An approach for prediction optimum crystallization conditions for formation of beta polypropylene by response surface methodology (RSM)

Abstract

In this work beta nucleating agent is synthesized and mixed with various grades of polypropylene (PP). The beta nucleating agent (β-NA) content, melt flow rate (MFR) of PP and cooling rate as independent variables are correlated to the beta crystal content (β-PP) by using Response Surface Methodology (RSM) models. Central cubic design was employed for experimental design. The crystallization behavior of various grades of PP at different percentage of beta nucleating agents is analyzed by differential scanning calorimetry (DSC) at three different cooling rates. The results showed that the enthalpy of fusion of beta crystals (△Hβ) are directly related to the amount of β-NA. The sensitivity of the alpha polymorph to beta nucleating agent concentration increased with increasing the cooling rate. The optimal condition to achieve to a maximum Kβ are obtained for the resin with MFR of 21 g/10min containing 0.59 %wt β-NA and cooling rate of 8 °C/min.

Keywords

• Polypropylene
• Beta nucleating agent
• Crystallization condition
• Nucleating agent content
• Melt flow rate (MFR)
• Cooling rate