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What is the mechanism of plasticizer in polymers?
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Lakshmi Priya
What is the mechanism of plasticizer in polymers?
Plasticisers do two things, Sumit.
They act as non-volatile solvents. For this to work, they need to be highly compatible with the polymer. They effectively dissolve the polymer, although which is the solvent, polymer or plasticiser when the polymer is in excess, is debatable. Plasticers like dibutyl phthalate will readily dissolve PVC, when hot, and it remains with the polymer when cold, although it does evaporate very slowly (years).
They act as diluents, thus making the polymer more rubbery. So, a polymeric plasticiser, such as a liquid polyester such as a glycol phthalate, is compatible with the hot PVC, and then remains with the polymer on cooling and is non-volatile and non-migratory. Sometimes the polyester chosen for cheapness, such as a glycol adipate, is not very compatible with the polymer and requires a small amount of a true plasticiser such as DOP (dioctyl phthalate) to make a better moulding. Incompatibility results in some liquid plasticiser migrating to the surface.
So the mechanism of plasticisers is as extender and softener, and a means of preventing brittleness in plastics. Highly polar polymers such as PVC will require polar plasticers for compatibility, although I understand some plasticisers can cause surface tack, which can be overcome with an inert liquid such as a paraffin wax, in small amounts. Many PVC plasticers are esters, but plastics such as casein can use aromatic sulphonate esters. Polyvinyl acetate and cellulose acetate also use esters such as citrates.
They act as non-volatile solvents. For this to work, they need to be highly compatible with the polymer. They effectively dissolve the polymer, although which is the solvent, polymer or plasticiser when the polymer is in excess, is debatable. Plasticers like dibutyl phthalate will readily dissolve PVC, when hot, and it remains with the polymer when cold, although it does evaporate very slowly (years).
They act as diluents, thus making the polymer more rubbery. So, a polymeric plasticiser, such as a liquid polyester such as a glycol phthalate, is compatible with the hot PVC, and then remains with the polymer on cooling and is non-volatile and non-migratory. Sometimes the polyester chosen for cheapness, such as a glycol adipate, is not very compatible with the polymer and requires a small amount of a true plasticiser such as DOP (dioctyl phthalate) to make a better moulding. Incompatibility results in some liquid plasticiser migrating to the surface.
So the mechanism of plasticisers is as extender and softener, and a means of preventing brittleness in plastics. Highly polar polymers such as PVC will require polar plasticers for compatibility, although I understand some plasticisers can cause surface tack, which can be overcome with an inert liquid such as a paraffin wax, in small amounts. Many PVC plasticers are esters, but plastics such as casein can use aromatic sulphonate esters. Polyvinyl acetate and cellulose acetate also use esters such as citrates.
Plasticisers do two things, Sumit.
So the mechanism of plasticisers is as extender and softener, and a means of preventing brittleness in plastics. Highly polar polymers such as PVC will require polar plasticers for compatibility, although I understand some plasticisers can cause surface tack, which can be overcome with an inert liquid such as a paraffin wax, in small amounts. Many PVC plasticers are esters, but plastics such as casein can use aromatic sulphonate esters. Polyvinyl acetate and cellulose acetate also use esters such as citrates.
Plasticisers do two things, Sumit.
So the mechanism of plasticisers is as extender and softener, and a means of preventing brittleness in plastics. Highly polar polymers such as PVC will require polar plasticers for compatibility, although I understand some plasticisers can cause surface tack, which can be overcome with an inert liquid such as a paraffin wax, in small amounts. Many PVC plasticers are esters, but plastics such as casein can use aromatic sulphonate esters. Polyvinyl acetate and cellulose acetate also use esters such as citrates.
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