Doctor of Philosophy

dissertationThe epoxy resin market is faced with an ever increasing demand for a "designer" range of properties for the epoxy end-use products. Therefore, it is necessary to obtain a complete mechanism and accurate kinetic model that has predictive capabilities. This dissertation addresses the issue in two sections. The first section is an analysis of systematic theoretical studies on the mechanisms of four main curing reactions, epoxy-amine, epoxy-phenol, epoxy-acid and epoxy-anhydride, at the molecular-level using B3LYP density functional theory. The strength of these mechanistic models is their ability to extrapolate to different reactions that use a particular epoxy resin, a particular curing agent and/or a particular catalyst. The examination of all possible reaction pathways for each curing system can allow us to predict the most preferable pathway in the system and can enable the development of a more accurate kinetic model for the system. In addition, it provides insight into the role of tertiary amines in catalyzing the curing reaction. The second section involves the development of a new kinetic model for the epoxy-amine curing system guided by quantum chemistry calculations. This accurate kinetic model for an epoxy-amine curing system has the potential to be applied to other curing systems, solving successfully an industrial issue by quantum chemistry calculation

ADVANCING THE DEVELOPMENT OF ADDITIVELY MANUFACTURED SEQUENTIALLY CURED INTERPENETRATING POLYMER NETWORKS

Recently vat photopolymerization (VPP), a type of additive manufacturing (AM), has the potential to be used for a variety of commercial and military applications due to the ability to make custom parts rapidly and with complex geometries. Many commercially available photopolymerizable resins consist of (meth)acrylate and epoxy functionality to ensure rapid cure time and minimal shrinkage. Today, researchers continue to find the optimal balance of (meth)acrylate/epoxy functionality in unique formulations and network configurations, such as interpenetrating polymer networks (IPN)s, to enhance processibility and the quality of the final printed part. This work explores the structure-property relationships of a set of VPP resins synthesized from select starting materials in addition to improving the one-pot, two-step reaction methodology that has been employed by the Sustainable Materials Research Laboratory (SMRL) at Rowan University. Epoxy-methacrylate IPNs were prepared via a sequentially cured AM technique and subsequently evaluated for their thermal and mechanical properties. Through the incorporation of higher degrees of aliphatic character, the 3D printed IPNs yield an enhancement in toughness while maintaining thermal properties. Resultant IPNs were found to maintain glass transition temperatures above 130 ⁰C (tan δ) and increase fracture energies by more than 160%

Toward Sustainable Phenolic Thermosets with High Thermal Performances

International audienc

Bisphenol, Diethylstilbestrol, Polycarbonate and the Thermomechanical Properties of Epoxy–Silica Nanostructured Composites

The report has a double character: it deals with the synthesis and preparation of a series of polymers based on bisphenol-A (BPA) monomer; a series of physical and thermomechanical properties are examined for one type (diglycidyl ether of BPA, DGEBA with nanosilica) of the prepared materials. The reactions involved in diepoxy curing with a diamine, functional group modelling for cross-linked polymers, formation of a polymer DGEBA, BPA polyaddition to DGEBA forming a polyether, DGEBA curing with Jeffamine and cross-linking to form a resin are analyzed. Nanocomposites of silica, coated with cross-linked epoxy–amine, are synthesized and examined by 29Si-magic-angle-spinning nuclear magnetic resonance and Fourier-transform infrared spectroscopies, thermogravimetric and dynamic mechanical analyses, differential scanning calorimetry and scanning electron microscopy. Epoxy matrix is filled with nanosilica to design materials with defined properties. A low weight percentage of filler results in matrix improvement

Développement de nouveaux produits époxy biosourcés à base de dioxyde de limonène

