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.

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.

Reclaiming of waste guayule natural rubber vulcanizate—reclaim rubber for green tire applications: An approach for sustainable development

2018 ◽  
Vol 51 (3) ◽  
pp. 193-210 ◽  
Author(s):  
Soumyajit Ghorai ◽  
Dipankar Mondal ◽  
Sawar Dhanania ◽  
Santanu Chattopadhyay ◽  
Madhusudan Roy ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Polymer Chains ◽  
Cross Link ◽  
Scanning Calorimetry ◽  
Infrared Study ◽  
Differential Scanning Calorimetry Study ◽  
Link Density ◽  
Cross Link Density ◽  
Silica Dispersion ◽  
The Fourier Transform

This article illustrates the reclaiming of guayule natural rubber (GNR) vulcanizate by bis[3-(triethoxysilyl)propyl] tetrasulfide (TESPT), and as-grown reclaim rubber facilitates the silica dispersion in GNR product application without adding any coupling agent. This article deals with the performance evaluation of silica-filled revulcanizates with promising application in green tire. The extent of reclaiming was monitored through the measurement of sol content, cross-link density, Mooney viscosity, and degree of reclaiming. The differential scanning calorimetry study was carried out to evaluate the fraction of immobilized polymer chains and its dependence on cross-link density of the vulcanizates. The Fourier transform infrared study and also sulfur analysis independently indicate the attachment of the fragmented TESPT with the polymer chain and cross-link bonds. The study of mechanical properties clearly shows that in revulcanized GNR, the optimum property is achieved when reclaiming time is set for 40 min. The effect of reclaiming time on dynamic mechanical behavior such as storage modulus and loss tangent was studied. The scanning electron microscopy studies show the coherency and homogeneity of silica-filled revulcanize rubber with reclaiming time.

Dielectric and ferroelectric behavior of an incipient ferroelectric Sr(1−3x/2)CexTiO3 novel solid solution

RSC Advances ◽  
2016 ◽  
Vol 6 (94) ◽  
pp. 91679-91688 ◽  
Author(s):  
Burhan Ullah ◽  
Wen Lei ◽  
Xiao-Hong Wang ◽  
Gui-Fen Fan ◽  
Xiao-Chuan Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Dielectric Properties ◽  
Phase Formation ◽  
Ferroelectric Phase Transition ◽  
Chemical Structure ◽  
Ferroelectric Phase ◽  
Phase Transition Behavior ◽  
Ferroelectric Behavior ◽  
Transition Behavior

Phase formation, chemical structure, microwave (MW) dielectric properties, and relaxor-to-ferroelectric phase transition behavior of a novel Sr(1−3x/2)CexTiO3 solid solution ceramic sintered in nitrogen have been investigated.

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.

scholarly journals Biobased Thermoplastic Elastomers: Structure-Property Relationship of Poly(hexamethylene 2,5-furanodicarboxylate)-Block-Poly(tetrahydrofuran) Copolymers Prepared by Melt Polycondensation

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 397
Author(s):  
Sandra Paszkiewicz ◽  
Izabela Irska ◽  
Agata Zubkiewicz ◽  
Anna Szymczyk ◽  
Elżbieta Piesowicz ◽  
...  
Keyword(s):  
Phase Transition ◽  
Shape Memory Polymer ◽  
Tensile Tests ◽  
Thermoplastic Elastomers ◽  
Sem Analysis ◽  
Transition Temperatures ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Phase Transition Temperatures

A series of poly(hexamethylene 2,5-furanodicarboxylate)-block-poly(tetrahydrofuran) (PHF-b-F-pTHF) copolymers were synthesized using a two-stage procedure, employing transesterification and polycondensation. The content of pTHF flexible segments varied from 25 to 75 wt.%. 1H nuclear magnetic resonance (NMR) and Fourier transformed infrared spectroscopy (FTIR) analyses were applied to confirm the molecular structure of the materials. Differential scanning calorimetry (DSC), dynamic mechanical measurements (DMTA), and X-ray diffraction (XRD) allowed characterizing the supramolecular structure of the synthesized copolymers. SEM analysis was applied to show the differences in the block copolymers’ morphologies concerning their chemical structure. The influence of the number of flexible segments in the copolymers on the phase transition temperatures, thermal properties, as well as the thermo-oxidative and thermal stability was analyzed. TGA analysis, along with tensile tests (static and cyclic), confirmed the utilitarian performance of the synthesized bio-based materials. It was found that an increase in the amount of pTHF caused the increase of both number-average and weight-average molecular weights and intrinsic viscosities, and at the same time causing the shift of the values of phase transition temperatures toward lower ones. Besides, PHF-b-F-pTHF containing 75 wt.% of F-pTHF units was proved to be a promising thermoplastic shape memory polymer (SMP) with a switching temperature of 20 °C.

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).

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.

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