrum in the carbonyl region, the following equations [8,9] were used:…”

“…However, these values are lower than for poly(etherurethane)s obtained from polyether polyols with a molecular weight of 1000 g/mol and 2700 g/mol, for respective [NCO]/[OH] molar ratio, in almost all cases (except for sample coded PUMIX_0.9). This is because better segments (HSs and SSs) mixing has been achieved [9]. Hardness increased constantly with increasing [NCO]/[OH] value and as a result of increasing the crystallinity of soft segments.…”

“…sum up, the DPS values are strongly dependent on the length of the used polyols [4,9]. Good microphase separation is related to high long-range connectivity of hard segments, hence the formation of interconnected hard phase is more presumable [13].…”

“…25°C. This peak is elated with the melting temperature of the soft segments and occurs in the samples prepared with the use of long chain bio--based polyether polyols [9,17]. Glass transition of hard segments is assigned at the width range of temperature above ca.…”