A Simple Model for Heterogeneous Nucleation of Isotactic Polypropylene

2013 ◽  
Vol 46 (16) ◽  
pp. 6593-6599 ◽  
Author(s):  
Michael P. Howard ◽  
Scott T. Milner
Keyword(s):  
Simple Model ◽  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation

scholarly journals The Friction of Structurally Modified Isotactic Polypropylene

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7462
Author(s):  
Natalia Wierzbicka ◽  
Tomasz Sterzyński ◽  
Marek Nowicki
Keyword(s):  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation ◽  
Total Content ◽  
Mold Temperature ◽  
Pimelic Acid ◽  
Reciprocating Motion ◽  
Shore Hardness ◽  
Β Phase ◽  
Forming Temperature ◽  
Injection Molded

The purpose of studies was to analyse an impact of heterogeneous nucleation of modified isotactic polypropylene (iPP) on its tribological properties. The iPP injection molded samples, produced by mold temperature of 20 and 70 °C, were modified with compositions of two nucleating agents (NA’s), DMDBS creating α-form and mixture of pimelic acid with calcium stearate (PACS) forming β–phase of iPP, with a total content 0.2 wt.% of NA’s. A polymorphic character of iPP, with both, monoclinic (α) and pseudo-hexagonal (β) crystalline structures, depending on the NA’s ratio, was verified. The morphology observation, DSC, hardness and tribological measurements as test in reciprocating motion with “pin on flat” method, were realized, followed by microscopic observation (confocal and SEM) of the friction patch track. It was found that Shore hardness rises along with DMBDS content, independent on mold temperature. The friction coefficient (COF) depends on NA’s content and forming temperature—for upper mold temperature (70 °C), its value is higher and more divergently related to NA’s composition, what is not the case by 20 °C mold temperature. The height of friction scratches and the width of patch tracks due to its plastic deformation, as detected by confocal microscopy, are related to heterogeneous nucleation modified structure of iPP.

A new calculation of the work of formation of bubbles and drops

2005 ◽  
Vol 461 (2062) ◽  
pp. 3313-3334 ◽  
Author(s):  
Jeffery Lewins
Keyword(s):  
Surface Tension ◽  
Statistical Theory ◽  
Simple Model ◽  
Thermodynamic Model ◽  
Heterogeneous Nucleation ◽  
Conventional Theory ◽  
Real Gas ◽  
Self Consistent ◽  
Consistent Approach ◽  
Thermodynamic Basis

The thermodynamic basis of surface tension for bubbles and drops is reformulated to take into account the variation in surface tension for very small, growing or incipient bubbles and drops. After assessing the magnitudes involved by means of conventional theory, a model is put forward for this variation that avoids the supposition of extreme pressures at small sizes in the simple model. The parameter of this new model is then set by consideration of the properties of real gases, determined by analysis of the incipient bubble and then extended, it is argued, to the incipient drop. van der Waals' model of a real gas is used to show how this combines with the Lewins model in a self-consistent approach to the thermodynamics of surface tension for bubbles and drops. The changes from the simple theory will then allow a revision of the dynamic statistical theory of auto-nucleation and a reassessment of the critical sizes for imposed or heterogeneous nucleation, based on a simple and self-consistent thermodynamic model.

Activated heterogeneous nucleation of isotactic polypropylene

1990 ◽  
Vol 9 (4) ◽  
pp. 495-496 ◽  
Author(s):  
L. Pospíšil ◽  
J. Jančář ◽  
F. Rybnikář
Keyword(s):  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation

scholarly journals CRYSTALLIZATION OF POLYPROPYLENE: APPLICATION OF DIFFERENTIAL SCANNING CALORIMETRY PART II. CRYSTAL FORMS AND NUCLEATION

2017 ◽  
Vol 29 (1-2) ◽  
Author(s):  
Luljeta Raka ◽  
Gordana Bogoeva-Gaceva
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermodynamic Parameters ◽  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation ◽  
Scanning Calorimetry ◽  
Crystal Forms ◽  
Kinetic And Thermodynamic Parameters ◽  
Dsc Measurements

A b s t r a c t: The influence of homogeneous and heterogeneous nucleation on crystallization processes of isotactic polypropylene(iPP) and its kinetic and thermodynamic parameters is summarized and discussed, as evaluated by DSC measurements.

Nonisothermal Crystallization Kinetics of Isotactic Polypropylene Filled with a Novel Nucleating Agent

2013 ◽  
Vol 652-654 ◽  
pp. 501-507
Author(s):  
Nai Xu ◽  
Li Sha Pan ◽  
Su Juan Pang ◽  
Qiang Lin
Keyword(s):  
Crystallization Kinetics ◽  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation ◽  
Nucleating Agent ◽  
Differential Scanning Calorimetric ◽  
Nonisothermal Crystallization ◽  
Crystallization Behaviors ◽  
Nucleation Effect ◽  
Nonisothermal Crystallization Kinetics ◽  
Kinetics Of

The nonisothermal crystallization kinetics of isotactic polypropylene (iPP) filled with a novel nucleating agent (TMC328) was studied by using differential scanning calorimetric. The commonly used Arami, Ozawa, and Mo models were used to model the crystallization kinetics, and it appears that Arami and Mo models can well describe the nonisothermal crystallization behaviors of iPP/TMC328 blends. The results indicate that a small amount of TMC328 can obviously enhance the kinetic crystallizability of iPP due to its heterogeneous nucleation effect.

Effect of heterogeneous nucleation on isotactic polypropylene-polyoxymethylene blends properties and miscibility

2015 ◽  
Vol 23 (9) ◽  
pp. 850-860 ◽  
Author(s):  
Mateusz Barczewski ◽  
Danuta Matykiewicz ◽  
Jacek Andrzejewski
Keyword(s):  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation
Sign in / Sign up

Export Citation Format

Share Document