Effects of polytrimethylene terephthalate on crystallization and melting behavior of beta-polypropylene in the blends

It has been observed that the formation of β-crystal is suppressed when β-polypropylene (β-PP) is blended with crystalline polymers, but the reason is still uncertain. In this study, we investigated the influence of the crystallization conditions of polytrimethylene terephthalate (PTT), such as melt crystallization, cold crystallization, isothermal crystallization temperature, and crystallization time on the β-nucleation behavior of PP phase in the β-PP/PTT blends. The results showed that the β-crystal content of PP phase in the blends decreases with increasing of PTT content. Cold crystallization of PTT would mainly induce the formation of α-crystal in PP component, whereas melt crystallization would induce the formation of β-crystal PP in their blends. The degree of crystallinity of PTT increases by improving the crystallization temperature or extending the time of crystallization, which leads to the production of more α-crystal in PP component. This means that the second component could inhibit the formation of β-crystal in PP.