Nonisothermal crystallization behavior and UV screening ability of poly(ethylene terephthalate)/carbon black transparent films

A UV absorbent was blended with virgin carbon black to prepare modified carbon black (m-CB) using a solid phase modification. The mixed solutions of poly(ethylene terephthalate) (PET)/CB and PET/m-CB were coated on glass substrates to fabricate light screening films. Scanning electron microscopy (SEM) showed that m-CB had better dispersibility than CB in PET matrix. Nonisothermal crystallization kinetics of virgin PET, PET/CB, and PET/m-CB films were investigated by differential scanning calorimetry (DSC). The data were described by a modified Avrami model. The results showed CB and m-CB acted as nucleating agents and increased the crystallization rate of PET. But due to the low crystallization capacity of copolymerized PET (co-PET) matrix, the nucleating effects were not as obvious as expected. The addition of 4 wt% m-CB improved the UV screening ability of the composite film significantly and just slightly increased their haze.