scholarly journals Effect of diacylhydrazine as chain extender on microphase separation and performance of energetic polyurethane elastomer

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 469-481
Author(s):  
Yang Gao ◽  
Jie Lv ◽  
Licheng Liu ◽  
Yingfeng Yu
Keyword(s):  
Hydrogen Bonding ◽  
Hard Segment ◽  
Microphase Separation ◽  
Low Cost ◽  
Ethylene Carbonate ◽  
Mechanical Analysis ◽  
Chain Extender ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Hard Segment Content

AbstractIt is low cost and feasible to improve the mechanical properties of polyurethane by using the chain extender with hydrogen bonding function to improve the degree of microphase separation. In this article, hydrazine hydrate was used to react with ethylene carbonate and propylene carbonate, respectively, to synthesize diacylhydrazines as the polyurethane chain extender with amide bonds, which were characterized by 1H nuclear magnetic resonance. Polyurethane with different contents of hard segment were prepared from poly-3,3-bis(azidomethyl)oxetane-tetrahydrofuran as the polyol and 4,4′-diphenylmethane diisocyanate as the isocyanate components. Fourier transform infrared spectroscopy showed that with the increase of the hard segment content, the proportion of hydrogen-bonded ordered carbonyl group increased to 94%, proving that diacylhydrazines could improve the degree of ordered hydrogen bonding, which led to clear microphase separation observed by field emission scanning electron microscopy and higher storage modulus of the polyurethane. Differential scanning calorimetry and dynamic mechanical analysis showed that polyurethane with higher hard segment content is likely to exhibit multiple thermal transitions caused by microphase separation. When the hard segment content was 40%, compared with polyurethane with 1,4-butanediol as the chain extender, the tensile strengths of polyurethanes with diacylhydrazines also improved by 30% and 76%, respectively.

Effect of cooling induced crystallization upon the properties of segmented thermoplastic polyurethanes

2017 ◽  
Vol 37 (5) ◽  
pp. 471-480 ◽  
Author(s):  
Daniel Ramirez ◽  
Juliana Nanclares ◽  
Marisa Spontón ◽  
Mara Polo ◽  
Diana Estenoz ◽  
...  
Keyword(s):  
Hard Segment ◽  
Chain Extender ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Thermoplastic Polyurethanes ◽  
Dsc Measurements ◽  
Atomic Force ◽  
Hard Segment Content ◽  
Induced Crystallization

Abstract An investigation on the cooling-induced crystallization in three thermoplastic polyurethanes based on MDI, PTMG, and 1.4-BD as chain extender with different hard segment content is reported. Thermal transitions were determined using differential scanning calorimetry (DSC) measurements at different cooling rates, and thermal stability was studied by thermogravimetric analysis. Changes in Raman spectra were useful to correlate the thermal transitions with changes in the morphology of the polymers. The dissimilarity in the composition gave different rheological behavior in the molten state, indicated by the temperature dependence of the viscosity. The mechanical properties and the crystallinity was influenced not only by the cooling rate but also by the hard segment content. Thermoplastic polyurethanes with more hard segment content formed more crystalline hard domains as evidenced by the DSC and atomic force microscopy results.

scholarly journals Synthesis and Properties of Novel Polyurethanes Containing Long-Segment Fluorinated Chain Extenders

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1292 ◽  
Author(s):  
Jia-Wun Li ◽  
Hsun-Tsing Lee ◽  
Hui-An Tsai ◽  
Maw-Cherng Suen ◽  
Chih-Wei Chiu
Keyword(s):  
Hard Segment ◽  
Soft Segment ◽  
Mechanical Analysis ◽  
Chain Extender ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chain Extenders ◽  
Relationship Of ◽  
The Relationship

