Toward reliable morphology assessment of thermosets via physical etching: Vinyl ester resin as an example

Grishchuk, S.; Bonyár, Attila; Elsäßer, J.; Wolynski, Alexander; Karger‐Kocsis, J.; Wetzel, Bernd

doi:10.3144/expresspolymlett.2013.38

Cited by 7 publications

(4 citation statements)

References 9 publications

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“…This was confirmed recently [59]. It is worth noting that entangling of the phases in semi and full IPN structures is never on molecular level though the materials may feature one single T g [60]. 'Full' IPN denotes that both constituent continuous phases are crosslinked polymers.…”

Section: Semi Interpenetrating Network (Semi Ipns)supporting

confidence: 52%

Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing

Karger‐Kocsis

Kéki

2014

Express Polym. Lett.

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Shape memory (SM) biodegradable polymers (SMPs) and related composites are emerging smart materials in different applications. SMPs may adopt one (dual-shape), two (triple-shape) or several (multishape) stable temporary shapes and recover their permanent shape (or other temporary shapes in case of multi-shape versions) upon the action of an external stimulus. The external stimulus may be temperature, pH, water, light irradiation, redox condition etc. In most cases, however, the SMPs are thermally activated. The 'switching' or transformation temperature (T trans ), enabling the material to return to its permanent shape, is either linked with the glass transition (T g ) or with the melting temperature (T m ).Thus, SMPs are often subdivided based on their switch types into T g -or T m -based SMPs. As reversible 'switches' other mechanisms such as liquid crystallization and related transitions, supermolecular assembly/disassembly, irradiation-induced reversible network formation, formation and disruption of a percolation network, may also serve [1]. The permanent shape is guaranteed by physical or chemical network structures. The latter may be both on molecular and supramolecular levels. Linkages of these networks are termed net points. The temporary shape is created by mechanical deformation above T trans . In some cases the deformation temperature may be below Abstract. Shape memory polymers (SMPs) are capable of memorizing one or more temporary shapes and recovering to the permanent shape upon an external stimulus that is usually heat. Biodegradable polymers are an emerging family within the SMPs. This minireview delivers an overlook on actual concepts of molecular and supramolecular architectures which are followed to tailor the shape memory (SM) properties of biodegradable polyesters. Because the underlying switching mechanisms of SM actions is either related to the glass transition (T g ) or melting temperatures (T m ), the related SMPs are classified as T g -or T m -activated ones. For fixing of the permanent shape various physical and chemical networks serve, which were also introduced and discussed. Beside of the structure developments in one-way, also those in two-way SM polyesters were considered. Adjustment of the switching temperature to that of the human body, acceleration of the shape recovery, enhancement of the recovery stress, controlled degradation, and recycling aspects were concluded as main targets for the future development of SM systems with biodegradable polyesters.

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Section: Semi Interpenetrating Network (Semi Ipns)supporting

confidence: 52%

Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing

Karger‐Kocsis

Kéki

2014

Express Polym. Lett.

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“…9/a and b show the structure of the individual resins. In case of the neat resins nanoheterogeneous structure can be found, this morphology is similar to former published results by other researchers [25,26] where the structure of EP and VE was detected by AFM. The EP/VE resin has more complex structure (Fig.…”

Section: Resultssupporting

confidence: 91%

Development and mechanical properties of carbon fibre reinforced EP/VE hybrid composite systems

Mészáros¹,

Turcsán²

2014

Period. Polytech. Mech. Eng.

