Hello all,
So as I said in my last topic that we will countinue .further i am starting .
There are many process techniques of polymerisations but as a conclusion we can say there are 4 main types of process polymerising
In actual practice there are many different techniques used to carry out polymerization reactions.
However, most involve one of four
general methods of polymerization: The
polymerization of the monomer or reactants in
bulk, in solution, in suspension, and in emulsion
forms. The bulk and solution methods are
used for the formation of both addition and
condensation type polymers, whereas suspension
and emulsion techniques are used largely
for addition polymerizations.
1.Bulk Polymerization. This type of polymerization
involves the reaction of monomers
or reactants among themselves without placing
Catalyst activated bond opening (ethylene
polymerization)
them in some form of extraneous media such
as is done in the other types of polymerizations.
Two types of behavior are observed in bulk
polymerizations.
first The polymer is
soluble in the monomer during all stages of the
polymerization, and a monomer-soluble initiator
is used. As polymerization progresses, viscosity
increases significantly, and chain growth
takes place in the monomer or polymers dissolved
in the monomer until all of the monomer
is consumed.
In the second case The polymer is insoluble
in the monomer system. In such systems, the po
lymerization is believed to occur within the
growing polymer chains because very high molecular
weights are formed even though the
polymer chain drops out of the monomer solution
2.Solution Polymerization. Solution polymerization is similar to bulk polymerization except
that the solvent for the forming polymer in bulk polymerization is the monomer, whereas the solvent in solution polymerization is usually a chemically inert medium. The solvents used may be complete, partial, or non solvents for the growing polymer chain. When the monomer and the polymer are both
soluble in the solvent, initiation and propagation of the growing polymer chains take place
in the oil or organic phase. Because of the mass action law, rates of polymerization in solvents
are slower than in bulk polymerizations, and the molecular weight of the polymers formed
is decreased.
3. Suspension Polymerization. Often called “pearl” polymerization,"pearl” polymerization, this technique normally is used only for catalyst-initiated or free radical addition polymerizations. The monomer is mechanically dispersed in a liquid, usually water, which is a non solvent for the monomer
as well as for all sizes of polymer molecules that form during the reaction.
4.Emulsion Polymerization. This is a technique in which addition polymerizations are camed out in a water medium containing an emulsifier (a soap) and a water-soluble initiator. It is used because emulsion polymerization is much more rapid than bulk or solution ipe, and reaction conditions provides additionalcontrols over the reaction. Polymerization techniques can have a significant
effect on the number, size, and characteristics of the polymer molecules formed and thus
will have a significant effect on the properties of the polymer. Thus, batches of a polymer
such as polystyrene, which can be made by any of the four polymerization techniques described
above, will differ, depending on which type of polymerization method was used to
make the material.
As I initially said thte polymers and plastic is a very very broad and sky is the limit so ,not even a part of it can ge coverd in the topic of mine , But I think that every plastic injection molder shoul know and be aware with. the the basic of polymer
Its ok for today and I will be here tommorow again with some new information and basic relevant to all the people who provide these PLASTIC ENGG SERVICES ,to the people of world , plastic ,plastic moulding,injection moulding , injection moulds and blow Molds
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