Influence of plasticizers suggests role of topology in polymer solidification at high cooling rates

Tensile testing on ductile iron GJS 400 with different microstructures produced through four different cooling rates was performed in order to investigate the relevance of the microstructure’s parameters on its plastic behaviour. Tensile flow curve modelling was carried out with the Follansbee and Estrin-Kocks-Mecking approach that allowed for an explicit correlation between plastic behaviour and some microstructure parameters. In the model, the ferritic grain size and volume fraction of pearlite and ferrite gathered in the first part of this investigation were used as inputs, while other parameters, like nodule count and interlamellar spacing in pearlite, were neglected. The model matched very well with the experimental flow curves at high strains, while some mismatch was found only at small strains, which was ascribed to the decohesion between the graphite nodules and the ferritic matrix that occurred just after yielding. It can be concluded that the plastic behaviour of GJS 400 depends mainly on the ferritic grain size and pearlitic volume fraction, and other microstructure parameters can be neglected, primarily because of their high nodularity and few defects.

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Crystallization of ethylene–octene copolymers at high cooling rates

Polymer ◽

10.1016/s0032-3861(99)00077-4 ◽

1999 ◽

Vol 40 (16) ◽

pp. 4717-4721 ◽

Cited By ~ 29

Author(s):

J Wagner ◽

S Abu-Iqyas ◽

K Monar ◽

P.J Phillips

Keyword(s):

Cooling Rates ◽

High Cooling Rates

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Non-Isothermal Crystallisation Kinetics of Polypropylene at High Cooling Rates and Comparison to the Continuous Two-Domain pvT Model

Polymers ◽

10.3390/polym12071515 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1515

Author(s):

Jonathan Alms ◽

Christian Hopmann ◽

Jian Wang ◽

Tobias Hohlweck

Keyword(s):

Injection Moulding ◽

Polymer Processing ◽

Nucleation And Growth ◽

Growth Theory ◽

Crystallisation Kinetics ◽

Cooling Rates ◽

Dsc Measurements ◽

Wide Range ◽

High Cooling Rates ◽

Kinetics Of

The modelling of the correlation between pressure, specific volume and temperature (pvT) of polymers is highly important for applications in the polymer processing of semi-crystalline thermoplastics, especially in injection moulding. In injection moulding, the polymer experiences a wide range of cooling rates, for example, 60 °C/min near the centre of the part and up to 3000 °C/min near the mould walls. The cooling rate has a high influence on the pvT behaviour, as was shown in the continuous two-domain pvT model (CTD). This work examined the Hoffman–Lauritzen nucleation and growth theory used in the modified Hammami model for extremely high cooling rates (up to 300,000 °C/min) by means of Flash differential scanning calorimeter (DSC) measurements. The results were compared to those of the empirical continuous two-domain pvT model. It is shown that the Hammami model is not suitable to predict the crystallisation kinetics of polypropylene at cooling rates above 600 °C/min, but that the continuous two-domain pvT model is well able to predict crystallisation temperatures at high cooling rates.

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Intentionally Deadheading SAGD ESPs - An Unconventional Approach to Improve Run Life

10.2118/204521-ms ◽

2021 ◽

Author(s):

J. Daine Studer ◽

Jesus E. Chacin ◽

Roger Walters ◽

Hoai Ann Nguyen

Keyword(s):

Fiber Optics ◽

Field Tests ◽

Field Trials ◽

Base Line ◽

Cooling Rates ◽

Temperature Changes ◽

Plant Maintenance ◽

High Cooling Rates ◽

Log Normal ◽

Log Normal Distribution

Abstract SAGD ESPs run at the highest motor temperatures current technology allows. However, they cool very rapidly when shutdown. High cooling rates promote motor oil volumetric contraction, eventually leading to wellbore fluid ingress and short-circuited motors. The Paper presents successful field tests designed to decrease ESP cooling rates by inducing controlled deadheads, rather than shutting down ESPs. Various extended deadhead field trials (up to 70+ days duration) validated the approach, while confirming that no deadhead related ESP damage was induced. ESP temperature changes were measured using fiber optics strings installed as part of the usual completion in 60+ wells, during a four week-long field-wide plant maintenance turn-around. While cooling rates varied somewhat from well to well, they all showed very similar behavior and were very well fitted with a log-normal distribution, R2factor > 95%. Most ESP temperatures decreased between 50°C to 120°C in a week. This data was used as a general baseline to support the deadheading field trials. An ESP was fitted internally with an RTD at the base of the motor and externally with a clamped fiber optics string. This ESP was operated normally at 55 Hz for a few months. An 8-hour shut down test established an initial base line cooling rate of 6.6°C/hour. Subsequent 6-hour deadhead tests at 30Hz and 45 Hz showed decreased cooling rates of 4.0°C/hour and 2.2°C/hour, respectively. This result clearly established the potential to deadhead at different frequencies to obtain different lower cooling rates. Finally, two extended deadhead tests (3 and 10 weeks in duration) were executed to help determine if it was possible to induce damage in SAGD ESPs by deadheading, as is usually the case in most non-thermal applications. These ESPs operated normally after the extended tests and one was dismantled upon failure, looking for any signs of deadhead damage. Results presented show that deadheading SAGD ESPs provides the opportunity to safely minimize ESP thermal cycles, which could lead to a significant improvement in ESP run life.

