Cis-Polyoctenamer: Thermodynamic Parameters of Fusion and Crystallization Kinetics

1976 ◽  
Vol 49 (1) ◽  
pp. 170-178 ◽  
Author(s):  
G. Gianotti ◽  
A. Capizzi ◽  
L. Del Giudice
Keyword(s):  
Melting Point ◽  
Thermodynamic Parameters ◽  
Melting Temperature ◽  
Crystallization Kinetics ◽  
Melting Points ◽  
Equilibrium Melting Temperature ◽  
Kinetics Of

Abstract The thermodynamic parameters of fusion and crystallization kinetics of cis-polyoctenamer were investigated. We adopted the cryoscopic method based on the melting point decrease in the presence of diluents, using toluene as a diluent. It was also possible to determine the equilibrium melting temperature by extrapolating the “kinetic” melting points, measured on polymers crystallized at various temperatures. The dependence of ΔHu and Teq on the cis content allows evaluation of their values for all-cis-polyoctenamer. Conclusions about the elastomeric properties of the polymer are drawn.

scholarly journals Equilibrium melting temperature and crystallization kinetics of α- and β′-PBN crystal forms

2011 ◽  
Vol 44 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Michelina Soccio ◽  
Nadia Lotti ◽  
Lara Finelli ◽  
Andrea Munari
Keyword(s):  
Melting Temperature ◽  
Crystallization Kinetics ◽  
Equilibrium Melting Temperature ◽  
Crystal Forms ◽  
Kinetics Of

A note on the melting-point of paraffins and fatty acids

1938 ◽  
Vol 34 (3) ◽  
pp. 459-464 ◽  
Author(s):  
E. B. Moullin
Keyword(s):  
Fatty Acids ◽  
Melting Point ◽  
Melting Temperature ◽  
Smooth Curve ◽  
Melting Points ◽  
Normal Paraffin ◽  
Simple Interpretation

The purpose of this note is to draw attention to a certain correspondence between the melting-points of normal paraffins and of fatty acids and to indicate a simple interpretation of this phenomenon. If the number of carbon atoms in a normal paraffin is plotted against the corresponding melting temperature, all the points in the diagram lie very close to a smooth curve drawn among them. If a similar diagram is made for the fatty acids, the points corresponding to an even number of carbon atoms lie on a curve of the same character as that found for paraffins. The points for an odd number of carbon atoms lie on a separate but similar curve, exemplifying the well-known alternation property.

Optimization of melting conditions for the analysis of crystallization kinetics of poly(3-hydroxybutyrate)

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Maria Laura Di Lorenzo ◽  
Pawel Sajkiewicz ◽  
Arkadiusz Gradys ◽  
Paola La Pietra
Keyword(s):  
Melting Point ◽  
Polymer Chain ◽  
Crystallization Kinetics ◽  
Crystallization Temperature ◽  
Degree Of Crystallinity ◽  
Thermal Treatments ◽  
Constant Rate ◽  
Kinetics Of ◽  
Final Degree ◽  
Melting Conditions

AbstractStudies of kinetics of polymer crystallization are generally performed by heating the material above the melting point, in order to erase previous thermal and mechanical history, followed by rapid cooling to the desired crystallization temperature or by cooling at a constant rate. For poly(3-hydroxybutyrate) this procedure implies some degradation of the polymer chain, which starts below the onset of melting. In this article the effects of melting conditions on the subsequent crystallization kinetics are discussed. It is shown that in order to sufficiently cancel memories of previous crystalline order of the analyzed PHB, it is necessary to bring the material at a temperature higher than 192 °C. Thermal treatments conducted at lower temperatures are not sufficient to destroy all solid aggregates, and crystallization of PHB has an anticipated onset of crystallization due to nucleation occurring via self-seeding. The chain degradation attained upon exposure at high temperatures has much lesser influence on crystallization kinetics than incomplete melting, with some effects detectable on the spherulitic morphology and on the final degree of crystallinity.

