scholarly journals The II–I Phase Transition Behavior of Butene-1 Copolymers with Hydroxyl Groups

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1315
Author(s):  
Yuanyuan Li ◽  
Tao Li ◽  
Wei Li ◽  
Yahui Lou ◽  
Liyuan Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Design ◽  
Nucleation Density ◽  
Hydroxyl Groups ◽  
Melt Crystallization ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Tetragonal Form ◽  
Stepwise Annealing ◽  
High Incorporation

The crystallization and II–I phase transition of functionalized polybutene-1 with hydroxyl groups were investigated by differential scanning calorimetry. The results show that the incorporated hydroxyl groups increase the nucleation density but decrease the growth rate in melt crystallization. Interestingly, for the generated tetragonal form II, the presence of polar hydroxyl groups can effectively accelerate the phase transition into the thermodynamically stable modification of trigonal form I, especially with stepwise annealing and high incorporation. Using stepwise annealing, II–I phase transition was enhanced by an additional nucleation step performed at a relatively low temperature, and the optimal nucleation temperature to obtain the maximum transition degree was ‒10 °C, which is independent from the content of hydroxyl groups. Furthermore, the accelerating effect of hydroxyl groups on the II–I transition kinetics can be increased by reducing the crystallization temperature when preparing form II crystallites. These results provide a potential molecular design approach for developing polybutene-1 materials.

Phase Transition Behavior of Main Chain Nematic Liquid-Crystalline Polymers Based on 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone

2012 ◽  
Vol 1403 ◽  
Author(s):  
Christain Melchert ◽  
M. Behl ◽  
A. Lendlein
Keyword(s):  
Phase Transition ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
Crystalline Polymers ◽  
Transition Behavior ◽  
X Ray Scattering

ABSTRACTThe control of phase transition behavior in liquid crystalline polymers could enable potential application in the field of actuators and sensors by enabling a higher actuator performance of liquid crystalline elastomers (LCE). In this context the phase transition behavior of siloxane based liquid crystalline copolymers synthesized from 1,1,3,3-tetramethyldisiloxane, 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-MeHq), and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-tBHq) was explored. The selected monomers provided different thermal stabilities of the nematic phase, while the non-flexible siloxane spacer suppressed a smectic phase. The mesogenic properties were studied by means of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X-ray scattering (WAXS). With increasing fraction of M-MeHq the nematic phase of the copolymer was stabilized and a tailoring of relatively low TNI was achieved.

scholarly journals Phase Transition and Melt-Recrystallization Behavior of Poly(Butylene Adipate) Investigated by Simultaneous Measurements of Wide-Angle X-Ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC)

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 75
Author(s):  
Mengfan Wang ◽  
Weiyu Cao
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Heating Process ◽  
Wide Angle ◽  
Melt Crystallization ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Simultaneous Measurements

Simultaneous measurements of wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) were carried out to investigate the phase transition and melting behaviors of poly(butylene adipate) (PBA). Thermal expansion changes along the a and b axes of the β form unit cell are different from each other during the heating process. At the beginning of the β to αH (high-temperature α phase) phase transition, the β phase melts very fast, while the recrystallization of the αH phase is delayed and slowed. With the further increment of the temperature, the melting rate of the β phase slows down, while the recrystallization of the αH phase accelerates. The diffraction peak intensity ratios of the β(020):β(110) and αH(020):αH(110) diffraction peaks during the first heating process have similar value. However, the above value is different from the value of α(020):α(110) during the following melt-crystallization process. This difference comes from the different orientations of the crystal lattices of the α and αH(β) crystals to the substrate plane, which indicates that the αH phase inherits the orientation of the β phase during phase transition and the orientation of αH form crystals is different from the α form crystals that crystallized from the melt.

Interaction of linear polyamines with negatively charged phospholipids: the effect of polyamine charge distance

2014 ◽  
Vol 395 (7-8) ◽  
pp. 769-778 ◽  
Author(s):  
Sebastian Finger ◽  
Christian Schwieger ◽  
Ahmad Arouri ◽  
Andreas Kerth ◽  
Alfred Blume
Keyword(s):  
Phase Transition ◽  
Lipid Membranes ◽  
Electrostatic Interactions ◽  
Lipid Vesicles ◽  
Molecular Crowding ◽  
Domain Formation ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Methylene Groups ◽  
Gel Phase

Abstract The binding of cationic polyamines to negatively charged lipid membranes is driven by electrostatic interactions and additional hydrophobic contributions. We investigated the effect of polyamines with different number of charges and charge separation on the phase transition behavior of vesicles of phosphatidylglycerols (dipalmitoylphosphatidylglycerol and dimyristoylphosphatidylglycerol) to differentiate between effects caused by the number of charges, the charge distance, and the hydrophobicity of the methylene spacer. Using differential scanning calorimetry and Fourier transform infrared spectroscopy complemented with monolayer experiments, we found that the binding constant of polyamines to negatively charged lipid vesicles depends as expected on the number of charges. However, for diamines, the effect of binding on the main phase transition of phosphatidylglycerols (PGs) is also strongly influenced by the charge distance between the ammonium groups in the backbone. Oligoamines with charges separated by two or three methylene groups bind more strongly and have larger stabilizing effects on the lipid gel phase of PGs. With multivalent polyamines, the appearance of several transition peaks points to effects of molecular crowding on the surface, i.e., binding of only two or three charges to the surface in the case of spermine, and possible concomitant domain formation.

