Thermorheological analysis of PVC blends

Abstract

ABSTRACT:The effect of temperature on dynamic viscoelastic measurements of miscible poly (vinyl chloride) (PVC)/ethylene-vinyl acetate-carbon monoxide terpolymer (EVA-CO) and immiscible PVC/high-density polyethylene (HDPE) and PVC/chlorinated polyethylene (CPE) molten blends is discussed. PVC plasticized with di(2 ethyl hexyl) phthalate (PVC/DOP) and CaCO 3 filled HDPE (HDPE/CaCO 3 ) are also considered for comparison purposes. Thermorheological complexity is analyzed using two time-temperature superposition methods: double logarithmic plots of storage modulus, GЈ, vs. loss modulus, GЉ, and loss tangent, tan ␦, vs. complex modulus, G*, plots. Both methods reveal that miscible PVC/EVA-CO and PVC/DOP systems are thermorheologically complex, which is explained by the capacity of PVC to form microdomains or crystallites during mixing and following cooling of the blends. For immiscible PVC/ HDPE and PVC/CPE blends the results of log GЈ vs. log GЉ show temperature independence. However, when tan ␦ vs. log G* plots are used, the immiscible blends are shown to be thermorheologically complex, indicating that the morphology observed by microscopy and constitued by a PVC phase dispersed in a HDPE or CPE matrix, is reflected by this rheological technique.

Effect of long chain branching on linear-viscoelastic melt properties of polyolefins

“…These observations are in accordance with findings by Koopmans for LDPE, LLDPE and branched mPEs [175]. The loss angle not only appears to be the most sensitive indicator of the presence of LCB, but plots of δ versus the complex modulus G* or reduced frequency ωη o have even been proposed to evaluate thermorheological complexity in polymers and blends [29,175,176]. Fig.…”

Novel results and potential applications of bitumen used as an additive for polyethylene

“…Mavridis-Shroff plots [5], phase angle δ versus complex modulus G* at different temperatures, configure a reliable method to analyse thermorheological complexity of polymer systems [6]. The data displayed in Figure 1 show a simple thermorheological behaviour, as time-temperature superposition holds in the investigated temperature range (145-190 ºC).…”

New Bitumens Obtained from Physical Distillation of a Conventional Bitumen Mixed with EVA Copolymer

“…During last decade we have chosen double logarithmic plots of phase angle versus complex modulus G* (the so called Black diagrams or Mavridis-Shroff plots [26]) to investigate the thermorheological complexity (breakup of frequencytemperature superposition) of some polymers [27][28][29]. Moreover, the failure of frequency-temperature superposition in dynamic viscoelastic results of bitumen has also been demonstrated using this rheological technique [12,25,30,31].…”