The state of dispersion of polypropylene/polyamide 6 blends (PP/PA6) was investigated through thermal analysis using differential scanning calorimetry (DSC). Maleic anhydride grafted PP (MAH-PP) was used as a compatibilizer. When MAH-PP was added to pure PP or pure PA6, peak crystallization temperature of PP in the cooling process of DSC measurement was not influenced, whereas that of PA6 increased about 6 degree. Although PP/PA6 (=40/60 by wt%) with MAH-PP did not show crystallization peak of PA6, addition of talc as a nucleating agent led to the crystallization of PA6. In contrast, in the process of heating PP/PA6 (=40/60 or 60/40) with MAH-PP after cooling without crystallization of PA6, a small exothermic peak, indicating the crystallization of PA6, was observed between the melting peaks of PP and PA6. Dyeability of fibers from these blends with various compositions of PP/PA6 depended on whether crystallization of PA6 occurred in the cooling process or not; however, blends with talc could not be dyed even though the PA6 component in this blend crystallized in the cooling process. These results indicated that dyeing behavior of fibers from these blends is governed by the state of the dispersion of the two components. In other words, fine dispersion of the PA6 component leads to suppression of both crystallizability and the dyeability. Addition of talc appears to enhance crystallization without changing the state of dispersion.
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