Controlled rheology of polypropylene: Modeling of molecular weight distributions

Asteasuain, Mariano; Sarmoria, Claudia; Brandolin, Adriana

doi:10.1002/app.11823

Cited by 27 publications

(22 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Peroxide initiated scission reactions efficiently result in polymers with tailor made properties. The polypropylenes produced this way are termed "controlledrheology polypropylenes" (CRPP) and they have improved melt flow characteristics due to reduced MW and narrowing MWD [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Fracture toughness of controlled-rheology polypropylenes

Salazar¹,

Rodríguez²,

Navarro³

et al. 2007

E-Polymers

View full text Add to dashboard Cite

Abstract:The rheological, thermal, tensile and fracture properties of controlledrheology polypropylene processed via organic peroxides have been evaluated. Different concentrations of di-tert-butylperoxide (DTBP) were used in this work. Both melt flow index and the crystallinity index increased slightly with the peroxide content while the melting temperature tend to decrease. This was attributed to the decrease in the molecular weight which mainly affects the amorphous region, especially the entanglement density of this semycrystalline polymer. As a consequence, the tensile stress and strain at break reduced as the peroxide content increased. The elastic-plastic response of the different polypropylenes at room temperature promotes the use of J-integral to determine the fracture toughness. A multiple specimens method was utilized. The crack initiation resistance and the crack propagation resistance were influenced by the molecular weight, decreasing as the peroxide content increased. The micromechanisms of failure were analyzed via scanning electron microscopy.

show abstract

Section: Introductionmentioning

confidence: 99%

Fracture toughness of controlled-rheology polypropylenes

Salazar¹,

Rodríguez²,

Navarro³

et al. 2007

E-Polymers

View full text Add to dashboard Cite

show abstract

“…Because of that, these products are referred to as Controlled-Rheology Polypropylenes (CRPP). The importance of this can be shown by referring to Several researchers have studied MWD of CRPP (Tzoganakis (1988, Malz (1995), Bonilla -Rios et al (1995), Carrot et al (1996), BonillaRios et al (1998), Asteasuain et al (2003)). In general, it has been concluded that CRPP resins have lower molecular weight, narrower MWD and reduced viscosity.…”

Section: Degradation Of Polypropylene (Pp)mentioning

confidence: 99%

Nitroxide‐mediated controlled degradation of polypropylene

Psarreas

Tzoganakis

McManus

et al. 2007

Polymer Engineering & Sci

View full text Add to dashboard Cite

Nitroxide-Mediated Controlled Degradation of PolypropyleneControlled-rheology polypropylene resins (CRPP) have been produced industrially for years using reactive extrusion processes employing peroxides as free radical initiators. The molecular weight characteristics of CRPP materials can be tailor-made depending on the final application in a very efficient and economic manner.A PP-based nitroxide (NOR) with the trade name Irgatec CR76 has been recently developed by CIBA Chemicals, as a source of radicals and it is currently being evaluated for the production of CRPP. NORs are well-known as powerful stabilizers to protect plastics from the negative influence of light and heat, and easy in handling during processing. Preliminary experimental results exhibit a qualitative difference between Irgatec CR76 and other commonly used peroxides.The purpose of this research work is to evaluate this new material as a potential replacement of commonly used peroxides in the production of CRPP. CRPP will be produced by reactive processing using varying amounts of Irgatec CR76 and the rheological properties of the materials produced will be investigated. By comparing results with Irgatec CR76 to those from other typical initiators, the effectiveness of Irgatec CR76 as an initiator will also be assessed.

show abstract

“…After Miller et al [56] have shown the potential of this method, Sarmoria [57][58][59][60][61] and collaborators have been using it in process modeling of several polymerization systems. In this latter series of papers, a general framework for the application of probability generating functions to mass balances was presented, a few inversion algorithms were tested, and their validation was performed by comparison with experimental results.…”

Section: Prediction Of Chain Length Distributionsmentioning

confidence: 99%

Transient Behavior and Gelation of Free Radical Polymerizations in Continuous Stirred Tank Reactors

Dias

Costa

2005

Macro Theory & Simulations

View full text Add to dashboard Cite

Summary: Using the authors' previously developed method for the general kinetic analysis of non‐linear irreversible polymerizations, the simulation of free radical homogeneous polymerization systems with terminal branching and chain transfer to polymer has been carried out for continuous stirred tank reactors. Its improved accuracy on the numerical evaluation of generating functions has been exploited in order to perform their numerical inversion and chain length distributions could also be estimated with or without the presence of gel. A comparison with alternative techniques emphasizing the effect of their simplifying assumptions on the accuracy of calculations is also presented.Predicted CLD before gelation (t = 1 h), after gelation (t = 15 h, steady state), and close to gel point for a free radical polymerization with transfer to polymer in a CSTR with τ = 60 min.magnified imagePredicted CLD before gelation (t = 1 h), after gelation (t = 15 h, steady state), and close to gel point for a free radical polymerization with transfer to polymer in a CSTR with τ = 60 min.

show abstract

Controlled rheology of polypropylene: Modeling of molecular weight distributions

Cited by 27 publications

References 25 publications

Fracture toughness of controlled-rheology polypropylenes

Fracture toughness of controlled-rheology polypropylenes

Nitroxide‐mediated controlled degradation of polypropylene

Transient Behavior and Gelation of Free Radical Polymerizations in Continuous Stirred Tank Reactors

Contact Info

Product

Resources

About