Some Attempts to Force Poly(Dimethylsiloxane) Chains through Zeolite Cavities to Improve Elastomer Reinforcement

1999 ◽  
Vol 72 (1) ◽  
pp. 138-151 ◽  
Author(s):  
Zhengcai Pu ◽  
James E. Mark ◽  
Gregory Beaucage
Keyword(s):  
Mechanical Properties ◽  
Polymer Chains ◽  
Synthetic Approach ◽  
Cavity Size ◽  
Strain Measurements ◽  
X Ray ◽  
X Ray Scattering ◽  
Pdms Elastomer ◽  
Equilibrium Swelling ◽  
Reinforcing Effects

Abstract The reinforcing effects of zeolites in poly(dimethylsiloxane) (PDMS) elastomers were characterized using two preparative approaches. In the first, end-functionalized polymer chains were blended into the zeolite, and were then endlinked into the required network structure. The second approach represented an attempt to force some chains through the cavities, by blending the monomer itself into the zeolite and then polymerizing it to obtain the PDMS elastomer. The two types of zeolite-filled PDMS were characterized using stress-strain measurements in elongation, equilibrium swelling, and small-angle X-ray scattering. The second synthetic approach did seem to give improvements in mechanical properties, particularly when the average cavity size of the zeolite particles was relatively large. Ascribing the observed improvements in reinforcement at least partly to the threading of some PDMS chains through the zeolites was supported by the results obtained in the swelling and scattering experiments.

Comparative Studies on Photoelasticity of Elastomers and Plastomers

1948 ◽  
Vol 21 (4) ◽  
pp. 790-798
Author(s):  
Wilfried Heller ◽  
Hans Oppenheimer
Keyword(s):  
Mechanical Properties ◽  
Film Structure ◽  
Polymer Chains ◽  
X Ray Diffraction ◽  
Photoelastic Method ◽  
Double Refraction ◽  
X Ray ◽  
Transparent Films ◽  
X Ray Scattering

Abstract Transparent films of elastomers and plastomers were found to differ sufficiently in their photoelastic behavior to make stress double refraction a useful criterion of the prospective mechanical properties of a given material. The stress double refraction in such films is mostly an effect of deformation, of orientation, or of both deformation and orientation of polymer chains. In such polymers, however, which crystallize under stress, a large part of the optical effect may be due to oriented crystallization. In addition to its practical value as a testing method for polymers, the photoelastic method offers, therefore, particularly in combination with simultaneous investigations of mechanical properties, the prospect of correlating mechanical properties of a polymer film with its internal structure, and of correlating changes in both qualities on exposure of the film to different degrees of stress. Although results obtained on such films, by means of x-ray diffraction or x-ray scattering and electron-diffraction, are, in general, easier to interpret, the photoelastic method has the considerable advantage of making possible a quantitative follow-up of rapid changes in film structure, e.g., of relaxations.

Preparations, Structures, and Properties of Polysiloxane-Silica Composites Prepared from a Variety of Hydrolyzable Precursors

1998 ◽  
Vol 520 ◽  
Author(s):  
J. M. Breiner ◽  
J. E. Mark ◽  
G. Beaucage
Keyword(s):  
Mechanical Properties ◽  
Small Angle ◽  
Stress Strain ◽  
Equilibrium Stress ◽  
Strain Measurements ◽  
X Ray ◽  
X Ray Scattering ◽  
Structures And Properties ◽  
Catalyzed Reactions

ABSTRACTPoly(dimethylsiloxane) (PDMS) networks were prepared by tetrafunctionally endlinking hydroxyl-terminated chains with tetraethoxysilane (TEOS). The resulting networks were filled in-situ by hydrolysis-condensation reactions that were either acid or base catalyzed reactions on some novel precursors. These precursors included star-shaped molecules, rings, linear comb-like chains, and pre-hydrolyzed products of silanes such as TEOS. Both monomethoxy and trimethoxy groups were used as hydrolyzable groups on these molecules. The structures of the resulting composites were examined by small-angle X-ray scattering, and their mechanical properties were determined using equilibrium stress-strain measurements in elongation. Novel precursors with monomethoxy functionalities did not generate stable particulates, but those with trimethoxy functionalities did, with some improvements in mechanical properties. Partially-hydrolyzed TEOS provided the best reinforcement of these PDMS elastomers.

