Epoxy Functional Groups Research Articles

Synthesis of Novel Multifunctional Siloxane Oligomers Using Sol−Gel Techniques and Their Photoinitiated Cationic Polymerization

Employing modified sol−gel techniques, trialkoxysilanes bearing either epoxy or 1-propenyl ether functional groups can be condensed under well controlled conditions to yield a series of soluble multifunctional siloxane oligomers. The key to the success of this synthetic approach was the use of weakly acidic ion-exchange resins as catalysts. The novel multifunctional oligomers displayed exceptionally high reactivity in photoinitiated cationic polymerization using diaryliodonium salts as photoinitiators. Polymerization involved not only addition polymerization of the pendant epoxide or 1-propenyl ether groups but also acid-catalyzed hydrolysis and condensation of residual alkoxy groups along the siloxane backbone.

Graft Copolymerization of Glycidylmethacrylate onto Fibrin Prepared from Slaughter-House Waste

Fibrin collected from the slaughter house in crude form was purified. The purified fibrin was graft copolymerised with poly-glycidylmethacrylate (PGMA) and characterised for the percentage of grafting. The infrared spectroscopy and thermogravimetric anlysis, of the composite were studied. This biomaterial could be used as a drug delivery system after coupling the suitable antibiotic through the epoxy functional groups introduced by PGMA.

Synthesis and photoinitiated cationic polymerization of monomers with the silsesquioxane core

A synthetic scheme was developed to prepare cationically polymerizable octafunctional monomers with silsesquioxane (T8) cores. Epoxy and 1-propenoxy functional groups were attached to the core by the hydrosilation of T with an appropriate precursor. The steric constraints and the requirements for the hydrosilation reaction are discussed. The monomers were fully characterized and then polymerized by exposure to ultraviolet irradiation in the presence of onium salt photoinitiators. The polymerization conditions for the monomers were optimized and compared with each other using real-time infrared spectroscopy. Thermal analysis was also performed on the resulting crosslinked polymers. © 1997 John Wiley & Sons, Inc.

Synthesis and photoinitiated cationic polymerization of monomers with the silsesquioxane core

A synthetic scheme was developed to prepare cationically polymerizable octafunctional monomers with silsesquioxane (T8) cores. Epoxy and 1-propenoxy functional groups were attached to the core by the hydrosilation of T with an appropriate precursor. The steric constraints and the requirements for the hydrosilation reaction are discussed. The monomers were fully characterized and then polymerized by exposure to ultraviolet irradiation in the presence of onium salt photoinitiators. The polymerization conditions for the monomers were optimized and compared with each other using real-time infrared spectroscopy. Thermal analysis was also performed on the resulting crosslinked polymers. © 1997 John Wiley & Sons, Inc.

Water‐based radiation‐curable latexes

Film-forming polystyrene/poly(n-butyl acrylate-co-glycidyl methacrylate) [PS/P(BA-co-GMA)] core–shell latex particles were prepared via a two-stage emulsion polymerization procedure using a polystyrene latex seed. Delayed addition of GMA was used in order to locate functional epoxy groups close to the particle surfaces. It was found that a temperature of 25°C at the second-stage polymerization, in combination with a redox initiator system, was essential for the formation of a uniform shell of BA–GMA copolymer around the PS core. The latex particle morphology was investigated by transmission electron microscopy (TEM). Reactive double bonds were introduced into the particle shells in order to produce a film-forming latex system that could be cured by ultraviolet (UV)-radiation without any need to use reactive multifunctional monomers or oligomers as crosslinkers. The surface-bound epoxy groups were used as grafting sites for amine or carboxyl functional unsaturated monomers, respectively. The grafting was demonstrated by Fourier transform infrared (FTIR) spectroscopy. Films prepared from modified and unmodified latexes were exposed to UV radiation in the presence of a photoinitiator. Crosslinking was tested by thermal mechanical analysis (TMA) and by determination of swelling and gel content of exposed films. It was demonstrated that films from the modified latexes after irradiation had significantly higher stiffness and gel content and showed lower swelling than unmodified ones. © 1996 John Wiley & Sons, Inc.

