Thermoreversible Crosslinking of Maleated Ethylene/Propylene Rubber Using Ionic Interactions, Hydrogen Bonding and a Combination Thereof

2008 ◽  
Vol 81 (1) ◽  
pp. 96-109 ◽  
Author(s):  
M. A. J. van der Mee ◽  
J. G. P. Goossens ◽  
M. van Duin
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Room Temperature ◽  
Microphase Separation ◽  
Distinct Advantage ◽  
Ionic Interactions ◽  
Ethylene Propylene ◽  
Bonded Materials ◽  
Compression Set ◽  
High Degree

Abstract Maleated ethylene/propylene copolymer (MAn-g-EPM) was thermoreversibly crosslinked using different routes, i.e. ionic interactions (ionomers), hydrogen bonding and a combination thereof. Microphase separation into polar MAn-rich aggregates occurs for MAn-g-EPM and all crosslinked materials, which act as physical crosslinks. The crosslink density does not change upon modification, but the strength of the aggregates is significantly increased, resulting in improved mechanical properties. All materials except the potassium ionomer with high degree of neutralization (DN) could be remolded into homogeneous and smooth films without chemical changes, indicating that the crosslinks are truly thermoreversible. A comparison of the mechanical properties, i.e. tensile properties and compression set at room temperature, for the different crosslinking routes showed that the poorest properties are obtained for hydrogen-bonded materials. The potassium ionomer with high DN has the best properties by far, but is difficult to process. Comparable mechanical properties are obtained for zinc ionomers, potassium ionomers with low DN and amide-salts, which combine ionic interactions and hydrogen bonding. The amide-salts have a distinct advantage in processing over the ionomers, since they can be compression molded at much lower temperatures, although high temperatures should be avoided because of irreversible imide formation.

Thermoreversible Cross-Linking of Maleated Ethylene/Propylene Copolymers Using Hydrogen-Bonding and Ionic Interactions

2006 ◽  
Vol 39 (9) ◽  
pp. 3441-3449 ◽  
Author(s):  
C. X. Sun ◽  
M. A. J. van der Mee ◽  
J. G. P. Goossens ◽  
M. van Duin
Keyword(s):  
Hydrogen Bonding ◽  
Ionic Interactions ◽  
Cross Linking ◽  
Ethylene Propylene

scholarly journals Preparation, Structural Characterization, and Biomedical Applications of Gypsum-Based Nanocomposite Bone Cements

2021 ◽  
Author(s):  
Hesham F. El-Maghraby ◽  
Yaser E. Greish
Keyword(s):  
Mechanical Properties ◽  
Calcium Phosphate ◽  
Structural Characterization ◽  
Room Temperature ◽  
Bone Cements ◽  
Calcium Phosphate Cements ◽  
Metallic Implants ◽  
Hard Tissues ◽  
Subsequent Conversion ◽  
High Degree

Hard tissues are natural nanocomposites comprising collagen nanofibers that are interlocked with hydroxyapatite (HAp) nanocrystallites. This mechanical interlocking at the nanoscale provides the unique properties of hard tissues (bone and teeth). Upon fracture, cements are usually used for treatment of simple fractures or as an adhesive for the treatment of complicated fractures that require the use of metallic implants. Most of the commercially available bone cements are polymer-based, and lack the required bioactivity for a successful cementation. Besides calcium phosphate cements, gypsum is one of the early recognized and used biomaterials as a basi for a self-setting cementation. It is based on the controlled hydration of plaster of Paris at room temperature and its subsequent conversion to a self-setting solid gypsum product. In our work, we have taken this process further towards the development of a set of nanocomposites that have enhanced bioactivity and mechanical properties. This chapter will outline the formation, characterization, and properties of gypsum-based nanocomposites for bone cement applications. These modified cements can be formulated at room temperature and have been shown to possess a high degree of bioactivity, and are considered potential candidates for bone fracture and defect treatment.

Effect of thermal processing temperature on the microphase separation and mechanical properties of BAMO/THF polyurethane

2017 ◽  
Vol 37 (2) ◽  
pp. 169-176 ◽  
Author(s):  
Jian Xiaoxia ◽  
Hu Yiwen ◽  
Zheng Qilong
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Thermal Processing ◽  
Microphase Separation ◽  
Mechanical Analysis ◽  
Processing Temperature ◽  
X Ray ◽  
X Ray Scattering ◽  
Bonding Phase ◽  
And Storage

Abstract This paper describes the influence of thermal processing temperature on the microphase separation, hydrogen bonding, phase transitions and mechanical properties of 3,3-bis(azidomethyl)oxetane (BAMO)/tetrahydrofuran (THF) polyurethane binder, which is used for propellant. Fourier transform infrared (FTIR) spectroscopy confirmed that the intended polyurethane was synthesized and was used to determine the state of the local hydrogen bonding in these polyurethanes. The results showed that the thermal processing clearly imparts significant changes to the H-bonded environment and this was confirmed in a quantitative fashion using small-angle X-ray scattering (SAXS). The dynamic mechanical analysis (DMA) revealed rather significant changes in dynamic segmental relaxations and storage moduli for this series of BAMO/THF polyurethanes, which are in keeping with the findings from other experiments.

