Internal and External Plasticization

Manufacturer: What do you mean by "Internal" and External" plasticizing?

 John Woon (Senior Latex Consultant):  There are basically two ways to soften or plasticize the polymer  (i.e. to reduce the Glass Transition Temperatures or Tg) - one is through copolymerization where more than one monomer are used while the other is by adding a plasticizer. This of course would also increase the plasticity and fluidity of the polymer.

The former method is termed "Internal Plasticization" while the latter, "External Plasticization".

Wherever possible, "Internal Plasticization" is the preferred route since adding a plasticizer entails careful selection for compatibility, processibility, permanence and other performance properties which in turns are dependable on solubility parameter, molecular weight and chemical structure, etc of the plasticizers. 

Examples of undesirable side effects are the gradual loss of the plasticizer and hence the increase in stiffness during service life through evaporation and leaching.