Microkinetic Modeling of Structural Properties of Poly(vinyl chloride)

Abstract

The free radical suspension polymerization of vinyl chloride is modeled at the elementary reaction level, systematically taking into account diffusion limitations. By deriving balances for structurally distinct polymer and radical species the formation of structural defects can be followed: monomer conversion, averages of the molar mass distribution and the structural defects content can be calculated as a function of polymerization time for industrially relevant conditions. A good agreement between literature reported and calculated values for these properties is obtained for a polymerization temperature range of 325-340 K, a dicetyl peroxydicarbonate and dimyristyl peroxydicarbonate initiator concentration range of 0.00069-1.0 wt %, and a monomer conversion range of 12-96%. The increase of the branching content and the decrease of the terminal double bond content at high monomer conversions can be explained in terms of a favoring of monomolecular reactions and the increasing importance of addition reactions to unsaturations at these conditions.

Development of MnO2/porous carbon microspheres with a partially graphitic structure for high performance supercapacitor electrodes

“…31 Emulsion polymerization is usually adopted to fabricate some commercially important polymers such as poly(vinyl chloride). 32,33 Recently, this method has been widely used for the synthesis of porous or spherical polymers (and carbon). [34][35][36][37] In this work, we demonstrate the design and fabrication of partially graphitic MnO 2 /micro-and mesoporous carbon microspheres (denoted as MnO 2 /carbon) for high performance supercapacitor electrodes.…”

Kinetic model for thermal dehydrochlorination of poly(vinyl chloride)

“…The relatively low thermal stability of PVC has been attributed by many researchers to the presence of thermally labile structural segments or defects that are responsible of this instability. Among those defects, the most important ones are structural defects such as branching, tertiary chlorine, unsaturations, oxygen containing groups, head-to-head structures and polymerization residues [14,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Due to the importance of defects from the point of view of the thermal degradation of PVC, several articles deal with the formation of these defects in PVC macromolecules [18,31,33].…”

Model-based design of the polymer microstructure: bridging the gap between polymer chemistry and engineering

“…[58][59][60] Another example is the negative impact of structural defects on the thermal stability of poly(vinyl chloride) (PVC) made by conventional free radical polymerization (FRP). [61][62][63] The PVC stability is negatively affected by the presence of internal allylic and tertiary chlorine groups, which are formed via specific secondary reactions. 64 For the improvement of PVC materials, process conditions that prohibit the occurrence of these side reactions should thus be identified.…”