Rheology of long‐chain branched polypropylene copolymers

Abstract

In this work, we provide more insight into the rheological properties of functionalized polypropylene copolymers with modified architectures, which originate long-chain branching. The evaluation of the average distance between branches and the fraction of long-chain branch points has been carried out quantitatively, by numerical fitting of experimental data according to a literature model, and the viscoelastic response of the samples has been analyzed in terms of a Carreau-Yasuda-like model and Cole-Cole plots. These analyses allowed us to discriminate the viscoelastic behavior of the samples on the basis of their feed composition. Moreover, we were able to highlight direct correlations between viscosity, long-chain branching level, distance between branching points and functionalization degrees of PP polymers. Copyright © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 201

Biodegradable poly(butylene succinate-co-butylene dimerized fatty acid)s: Synthesis, crystallization, mechanical properties, and rheology

“…It was clearly observed that G' and G'' of polyester melts decreased with increasing DFA content, especially at low frequency region. In addition, the loss modulus G'' for all polyesters always maintained higher values than their storage modulus G' in the investigated frequency region as expected for materials characterized by a mainly viscous response [36].…”

Melt rheology of linear and long-chain branched polypropylene blends

“…The main characteristics of testing materials are shown in Table 1. All PPs used in this work have a density about 0.9 g/cm 3 .…”

“…However, commercial polypropylene produced by ZieglerNatta or metallocene catalysts has linear chains and a relatively narrow molecular weight distribution [1][2][3]. Linear polypropylene has relatively low melt strength and exhibits no strain hardening, and as a result its application is restricted in processes where elongational properties, such as thermoforming, foaming, and blow molding are dominant [4,5].…”

A rheological study on non-rubber component networks in natural rubber

“…Two terminal groups, referred to as α and ω, have been postulated to link with mono-and di-phosphate groups associated with phospholipids by H-bonding at the α-terminal, whereas the ω-terminal is postulated to be a modified dimethylallyl group linked to protein by H-bonding [19]. Rheological property is highly sensitive to long chain branching because even a low degree of long-chain branching has a significant effect on the viscoelasticity in polyethylenes [23][24][25][26][27][28] or polypropylene [29]. [20]But since Goodyear medal [19] in 2001, no clear evidence of structure of end-linking network is reported yet.…”

“…After the removal of protein and phospholipid, linear rubber chain can be obtained. [28] The stress relaxation behavior of natural rubber is often investigated in vulcanized rubber [29][30][31], while scare reports in unvulcanized regime is reviewed if there were. While spectroscopy method is static and mostly accompanied by solvent, and X-ray characterization is indirect in "natural occurring" networking characterization.…”