heterogeneous ziegler-natta and homogeneous metallocene catalysts exhibit greatly different active sitenature in olefin polymerization. in our previous study, it was reported that mgcl2-supported titanocenecatalysts can generate both ziegler-natta-type and metallocene-type active sites according to the type of activators.the dual active site nature of the supported titanocene catalysts was furt...

a fourth-generation ziegler-natta catalyst was prepared to synthesize polypropylene (pp), which was stabilized by in situ polymerization employing lignin as antioxidant. the antioxidant properties of lignin were compared with those of the commercial antioxidant irganox 1010. the presence of lignin in the reaction medium slightly decreased the catalytic activity of the reaction. the isotacticity...

Many PID controller tuning methods have been presented since Ziegler and Nichols published their method in 1942, but none of those methods were used widely. The Ziegler and Nichols method has several advantages over newer methods: it is easy to conduct, the relations for controller parameter computation are simple, the method relies on experiment, and it does not require any model. Newer tuning...