Phase relations in poly(vinyl chloride)/ethylene--vinyl acetate copolymer blends with low contents of the EVA polymer

✍ Scribed by S. E. Svanson; C. Elmqvist; Young J. Shur; B. Rånby

• Publisher: John Wiley and Sons
• Year: 1977
• Tongue: English
• Weight: 218 KB
• Volume: 21
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1977.070210407

✦ Synopsis

A series of polymer blends of commercial poly(viny1 chloride) (suspension-polymerized powder) and an ethylene-vinyl acetate copolymer (EVA with 45 w t % VA) containing 2-10 wt % EVA were prepared by mixing at room temperature (0) and by milling at 160°C for 15 min (I) and then heat treated at 170°C for 20 min (11) and 40 rnin (111). Wide-line NMR measurements for protons at room temperature show a broad band (assigned to PVC phase) and a superimposed narrow band (assigned to mobile EVA phase). The 0-samples had a narrow band intensity corresponding to the total EVA content; the I-samples had a less intense narrow band than expected, indicating that 2-3% EVA was included in the rigid PVC phase. Heat treatment for 20 rnin (11) and 40 min (111) increased the narrow band intensity toward the 0-samples showing phase separation except for milled blends containing 2 wt % EVA, which had no separable narrow band and remained so. These results indicate that about 2 wt % EVA is compatible with the PVC phase and in equilibrium, while milled blends with more than 2 wt % EVA are metastable.