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Abstract
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Microcapsules containing paraffin wax as cores and polystyrene as shells were prepared by suspension
polymerization technique. The influence of four experimental factors, including percentage of initiator/
styrene mass ratio (BPO/St wt.%), paraffin wax/styrene mass ratio (PCM/St), percentage of stabilizer/
styrene mass ratio (PVP/St wt.%), and water/styrene mass ratio (H2O/St), on microcapsules properties
were investigated. Each factor was in five levels. Response surface methodology (RSM) was implemented
for statistical design and analysis of experiments and process modeling. Two mathematical models were
derived for prediction of melting latent heat of microcapsules and their average particle size. Analysis of
variance showed that PCM/St mass ratio was the most significant factor affecting melting latent heat of
parameters, while average particle size is affected by PVP/St wt.% and H2O/St mass ratio. In process
optimization, maximum values of melting latent heat were achieved as 148.5 J/g. Using BPO/St wt.% of
2.18%, PCM/St mass ratio of 1.94, PVP/St wt.% of 8.84%, and H2O/St mass ratio of 11.67, encapsulation ratio
of 78.5% were obtained.
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