Abstract : Nowadays, polymers are used in various parts of life, and it can be said that polymers have become an integral part of the industry. Epoxy monomers have several three-membered rings consisting of an oxygen atom joined by single bonds to two adjacent carbon atoms. Epoxy polymers are one of the most widely used polymers in various sectors such as automobiles, coatings, semiconductor encapsulants, paints, adhesives, and aerospace. They possess interesting properties such as dimensional stability, chemical resistance, dimensional stability, excellent mechanical strength, and toughness. Epoxy monomers usually have at least two epoxide functions, while the compounds with one functional epoxide are used as reactive diluents.1 Diglycidyl ether bisphenol A (DGEBA) was introduced in the 1940s as the first commercial epoxy monomer. Gradually, epoxy polymers have become a significant category of industrial polymers, and the global demand for epoxy polymers has increased over time. DGEBA results from the reaction between bisphenol A (BPA) and epichlorohydrin (ECH). Nowadays, many efforts are being made to replace DGEBA by a biobased source because it is petroleum-based and based on BPA which is toxic. Many bio-materials have been presented in the literature as a replacement to DGEBA. However, most of them are functionalized with ECH which is a toxic molecule, too.1,2 Among all biomaterials, limonene dioxide (LDO) can be an interesting candidate. First of all, ECH is not used to functionalize this molecule. Also, this molecule originates from limonene, which is an extract from the orange peel. LDO is constituted by a mixture of four stereoisomers that do not react in the same way. This study attempts to synthesize a new epoxy polymer using LDO as epoxy monomer. Several epoxy monomers and two different curing agents were used in a new LDO based formulation, and were compared with industrial formulations containing DGEBA.3 When preparing an epoxy polymer, the time it takes to transform the liquid mixture to solid polymer (reaction time) is a critical factor to control. Various catalysts have been proposed to reduce this reaction time. These catalysts must be soluble in the epoxy monomer or curing agent, must withstand environmental conditions and must not be expensive due to the widespread use of the epoxy polymer. Even though many catalysts have been reported for ring-opening of epoxides in solution, only a small number of catalysts is useful for the curing of epoxy, especially in the presence of amines.4,5 The first chapter of this thesis consists in a presentation of the essential theoretical notions in the field of epoxy polymer. vii Chapter 2 presents an article on the use of LDO, as an alternative to BADGE. Different samples containing various amounts of epoxy monomers were prepared. The resulting samples were characterized by different tests such as swelling test, Dynamic Mechanical Analysis (DMA), and tensile test. The results are presented in an article form, which has been submitted to the journal Polymer. Chapter 3 presents an article showing that lanthanide dodecyl sulfates (LnDSx) effectively catalyze reaction of amines with epoxy functions. It was demonstrated that the new catalysts could be synthesized from the reaction between lanthanide salts with sodium dodecyl sulfate. Catalysts were characterized by different techniques such as Nuclear Magnetic Resonance (NMR), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results of these analyses are presented in an article form, which will be submitted to Chemical Communications.De nos jours, les polymères sont utilisés dans diverses parties de la vie, et on peut dire que les polymères sont devenus une partie intégrante de l'industrie. Les monomères époxy ont plusieurs cycles à trois chaînons constitués d'un atome d'oxygène lié par des liaisons simples à deux atomes de carbone adjacents. Les polymères époxy sont l'un des polymères les plus largement utilisés dans divers secteurs tels que l'automobile, les revêtements, les encapsulants semi-conducteurs, les peintures, les adhésifs et l'aérospatiale. Ils possèdent des propriétés intéressantes telles que la stabilité dimensionnelle, la résistance chimique, une excellente résistance mécanique et la ténacité. Les monomères époxy ont généralement au moins deux fonctions époxyde, tandis que les composés à un époxyde fonctionnel sont utilisés comme diluants réactifs. Le diglycidyl éther bisphénol A (DGEBA) a été introduit dans les années 1940 en tant que premiers monomères époxy commerciaux. Peu à peu, les polymères époxy sont devenus une catégorie importante de polymères industriels, et la demande mondiale de polymères époxy a augmenté au fil du temps. Les monomères DGEBA résultent de la réaction entre le bisphénol A (BPA) et l'épichlorhydrine (ECH). De nos jours, de nombreux efforts sont faits pour remplacer le DGEBA par une source biosourcée car il est à base de pétrole et à base de BPA qui est toxique. De nombreux biomatériaux ont été présentés dans la littérature en remplacement du DGEBA. Cependant, la plupart d'entre eux sont fonctionnalisés avec ECH qui est également une molécule toxique.1,2 Parmi tous les biomatériaux, le dioxyde de limonène (LDO) peut être un candidat intéressant. Tout d'abord, ECH n'est pas utilisée pour fonctionnaliser cette molécule. En outre, cette molécule provient du limonène, qui est un extrait de la peau d'orange. Le LDO est constitué d'un mélange de quatre stéréoisomères qui ne réagissent pas de la même manière. Cette étude tente de synthétiser un nouveau polymère époxy en utilisant le LDO comme monomère époxy. Plusieurs monomères époxy et deux agents de durcissement différents ont été utilisés dans une nouvelle formulation à base de LDO, et ont été comparés à une formulation industrielle contenant du DGEBA. Lors de la préparation d'un polymère époxy, le temps nécessaire pour passer du mélange liquide au polymère solide (temps de réaction) est un facteur critique à contrôler. Divers catalyseurs ont été proposés pour réduire le temps de réaction. Ces catalyseurs doivent être solubles dans le monomère époxy ou l'agent de durcissement, doivent résister aux conditions environnementales et ne doivent pas être coûteux en raison de l'utilisation répandue du polymère époxy. Même si de nombreux catalyseurs ont été rapportés pour l'ouverture du cycle d'époxydes en solution, et un petit nombre de catalyseurs sont utiles pour le durcissement de l'époxy, en particulier en présence d'amines. Le premier chapitre de cette thèse consiste en une présentation des notions théoriques essentielles dans le domaine des polymères époxy. Le chapitre 2 présente un article sur l'utilisation de LDO, comme alternative à BADGE. Différents échantillons contenant diverses quantités de monomères époxy ont été préparés. Les échantillons résultants ont été caractérisés par différents tests tels que le test de gonflement, l'analyse mécanique dynamique (DMA) et le test de traction. Les résultats sont présentés sous forme d'article, qui a été soumis à la revue Polymer. Le chapitre 3 présente un article montrant que les dodécyl sulfates de lanthanide (LnDSx) catalysent efficacement la réaction des amines à fonctions époxy. Il a été démontré que les nouveaux catalyseurs pouvaient être synthétisés à partir de la réaction entre des sels de lanthanide et du dodécyl sulfate de sodium. Les catalyseurs ont été caractérisés par différentes techniques telles que la résonance magnétique nucléaire (RMN), la spectroscopie infrarouge à transformée de Fourier (FTIR), la spectroscopie photoélectronique à rayons X (XPS), la spectrométrie de masse à plasma à couplage inductif (ICP-MS). Les résultats de ces analyses sont présentés sous forme d'article, qui sera soumis à Chemical Communications

