Correlation between Mechanical Properties and Structure in Polymer Gels with Controlled Network Structure

2014 ◽  
Vol 1622 ◽  
pp. 7-16
Author(s):  
Takamasa Sakai ◽  
Yuki Akagi ◽  
Ung-il Chung
Keyword(s):  
Elastic Modulus ◽  
Fracture Energy ◽  
Molecular Design ◽  
Structural Parameters ◽  
Polymer Network ◽  
Polymer Networks ◽  
Network Models ◽  
Polymer Gels ◽  
Reaction Conversion ◽  
First Time

ABSTRACTElastmeric materials are of great importance in both academic and industrial field due to the soft and highly stretchable properties. Thus, many theories and models are proposed to correlate the physical properties and structural parameters. However, in general, it is difficult to validate these models experimentally. Thus, to this day, we do not know the requirement conditions for each model or even the validity of each model. The validation of these models has been inhibited by the inherent heterogeneity of polymer networks.Recently, we, for the first time, succeeded in fabricating polymer network with extremely suppressed heterogeneity with a novel molecular design of prepolymers. The homogeneous polymer network, called Tetra-PEG gel, is prepared by AB-type crosslink-coupling of mutually reactive tetra-arm prepolymers. In this study, we examined the models of elastic modulus and fracture energy using Tetra-PEG gel as a model system. We controlled the structural parameters with tuning the molecular weight and concentration of prepolymers, and reaction conversion of the reaction. This series of controlled network structures, for the first time, enabled us to quantitatively examine these models. We performed the stretching and tearing measurements for these polymer gels. As for the elastic modulus, we observed the shift of the models from the phantom to affine network models around the overlapping concentration of prepolymers. As for the fracture energy, we confirmed the validity of the Lake-Thomas model, which is the most popular model predicting fracture energies of elastomers.

Bimodality and Increased Amount of Crosslinker Enhances Tensile Properties of the Silicone Networks

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Gul Bali Shah
Keyword(s):  
Elastic Modulus ◽  
Tensile Properties ◽  
Phase Inversion ◽  
Volume Fraction ◽  
Polymer Networks ◽  
Short Chain ◽  
Percent Elongation ◽  
Bimodal Networks ◽  
Crosslinker Concentration ◽  
First Time

AbstractThe effect of bimodality i.e. blending short and long chain (0 to 80 % w/w) silicone prepolymers, and that of concentration of the crosslinker on the tensile properties such as percent elongation at break (%Eb), ultimate tensile strength (UTS), 100 % modulus and elastic modulus (E) has been investigated. It was found out that the greater amount of crosslinker used for crosslinking provide an additional reinforcement to the silicone network whereas bimodality further significantly accentuates this effect. Remarkably, the %Eb of the silicone networks was found to increase to an average of 2.4 times than that of the monomodal network, cured in each of the three series of bimodal networks cured with 3.9, 9.1 and 12.3% of crosslinker. The optimum property in each case was observed at about 70 mol % of P100. The over all order of sensitivity of these properties up to about 70 mol % of short chain prepolymer has been observed to be as: %Eb > UTS > 100% modulus > elastic modulus. It has been shown that in addition to the previously published reports the tensile properties are acutely dependent not only upon the degree of crosslinking and primary molecular weight; but also on bimodality and crosslinker concentration for preparation of the unfilled silicone polymer networks. The concept of phase inversion (or phase transition) associated with the optimum properties in polymer blends has for the first time been applied to the bimodal polymer networks. It has been observed that the maxima in tensile properties generally corresponds to phase inversion which takes place at 0.5 volume fraction (70 mol %) of short chain (P100) prepolymer which is in accordance with the literature for other systems.

scholarly journals A Guide through the Dental Dimethacrylate Polymer Network Structural Characterization and Interpretation of Physico-Mechanical Properties

