Enhancement in the Glass Transition Temperature in Latent Thiol-Epoxy Click Cured Thermosets

Guzmán, Dailyn; Ramis, Xavier; Fernández‐Francos, Xavier; Serra, Àngels

doi:10.3390/polym7040680

Cited by 41 publications

(43 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A negative side effect would be that the exothermicity of the second process would increase because of the higher excess of epoxy groups, but the reaction rate would still be low and therefore the crosslinking process could be easily controlled anyway. In addition, one can use other epoxy monomers/resins and change the amount of initiator or type of catalyst to control the reactivity of the curing process. Other dual‐curing thermosetting systems such as off‐stoichiometric thiol–acrylate or epoxy–amine could be used as well, providing suitable catalysts or initiators were used to activate the curing reactions in a controlled way in order to achieve a SHR and therefore enable easy thermal management during processing.…”

Section: Resultsmentioning

confidence: 99%

Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Romero

Fernández‐Francos

Ramis

2018

Polymer International

Self Cite

View full text Add to dashboard Cite

The sequential heat release (SHR) taking place in dual‐curing systems can facilitate thermal management and control of conversion and temperature gradients during processing of thick composite parts, hence reducing the appearance of internal stresses that compromise the quality of processed parts. This concept is demonstrated in this work by means of numerical simulation of conversion and temperature profiles during processing of an off‐stoichiometric thiol–epoxy dual‐curable system. The simulated processing scenario is the curing stage during resin transfer moulding processing (i.e. after injection or infusion), assuming one‐dimensional heat transfer across the thickness of the composite part. The kinetics of both polymerization stages of the dual‐curing system and thermophysical properties needed for the simulations have been determined using thermal analysis techniques and suitable phenomenological models. The simulations show that SHR makes it possible to reach a stable and uniform intermediate material after completion of the first polymerization process, and enables a better control of the subsequent crosslinking taking place during the second polymerization process due to the lower remaining exothermicity. A simple optimization of curing cycles for composite parts of different thickness has been performed on the basis of quality–time criteria, producing results that are very close to the Pareto‐optimal front obtained by genetic algorithm optimization procedures. © 2018 Society of Chemical Industry

show abstract

Section: Resultsmentioning

confidence: 99%

Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Romero

Fernández‐Francos

Ramis

2018

Polymer International

Self Cite

View full text Add to dashboard Cite

show abstract

“…Tertiary amines are commonly used as base catalysts in thiol-epoxy formulations, but they are usually too reactive, making it hard to control the reaction and shortening their pot-life. It was recently shown [25,26] that it is possible to increase the pot life of thiol-epoxy formulations by means of polymer-encapsulated amines or thermally stable aromatic-aliphatic ureas, being the former the most effective way. Thus, it is possible to prepare formulations, store them safely before application, and process them at temperatures high enough to quickly release the amine catalyst and produce a completely cured material in a short period of time.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Network Structure and Programming Temperature on the Shape-Memory Response of Thiol-Epoxy “Click” Systems

et al. 2015

Self Cite

View full text Add to dashboard Cite

This paper presents a new methodology to develop "thiol-epoxy" shape-memory polymers (SMPs) with enhanced mechanical properties in a simple and efficient manner via "click" chemistry by using thermal latent initiators. The shape-memory response (SMR), defined by the mechanical capabilities of the SMP (high ultimate strength and strain), the shape-fixation and the recovery of the original shape (shape-recovery), was analyzed on thiol-epoxy systems by varying the network structure and programming temperature. The glass transition temperature (T g ) and crosslinking density were modified using 3-or 4-functional thiol curing agents and different amounts of a rigid triglycidyl isocyanurate compound. The relationship between the thermo-mechanical properties, network structure and the SMR was evidenced by means of qualitative and quantitative analysis. The influence of the programming temperature (T prog ) on the SMR was also analyzed in detail. The results demonstrate the possibility of tailoring SMPs with enhanced mechanical capabilities and excellent SMR, and intend to provide a better insight into the relationship between the network structure properties, programming temperature and the SMR of unconstrained (stress-free) systems; thus, making it easier to decide between different SMP and to define the operative parameters in the useful life.

show abstract

“…Other typical hardeners of epoxy resins are polythiols [156][157][158][159] and polyisocyanates [160][161][162][163]. Like carboxylic acids, their nucleophilicity is usually much lower than amines or dihydrazides and base-catalyzed conditions must be used to observe adequate curing rates.…”

Section: Thiols and Isocyanatesmentioning

confidence: 99%

Control of reactions and network structures of epoxy thermosets

Vidil¹,

Tournilhac²,

Musso

et al. 2016

Progress in Polymer Science

312

252

View full text Add to dashboard Cite

Recent advances in macromolecular chemistry have revolutionized the way we perceive the synthesis of polymers. Polymerization, to be modern, must be "controlled", which usually means capable of producing macromolecules of well-defined structure. The purpose of this review is to examine how the chemistry of epoxy resins, an almost century-old chemistry, is also involved in this movement. Epoxy resins are characterized by both the flexibility of implementation and the qualities of the polymers obtained. Key materials in health-, mobility-and energy related technologies, these resins are heavily present in high-performance composites, electronic boards, adhesives and coatings. Currently, a large number of resins and hardeners are available on the market or described in the literature and an interesting point is that almost any combination of the two is possible. Common to all these recipes and processes is that a liquid (or soluble) resin at some point becomes insoluble and solid. It is very important to know how to manage this transition, physically known as the gel point, as it is the point after which the shape of the object is irreversibly set. Taking into account the variety of epoxy polymerization processespolyaddition, anionic or cationic polymerization-we detail a number of methods to program the occurrence of the gel point and how this type of control affects the structure of the growing network.

show abstract

Enhancement in the Glass Transition Temperature in Latent Thiol-Epoxy Click Cured Thermosets

Cited by 41 publications

References 16 publications

Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Effect of the Network Structure and Programming Temperature on the Shape-Memory Response of Thiol-Epoxy “Click” Systems

Control of reactions and network structures of epoxy thermosets

Contact Info

Product

Resources

About