Rheology of Polymeric Systems

Carreau, Pierre J.; Kee, Daniel C.R. De; Chhabra, R.P.

doi:10.3139/9781569907238.fm

Cited by 20 publications

(22 citation statements)

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“…The zero shear viscosity was calculated by fitting the data using the Carreau equation with the Cox−Merz rule, η(γ)/η 0 ≈ (1 + (γτ n ) 2 ) (n − 1)/2 , where η 0 is the zero shear rate viscosity, γ is the shear rate, τ n is the characteristic time, and n is a parameter. 38 The zero shear rate viscosity has reached the highest value for the specimen containing 0.1 ratio diamine. Its zero shear rate viscosity is surprisingly ca.…”

Section: ■ Results and Discussionmentioning

confidence: 92%

Effect of Diamine Addition on Structural Features and Physical Properties of Polyamide 6 Synthesized by Anionic Ring-Opening Polymerization of ε-Caprolactam

Kim

Seo

2019

ACS Omega

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Synthesis of ε-caprolactam in a twin screw extruder by anionic ring-opening polymerization was successfully carried out to prepare a novel nylon 6 (polyamide 6 (PA6)) containing a small amount of diamine moiety. The produced PA6 shows a remarkable improvement of the physical properties (mechanical properties as well as rheological properties). Added diamine molecules led to some structural changes in the synthesized PA6. The molar ratio of the additive (diamine) to the initiator appeared to be optimum at ca. 0.1. Although the molar mass of the PA6 has not changed significantly, less than twice the PA6 molar mass, the physical properties of the polymers produced have been markedly improved. The zero shear rate viscosity of the PA6 at the optimum diamine concentration appeared to be increased by almost 30 times that of the pure PA6. We have attributed this remarkable increase in viscosity to structural changes (branching formation during synthesis) and increased molar mass. The storage modulus at a low shear rate increased more than 100 times that of the pure PA6, but the loss modulus increased only 10-fold. This indicates that the elastic properties dominated due to the enhanced chain entanglements. In addition, the mechanical properties were significantly improved at the optimal amount of diamine reagent concentration. The elongation at break for the sample with optimum diamine addition was increased to twice that of neat PA6, whereby the tensile toughness was also doubled. Produced PA6 has a merit of processibility in the extrusion process such as a blow molding process in which stability against sagging under gravity is required and other processes in which elongational properties dominate.

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Section: ■ Results and Discussionmentioning

confidence: 92%

Effect of Diamine Addition on Structural Features and Physical Properties of Polyamide 6 Synthesized by Anionic Ring-Opening Polymerization of ε-Caprolactam

Kim

Seo

2019

ACS Omega

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“…Zero-shear-rate viscosity was determined from dynamic measurements extrapolated by Carreau–Yasuda model [ 39 ]. The reference material was PP polymer.…”

Section: Resultsmentioning

confidence: 99%

“…The oscillation rheometer measures at a low shear rate range, so it is appropriate for determining the zero-shear-rate viscosity. The early period of the viscosity-shear rate curve is generally extrapolated by Carreau–Yasuda model for polymers, sufficiently good for the viscous flow behavior in the region of the very small as well as the very large shear rates (Equation (3) [ 39 ]).

where [ t 1 ] is a time-featured quantity, a parameter that characterizes the transition between zero-shear-rate viscosity and the measured part of the viscosity curve, [ n ] exponent is known from the power law.…”

Section: Methodsmentioning

confidence: 99%

Effect of Recycling on the Mechanical, Thermal and Rheological Properties of Polypropylene/Carbon Nanotube Composites

2022

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In this research the effect of physical recycling on the mechanical, thermal, and rheological properties of polypropylene (PP)/multiwalled carbon nanotube (MWCNT) was investigated. After melt homogenization by extrusion, specimens were injection moulded with 0.1 and 0.5 wt% MWCNT content. The recycling process was simulated by multiple grinding and re-moulding, then we compared the behavior of original and recycled PP/MWCNT composites. Differential scanning calorimetry (DSC) measurements proved that MWCNT had double the effect on the morphology of the PP matrix: on the one hand nucleating effect can be detected because 0.5 wt% MWCNT increased the onset temperature of crystallization by 10°C, compared to the basic PP material; on the other hand, the crystalline fraction of the recycled composite materials decreased compared to the original PP material with the same MWCNT content. This resulted in a slight decrease in strength and stiffness but an increase in elongation at break. However, compared to the original unreinforced PP reference, even the recycled materials have better properties. The mechanical test results showed that recycled PP/MWCNT 0.5 wt% increased the elastic modulus (~15%) and decreased the tensile strain at yield (~10%). However, in the values of tensile stress at yield, relevant difference was not found. It was also shown by oscillatory rheometry that MWCNT had a significant effect on the rheological properties (storage and loss modulus, complex viscosity) of PP compounds in a wide temperature range (190–230 °C).

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“…Both cascara and the cotton/IL solutions experience a rise in viscosity with increasing biomass loading and show characteristic shear thinning at higher shear rates, as expected. The solutions were assumed to fit the Cox-Merz rule, [50,51] and zero shear values were calculated using both Newtonian plateau determination and the Carreau model fitting (Table 3). The cotton/IL solutions are much more viscous compared to equivalent concentrations of the cascara biomass evaluated under the same conditions.…”

Section: Rheological Analysismentioning

confidence: 99%

Ionic Liquid‐Mediated Biopolymer Extraction from Coffee Fruit

Rieland,

Nikafshar,

et al. 2023

Macro Materials & Eng

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Ionic liquids (ILs) are effective solvents for biomass. Refined cellulose is commonly used; however, recent interest has grown to consider woody and herbaceous biomass and industrial crop residues like fruit peels. Here, the authors report results on the dissolution and shaping of cotton and coffee fruit (cascara) in 1,8‐diazabicyclo[5.4.0]undec‐7‐inium acetate ([DBUH][OAc]). Cascara is a high‐volume, low‐value crop residue that poses an environmental and economic burden in producer countries leading to a high‐value proposition if recoverable. Fruit/ionic liquid solutions (0–15% w/w dissolved at 60 °C) were characterized with respect to biomass concentration and shaped into fibers and films coagulated in DI water and methanol. Rheology was assessed using parallel plate rheometry. Cotton/IL mixtures formed better fibers compared to cascara‐based solutions, which required 2.6× more biomass in solution for viable fiber formation. At 10% loading, fibers could be produced from untreated coffee fruit with diameters ranging from 18–100 microns. Coffee fruit residues and their precipitated films show that both cellulose and lignin dissolve in pure [DBUH][OAc]. Chemical characterization of cascara and cascara films demonstrates the conveyance of high concentrations of lignin and extracts that result in weaker mechanical properties. Further purification of cascara is required for effective use in structural applications.

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Rheology of Polymeric Systems

Cited by 20 publications

References 0 publications

Effect of Diamine Addition on Structural Features and Physical Properties of Polyamide 6 Synthesized by Anionic Ring-Opening Polymerization of ε-Caprolactam

Effect of Diamine Addition on Structural Features and Physical Properties of Polyamide 6 Synthesized by Anionic Ring-Opening Polymerization of ε-Caprolactam

Effect of Recycling on the Mechanical, Thermal and Rheological Properties of Polypropylene/Carbon Nanotube Composites

Ionic Liquid‐Mediated Biopolymer Extraction from Coffee Fruit

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