Polymer blends of polyamide-6 and poly(phenylene oxide) compatibilized by styrene-co-glycidyl methacrylate

Incompatible polymer blends between polyamide-6 (PA6) and poly(phenylene oxide) (PPO) have been compatibilized in situ by the styrene-glycidyl methacrylate (SG) reactive copolymers. The epoxy functional groups in SG copolymers can react with the PA6 amine and carboxylic endgroups at interface to form various SG-g-PA6 copolymers. These in situ-formed grafted copolymers tend to anchor along interface to function as compatibilizer of the blends. The styrene and the SG segments of the grafted copolymers are miscible (or near miscible) with PPO; whereas the PA6 segments are structurally identical with PA6 phase. The compatibilized blend, depending on quantity of the compatibilizer addition and the glycidyl methacrylate (GMA) content in the SG copolymer, results in smaller phase domain, higher viscosity, and improved mechanical properties. About 5% GMA is the optimum content in SG copolymer that produces the best compatibilization of the blends. This study demonstrates that SG reactive copolymers can be used effectively in compatibilizing polymer blends of PA6 and PPO. © 1996 John Wiley & Sons, Inc.

In situ compatibilized polypropylene/liquid crystalline polymer blends

Ethylene-glycidyl methacrylate copolymer (EGMA) has been investigated as a reactive compatibilizer for the immiscible and incompatible blends of polypropylene (PP) and a liquid crystalline polymer (LCP). The epoxy functional groups of the EGMA copolymer can react with the car☐ylic acid and/or hydroxyl end-groups of the liquid comptalline copolyester. The in situ-formed EGMA- g-LCP copolymer tends to reside along the interface of the PP-LCP and reduces the interfacial tension during melt processing. The compatibilized PP/LCP blends show finer disperse LCP domains and tend to shift the LCP fibrous structure near the skin region of the uncompatibilized blends into the droplet domains. The PP crystallinity in the compatibilized PP/LCP blends is lower than that of the corresponding uncompatibilized blends due to interference in the PP crystallization by the in situ-formed EGMA- g-LCP copolymers. The lower PP crystallinity of the compatibilized blends is reflected in a substantial reduction in stiffness (in terms of the tensile modulus). However, the improved adhesion of the compatibilized blends results in an improvement in the toughness (in terms of the tensile elongation and impact strength).

Polymer blends of PBT and PP compatibilized by ethylene-co-glycidyl methacrylate copolymers

SYNOPSIS The ethylene-co-glycidyl methacrylate (EG) copolymer is an efficient reactive compatibilizer for polymer blends of poly(buty1ene terephthalate) (PBT) and polypropylene (PP). During melt processing, the epoxy functional group of the EG copolymer can react with the PBT carboxylic acid and/or hydroxyl terminal groups at the interface to form various EG-gPBT copolymers. These in situ formed grafted copolymers tend to concentrate along the interface to reduce the interfacial tension at the melt and result in finer phase domains. Higher glycidyl methacrylate (GMA) content in the EG copolymer or a higher quantity of the EG compatibilizer in the blend results in a better compatibilized blend in terms of finer phase domains, higher viscosity, and better mechanical properties. The presence of only 50 ppm catalyst (ethyltriphenyl phosphonium bromide) in the EG compatibilized blend further improves the blend compatibility substantially. 0 1996 John Wiley & Sons, Inc.

Application of Near-Infrared Attenuated Total Reflectance Spectroscopy for Monitoring Epoxy Resin/Amine Cure Reactions

Product quality in composite processing will be improved by dependable methods for monitoring the process. In this paper, the feasibility of using near-infrared attenuated total reflection (NIR ATR) spectroscopy as a sensor for monitoring epoxy resin cure is demonstrated. An ATR crystal serves as a contact sensor, which has several potential advantages over embedded optic fiber techniques previously reported. NIR ATR spectra obtained from several epoxy/amine systems show that both primary amine and epoxy functional groups have well-isolated absorption peaks in the near-infrared region. The utility of NIR ATR spectroscopy for in situ cure monitoring is demonstrated by following the reaction between phenyl glycidyl ether and butylamine at ambient temperature.

