Rubber-Modified Glassy Amorphous Polymers Prepared via Chemically Induced Phase Separation. 4. Comparison of Properties of Semi- and Full-IPNs, and Copolymers of Acrylate−Aliphatic Epoxy Systems

Jansen, Bjp Bernard; Rastogi, Sanjay; Meijer, Heh Han; Lemstra, PJ Piet

doi:10.1021/ma981407f

Cited by 50 publications

(52 citation statements)

References 13 publications

(19 reference statements)

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“…This was inspired by synchrotron experiments on a similar system, PMMAaliphatic epoxy blends with extremely small structures in the order of 30 nm. [56][57][58][59] Under low speed testing ductile behavior was found since the material was able to initiate voids within the rubbery domain prior to shear yielding. Under high loading rates, realized by notching the sample, the material behaved brittle and no cavitation occurred.…”

Section: Results Of Analyses Of Improved Microstructuresmentioning

confidence: 99%

Multi‐Scale Analysis of Mechanical Properties of Amorphous Polymer Systems

Meijer

Govaert

2003

Macro Chemistry & Physics

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Use of proper constitutive equations for the intrinsic behavior of glassy polymers (including yield, strain softening and hardening) allows nowadays for analyzing the mechanical response of homogeneous and heterogeneous polymer systems in great detail. Analyses are performed on both the periodic RVE, representative volume element, level and, via a MLFEM, multi‐level finite element method, also on the macroscopic level of e.g. a notched, scratched tensile test bar. Introduction of a failure criterion, in this case the critical tri‐axial stress that initiates crazing, allows for the prediction of brittle‐to‐tough transitions, both as a function of temperature as well as of the absolute critical local material thickness. The analyses give clear suggestions towards possible directions to optimize the microstructure in heterogeneous polymer systems in order to obtain the ultimate toughness of polymers.

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Section: Results Of Analyses Of Improved Microstructuresmentioning

confidence: 99%

Multi‐Scale Analysis of Mechanical Properties of Amorphous Polymer Systems

Meijer

Govaert

2003

Macro Chemistry & Physics

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“…Relative low temperatures, between 80 and 120°C, are required to obtain homogeneous solutions. The cloud point temperatures reported in the literature 4,15 for high molar mass PPE/epoxy blends are in the range of 160°C. As expected, the decrease in the PPE molar mass enhances the miscibility of the system, resulting in a considerable shift of the cloud point curve to lower temperatures.…”

Section: Initial Phase Diagrammentioning

confidence: 94%

“…The chemical structure of the substituted imidazoles does not influence greatly the mechanism of epoxy homopolymerization, 8,11 except when the Nhydrogen function is reacted 9 (1-substitution). The blending of epoxy TS with high-temperatureresistant TP, like polyetherimide (PEI) 2,3,6,13,14 and poly(phenylene ether) (PPE), 4,[15][16][17][18][19] have been widely studied as a means to toughen epoxy network 6,14,15 or to improve processing of the TP polymer. 4 Most of the studies reported use nonreactive high molar mass TP, which significantly improve the fracture toughness only when bicontinuous or inverted structures are generated.…”

Section: Introductionmentioning

confidence: 99%

Poly(phenylene ether)/epoxy thermoset blends based on anionic polymerization of epoxy monomer

Prolongo

Cabanelas

Fine

et al. 2004

J of Applied Polymer Sci

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Low molar mass poly (phenylene ether) (LMW-PPE) with phenol-reactive chain ends was used as modifier of epoxy thermoset. The epoxy monomer was diglycidylether of bisphenol A (DGEBA), and several imidazoles were used as initiators of anionic polymerization. The curing and phase separation processes were investigated by different techniques: Differential Scanning Calorimetry, Size Exclusion Chromatography, and Light Transmission measurements. The final morphology of blends was observed by Environmental Scanning Electron Microscopy and Transmission Electron Microscopy. The epoxy network is obtained by imidazole initiated DGEBA homopolymerization. Initial LMW-PPE/DGEBA mixtures show an UCST behavior with cloud point temperatures between 40 and 90°C. PPE phenol end-groups can react with epoxy, leading to a better interaction between phases. The curing mechanism and phase separation process are not influenced by the chemical structure of initiators, except when reactive amine groups are present. The phase inversion is observed at 30 wt % of PPE. The mixtures with amine-substituted imidazole present important differences in the initial miscibility and curing process interpreted in terms of fast room temperature amine-epoxy reaction during blending. Final domain size is affected by this prereaction.