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4057 ◽  
Author(s):  
Izabela Maria Barszczewska-Rybarek
Keyword(s):  
Mechanical Properties ◽  
Chemical Structure ◽  
Structural Parameters ◽  
Polymer Network ◽  
Polymer Networks ◽  
Impact Resistance ◽  
Organic Matrices ◽  
Dental Restorative

Material characterization by the determination of relationships between structure and properties at different scales is essential for contemporary material engineering. This review article provides a summary of such studies on dimethacrylate polymer networks. These polymers serve as photocuring organic matrices in the composite dental restorative materials. The polymer network structure was discussed from the perspective of the following three aspects: the chemical structure, molecular structure (characterized by the degree of conversion and crosslink density (chemical as well as physical)), and supramolecular structure (characterized by the microgel agglomerate dimensions). Instrumental techniques and methodologies currently used for the determination of particular structural parameters were summarized. The influence of those parameters as well as the role of hydrogen bonding on basic mechanical properties of dimethacrylate polymer networks were finally demonstrated. Mechanical strength, modulus of elasticity, hardness, and impact resistance were discussed. The issue of the relationship between chemical structure and water sorption was also addressed.

Nanostructural heterogeneity in polymer networks and gels

2015 ◽  
Vol 6 (31) ◽  
pp. 5515-5528 ◽  
Author(s):  
F. Di Lorenzo ◽  
S. Seiffert
Keyword(s):  
Polymer Network ◽  
Polymer Networks ◽  
Polymer Gels ◽  
Network Heterogeneity

Many polymer gels display network defects and crosslinking inhomogeneity. This review reflects and interrelates investigations on the characterization of such polymer-network heterogeneity and on its impact on the swelling, elasticity, and permeability of polymer gels.

Effect of Nematic Order Coupling on the Phase Diagrams of Side-Chain Polymer Gels with Liquid Crystal Solvent

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Richard Vendamme ◽  
Ulrich Maschke
Keyword(s):  
Phase Diagram ◽  
Polymer Network ◽  
Polymer Networks ◽  
Polymer Gels ◽  
Side Chain ◽  
Miscibility Gap ◽  
Polymer Backbone ◽  
Chain Polymer ◽  
Nematic Order ◽  
Solvent Lead

AbstractWe have explored the influence of nematic order coupling on the swelling and phase diagram of polymer networks in nematogenic low molar weight LC solvent, in view of the increasing importance of such systems in advanced optical devices. Firstly, one isotropic polyacrylate network and one nematic sidechain polyacrylate network is prepared. Immersing these two networks in nematic LC solvent lead to the formation of well-defined polymer gels with LC solvents and allow us to establish the phase diagram of these relatively new materials in the concentration-temperature frame. Results were critically analysed as a function of temperature and network nature (isotropic or nematic). We demonstrate that in the case of gel made from an isotropic polymer network, the LC solvents fails to form a nematic phase inside the gel due to the lack of anisotropic coupling. Moreover, in that case the gel shrinks below TNI Solvent because of a strong “entropic” incompatibility between the isotropic flexible coils and the LC nematogens. However, the situation is drastically different in the case of LC side-chain network due to a strong coupling of the nematic order between the mesogens of the solvents and those of the polymer backbone. In that case, tremendous distortions appear in the phase-diagram, in which we especially emphasize the apparition of a stable nematic gel phase and a miscibility gap between TNI Solvent and TNI Gel. Finally, results are critically examined and compared to the few studies found in the literature.