Poly(Dimethylsiloxane) Elastomers from Aqueous Emulsions: II. Mechanical Properties

1998 ◽  
Vol 71 (5) ◽  
pp. 928-940 ◽  
Author(s):  
J. E. Mark ◽  
D. W. McCarthy
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Extension ◽  
Preceding Paper ◽  
Aqueous Environment ◽  
Strain Measurements ◽  
Tin Catalyst ◽  
Equilibrium Swelling ◽  
Crosslinker Concentration ◽  
Reinforcing Effects ◽  
State Increase

Abstract Stress—strain measurements in simple uniaxial extension were used to characterize the mechanical properties of the elastomers prepared from poly(dimethylsilxoxane) emulsions as described in the preceding paper. The studies were carried out on the materials in the unswollen state, after they had received different treatments, specifically no aging, aging in the dry state, or aging in the wet (emulsion) state. Increase in silane crosslinker concentration was found to increase nominal stresses and moduli but to decrease extensibility, two changes that parallel the observed decreases in soluble polymer fractions and extents of equilibrium swelling reported earlier. The energy for rupture (“toughness”) frequently stays roughly constant because the decreased extensibility at least partially offsets the increased stresses. The changes in mechanical properties are due both to increased crosslinking and to reinforcing effects from silica generated from the silane, with the latter effect generally being the more important. The mechanical properties are much more affected by aging in the wet state, as opposed to aging in the dry state. For example, wet-aged elastomers generally had values of the nominal stress and modulus that were consistently lower than those for the unaged elastomers. Wet aging appears to be the result of the continual breaking and reforming of siloxane bonds in the aqueous environment of the emulsion, as probably accelerated by the presence of the tin catalyst.

scholarly journals Copper Containing Glass-Based Bone Adhesives for Orthopaedic Applications: Glass Characterization and Advanced Mechanical Evaluation

2020 ◽  
Author(s):  
Sahar. Mokhtari ◽  
Anthony.W. Wren
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Viscoelastic Behavior ◽  
Polymer Chains ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compression Data

AbstractThis study addresses issues with currently used bone adhesives, by producing novel glass based skeletal adhesives through modification of the base glass composition to include copper (Cu) and by characterizing each glass with respect to structural changes. Bioactive glasses have found applications in fields such as orthopedics and dentistry, where they have been utilized for the restoration of bone and teeth. The present work outlines the formation of flexible organic-inorganic polyacrylic acid (PAA) – glass hybrids, commercial forms are known as glass ionomer cements (GICs). Initial stages of this research will involve characterization of the Cu-glasses, significant to evaluate the properties of the resulting adhesives. Scanning electron microscopy (SEM) of annealed Cu glasses indicates the presence of partial crystallization in the glass. The structural analysis of the glass using Raman suggests the formation of CuO nanocrystals on the surface. X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy (XPS) further confirmed the formation of crystalline CuO phases on the surface of the annealed Cu-glass. The setting reaction was studied using Fourier transform infrared spectroscopy (ATR-FTIR). The mechanical properties of the Cu containing adhesives exhibited gel viscoelastic behavior and enhanced mechanical properties when compared to the control composition. Compression data indicated the Cu glass adhesives were efficient at energy dissipation due to the reversible interactions between CuO nano particles and PAA polymer chains.

Inorganic-Organic Hybrid Polymers from Surface-Modified Oxometallate Clusters

2000 ◽  
Vol 628 ◽  
Author(s):  
Ulrich Schubert ◽  
Gregor Trimmel ◽  
Bogdan Moraru ◽  
Walter Tesch ◽  
Peter Fratzl ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Cluster Size ◽  
Polymer Chains ◽  
Scattering Data ◽  
Hybrid Polymers ◽  
X Ray ◽  
Organic Hybrid ◽  
X Ray Scattering ◽  
Solvent Uptake ◽  
Surface Modified

ABSTRACTInorganic-organic hybrid polymers were prepared by radical polymerization of methacrylic acid or methyl methacrylate with the (meth) acrylate-substituted oxozirconium and oxotitanium clusters Zr6(OH)4O4(OMc)12(OMc = methacrylate), Zr4O2(OMc)12, Ti6O4(OEt)8(OMc)8 and Ti4O2(OPri)6(OAcr)6(OAcr = acrylate). A few mol% of cluster is sufficient for an efficient cross-linking of the polymer chains. Small-angle X-ray scattering data indicate that the cluster size is retained in the polymers and that the microstructure of the cluster cross-linked samples can be described by a dispersion of identical spherical or disk-shaped clusters in the polymer. The obtained hybrid polymers exhibit a higher thermal stability because depolymerization reactions are inhibited. Contrary to undoped poly (methyl methacrylate), the cluster cross-linked polymers are insoluble but swell in organic solvents. The solvent uptake upon swelling decreases with an increasing amount of polymerized cluster.