Dehydration Time Dependence on Piezoelectric and Mechanical Properties of Bovine Cornea

1999 ◽  
Vol 600 ◽  
Author(s):  
A. C. Jayasuriya ◽  
J. I. Scheinbeim ◽  
V. Lubkin ◽  
G. Bennett ◽  
P. Kramer
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Fourier Transform ◽  
Room Temperature ◽  
Piezoelectric Coefficient ◽  
Water Molecules ◽  
Wide Angle ◽  
X Ray ◽  
Mechanical Responses ◽  
Infra Red

AbstractThe Young's Modulus (E) and piezoelectric coefficient (d31) have been investigated as a function of dehydration time for bovine cornea at room temperature. The piezoelectric and mechanical responses observed were anisotropic for bovine cornea and d31 decreased, while E increased with dehydration. In addition, water molecules appear to increase the crystallinity (of collagen) in the cornea. With dehydration of the cornea, reduction of crystallinity and changes in hydrogen bonding were observed by Fourier Transform Infra Red (FTIR) and Wide Angle X-ray Diffracion (WAXD) measurements.

Effect of the Starting NCO/OH Molar Ratio on the Structure and Properties of Polyurethane

2011 ◽  
Vol 415-417 ◽  
pp. 1261-1264
Author(s):  
Yu Hua Yi ◽  
Hao Shi
Keyword(s):  
Mechanical Properties ◽  
Microphase Separation ◽  
Dynamic Mechanical Properties ◽  
Toluene Diisocyanate ◽  
Molar Ratio ◽  
Structure And Properties ◽  
Dynamic Mechanical ◽  
Compression Set

The present study described the effect of the starting NCO/OH molar ratio on the structure and properties of castable polyurethanes based on polytetrahydrofuran glycol (PTMG) and 2,4- toluene diisocyanate (TDI). The structural was tested by SEM. The result showed that higher starting NCO/OH molar ratio can lead to higher degree of microphase separation, decrease the compression set and improve the dynamic mechanical properties.

Effect of annealed titania on dielectric and mechanical properties of ethylene propylene diene monomer-titania nanocomposites

e-Polymers ◽  
2014 ◽  
Vol 14 (4) ◽  
pp. 267-275 ◽  
Author(s):  
Rakesh Manna ◽  
Suryakanta Nayak ◽  
Mostafizur Rahaman ◽  
Dipak Khastgir
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Ethylene Propylene Diene Monomer ◽  
Ethylene Propylene ◽  
Transmission Electron ◽  
Lower Dielectric Constant ◽  
Dynamic Light Scattering Technique ◽  
Dielectric And Mechanical Properties ◽  
Light Scattering Technique

AbstractFlexible ethylene propylene diene monomer (EPDM)-titania nanocomposites of different compositions were prepared by room temperature mixing using both neat and annealed titania. All these composites showed composition-dependent dielectric and mechanical properties, and composites with controlled dielectric properties could be made through judicial adjustment of the composition. The effect of moisture/filler heat treatment was also studied and found that composites with annealed titania showed lower dielectric constant than composites with normal titania. There was a significant improvement in mechanical properties, where composites with 60 parts per hundred parts of titania gave the optimum tensile strength. The particle size of titania particles was analyzed by high-resolution transmission electron microscopy (HRTEM) and a dynamic light scattering technique. The morphology and dispersion of titania particles in the EPDM matrix were studied by field emission scanning electron microscopy and HRTEM. Finally, different dielectric models were compared with experimental data, and the best match was achieved by the Lichtenecker model, which can be used as a predictive rule for different volume contents of titania filler in the EPDM matrix.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Solvent-assisted osmium staining of butyl acrylate and ethylene-propylene-diene in a styrene acrylonitrile matrix

1993 ◽  
Vol 51 ◽  
pp. 900-901 ◽  
Author(s):  
Gudrun A. Hutchins
Keyword(s):  
Butyl Acrylate ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Staining Procedure ◽  
Reactive Site ◽  
Ethylene Propylene ◽  
Minimal Distortion ◽  
Styrene Acrylonitrile ◽  
Engineering Polymers ◽  
Effective Reaction

In order to optimize the toughening effect of elastomers in engineering polymers, it is necessary to characterize the size, morphology and dispersion of the specific elastomer within the polymer matrix. For unsaturated elastomers such as butadiene or isoprene, staining with osmium tetroxide is a well established procedure. The residual carbon-carbon double bond in these materials is the reactive site and forms a 1,2-dilato complex with the OsO4. Incorporation of osmium tetroxide into the elastomer not only produces sufficient contrast for TEM, but also crosslinks the elastomer sufficiently so that ultramicrotomy can be accomplished at room temperature with minimal distortion.Blends containing saturated elastomers such as butyl acrylate (BA) and ethylene propylene diene monomer (EPDM) cannot be stained directly with OsO4 because effective reaction sites such as C=C or -NH2 are not available in sufficient number. If additional reaction sites can be introduced selectively into the elastomer by a chemical reaction or the absorption of a solvent, a modified, two-step osmium staining procedure is possible.

Autonomous self-healing polyisoprene elastomers with high modulus and good toughness based on the synergy of dynamic ionic crosslinks and highly disordered crystals

2020 ◽  
Vol 11 (41) ◽  
pp. 6549-6558
Author(s):  
Yohei Miwa ◽  
Mayu Yamada ◽  
Yu Shinke ◽  
Shoichi Kutsumizu
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Self Healing ◽  
High Modulus ◽  
Disordered Crystals ◽  
Ionic Crosslinks

We designed a novel polyisoprene elastomer with high mechanical properties and autonomous self-healing capability at room temperature facilitated by the coexistence of dynamic ionic crosslinks and crystalline components that slowly reassembled.

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