Mechanical and dielectric relaxation of crystalline polymers in relation to degree of crystallinity and morphology

1964 ◽  
Vol 4 (3) ◽  
pp. 169-177 ◽  
Author(s):  
E. Passaglia
Keyword(s):  
Dielectric Relaxation ◽  
Degree Of Crystallinity ◽  
Crystalline Polymers

Prediction of crystallinity profile and eject time of injection molded parts using finite element method (FEM)

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Mehdi Mostafaiyan ◽  
Farhad Sharif
Keyword(s):  
Finite Element ◽  
Degree Of Crystallinity ◽  
Element Analysis ◽  
Melt Temperature ◽  
Crystalline Polymers ◽  
Molded Parts ◽  
Time Part ◽  
Injection Molded ◽  
The Subject

AbstractQuality of injection molded parts of semi-crystalline polymers has been the subject of intense interest from both analytical and industrial points of view. Crystallinity profile plays an important role in determining mechanical properties of a part and its quality. Therefore it is important to analyze the effect of injection molding parameters on the crystallinity profile of the molded parts. In this study, finite element analysis has been used to solve the equations of mass, momentum, and energy conservation simultaneously with the equation of crystallization kinetics to predict melt front, its solidification and crystallinity profile. The results from our numerical analysis have been compared with the reported experimental results. Furthermore, progress of the crystallization is proposed to be a proper criterion for estimation of the eject time. Finally, the effects of mold and melt temperature on the eject time; part temperature and average degree of crystallinity, for a specific compound are also presented.

Dielectric relaxation around the nematic-isotropic transition of liquid crystalline polymers

1994 ◽  
Vol 172-174 ◽  
pp. 966-971 ◽  
Author(s):  
A Alegría ◽  
J.M Echave ◽  
F.J Davis ◽  
W Guo ◽  
G.R Mitchell
Keyword(s):  
Dielectric Relaxation ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Crystalline Polymers

Dielectric relaxation of liquid crystalline dendrimers and liquid crystalline polymers with pendant nitro groups

Polymer ◽  
2001 ◽  
Vol 42 (25) ◽  
pp. 10027-10033 ◽  
Author(s):  
J Örtegren ◽  
J Tidlund ◽  
M Nykvist ◽  
P Busson ◽  
A Hult ◽  
...  
Keyword(s):  
Dielectric Relaxation ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Crystalline Polymers ◽  
Liquid Crystalline Dendrimers

scholarly journals Thermotropic Liquid Crystalline Polymers with Various Alkoxy Side Groups: Thermal Properties and Molecular Dynamics

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 992 ◽  
Author(s):  
Gi Tae Park ◽  
Jin-Hae Chang ◽  
Ae Ran Lim
Keyword(s):  
Molecular Dynamics ◽  
Thermal Properties ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Magic Angle Spinning ◽  
Degree Of Crystallinity ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Crystalline Polymers ◽  
Thermotropic Liquid Crystalline Polymers

Two series of thermotropic liquid-crystalline polymers (TLCPs) were synthesized by reacting various dialkoxy terephthalate units with hydroquinone (HQ) and 2,6-naphthalene diol (Naph). The dialkoxy terephthalate moieties used in this study include 2,5-diethoxyterephthalate, 2,5-dibutoxyterephthalate, and 2,5-dihexyloxy-terephthalate. All the TLCPs synthesized in this study formed nematic phases. The molecular motions according to the length of the dialkoxy side groups in the TLCPs were evaluated by 13C cross-polarization/magic angle spinning nuclear magnetic resonance spectroscopy. The thermal properties and molecular dynamics of the TLCPs are found to be affected by the length of the dialkoxy side group and the aromatic diol unit in the main chain. Further, the thermal behaviors, liquid crystalline mesophases, and degree of crystallinity of the two series of TLCPs, i.e., HQ- and Naph-TLCPs, are compared.

scholarly journals Image analysis as a useful tool for fast detection of dimensional and structural changes of poly(ethylene terephthalate) containers

2018 ◽  
Vol 72 (6) ◽  
pp. 351-361
Author(s):  
Nenad Jevremovic ◽  
Sava Velickovic ◽  
Melina Kalagasidis-Krusic ◽  
Vesna Panic ◽  
Tatjana Volkov-Husovic ◽  
...  
Keyword(s):  
Image Analysis ◽  
Structural Changes ◽  
Ethylene Terephthalate ◽  
Degree Of Crystallinity ◽  
Crystalline Polymers ◽  
Fast Detection ◽  
Poly Ethylene Terephthalate ◽  
One Step ◽  
Poly Ethylene ◽  
Continuous Material

The aim of this paper is to present image analysis as a useful technique for fast, reliable and non-destructive detection of dimensional and structural changes in polymers. The possibility of applying image analysis was demonstrated in the case of solvent-induced crystallization of poly(ethylene terephthalate) (PET) containers filled with commonly used organic solvents: chlorobenzene, isophorone, xylene, Espesol, Shellsol A 100, Solvesso 150, propylene glycol, glycerin and water and subjected to the storage stability test at 54 ?C for 14 days (CIPAC 1-MT 46.1.3). In addition, the obtained results were analyzed using one-step analysis of variance (ANOVA) combined with the Duncan?s statistical test (p<0.05). According to the achieved results, three main impacts of the presented paper could be distinguished: 1) dimensional and transparency changes could be precisely followed by image analysis in both following cases: for small changes in water, as well as for significant ones in chlorobenzene; 2) a correlation between the changes in the degree of crystallinity and transparency could be obtained without the continuous material testing by DSC; 3) image analysis is potentially applicable for assessment of other crystalline polymers.

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