The Effect of Humping Semi-Enclosed Cage Structure on Polymer Chains Characteristics of TSI-POSS/PU Hybrid Composites

2015 ◽  
Vol 751 ◽  
pp. 30-34 ◽  
Author(s):  
Rui Pan ◽  
Robert Shanks ◽  
Yong Liu
Keyword(s):  
Hybrid Composites ◽  
Mean Square Displacement ◽  
Phenyl Isocyanate ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Cage Structure ◽  
X Ray ◽  
X Ray Scattering ◽  
The Mean ◽  
Oligomeric Silsesquioxane

Trisilanolisobutyl polyhedral oligomeric silsesquioxane (TSI-POSS) with the humping semi-enclosed cage structure, was incorporated in concentrations of 7, 13 and 22 wt% into 4,4’-methylenebis (phenyl isocyanate) (MDI) and glycerol propoxylate to prepare TSI-POSS/PU hybrid composites, respectively. The polymer chain characteristics of these composites were investigated by wide angle X-ray scattering (WAXS) and molecular dynamics simulation approach. The results indicate that with TSI-POSS concentration increasing up to 22 wt% in hybrid composites, due to the humping semi-enclosed cage structure, distinct crystallite clusters are formed which lead to the micro-phase separation in composites. Meanwhile, the mobility of TSI-POSS cores and backbones in PU composites has been evaluated by the mean square displacement, which confirms that as the concentration of TSI-POSS increasing, the mobility of polymer chains are restricted apparently. Furthermore, it also indicates that the incorporation of TSI-POSS is as the rigid core in hybrid composites.

Reinforcement from In-Situ Precipitated Silica in Polysiloxane Elastomers under Various Types of Deformation

1992 ◽  
Vol 274 ◽  
Author(s):  
James E. Mark ◽  
Shuhong Wang ◽  
Ping Xu ◽  
Jianye Wen
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Elongation ◽  
Compression Set ◽  
Precipitated Silica ◽  
Equilibrium Swelling ◽  
Rupture Energy ◽  
End Linking ◽  
Reinforcing Effects

ABSTRACTElastomeric networks prepared by tetrafunctionally end linking hydroxyl-terminated poly(dimethylsiloxane) chains (PDMS) were filled by the in-situ precipitation of silica. The resulting networks were investigated under uniaxial elongation, biaxial extension, shear, and torsion in order to characterize the resulting changes in mechanical properties. Compared with the unfilled networks, the silica-filled materials showed large reinforcing effects. Specifically, their values of the modulus, ultimate strength, and rupture energy increased significantly. The results thus indicate that the PDMS networks filled by the in-situ precipitation of silica have very good mechanical properties in several, rather different deformations. Examples of other deformations of interest are equilibrium swelling, and dynamic cycling for characterization of compression set.

Structure Evolution of Thermotropic Polymers by Thermal Annealing. A Light and X-Ray Scattering Study

2015 ◽  
Vol 1765 ◽  
pp. 65-70
Author(s):  
Adriana Reyes-Mayer ◽  
Angel Romo-Uribe ◽  
Michael Jaffe
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Treatment ◽  
Structure Evolution ◽  
Wide Angle ◽  
Extrusion Axis ◽  
X Ray ◽  
X Ray Scattering ◽  
Extruded Films ◽  
Ray Scattering

ABSTRACTSmall-angle light scattering (SALS) and wide-angle X-ray scattering (WAXS) were used to study the influence of heat treatment on the texture and microstructure of extruded films of high-performance thermotropic liquid crystal polymers (LCPs). The microstructure was correlated with tensile mechanical properties. LCPs based on random units of hydroxybenzoic acid (B), hydroxynaphthoic acid (N), terephthalic acid (TA) and biphenol (BP) were supplied by the former Hoechst Celanese Corp. as 50 μm thick extruded films. The LCPs, denoted B-N, COTBP and RD1000, have B and N as common co-monomers and vary the other co-monomers. Thus, this study also enabled the investigation of the influence of monomer composition on microstructure and mechanical properties. Heat treatments were carried out at temperatures close to the solid-to-nematic transition (Ts→n) for periods up to 5 h, under dry air conditions. The thermal treatment produced either two endotherms or a small increase of Ts→n (B-N and RD1000), or Ts→n increased significantly (COTBP). Moreover, when heat treatment was carried out approximately 40°C below the respective Ts→n, the mechanical Young’s modulus, E, along the extrusion axis increased for all LCPs. Strikingly, for COTBP, E increased over 100% relative to the as-extruded film. The results also showed that the optimum treatment time for improving the Young modulus was between 3 and 4 h. Wide-angle X-ray scattering showed a significant sharpening of crystalline reflections and concentration of the 002 meridional reflection as a result of thermal treatment, suggesting the elimination of defects and a better alignment of the molecular chains along the extrusion axis. This would explain the increase in tensile modulus.

Sign in / Sign up

Export Citation Format

Share Document