scholarly journals Phase transition behavior of silicone based liquid crystalline polymers

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
R. N. Jana ◽  
H. Bhunia ◽  
C. Im
Keyword(s):  
Phase Transition ◽  
Liquid Crystalline ◽  
Crosslinking Agent ◽  
Transition Temperatures ◽  
X Ray Diffraction ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Transition Behavior ◽  
Ft Ir

AbstractPhase transition behavior of silicone based liquid crystalline (LC) polymers with variable isotropic transition temperatures (Ti), synthesized from poly(methyl hydrosiloxane), 10-undecenoic acid based crosslinking agent and cholesterol based side chain mesogen, was studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. The chemical structure of the mesogenic monomer and the LC polymers were confirmed by Fourier transform infra-red (FT-IR) spectroscopy and 1HNMR spectroscopy. DSC studies showed that the glass transition temperatures (Tg) and Ti of the LC polymers decreased with increasing proportion of mesogenic crosslinking agent at its low proportion and at its higher proportion Ti disappeared completely indicating that the polymeric chains had less chance to orient in the network structure. The results were consistent with the XRD and POM studies.

Controlling Phase Transition Behavior of Thermally Responsive Metal Affinity Hydrogels:  A Molecular Design Approach

2007 ◽  
Vol 40 (16) ◽  
pp. 5850-5857 ◽  
Author(s):  
Ganesh Iyer ◽  
Pallavi Iyer ◽  
L. M. Viranga Tillekeratne ◽  
Maria R. Coleman ◽  
Arunan Nadarajah
Keyword(s):  
Phase Transition ◽  
Molecular Design ◽  
Design Approach ◽  
Phase Transition Behavior ◽  
Metal Affinity ◽  
Transition Behavior ◽  
Thermally Responsive

Differential Scanning Calorimetry Study of Natural Rubber and Epoxidized Natural Rubber and Their Binary Blends

1989 ◽  
Vol 62 (4) ◽  
pp. 585-591 ◽  
Author(s):  
S. C. Ng ◽  
K. K. Chee
Keyword(s):  
Phase Transition ◽  
Natural Rubber ◽  
Chemical Structure ◽  
Specific Interactions ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Binary Blends ◽  
Differential Scanning Calorimetry Study ◽  
Molecular Weights ◽  
Uniform Composition

Abstract In summary, the ENR exhibits a single Tg, whereas blending two different ENR samples of sufficiently high molecular weights would have no significant effects on their individual phase transition behavior in any event. This important finding implies that the epoxidation of NR basically leads to copolymers of random chemical structure and uniform composition, in line with the theoretical prediction of Scott. Moreover, the specific interactions presumably between the hydrogens of isoprene units and the oxirane oxygens of epoxidized isoprene moieties, are discovered to be strikingly weak, in the sense that the NR and ENR rubbers are positively immisicible.

scholarly journals Phase transition behavior and deformation mechanism of polytetrafluoroethylene under stretching

RSC Advances ◽  
2021 ◽  
Vol 11 (63) ◽  
pp. 39813-39820
Author(s):  
Cong Luo ◽  
Jingke Pei ◽  
Wenyue Zhuo ◽  
Yanhua Niu ◽  
Guangxian Li
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Small Angle ◽  
Deformation Mechanism ◽  
X Ray Diffraction ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transition Behavior ◽  
X Ray Scattering

The deformation mechanism and phase transition behavior of polytetrafluoroethylene (PTFE) under stretching conditions (25, 50, 100 °C) were investigated by using differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and X-ray diffraction (XRD).

Irradiation assisted interaction behavior of Regioreguler Poly(3-hexylthiophene) nanotube composites

2006 ◽  
Vol 963 ◽  
Author(s):  
Ananta Adhikari ◽  
Hassaram Bakhru ◽  
Mircea Chipara ◽  
Chang Y. Ryu ◽  
Pullickel Ajayan
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Substantial Improvement ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Basic Step ◽  
Transition Behavior ◽  
Wide Range ◽  
Composite Formation ◽  
The Matrix

ABSTRACTThe basic step to optimize the properties of filler in composite is the interfacial interaction between the matrix and the filler. Irradiation, a novel technique, was used in this work to introduce a wide range of defects in Single-walled Carbon nanotubes (SWNTs) as filler prior to composite formation. The thermal stability along with phase transition behavior of an organic conducting polymer Poly(3-hexylthiophene) (P3HT) loaded with pristine and ion implanted SWNTs has been investigated using Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC), and Electron Spin Resonance (ESR). Interestingly, we observed substantial improvement on the thermal stability and the phase transition behavior of the composite with pristine and irradiated fillers.

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