In this study, novel biodegradable long-segment fluorine-containing polyurethane (PU) was synthesized using 4,4′-diphenylmethane diisocyanate (MDI) and 1H,1H,10H,10H-perfluor-1,10-decanediol (PFD) as hard segment, and polycaprolactone diol (PCL) as a biodegradable soft segment. Nuclear magnetic resonance (NMR) was used to perform 1H NMR, 19F NMR, 19F–19F COSY, 1H–19F COSY, and HMBC analyses on the PFD/PU structures. The results, together with those from Fourier transform infrared spectroscopy (FTIR), verified that the PFD/PUs had been successfully synthesized. Additionally, the soft segment and PFD were changed, after which FTIR and XPS peak-differentiation-imitating analyses were employed to examine the relationship of the hydrogen bonding reaction between the PFD chain extender and PU. Subsequently, atomic force microscopy was used to investigate the changes in the microphase structure between the PFD chain extender and PU, after which the effects of the thermal properties between them were investigated through thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. Finally, the effects of the PFD chain extender on the mechanical properties of the PU were investigated through a tensile strength test.

scholarly journals Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4705
Author(s):  
Boer Liu ◽  
Xi Chen ◽  
Glenn A. Spiering ◽  
Robert B. Moore ◽  
Timothy E. Long
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Random Copolymer ◽  
Thermomechanical Properties ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Central Block ◽  
Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

New Waterborne Polyurethane Dispersions from the Soybean-Oil-Based Polyols by Ring Opening of ESO with Glycol

2011 ◽  
Vol 197-198 ◽  
pp. 1196-1200
Author(s):  
Kun Peng Wang ◽  
Li Ting Yang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Soybean Oil ◽  
Thermophysical Properties ◽  
Ring Opening ◽  
Hard Segment ◽  
Waterborne Polyurethane ◽  
Hardness Testing ◽  
Scanning Calorimetry ◽  
Hard Segment Content ◽  
Polyurethane Dispersions

A series of polyols (GSOLs) with a range of hydroxyl numbers based on epoxidized soybean oil (ESO) were prepared by ring opening with glycol. These Polyols of hydroxyl (OH) numbers ranging from 111 to 162 mg KOH/g were obtained. The environmentally friendly soybean-oil-based waterborne polyurethane dispersions (SPU) with very promising properties have been successfully synthesized from a series of soybean-oil-based polyols (GSOLs) with different hydroxyl numbers by a polyaddition reaction with toluene 2,4-diisocyanate (2,4-TDI). The structure and thermophysical properties of the resulting SPU films have been studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and hardness testing. The experimental results showed that the functionality of the GSOLs and the hard segment content play a key role in controlling the structure and the thermophysical properties of the SPU films.

Thermomechanical Characterization of Bismuth Telluride Based Thermoelectric Materials

2001 ◽  
Vol 691 ◽  
Author(s):  
Witold Brostow ◽  
Kevin P. Menard ◽  
John B. White
Keyword(s):  
Bismuth Telluride ◽  
Van Der Waals ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Direction Parallel ◽  
Crystalline Polymers ◽  
Structural Metals ◽  
P Type

ABSTRACTThe thermoelectric properties of bismuth telluride based thermoelectric (TE) materials are well-characterized, but comparatively little has been published on the mechanical and thermomechanical properties of these materials. In this paper, we present the initial dynamic mechanical analysis (DMA) data for n-type and p-type bismuth telluride based TE materials. The materials' tan δ values, indicative of viscoelastic energy dissipation modes, approach that of glassy or crystalline polymers and are greater than ten times the tan delta of structural metals. TE samples measured perpendicular to the van der Waals planes have higher tan δ values. Thermal scans in the DMA compressive mode showed changes in mechanical properties versus temperature with clear hysteresis effects. These changes were correlated to differential scanning calorimetry (DSC) thermal transitions. The expected anisotropy was shown in flexural 3-point bending results for one n-type material that showed a storage modulus of 0.10 to 0.45 GPa in the direction parallel to the van der Waals planes and 0.07 to 0.2 GPa in the perpendicular direction.