Thermal behavior of fullerenes in different gas atmospheres

The reactivity of a C 60 + 15% C 70 fullerene mixture in various gases was studied using thermal analysis (TG/DTA) and infrared spectroscopic techniques. The thermal behavior of fullerenes was found to be complex and strongly dependent on the heating rate, overlapping of different phenomena taking place. Comparison with the behavior of a number of carbon materials showed that the reactivity of fullerenes in air is similar to that of the least ordered forms of carbon. An interesting feature is the appearance of various exothermal O 2 gasification peaks as the heating rate is increased. C 60 undergoes concurrent sublimation and partial decomposition during heat treatment, leaving carbonaceous residues which are partially or totally gasified depending on the reactivity of the surrounding atmosphere. Condensed solids from the sublimation process could be recovered on the cool parts of the thermobalance; mixtures richer in C 60 than the starting one were obtained in Ar whereas heating in CO 2 led to recovery of oxygenated fullerene derivatives. Carbonaceous residues from pyrolysis in Ar and CO 2 were strong infrared absorbers and contained oxygenated (epoxy and carbonyl) functional groups.

In situ compatibility of polystyrene and liquid crystalline polymer blends

The styrene-glycidyl methacrylate (SG) copolymer can be used to compatibilize the immiscible and incompatible blends between polystyrene (PS) and liquid crystalline polymer (LCP) copolyester. The epoxy functional groups present in the SG copolymer can react with the carboxylic and/or the hydroxyl terminal groups of the LCP at interface to form the SG-g-LCP copolymer during melt processing. This in situ-formed graft copolymer tends to reside along the interface to reduce the interfacial tension in the melt state and to increase the interphase adhesion in the solid state. However, the compatibilized PS/LCP blends reduce the number of LCP fibrils formed and have a tendency to form droplet LCP domains. The overall mechanical properties, stiffness and toughness of the blends improved after compatibilization, but the extent of the improvement is not very significant. It appears that the gain from the adhesion enhancement is more than offset by the loss due to the reduction in LCP fibril formation. The ethyl triphenylsphosponium bromide catalyst can further improve the compatibility of the blends by increasing the rate of the graft reaction.

Synthesis and characterization of polyfunctional crosslinking agents for cyanate resins

AbstractAn efficient crosslinking monomer for a mixed cyanate/epoxy resin system, bisphenol‐A‐monocyanate monoglycidyl ether 3, has been synthesized and characterized. The intermediate compound, the monoglycidyl ether of bisphenol‐A 2, was also isolated and purified by extraction and chromatographic separation using a silica gel column. The cyanate functional group in the crosslinking monomer 3 can be cured easily by heat to form a triazine structure 8, but the epoxy functional group in the crosslinking monomer 3 can not be cured without affecting the cyanate group because the latter is more reactive both under heat and basic conditions. A practical approach for the application of the crosslinking monomer 3 is discussed and tested. Most interestingly, under heat curing, a very tough and strong resin material was produced from this crosslinking mixed resin mixture. By using a secondary amine, diethylamine, as a curing agent, the cyanate groups in the crosslinking monomer 3 react to form the structures 11 or 12, depending on the molar ratio of monomer 3 to diethylamine. A bifunctional crosslinking agent for a mixed cyanate (thermoset) and polyolefin (thermoplastic) resin system, 2‐allylphenyl cyanate 16, has also been synthesized and characterized. Like 3, 2‐allylphenyl cyanate 16 easily forms the crosslinking triazine compound 17 upon heating. 17 is a crystalline solid with mp = 110–111°C. As a crosslinking agent, 2‐allylphenyl cyanate 16 reacts not only with itself, but also with other cyanates to form heterogeneous triazine rings, exemplified by triazines 18 and 19. Even though it does not self polymerize through the allyl double bond, it can copolymerize with an other olefinic monomer, such as methyl methacrylate, to form a crosslinked and insoluble polymer. © 1995 John Wiley & Sons, Inc.

