Viscoelastic Properties of Blends of Poly(methyl methacrylate)s
1970; Springer Nature; Volume: 1; Issue: 5 Linguagem: Inglês
10.1295/polymj.1.542
ISSN1349-0540
AutoresShigeharu Onogi, Toshiro Masuda, Namihiro Toda, Kazuyo Koga,
Tópico(s)Material Dynamics and Properties
ResumoThe viscoelastic properties of molten blends of poly(methyl methacrylate)s having different molecular weights were measured, and several characteristic parameters resulting from these measurements were determined.The Vogel temperature T0, plotted against the weight fraction of the high molecular-weight component, w2, has a minimum at about w2=0.2, while the temperature coefficient of the fractional free volume, αf, is almost constant in the entire range of w2. The steady-state compliance Je0 of the blends is inversely proportional to w22, when w2 is near unity, but it decreases with decreasing w2 after passing through a maximum at about w2=0.2. At this point the higher molecular-weight component shows a shoulder rather than a clear peak on the molecular weight distribution curve for the blend.The horizontal and vertical shift factors aM and cM obtained from the time-composition superposition proposed in our previous papers are respectively related to the interaction parameter λ2 in the Ninomiya theory and to the steady-state compliance Je0. Further, aM is proportional to M1.2–2.5, and cM to M−2.5−–2.8, where M is the calculated weight-average molecular weight of the blend.
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