Differential scanning calorimetry analysis of silicon‐containing and phosphorus‐containing segmented polyurethane. II Annealing effect

Abstract

ABSTRACT:The effect of thermal annealing on the multiple endothermic behavior and morphological changes in the silicon-containing and phosphorus-containing segmented polyurethane (Si-PU and P-PU) has been studied by differential scanning calorimetry (DSC). In the amorphous hard segments of the Si-PU and P-PU polymers that were annealed below T2, both the T1 temperature, and magnitude of T1 endotherm increased linearly as a function of the logarithmic annealing time (log t a ). This result demonstrated that the endothermic behavior (T1 endotherm) is typical of enthalpy relaxation resulting from the physical aging of the amorphous hard segment. Furthermore, the P-PU polymer was unstable than the Si-PU polymer due to the fact that the phosphorus-containing hard segment produce aged more easily. Dissociation of domains and enthalpy relaxation of hard segments for the Si-PU polymer was associated with T2 endothermic behavior. However, the enthalpy relaxations of the T2 endothermic behavior for P-PU polymer was absent, which could be attribute to the behavior of degradation in the temperature range of T2 endotherm.

Synthesis and characterization of phosphorus‐containing waterborne polyurethanes: Effects of the organophosphonate content on the flame retardancy, morphology, and film properties

“…Chen et al29 studied endothermic behavior of short‐range ordering dissociation in SPU based on 4, 4′‐diphenylmethane diisocyanate and 1, 4‐butanediol and suggested that the nature of the behavior was typical of enthalpy relaxation and resulted from the physical aging of the amorphous hard segment. Shu et al30 verified that the easy physical aging of the amorphous phosphorous hard segment led to a higher temperature of short‐range ordering dissociation. In this study, the phosphorous segments served as soft segments in the WPU films, and T gh shifted to higher temperatures with the incorporation of this segment, as summarized in Table II.…”

Recycling and Application Characteristics of Fly Ash from Municipal Solid Waste Incinerator Blended with Polyurethane Foam

“…3 to 6. Similarly to the effect of high-temperature annealing on the thermal behavior of PU (Shu et al, 2001;Tsen and Chuang, 2006), the hard-segment domain with a diameter of 200-500 nm would be associated with the short-range ordering of PU annealed at 80°C for 1 h. The structure of the PU had moved into the more stable and the long-range ordering of the hardsegments domain with a size of ϳ800 nm of PU annealed at 140°C for 1 h. Therefore, the microstructure of PU/fly ashes blend curing at 80°C for 30 min can also form a similar stabilized domain and fine network structure to limit the mobilization of heavy metals in PU/fly ashes blend. The particle sizes of fly ash in this investigation are from 1-100 m. Thus, the fly ashes particles can be encapsulated in the microstructure of the hard and soft segments domain of PU, causing the leaching concentrations of heavy metals from the blend to decrease significantly with an increase in temperature during the aging treatment test.…”

“…The hardsegment phase, which reinforces the soft-segment phase, acts as filler particles dispersed in the soft-segment phase, while hard-segment domains at room temperature strongly influence the physical characteristics of PU copolymers. According to the literature (Shu et al, 2001;Tsen and Chuang, 2006), suitable annealing conditions may increase the completeness of the structure of the hard-segment domains. In our study, different fractions of fly ashes, poly (tetramethylene glycol) (PTMG), and excess 4,4Ј-diphenylmethane diisocyanate (MDI) are added into a reactor to form the PU/fly ashes blend.…”

Characteristics of Polycarbonate Soft Segment-Based Thermoplastic Polyurethane

“…Therefore, DSC thermograms of TPU are likely to display four transition regions as both phases crystallize. However, the structure and concentration of the hard and soft segments and the molecular weights and types of soft segments all influence the phase transition regions in DSC thermograms [44][45][46]. Therefore, not all phase transition regions are displayed on DSC thermograms.…”