Two series of polyether polyurethaneureas (PEUU) based on 4,4'-methylenebis(phenylene isocyanate), ethylenediamine, and either 1000 or 2000 molecular weight poly(tetramethylene oxide) were synthesized. The effect of the urea linkage, hard segment content, and block length on the extent of phase separation, domain structure, and physical properties was studied by utilizing differential scanning calorimetry, dynamic mechanical, stress-strain, stress hysteresis, and infrared dichroism experiments. The mechanical properties of these polyurethanes depend primarily on the sample's hard segment content, although a higher concentration of urea groups in the PEUU-2000 series results in properties superior to those of the PEUU-1000 series at similar hard segment weight fractions. The presence of three-dimensional hydrogen bonding within hard domains leads to the unusually strong hard domain cohesion. Upon decrease of the hard segment content, a change of morphology from interconnecting to more isolated hard domains took place. Orientation behavior of chain segments within either domain and in the interfacial region is described and related to sample morphology.

SynopsisThe objective of this research was to study the morphology and properties of PVC-polyurethane blends. Studies on blends of a segmented polyether polyurethane with PVC were carried out utilizing differential scanning calorimetry, Rheovibron, stress-strain, infrared peak position studies, and infrared dichroism experiments. This thermodynamically incompatible system was made kinetically compatible by precipitation from tetrahydrofuran (THF) solutions. THFclioxane solution casting and melt processing produced an incompatible system. The compatible polyurethane-PVC system contains a well-mixed PVC-polyether matrix phase as evidenced by Tg shifts, orientation characteristics, and infrared peak position changes. The aromatic urethane segments which exhibit microphase separation in the pure polyurethane are not solubilized by blending with PVC by any of sample preparation methods used in this study.

The objective of this research was to study the structure‐property relationships of two poly(vinyl chloride) (PVC)–poly(butadiene‐co‐acrylonitrile) (BAN) blends which exhibit differences in blend compatibility. Studies were carried out utilizing differential scanning calorimetry, dynamic mechanical testing, stress–strain, transmission electron microscopy (TEM), and infrared dichroism experiments at different temperatures. The BAN 31/PVC (BAN containing 31% acrylonitrile) system is considered to be nearly compatible as evidenced by Tg shifts, stress–strain results, orientation characteristics, and TEM micrographs. Similar experiments indicate that the BAN 44/PVC system is incompatible, and contains a mixed phase of BAN 44‐PVC and a pure BAN 44 phase. The extent of heterogeneity in the compatible BAN 31/PVC system, however, plays an important role in the orientation characteristics of the blends.

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