4.4.2.1polymerizationBranching can occur at hightemperatures whilst star-shapedmay be produced by the use oftrifunctional or tetrafunctionalalkyllithiums
Branching can occur at high temperatures whilst star-shaped may be produced by the use of trifunctional or tetrafunctional alkyllithiums 4.4.2.1 polymerization
4.4.2.1polymerizationThe Ziegler Natta catalystsarecombination of two materials:1.An aluminiumalkyl2. A derivative of a Group IV VIIItransitionmetal
The Ziegler Natta catalysts are combination of two materials: 1. An aluminium alkyl 2. A derivative of a Group IV VⅢ transition metal. 4.4.2.1 polymerization
4.4.2.1polymerizationthree Conventional butadiene rubbers:1.High-cis(c.97%):cobaltsystem2.Medium-cis(92%):aluminiumalkyl/titaniumtetraiodidesystem3.Low-cis(c.40%):alkyllithiumcatalystsystems
three Conventional butadiene rubbers: ▪1.High-cis (c. 97%) : cobalt system ▪2.Medium-cis (92%) : aluminium alkyl/titanium tetraiodide system ▪3. Low-cis (c. 40%): alkyllithium catalyst systems 4.4.2.1 polymerization
4.4.2.2 Structure and properties1.4-polymers:very low glass transitions-high Tm of the trans polymer
1.4-polymers: ▪very low glass transitions ▪ high Tm of the trans polymer 4.4.2.2 Structure and properties
4.4.2.2Structureandpropertieshigh deformationlevel:lowerresilience limited in tyresthereasons:BR blendedwith NRorSBR
▪high deformation level : lower resilience limited in tyres ▪the reasons: BR blended with NR or SBR. 4.4.2.2 Structure and properties