| 摘要 |
A high melt strength polypropylene of wide or bimodal molecular weight distribution is described, which imparts to the product rheological characteristics such as it can be formed in machines normally used for resins such as polystyrene. Molded articles produced from the inventive polypropylene are also described. Also described is a continuous process for producing the high melt strength polypropylene which is obtained in the presence of a Ziegler-Natta type catalyst system, using at least two polymerization vessels connected in series, the control of the molecular weight being effected by the addition of discrete amounts of a molecular weight regulator, such as hydrogen, to at least one of the various polymerization vessels, so as to obtain in the first polymerization vessel a portion of higher molecular weight and in the following polymerization vessels, polymer portions of lower molecular weight, whereby the total polymer shows a wide or bimodal molecular weight distribution, which impart to the product interesting rheological properties. |
