Effect of Long-chain Branching

Parameter characterizing the effect of long-chain branches on the size of a branched molecule in solution and defined as the ratio of the mean-square radius of gyration of a branched molecule, si), to that of an otherwise identical linear molecule si), with the... 

This work examines the effect of long-chain branching on the low-shear concentrated solution viscosity of polybutadienes over a broad range of molecular weights and polydispersity. It will show that the reduction in molecular coil dimension arising from long-chain branching is more sensitively measured in concentrated than in dilute solutions for the polymers examined. 

Trementozzi, Q. A. Effect of long-chain branching on some solution properties of polyethylene. J. Polymer Sci. 23, 887 (1957). 

Nam GJ, Yoo JH, Lee JW (2005) Effect of long-chain branches of polypropylene on rheological properties and foam-extrusion performances. J Appl Polym Sci 96 1793-1800... 

Vega, J. Aguilar, M. Peon, J. Pastor, D. Martinez-Salazar, J. Effect of long chain branching on linear-viscoelastic melt properties of polyolefins. E-Polymers 2002, 46, 1-35. 

Yan, D., W. J. Wang, and S. Zhu. 1999. Effect of long chain branching on rheological properties of metallocene polyethylene. Polymer 40 1737-1744. 

Fig. 4.10. The effect of long-chain branching on the melting process. Plots of relative volume against temperature for linear polyethylene (curve A) and branched polyethylene (curve B). (Reproduced from [21], copyright 1953, American Chemical Society.)...

Stange, J. and Munstedt, H. 2006. Effect of long-chain branching on the foaming of polypropylene with azodicarbonamide. Journal of Cellular Plastics 42 445-467. 

Bersted, B. H., Effect of long chain branching on polymer rheology, in Encyclopedia of Fluid Mechanics (N. Cheremisinoff, ed.). Gulf Publishing Co., (1988), Vol. 7, pp. 635-666. 

We present here some experimental studies on the rheological behavior of branched flexible homopolymers. Our presentation follows the same spirit as that presented previously for linear flexible homopolymers fhaf is, we will use log versus log a and log G versus log G" plots to discuss the effect of long-chain branching on the rheological behavior of flexible homopolymers. 

However, for a complex branching structure, this parameter provides no information about the topology of the chains. The various distribution functions mentioned above are required for a hill description of such a structure. In various sections of this book, the effects of long-chain branching are discussed in several contexts. 

The effects of long-chain branching on the zero-shear viscosity are discussed in Section 5.11. 

Effect of Long-Chain Branching on Linear Viscoelastic Behavior... 

However, without theories that explicitly consider the effect of long-chain branching on rheology, we can say nothing beyond affirming that the samples contain LCB. In what follows, we will describe some recently developed theories for predicting the linear viscoelasticity of long-chain-branched polymer melts. Theories for the nonlinear viscoelasticity of branched polymers are covered in Section 11.6. 

Wood-Adams, P. M. The effect of long chain branches on the shear flow behavior of polyethylene. 

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