DSC study of foamable poly (vinyl chloride‐co‐vinyl acetate) plastisols of different commercial plasticizers

Abstract

In this article the characterization of the thermal behavior of foamable PVC (Poly (vinyl chloride)) plastisols from 20 different plasticizers has been studied by differential scanning calorimetry (DSC). The interactions between the resin and the plasticizer as well as the decomposition of the azodicarbonamide (ADC)-the chemical blowing agent (CBA) used-have been analyzed. The latter process is of crucial importance for the knowledge of plasticized PVC flexible foam formation. Clear effects of the chemical nature of the plasticizers and their molecular weight (M w ) have been observed, both in the interactions (swelling and early stages of gelation) between the resin and the plasticizer, as well as in the temperature of the ADC decomposition and the shape of the DSC peak.

A new biobased plasticizer for poly(vinyl chloride) based on epoxidized cottonseed oil

“…For a particular curing cycle of 190 °C and 7.5 min [Figure (c)], slight presence of spherical shapes on the fractured surface can be observed. The effect of curing time is evident if we compare this structure with the sample corresponding to a curing cycle of 190 °C for 17.5 min [Figure (c)], which is characterized by a clear homogeneous surface without spherical shapes; this fact is indicative of optimum gelation‐curing process and, consequently, good mechanical properties as described before . For curing temperatures over 205 °C [Figures (g,e) and (d,e)], the fractured surfaces do not show presence of free plasticizer and spherical shapes thus indicating that the gelation is complete .…”

“…Figure 3(c)], which is characterized by a clear homogeneous surface without spherical shapes; this fact is indicative of optimum gelation-curing process and, consequently, good mechanical properties as described before. 31 For , the fractured surfaces do not show presence of free plasticizer and spherical shapes thus indicating that the gelation is complete. 32 The degradation effects because of exposure to high temperature-time profiles can be observed in Figure 3(e), in which dark regions can be observed due to plasticizer remove and/or thermal degradation of PVC subjected to high temperature.…”

Rheometric study of the gelation and fusion processes of poly(vinyl chloride‐co‐vinyl acetate) plastisols with different commercial plasticizers

“…i. e., after the initial decrease of the complex viscosity with the temperature corresponding to the initial suspension, the viscosity increases significantly as a consequence of the interactions between the particles of the resin and the plasticizer, then at a determined temperature the gelation process starts to take place. Solvation [45], swelling [15, 21, 22] of the resin and fusion take place on further heating. These processes have been widely described in the literature [46–48].…”

“…The typical curves obtained [4, 20] show an initial decrease of the complex viscosity with temperature corresponding to the expected behavior of the initial suspension dominated by the plasticizer behavior. Further heating causes the swelling [15, 21, 22] of the PVC particles by the plasticizer that initiates their interaction yielding a marked increase in the viscosity that converts the paste into a gel [23]. With increasing temperature, two other processes may occur to different extents: the decrease of viscosity of the already gelled phase, as well as the increase of the amount of gelled phase by the incorporation of more polymers from the core of the PVC particles.…”

Plastisol foaming process. Decomposition of the foaming agent, polymer behavior in the corresponding temperature range and resulting foam properties

“…The chosen foaming agent is azodicarbonamide (ADC) which is commonly used in such applications [13]. The decomposition of ADC is exothermic, that allows using DSC for kinetic studies.…”