In situ reactive compatibilized noryl/LCP blends

AbstractThis article reveals that the already known improved properties of the thermoplastic–liquid crystalline polymer (LCP) blends can be further improved substantially over the corresponding noncompatibilized counterparts by using a reactive in situ type compatibilizer, the styrene–glycidyl methacrylate (SG) copolymer. This SG copolymer has been demonstrated in this article to be an effective reactive compatibilizer to improve the processability, heat deflection temperature, and mechanical properties of Noryl/LCP blends. The epoxy functional groups of the SG copolymer can react with the end groups of PPO (in Noryl) and LCP. The in situ‐formed SG–g–LCP copolymer tends to reside along the interface of Noryl–LCP and reduces the interfacial tension during melt processing. The resultant LCP fibers in the Noryl matrix of the compatibilized blends have a higher aspect ratio because the fibers become finer, longer, and tend to form lamellate domains with a greater interphase contact area than those from the noncompatibilized blends. The compatibilized blends also improve the interphase adhesion between Noryl and LCP. The presence of ethyl triphenylphosphonium bromide catalyst promotes the grafting reaction to improve blend compatibilization. © 1995 John Wiley & Sons, Inc.

In situ compatibilization of PET/PS blends through reactive copolymers

AbstractPolymer blends of poly(ethylene terephthalate) (PET) and polystyrene (PS) are immiscible and incompatible, which has been well recognized. Styrene–glycidyl methacrylate (SG) copolymer has been synthesized by suspension polymerization and employed in this study as an in situ compatibilizer for the polyblends of PET and PS. This copolymer contains reactive epoxy functional groups that are able to react with PET end groups OH and COOH) under melt conditions to from SG‐graft‐PET copolymer. The presence of a small amount of phosphonium catalyst (200 ppm) accelerated the graft reaction and results in a better compatibilized blend. The compatibilized PET/PS blend has a smaller phase domain and higher viscosity than does the corresponding noncompatibilized blend. Mechanical properties of the compatibilized blends have also been improved significantly over the corresponding noncompatibilized blends. © 1993 John Wiley & Sons, Inc.

Applications of On‐Line SFE/SFC in Environmental Analysis

AbstractPolycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorinated Pesticides (OCPs) on different absorbents were extracted and analyzed by a directly coupled supercritical fluid extraction and supercritical fluid chromatography system (on‐line SFE/SFC). The influence of various absorbents as sample matrixes on extraction efficiencies was evaluated. In general, the extraction efficiencies were decreased if a matrix had a larger surface area and a smaller pore size. The recoveries of PAHs and PCBs were decreased in inverse proportion to their molar mass. Recoveries of OCPs containing epoxy functional groups were greater than for OCPs lacking this functional group. In conclusion, online SFE/SFC is a rapid (1‐2 h) and high recovery (70%‐100%) analytical technique.

Development of a sampling and analytical method for measuring the epoxy content of aerosols: II. Application of the method to epoxy-containing aerosols.

Aerosols generated by epoxy spray painting consist of droplets containing partially-cured mixtures of epoxy resins and curing agents, as well as pigments, solvents and diluents. A sampling and analytical method has been developed to measure the epoxy content of these aerosols. The method collects the aerosol in a midget impinger containing dimethyl formamide, which inhibits the curing reaction between the epoxy and curing agent, preserving the unreacted epoxy functional groups present in the aerosol. The impinger contents are analyzed by reacting the epoxy with an excess of bromide generated in situ from tetraethylammonium bromide, and measuring the unreacted bromide in the reaction mixture by normal pulse polarography. The precision and accuracy of the method have been evaluated using a pure epoxy resin as a model compound. The method was applied to aerosols containing mixtures of epoxy resin and amine curing agents in various degrees of cure, to aerosols containing large quantities of nonepoxy compounds, and to aerosols of epoxy surface coatings. The method is capable of precise and accurate measurement of epoxide functionality, and it applicable to the measurement of epoxy-containing aerosols in spray finishing operations.