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“…That means that to some extent there was a microscopic phase separation of both networks, which has been proven in other IPN structures. [33] As a result, simultaneous IPN hydrogels exhibit two separated LCST.…”

Section: Thermal Analysismentioning

confidence: 99%

Temperature‐Sensitive Simultaneous Interpenetrating Polymeric Networks With Improved Mechanical Properties and Shrinking Kinetics

et al. 2009

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Hydrogels are hydrophilic, three-dimensional polymeric networks, which can absorb and retain a large amount of water, but do not dissolve in it due to the existence of crosslinking points. [1,2] In the past three decades, stimuli-responsive hydrogels, which exhibit drastic volume phase transitions in response to environmental changes, have been considerably investigated. [1][2][3][4] Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels undergo sharp swelling/deswelling behavior at around 32-34 8C, which is called lower critical solution temperature (LCST). Due to the unique property, PNIPAAm-related hydrogels have been developed to design different biodevices, such as drug release systems, biosensors, matrix for tissue engineering, etc. [5][6][7][8][9][10] Conventional PNIPAAm hydrogels have certain limitations, such as a slow deswelling rate when changing the temperature from below to above LCST due to the formation of a thick, dense layer on the surface region, which prevents the freed water molecules from diffusing out. In some applications, such as controlled release systems and sensors, fast responsive properties are critically important. Many approaches, such as the phase separation technique, [11][12][13][14] and template polymerization [15,16] have been explored to prepare fast responsive PNIPAAm hydrogels with porous microstructures. These porous structures are able to destroy the dense surface layer and allow water molecules to diffuse out freely, so these PNIPAAm hydrogels exhibited fast responsive properties. However, due to the porous and heterogeneous structures, the polymer fractions of these networks are very low and the water swelling ratios (SRs) are high, leading to poor mechanical strength, which made it difficult to handle these materials. For example, when the hydrogels are used as an implant drug delivery device, the materials need to be implanted as well as removed once the release is finished. If these materials were too soft and easy to break during handling, it would be difficult to be completely removed through traditional surgical procedures. [5] There exists a need to improve the mechanical properties of the hydrogels.Much attention has been dedicated to the enhancement of the mechanical properties of PNIPAAm hydrogels. Introducing another polymeric network into PNIPAAm hydrogel to form interpenetrating polymeric networks (IPN) is also a promising and exciting choice to obtain improved properties as compared to the conventional PNIPAAm hydrogel. [17][18][19][20][21][22] According to the synthesis process, there are two different types: sequential IPN and simultaneous IPN. [18] For sequential IPN, one network is firstly obtained and then swollen with a second cross-linking system consisting of monomer(s), cross-linker and initiator, which is subsequently polymerized within the first one. In the case of simultaneous IPN, precursors or monomers for both kinds of polymeric networks are mixed together with their specific cross-linking agents and initiators, and then the resulting mixture is c...

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Rubber-Modified Glassy Amorphous Polymers Prepared via Chemically Induced Phase Separation. 4. Comparison of Properties of Semi- and Full-IPNs, and Copolymers of Acrylate−Aliphatic Epoxy Systems

Cited by 50 publications

References 13 publications

Multi‐Scale Analysis of Mechanical Properties of Amorphous Polymer Systems

Multi‐Scale Analysis of Mechanical Properties of Amorphous Polymer Systems

Poly(phenylene ether)/epoxy thermoset blends based on anionic polymerization of epoxy monomer

Temperature‐Sensitive Simultaneous Interpenetrating Polymeric Networks With Improved Mechanical Properties and Shrinking Kinetics

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