New epoxy thermosets derived from clove oil prepared by epoxy-amine curing

New thermosets from a triglycidyl eugenol derivative (3EPOEU) as a renewable epoxy monomer were obtained by an epoxy-amine curing process. A commercially-available Jeffamine® and isophorone diamine, both obtained from renewable resources, were used as crosslinking agents, and the materials obtained were compared with those obtained from a standard diglycidylether of bisphenol A (DGEBA). The evolution of the curing process was studied by differential scanning calorimetry and the materials obtained were characterized by means of calorimetry, thermogravimetry, thermodynamomechanical analysis, stress–strain tests and microindentation. 3EPOEU formulations were slightly less reactive, and the thermosets obtained showed higher Tgs than those prepared from DGEBA, since they had higher crosslinking density than formulations with DGEBA because of the more compact structure and higher functionality of the eugenol derivative. 3EPOEU thermosets showed good thermal stability and mechanical properties. The results obtained in this study allow us to conclude that the triglycidyl derivative of eugenol, 3EPOEU, is a safe and environmentally friendly alternative to DGEBA.Postprint (published version

New and improved thermosets based on epoxy resins and dendritic polyesters

Epoxy resins constitute a class of thermosets which contains more than one epoxide group per molecule, which are very reactive to many curing agents like aromatic or aliphatic amines, acid anhydrides or isocyanates. They are used as reinforced composites, adhesives, high performance coatings and encapsulating materials. Epoxy thermosets have excellent electrical and mechanical properties, good adhesion to many metals and resistance to moisture and thermal and environment exposure. Curing agents that show no activity under normal conditions but show activity by external stimulation, like temperature, can be called ’’latent curing agents”. Among the thermal latent curing agents dicyandiamide (DICY) is one of the most employed in epoxy resin technology. The latent nature of this type of curing agents is due to the insolubility in epoxy resins at room temperature. The use of dihydrazides as curing agents has been scarcely reported in scientific literature but there are some dihydrazides commercially available as latent curing agents. In the present study a series of dihydrazides with different structures were prepared by reaction of dicarboxylic diester with hydrazine hydrate in ethanol. These compounds were studied as curing agents in DGEBA/dihydrazide 2:1 (mol/mol) formulations demonstrating their latent character. In the dihydrazides we have prepared, with aliphatic, cycloaliphatic and aromatic moieties a relationship between the melting point of the dihydrazides and the initial curing temperature was observed with the exception of the cycloaliphatic dihydrazide, which was amorphous but initiate the cure at the highest temperature.En esta tesis, hemos sintetizado y caracterizado una familia de dihidrazidasque han sido utilizadas en el curado térmico de resinas epoxi (DGEBA). Asimismo, se han sintetizado nuevos poliestereshiperramificados con grupos finales no reactivos como modificantes de resinas epoxi, curadas con dihidrazidas y con anhídridos y se han caracterizado los termoestables obtenidos. También hemos sintetizando estructuras dendríticas tipo estrella con núcleos de poliéster aromáticos y brazos de policaprolactona. Estas estructuras se han utilizado como agentes modificantes de sistemas epoxi/anhídrido y epoxi/triflato de iterbio. Se ha podido demostrar la mejora de la tenacidad en los materiales termoestables y de su degradabilidad química, manteniendo sus buenas características termomecánicas

Toughening Of Epoxy Resin With Modified Liquid Natural Rubbers And Acrylonitrile-Butadiene Liquid Rubbers [TP1180.E6 A136 2005 f rb].

The preparation of liquid natural rubber (LNR) by depolymerizing deprotenized natural rubber latex was carried out. Getah asli cecair (LNR) disediakan dengan cara penyahpempolimeran penyahprotinan lateks getah asli ternyahprotin