Development of a Sampling and Analytical Method for Measuring the Epoxy Content of Aerosols: II. Application of the Method to Epoxy-Containing Aerosols

Aerosols generated by epoxy spray painting consist of droplets containing partially-cured mixtures of epoxy resins and curing agents, as well as pigments, solvents and diluents. A sampling and analytical method has been developed to measure the epoxy content of these aerosols. The method collects the aerosol in a midget impinger containing dimethyl formamide, which inhibits the curing reaction between the epoxy and curing agent, preserving the unreacted epoxy functional groups present in the aerosol. The impinger contents are analyzed by reacting the epoxy with an excess of bromide generated in situ from tetraethylammonium bromide, and measuring the unreacted bromide in the reaction mixture by normal pulse polarography. The precision and accuracy of the method have been evaluated using a pure epoxy resin as a model compound. The method was applied to aerosols containing mixtures of epoxy resin and amine curing agents in various degrees of cure, to aerosols containing large quantities of nonepoxy components, and to aerosols of epoxy surface coatings. The method is capable of precise and accurate measurement of epoxide functionality, and it is applicable to the measurement of epoxy-containing aerosols in spray finishing operations.

3] High-performance liquid chromatography of triglycerides

Publisher Summary This chapter describes the separation of triglyceride mixtures using high-performance liquid chromatography (HPLC). HPLC of triglycerides has no unusual requirements for pumping or injection systems. An ideal detector for triglycerides does not now exist. Ultraviolet (UV) detection, probably HPLC's most popular and sensitive detector, is not generally useful for triglyceride mixtures because there is usually no chromophore above 200 nm to monitor. Reverse-phase HPLC columns are made by bonding functional groups to the silica by reaction of the appropriate chloro- or alkoxysilane with fully hydroxylated silica. It is found that for stearic reasons, complete reaction of all silanol groups does not occur, and the resulting silica surface is a mixture of silanols and bonded functionals. Class separations of hydroxyepoxy- or ketoacyl-containing tri-glycerides are routinely made by TLC and column chromatography. These separations are easy to adapt to HPLC with silica columns. In RP-HPLC, the hydroxy, keto, and epoxy functional groups increase polarity and thus decrease retention volume. It is suggested that HPLC has provided an important tool for the study of triglycerides with unusual structures and dimerized or oxidized oils.

Mutation induction by difunctional alkylating agents in Neurospora crassa.

The genetic characterization of ad-3 mutants of Neurospora crassa induced by two carcinogenic difunctional akylating agents, 1,2,4,5-diepoxypentane (DEP) and 1,2,7,8-diepoxyoctane (DEO), has shown that point mutations at the ad-3B locus have similar complementation patterns. In addition to the induction of point mutations, DEP induces a low frequency (7.5%) of multilocus deletions, whereas DEO induces an extremely high frequency (42.0%). The distribution of the different classes of ad-3 mutants and the frequency of multilocus deletion mutants among DEP-induced mutants are not significantly different from those induced by the monofunctional alkylating agents EI, EMS and ICR-177 at comparable forward-mutation frequencies. Moreover, the frequencies of DEP-induced ad-3B mutants showing allelic completion or having nonpolarized complementation patterns are similar to those of ad-3B mutants induced by monofunctional agents. It is suggested, therefore, that the mechanism of mutation-induction by DEP in N. crassa is similar to that of monofunctional alkylating agents. Mutation-induction by DEO probably results both from the mechanism of action of monofunctional alkylating agents and from inter-strand cross-linkage of the DNA molecular by the two functional epoxy groups.

Plastisol Sealants for Automotive Applications

Plastisol sealants are widely used in the automotive industry both as structural adhesives and as water-proofing compounds. Over the years, a variety of materials have been used to promote adhesion in formulated plastisol sealants. This paper covers experimental work with a series of plastisol sealants using silane coupling agents as integral blend adhesion promoters. Silanes with cyclic epoxy, mer capto, amino, and diamino functional groups have been studied. The influence of silane structure on adhesion, viscosity, viscosity stabil ity, flow properties, and sag resistance has been examined. After detailed study of formulating variables, it has been found that silane coupling agents will contribute significantly to the improvement of a number of essential sealant characteristics.