Industrial Techniques of Polymerization Flashcards
Polymerization techniques comprise a wide range of techniques that are essential for the synthesis of polymers. These methods may be divided into two primary categories:
homogeneous polymerization reactions and heterogeneous polymerization reactions.
A type of polymerization process that occurs in a single uniform phase
homogeneous polymerization
every element in the reaction vessel—the monomers, initiators, solvents, and the growing polymer chains—is miscible and well mixed.
homogeneous polymerization
According to Fried (1995), ____is the simplest technique and gives a high purity of polymer.
Bulk Polymerization
used in the manufacturing of nylon, Kevlar, polyester, Bakelite, Melamine, polycarbonates, polyurethanes, epoxies etc.
Bulk Polymerization
only requires monomer, initiator, and chain
transfer agent, this chain transfer agent is used to
control the molecular weight.
Bulk Polymerization
The monomer is in liquid phase and the initiator, and the chain transfer agent is dissolved in the monomer thus the system is in ____
homogeneous phase
The polymerization reaction is mildly exothermic and most of the reaction occurs at low viscosity to allow ready mixing, heat transfer and bubble elimination
Bulk Polymerization
Offers several advantages, including high yield per reactor volume, easy polymer recovery, and the ability to cast the polymerization mixture into its final product form.
Bulk Polymerization
also faces limitations, such as the challenge of removing the last trace of monomer and managing the heat generated during the polymerization process
Bulk Polymerization
This gell effect causes the formation of usually high molecular weight polymers because of the increased viscosity that results in autoacceleartation is advantageous for cast plastics but nor for those that must be molded or extruded
auto acceleration, called the Norris-Trommsdorff or the gell effect
example of bulk polymerization
Vinyl monomer polymerization
The reactions of this polymerization are highly exothermic and proceed at a rate that is strongly dependent on temperature with the usual thermally decomposed initiators. This, coupled with the problem in heat transfer incurred because viscosity increases early in the reaction, leads to difficulty in control and a tendency to the development of localized “hot spots” and “runaways.
Vinyl monomer polymerization
The heat problem in bulk polymerization can be solved using _____due to the use of solvent or water
solution polymerization
The initiator and monomer must be soluble in the solvent and the solvent has low chain-transfer constant and suitable melting and boiling point for the condition of polymerization.
sOLUTION polymerization
