Non-isothermal melt-crystallization and subsequent melting behavior of pigmented medium-density polyethylene

Non-isothermal melt-crystallization and subsequent melting behavior of neat MDPE and MDPE filled with three types of pigment (i.e. quinacridone, phthalocyanine, and diarylide) in various amounts ranging between 0.1 and 0.4 phr were investigated using differential scanning calorimetry. The cooling rate range investigated was between 5 and 30 °C min−1. For each type of sample investigated, the crystallization exotherm became wider and shifted towards a lower temperature range with increasing cooling rate. All of the pigments investigated were able to shift the crystallization exotherm towards a higher temperature range. Among the various pigments, phthalocyanine was the best in shifting the crystallization exotherm towards a higher temperature range, followed by quinacridone and diarylide, respectively. However, diarylide was the only pigment that was effective in accelerating the crystallization processes of the filled polymer.