Freeze-etch TEM of aqueous polymer gel network morphology

1986 ◽  
Vol 44 ◽  
pp. 796-797
Author(s):  
J. A. N. Zasadzinski ◽  
R. K. Prud'homme
Keyword(s):  
Metal Ion ◽  
Polymer Network ◽  
Polymer Gels ◽  
Polymer Gel ◽  
Deformation History ◽  
Crosslinked Polymer ◽  
Aqueous Polymer ◽  
History Of ◽  
Gel Network ◽  
Network Morphology

The rheological and mechanical properties of crosslinked polymer gels arise from the structure of the gel network. In turn, the structure of the gel network results from: thermodynamically determined interactions between the polymer chain segments, the interactions of the crosslinking metal ion with the polymer, and the deformation history of the network. Interpretations of mechanical and rheological measurements on polymer gels invariably begin with a conceptual model of,the microstructure of the gel network derived from polymer kinetic theory. In the present work, we use freeze-etch replication TEM to image the polymer network morphology of titanium crosslinked hydroxypropyl guars in an attempt to directly relate macroscopic phenomena with network structure.

scholarly journals Monoclinic and Orthorhombic NaMnO2 for Secondary Batteries: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1230
Author(s):  
Jessica Manzi ◽  
Annalisa Paolone ◽  
Oriele Palumbo ◽  
Domenico Corona ◽  
Arianna Massaro ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Reversible Capacity ◽  
Beta Phase ◽  
X Ray Diffraction ◽  
Positive Electrodes ◽  
Detailed Structural Analysis ◽  
Physico Chemical ◽  
Sodium Batteries ◽  
The Impact ◽  
First Time

In this manuscript, we report a detailed physico-chemical comparison between the α- and β-polymorphs of the NaMnO2 compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic α-NaMnO2 shows larger reversible capacity exceeding 175 mAhg−1 at 10 mAg−1.

scholarly journals Shape memory polymer network with thermally distinct elasticity and plasticity

2016 ◽  
Vol 2 (1) ◽  
pp. e1501297 ◽  
Author(s):  
Qian Zhao ◽  
Weike Zou ◽  
Yingwu Luo ◽  
Tao Xie
Keyword(s):  
Shape Memory ◽  
Molecular Design ◽  
Shape Change ◽  
Shape Memory Polymer ◽  
Polymer Network ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Device Applications ◽  
Temperature Ranges ◽  
Rational Molecular Design

Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices.

Analysis of Microstructural Changes with Temperature of Thermally Sprayed WC-Co Coatings by Mechanical Spectroscopy

2012 ◽  
Vol 184 ◽  
pp. 313-318 ◽  
Author(s):  
Daniele Mari ◽  
L.M. Berger ◽  
S. Stahr
Keyword(s):  
Elastic Modulus ◽  
Sudden Increase ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
Hvof Spraying ◽  
Mechanical Parts ◽  
Spark Erosion ◽  
Temperature Scanning ◽  
First Time ◽  
Thermally Sprayed

Thermally sprayed hardmetal coatings can be used to improve the wear or fatigue resistance of mechanical parts. Depending on the deposition conditions, their microstructure and phase composition are out of equilibrium at different levels due to the extreme heating/cooling rates. In the present study, the changes that occur with temperature variation are monitored by mechanical spectroscopy. Requirements to specimen of mechanical spectroscopy created the need to prepare WC-17%Co coatings of 1.2 mm thickness by high velocity oxy-fuel (HVOF) spraying. The coatings, separated from the substrate by spark erosion, were tested in a forced torsion pendulum between room temperature and 1570 K at a temperature scanning rate of 1K/min. The mechanical loss spectrum shows different features. At 800 K, a maximum M1 is observed in coincidence with a sudden increase of the elastic modulus. The change of the elastic modulus is due to a densification of the material possibly related to cobalt recrystallization. A relaxation peak located at about 1100 K is typically found in WC-Co hardmetals. It is attributed to the movement of dislocations in the cobalt phase. A sharp peak is observed at 1510 K on heating and at 1410 K on cooling. Such peak is due to the reversible transition from W3Co3C at high temperature to W6Co6C at low temperature as proven by X-ray diffraction. The reversibility of such transformation was observed for the first time.

