Home                                  Polyester Preparation

This program calculates the charges for the preparation of a polyester resin by condensation reaction and also from ring-opening of lactones. It also calculates the average functionality and molecular weight of the resulting product. It also estimates the weight loss from the condensation reaction. Polyester or alkyds prepared by condensation reaction also lose some glycol during the reaction. An estimated loss of glycol can be entered and the results will show in the "scaled up weight" calculation. This program has been written to calculated the polymer properties with an excess of hydroxyl groups, it will give erroneous calculations if the carboxyl content exceeds the hydroxyl level. Condensation reactions do not proceed to 100 % conversions of functional groups, The conversion level can be adjusted in the calculation and has a large effect on molecular weight and functionality. More than 55 polyols and polycarboxylic acids can be selected. If a diol and acid is missing from this selection send me a note with the required data and I will incorporate it.
Data Input  


   Charge Reactants (polyols and carboxylic acids)



Scale up

Mole Mole




+ Glycol loss Hydroxyl Carboxyl
Catalyst, %    
Polyester Preparation          
Polyol, glycol loss, %        
Scale up factor        
Error message

Properties Average Monomer Unit (intermediate information used in calculation    
Molecular weight        
Properties of Polymer          
Acid or Methoxy number in KOH mg/g        
Acid or Methoxy content MEQ/g        
Acid or Methoxy content, Mol per polymer chain        
Degree of Polymerization        
Molecular weight        
Hydroxyl Number, KOH mg/g        
Hydroxyl Equivalent Weight        
Unsaturation per Chain        
Product Scaled up          
Reactant water or methanol and glycol weight loss        
Product yield, weight - -    
"Scale up" calculation contains the addition of the estimated loss of glycol in the reaction, "charge weight " does not.

Automatic recalculation 

Last edited on:

October 20, 2010

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