Photolysis of segmented polyurethanes. The role of hard-segment content and hydrogen bonding

1987 ◽  
Vol 34 (2) ◽  
pp. 763-774 ◽  
Author(s):  
Charles E. Hoyle ◽  
Kyu-Jun Kim ◽  
Y. G. No ◽  
G. L. Nelson
Keyword(s):  
Hydrogen Bonding ◽  
Hard Segment ◽  
Hard Segment Content ◽  
Segmented Polyurethanes

Application of dynamic mechanical analysis techniques to bismuth telluride based thermoelectric materials

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Witold Brostow ◽  
Kevin P. Menard ◽  
John B. White
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Bismuth Telluride ◽  
Polymeric Materials ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Tan Δ ◽  
Te Material

Abstract Dynamic mechanical analysis (DMA) techniques are commonly applied to characterize polymer-based materials - but little if at all to characterize semiconductor thermoelectric (TE) materials. TE materials may be coupled with polymeric materials in advanced thermoelectric devices, and the knowledge of TE material properties will be useful in the choice of materials for future applications. We have obtained DMA results for both n-type and p-type bismuth telluride based TE materials. We find that tan δ values, indicative of viscoelastic energy dissipation modes, approach the values for glassy or semi-crystalline polymers, and are larger by more than a whole order of magnitude than the tan δ of structural metals. DMA thermal scans show clear hysteresis-type effects and a correlation with differential scanning calorimetry thermal transitions. DMA properties as a function of frequency are briefly discussed. Our results show that DMA techniques are useful in the evaluation of thermophysical and thermomechanical properties of these TE materials and of assembled coolers. The viscoelastic effects we report may provide a damping mechanism for severe stresses inherent to service conditions of the TE coolers.

Investigating the Properties and Structure of Polyurethane Elastomers with Monoethylene Glycol Chain Extender

2020 ◽  
Vol 986 ◽  
pp. 18-23
Author(s):  
Patcharapon Somdee ◽  
Timea Lassu-Kuknyo ◽  
Csaba Konya ◽  
Tamás Szabó ◽  
Kálmán Marossy
Keyword(s):  
Hard Segment ◽  
Chain Extender ◽  
Polypropylene Glycol ◽  
Polyurethane Elastomers ◽  
Elongation At Break ◽  
Peak Intensity ◽  
Hard Segment Content ◽  
Polymeric Chains ◽  
Monoethylene Glycol ◽  
Hardness Values

The effect of monoethylene glycol (mEG) acting as chain extender in polypropylene glycol (PPG-4000) and 4,4ʹ-diphenylmethane diisocyanate (MDI) reaction was investigated. Polyurethane elastomers (PUR) were changed from flexible to rigid materials by varying the mEG content. Results show that Shore A and D hardness values trend to increase with increasing mEG content. It appears that increasing the chain extender content increases the hard segment content in the polyurethane structure. Moreover, increasing the mEG content increases Young’s modulus and the tensile strength of PUR, while elongation at break decreases. The chemical structure of the hard segment of PUR was characterized by Infrared (IR) spectroscopy. IR spectra exhibited the bands typical for PUR consisting of –NH, CH2– and C=O groups. The spectra reveal a few interactions between the polymeric chains that appear to be responsible for the shift of transmittance peak and decrease of some peak intensity. This may be due to the hard segment aggregating more to form domains in the PUR when mEG content was increased.

scholarly journals Effect of Phenolic Resin Oligomer Motion Ability on Energy Dissipation of Poly (Butyl Methacrylate)/Phenolic Resins Composites

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 490
Author(s):  
Xing Huang ◽  
Songbo Chen ◽  
Songhan Wan ◽  
Ben Niu ◽  
Xianru He ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hydrogen Bonding ◽  
Glass Transition ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Butyl Methacrylate ◽  
Scanning Calorimetry ◽  
Phenolic Resins ◽  
Dynamic Mechanical ◽  
The Matrix

Poly (butyl methacrylate) (PBMA) was blended with a series of phenolic resins (PR) to study the effect of PR molecular weight on dynamic mechanical properties of PBMA/PR composites. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) found a similar variation of glass transition temperature (Tg). The maximum loss peak (tanδmax) improved in all PBMA/PR blends compared with the pure PBMA. However, tanδmax reduced as the molecular weight increased. This is because PR with higher molecular weight is more rigid in the glass transition zone of blends. The hydrogen bonding between PBMA and PR was characterized by Fourier transform infrared spectroscopy (FTIR). Lower molecular weight PR formed more hydrogen bonds with the matrix and it had weaker temperature dependence. Combined with the results from DMA, we studied how molecular weight affected hydrogen bonding and thus further affected tanδmax.

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