scholarly journals Single-Macromolecular Level Imaging of a Hydrogel Structure

2021 ◽  
Author(s):  
Ryuji Kiyama ◽  
Takayuki Nonoyama ◽  
Sedlacik Tomas ◽  
Hiroshi Jinnai ◽  
Jian Ping Gong
Keyword(s):  
Polymer Network ◽  
Mesh Size ◽  
Fixation Method ◽  
Gel Properties ◽  
Cell Scaffolds ◽  
Transmission Electron ◽  
Hydrogel Network ◽  
Network Observation ◽  
Surface Network ◽  
First Time

Hydrogels are promising materials for several applications, including cell scaffolds and artificial load-bearing substitutes (cartilages, ligaments, tendons, etc.). Direct observation of the nanoscale polymer network of hydrogels is essential in understanding its properties. However, imaging of individual network strands at the molecular level is not achieved yet due to the lack of suitable methods. Herein, for the first time, we developed a novel mineral-staining method and network fixation method for transmission electron microscopy observation to visualize the hydrogel network in its unperturbed conformation with nanometer resolution. Surface network observation indicates that the length of surface dangling chains, which play a major role in friction and wetting, can be estimated from the gel mesh size. Moreover, bulk observations reveals a hierarchical formation mechanism of gel heterogeneity. These observations have the great potential to advance gel science by providing comprehensive perspective that link bulk gel properties with nanoscale.

scholarly journals In Vivo Reconstruction of the Acetabular Bone Defect by the Individualized Three-Dimensional Printed Porous Augment in a Swine Model

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jun Fu ◽  
Yi Xiang ◽  
Ming Ni ◽  
Xiaojuan Qu ◽  
Yonggang Zhou ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Bone Defect ◽  
Bone Ingrowth ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Acetabular Bone ◽  
Acetabular Bone Defect ◽  
3D Printed ◽  
Matching Degree

Background and Purpose. This study established an animal model of the acetabular bone defect in swine and evaluated the bone ingrowth, biomechanics, and matching degree of the individualized three-dimensional (3D) printed porous augment. Methods. As an acetabular bone defect model created in Bama miniswine, an augment individually fabricated by 3D print technique with Ti6Al4V powders was implanted to repair the defect. Nine swine were divided into three groups, including the immediate biomechanics group, 12-week biomechanics group, and 12-week histological group. The inner structural parameters of the 3D printed porous augment were measured by scanning electron microscopy (SEM), including porosity, pore size, and trabecular diameter. The matching degree between the postoperative augment and the designed augment was assessed by CT scanning and 3D reconstruction. In addition, biomechanical properties, such as stiffness, compressive strength, and the elastic modulus of the 3D printed porous augment, were measured by means of a mechanical testing machine. Moreover, bone ingrowth and implant osseointegration were histomorphometrically assessed. Results. In terms of the inner structural parameters of the 3D printed porous augment, the porosity was 55.48 ± 0.61 % , pore size 319.23 ± 25.05   μ m , and trabecular diameter 240.10 ± 23.50   μ m . Biomechanically, the stiffness was 21464.60 ± 1091.69   N / mm , compressive strength 231.10 ± 11.77   MPa , and elastic modulus 5.35 ± 0.23   GPa , respectively. Furthermore, the matching extent between the postoperative augment and the designed one was up to 91.40 ± 2.83 % . Besides, the maximal shear strength of the 3D printed augment was 929.46 ± 295.99   N immediately after implantation, whereas the strength was 1521.93 ± 98.38   N 12 weeks after surgery ( p = 0.0302 ). The bone mineral apposition rate (μm per day) 12 weeks post operation was 3.77 ± 0.93   μ m / d . The percentage bone volume of new bone was 22.30 ± 4.51 % 12 weeks after surgery. Conclusion. The 3D printed porous Ti6Al4V augment designed in this study was well biocompatible with bone tissue, possessed proper biomechanical features, and was anatomically well matched with the defect bone. Therefore, the 3D printed porous Ti6Al4V augment possesses great potential as an alternative for individualized treatment of severe acetabular bone defects.

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