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Atomic-scale simulations of strain localization in a single-component three-dimensional model amorphous solid

MRS Proceedings ◽

10.1557/proc-0903-z16-05 ◽

2005 ◽

Vol 903 ◽

Author(s):

Yunfeng Shi ◽

Michael L Falk

Keyword(s):

Shear Bands ◽

Three Dimensional ◽

Amorphous Solid ◽

Single Component ◽

Atomic Scale ◽

Dimensional Model ◽

Three Dimensional Model ◽

Localized Deformation ◽

Cooling Rates ◽

High Cooling Rates

AbstractMolecular dynamics is used to simulate model non-crystalline solids described by a single-component Dzugutov system. The solids are produced by quenching equilibrium liquids at different cooling rates. These are then tested in uniaxial compression. Samples produced at high cooling rates exhibit homogenous deformation while samples quenched at low cooling rates exhibit localized deformation. Shear bands are shown to correspond to regions of depleted short-range order as determined by a Frank-Kasper criterion.

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The Role of Microstructure on Tensile Plastic Behavior of Ductile Iron GJS 400 Produced through Different Cooling Rates, Part I: Microstructure

Metals ◽

10.3390/met9121282 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1282 ◽

Cited By ~ 3

Author(s):

Giuliano Angella ◽

Dario Ripamonti ◽

Marcin Górny ◽

Stefano Masaggia ◽

Franco Zanardi

Keyword(s):

Grain Size ◽

Tensile Properties ◽

Ductile Iron ◽

Microstructural Characterization ◽

Graphite Nodule ◽

Plastic Behavior ◽

Quantitative Metallography ◽

Cooling Rates ◽

X Ray

A series of samples made of ductile iron GJS 400 was cast with different cooling rates, and their microstructural features were investigated. Quantitative metallography analyses compliant with ASTM E2567-16a and ASTM E112-13 standards were performed in order to describe graphite nodules and ferritic grains. The occurrence of pearlite was associated to segregations described through Energy Dispersive X-ray Spectroscopy (EDS) analyses. Results were related to cooling rates, which were simulated through MAGMASOFT software. This microstructural characterization, which provides the basis for the description and modeling of the tensile properties of GJS 400 alloy, subject of a second part of this investigation, highlights that higher cooling rates refines microstructural features, such as graphite nodule count and average ferritic grain size.

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The Origin of High Ice Crystal Number Densities in Cirrus Clouds

Journal of the Atmospheric Sciences ◽

10.1175/jas3487.1 ◽

2005 ◽

Vol 62 (7) ◽

pp. 2568-2579 ◽

Cited By ~ 97

Author(s):

C. R. Hoyle ◽

B. P. Luo ◽

T. Peter

Keyword(s):

Cirrus Clouds ◽

Small Scale ◽

Ice Crystal ◽

Cooling Rates ◽

Density Distributions ◽

In Situ Forming ◽

Independent Particle ◽

Scale Temperature ◽

High Cooling Rates ◽

Homogeneous Freezing

Abstract Recent measurements with four independent particle instruments in cirrus clouds, which formed without convective or orographic influence, report high number densities of ice particles (as high as nice = 50 cm−3) embedded in broad density distributions (nice = 0.1–50 cm−3). It is shown here that small-scale temperature fluctuations related to gravity waves, mechanical turbulence, or other small-scale air motions are required to explain these observations. These waves have typical peak-to-peak amplitudes of 1–2 K and frequencies of up to 10 h−1, corresponding to instantaneous cooling rates of up to 60 K h−1. Such waves remain unresolved in even the most advanced state-of-the-art global atmospheric models. Given the ubiquitous nature of these fluctuations, it is suggested that the character of young in situ forming cirrus clouds is mostly determined by homogeneous freezing of ice in solution droplets, driven by a broad range of small-scale fluctuations (period ∼a few minutes) with moderate to high cooling rates (1–100 K h−1).

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Crystallization kinetics and solidified structure in iPP under high cooling rates

Polymer ◽

10.1016/s0032-3861(02)00762-0 ◽

2003 ◽

Vol 44 (1) ◽

pp. 307-318 ◽

Cited By ~ 89

Author(s):

I Coccorullo ◽

R Pantani ◽

G Titomanlio

Keyword(s):

Crystallization Kinetics ◽

Cooling Rates ◽

High Cooling Rates

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