No abstract

A series of segmented polyurea urethane and polyurea block copolymers based on a hexane diisocyanate (HDI) modified aminopropyl terminated polydimethylsiloxane soft segment was synthesized. The hard segments consisted of 4,4′‐methylene diphenylene diisocyanate (MDI) which was chain extended with 1,4‐butanediol (BD), N‐methyldiethanolamine (MDEA), or ethylene diamine. Zwitterionomers were prepared by quaternizing the tertiary amine of the MDEA extended material with γ‐propane sultone. The effect of chemical structure on the extent of phase separation and physical properties was studied using a variety of techniques including thermal analysis, dynamic mechanical spectroscopy, tensile testing, and small‐angle x‐ray scattering. It was observed that the compatibility between the nonpolar polydimethylsiloxane soft segments and the polar urethane hard segments was improved by inserting HDI linkages into the polydimethylsiloxane soft segments. The aggregation of hard segments was enhanced by increasing hard‐segment content or by the introduction of ionic functionality. The tensile strength and modulus of these materials was higher than those of polyurethanes containing soft segments based on polydimethylsiloxane and its derivatives.

No abstract

The nylon 6 (PA6)/polyurethane (PU) debris produced during the sanding process would result in a serious resource waste and environmental hazard if disposed of inappropriately. Therefore, this study proposed a simple process for separating and recycling PA6 and PU components of PA6/PU debris. Results revealed that the instantaneous dissolution of PU in N,N-dimethylformamide was independent of temperature and time but related to the quantity of the solvent. Further investigation showed that 43.2% of waste PA6/PU debris was dissolved at room temperature, with pulp density of 10% and within 10 minutes, indicating that PA6 and PU could be quickly separated from the waste PA6/PU debris. In addition, proton nuclear magnetic resonance indicated that the dissolved PU could be recovered by selective precipitation-stripping using an equal amount of deionized water. Moreover, the chemical structure analysis disclosed that the PU in PA6/PU debris should be polyether PU synthesized by reacting with methylene diphenyl diisocyanate and polyether polyols. Besides, the stable chemical structure and thermal properties of separated samples observed from differential scanning calorimetry and thermogravimetry results confirmed that the recycling products could be reused as recycled plastic materials.