HIGH MELT STRENGTH POLYPROPYLENE WITH HIGH STIFFNESS AND CLARITY

A polypropylene comprises within a range from 0.1 wt% to 4 wt% ethylene and/or C4 to C12 a-olefin derived units, one or more clarifiers, or both, wherein the polypropylene has a flexural modulus of atleast 200 kpsi (0.05 in/min ASTM D790(A)) and an Mz/Mw of at least 4. The polypropylenes may be made by combining propylene and a comonomer with a Ziegler-Natta catalyst and at least two external electron donors, wherein the concentration of the electron donors is within a range from 1 to 100 ppm. The concentration of electron donors may be decreased to control the haze level of the polypropylene, and/or the level of comonomer derived units may be controlled to reduce the haze level of the polypropylene. 一种聚丙烯，其包含0.1wt％-4wt％的乙烯和/或C4-C12α-烯烃衍生的单元，一种或多种澄清剂或者二者；其中所述聚丙烯的挠曲模量是至少200kpsi(0.05in/min ASTM D790(A))和Mz/Mw是至少4。该聚丙烯可以通过将丙烯和共聚单体与齐格勒-纳塔催化剂和至少两种外给电子体合并来制造，其中所述给电子体的浓度是1-100ppm。给电子体的浓度可以降低来控制聚丙烯的雾度水平，和/或可以控制共聚单体衍生的单元的水平来降低聚丙烯的雾度水平。