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In this study epoxy/vinyl ester (EP/VE) based hybrid thermoset resin was developed and used as a matrix in unidirectional Keywords Hybrid resin · fatigue · composite · epoxy · vinyl ester · IPN IntroductionIn the field of thermoset polymer composites the researchers work on materials and their combinations which give more favourable mechanical properties. The thermoset structural composites have great strength and modulus, but their toughness properties are often worse than that of ductile metals and alloys or thermoplastic matrix polymer composites. These high performance materials usually give rigid reactions to quickly forthcoming actions, loadings. The solution for toughening can be found in the micro-, or nano-scale structure of the thermoset polymer. In the fibre reinforced composites usually the matrix is responsible for the toughness, therefore mainly the matrix should be modified to improve of this property [1,2].Basically, there are two different ways to create micro-, or nano-structure in the polymers. The first opportunity is the hybridization of the reinforcing materials with micro or nano sized particles. Nowadays this technique is quite popular among researchers and manufacturers, because of the easy reproducibility of these composites. The effectiveness of this third phase is based on the properties of the particle itself and on the surface to volume ratio that has main role in the quality of the adhesion. The specific surface can be extremely huge in case of nanoparticles. Another way to achieve micro-or nanostructured systems is to change the matrix morphology by blending. In this approach researchers try to make a mixture of different polymers, which are well distributed in each other and the border area of their phases (interphases) has large surface, where a lot of secondary bounds are present. One example of such structure is the interpenetrating polymer network (IPN) system, in which the different polymer phases are not separated, but the polymer chains penetrates into the other crosslinked structure of the other phase. In these systems a sort of synergistic effects there can be found. Due to this fact the IPN structure can absorb remarkable amount of energy by their flexible properties. This feature can be manifested in mechanical, thermal and thermo-mechanical properties too [1][2][3].The mentioned synergistic effects and the compatibility of mixed polymers affect the thermo-mechanical properties.

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“…This kind of physical etching should reveal the morphology supposing that the ablation/degradation behavior of the morphology constituents is different. Detailed information to this section can be taken from our previous work .…”

Section: Methodsmentioning

confidence: 99%

Curing, gelling, thermomechanical, and thermal decomposition behaviors of anhydride‐cured epoxy (DGEBA)/epoxidized soybean oil compositions

Karger‐Kocsis

Grishchuk

Sorochynska

et al. 2013

Polymer Engineering & Sci

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The present work was aimed at studying the effects of incorporation of epoxidized soybean oil (ESO) in a standard bisphenol A-type epoxy resin (EP) cured by anhydride hardener. The EP/ESO ratio was set for 100/0, 75/25, 50/50, 25/75 and 0/100 (wt.%/wt.%). The investigations performed covered the curing, rheology (gelling), thermomechanical (TMA) and thermogravimetric analysis (TGA) of the EP/ESO compositions. The results showed that the dilution of EP with ESO was accompanied with marked changes in the curing, gelling behavior and final properties. Differential scanning calorimetry (DSC) revealed that the crosslinking of EP/ESO≥50/50 occurred in two steps. This has been considered for the cure schedule set. The gel time of EP/ESO, determined at T=100, 120, 140 o C, respectively, increased with increasing ESO content. The activation energy of gelling increased with increasing ESO content. The glass transition temperature decreased with increasing ESO content of the transparent samples. According to TMA the coefficient of thermal expansion in the glassy state increased with increasing ESO content but was independent of the latter in the rubbery stage. TGA indicated that with increasing ESO content the thermal degradation started earlier and the char yield decreased. The Ozawa, Flynn and Wall (OFW) approach was adapted to TGA tests to calculate 2 the activation energy of thermal degradation. The activation energy depended on the ESO content of the EP/ESO blends and also on their actual decomposition stage. The latter means a limitation for the OFW approach.

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Toward reliable morphology assessment of thermosets via physical etching: Vinyl ester resin as an example

Cited by 7 publications

References 9 publications

Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing

Biodegradable polyester-based shape memory polymers: Concepts of (supra)molecular architecturing

Development and mechanical properties of carbon fibre reinforced EP/VE hybrid composite systems

Curing, gelling, thermomechanical, and thermal decomposition behaviors of anhydride‐cured epoxy (DGEBA)/epoxidized soybean oil compositions

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