Effect of Deformation on the Crystallization of Supercooled Cured and Uncured Rubbers

1964 ◽  
Vol 37 (2) ◽  
pp. 404-407 ◽  
Author(s):  
M. F. Bukhina
Keyword(s):  
General Theory ◽  
Natural Rubber ◽  
Mechanical Stress ◽  
Melting Temperature ◽  
Crystallization Kinetics ◽  
Crystallization Rate ◽  
Approximate Expression ◽  
Supercooled Liquids ◽  
Half Time ◽  
Equilibrium Melting Temperature

Abstract 1. The dependence of the polymer crystallization rates on temperature is considered on the basis of the general theory of crystallization kinetics for supercooled liquids. The coefficients in the equations relating the crystallization half time, τ½, to the degree of supercooling are calculated for natural rubber. 2. An approximate expression is obtained which relates the equilibrium melting temperature of deformed rubber with the mechanical stress applied when crystallization starts. 3. The acceleration of crystallization which is induced by deformation is shown to be basically associated with an increase of the equilibrium melting temperature. 4. The possibility of calculating the crystallization rate at all temperatures and stresses from the results of a small number of experiments is established.

scholarly journals Development of a new method for identifying species affiliation based on forensic hair examination

2020 ◽  
Vol 75 (05) ◽  
pp. 6265-2020
Author(s):  
BALJI Y. A. ◽  
ADILBEKOV J. SH. ◽  
WIŚNIEWSKI J. ◽  
BEŁKOT Z. ◽  
ANUSZ K.
Keyword(s):  
Melting Point ◽  
Melting Temperature ◽  
Animal Species ◽  
Automated System ◽  
Melting Points ◽  
Melting Temperatures ◽  
Research Material ◽  
Hair Samples ◽  
Initial Melting ◽  
Animal Hair

The aim of the research was to develop a method for determining the species affinity of animal hair by determining its melting temperature. The research material was selected from hair samples of livestock and wild animals. We investigated 170 hairs of 16 animal species and humans. The hair melting point was determined by an automated system for melting temperature determination Opti Melt (MPA100). In the present study, we suggest that species affiliation can be effectively determined by examining physical properties of hair, in particular by determining its melting temperature. The hair melting temperatures for different animal species are in different ranges, but the initial melting points for hair of certain animal species are similar. For example, the initial melting point for cat, sheep, hare, rabbit, and rat hair ranged from 100 to 111 ° C, and the hair of the wolf, bear, and fox began to melt at 139.2 to 141.2 ° C. The results of this research make it possible to determine the species affinity of animals according to their hair melting temperature, which had not been done before. The proposed method yields rapid results and can be used as an auxiliary method in ambiguous cases in which data obtained by microscopic examination are insufficient. It will greatly facilitate the work of forensic specialists, enriching the arsenal of available methods.

scholarly journals Cocoa butter equivalent from Kpangnan butter and Pequi oil

2021 ◽  
Author(s):  
Saeed Mirzaee Ghazani ◽  
Andrea Madalena Guedes ◽  
Rosemar Antoniassi ◽  
Alejandro Marangoni
Keyword(s):  
Melting Point ◽  
Cocoa Butter ◽  
Crystal Form ◽  
Melting Behavior ◽  
Cocoa Butter Equivalent ◽  
Melting Points ◽  
Binary Blends ◽  
Oil Mixtures ◽  
Kinetics Of ◽  
Triclinic Form

Novel cocoa butter equivalents were designed using dry fractionated Pequi oil and solvent fractionated Kpangnan butter. Static crystallization of binary mixtures of these two fractions into the triclinic form (β2) was achieved after 12 days for all mixtures and after 4 days for the 80:20 w/w and 90:10 w/w fractionated Kpangnan:Pequi oil mixtures. Moreover, after 60 days of storage at 22oC, all binary blends (except 100% fractionated pequi oil and 100% fractionated Kpangnan butter) were crystallized in the most stable triclinic crystal form (β1). Here we also discovered an unusual melting behavior for the fractionaled 30:70 w/w and 20:80 w/w fractionated Kpangnan:Pequi oil mixtures, where after 4 days of static crystallization at room 22oC, these mixtures displayed higher than predicted melting points, 41.89 oC and 33.32 oC, respectively. This suggested a faster kinetics of transformation to the triclinic β2 form for those mixtures. Our results suggest that the 30:70 w/w fractionated Kpangnan:Pequi oil mixture with a melting point of 34oC after 60 days storage at 22oC, a stable triclinic β2 form, and a triglyceride composition of 28% POP, 4.6% POS and 33% SOS displayed solid state characteristics, melting point and crystal structure, of a commercial cocoa butter equivalent.

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