CROSS-LINKING OF EPOXY-OLIGOESTERIC MIXTURES IN THE PRESENCE OF CARBOXY-CONTAINING DERIVATIVE OF ED-24 EPOXY RESIN

Abstract. Cross-linking of epoxy-oligomeric mixtures has been studied at room temperature and at heating to 383, 403 and 423 K for 15, 30, 45, 60 and 75 min in the presence of polyethylenepolyamine. The mixtures consist of industrial ED-20 epoxy resin, oligoesteracrylate TGM-3 and carboxy-containing derivative of ED-24 epoxy resin. The effect of mixture composition, temperature and process time on the gel-fraction content and hardness of polymeric films has been examined. Using IR-spectroscopy the chemism of network formation has been determined

Influence of Modified Epoxy Dian Resin on Properties of Nitrile-Butadiene Rubber (NBR)

Due to the increasingly higher requirements for rubber vulcanizates, following the example of previous research on the effect of resin addition on mechanical properties and adhesion of rubbers, the following studies investigated the relationship between the addition of adipic acid-modified epoxy dian resin (ED-24 AK) to butadiene-acrylonitrile rubber (NBR). It can be seen that the addition of ED-24 AK, compared to the reference additive ED-20 (Epidian 5), additionally increase crosslinking density of the system, changes its mechanical and tribological properties, and exerts a positive effect on adhesion of the rubber vulcanizates to glass fiber. ED-20 and ED-24 AK resins do not enter the structure of the vulcanized rubber but act as the additives. ED-20 acts without changes in its structure, and ED-24 AK is a partially crosslinked additive. Modification, especially with ED-24 AK, makes mechanical strength of NBR increased even up to 240% in comparison to virgin rubber vulcanizate. This is responsible for lower friction of the vulcanizates. The decrease in the friction force of NBR due to the modified dian resin addition can reach up to 40%. Adhesion of the modified NBR to glass fibers increases due to its modification with the epoxy resins, however this time the ED-24 is more efficient than ED-24 AK reaching ca. 50% increase comparing to ca. 20% improvement, respectively. The best performance of the resins Generally, the best modification results were obtained when the addition of resins did not exceed 5 phr

Adhesion in Bitumen/Aggregate System: Adhesion Mechanism and Test Methods

A literature review of the five main theories describing the interaction mechanisms in the bitumen/aggregate system was conducted: theory of weak boundary layers, mechanical theory, electrostatic theory, chemical bonding theory, and thermodynamic theory (adsorption theory). The adhesion assessment methods in the bitumen/aggregate system are described, which can be divided into three main groups: determination of adhesion forces for bitumen with different materials, determination of bitumen resistance to the exfoliating action of water with different materials, and determination of adhesion as a fundamental value (contact angle measurements, interfacial fracture energy, adsorption capacity and others). It is proposed to evaluate the quality of adhesive interaction in the bitumen/aggregate system in two stages. The authors recommend using the adhesion determination methods for these two stages from the second group of methods the determination of bitumen resistance to the exfoliating action of water with different materials. In the first stage, the adhesion in the bitumen/aggregate system is determined by an accelerated technique in which the used bitumen binder and mineral material are considered as test materials. After the first stage, there are positive results in the second tests on compacted mixtures (indirect tensile strength test, Modified Lottman indirect tension test, immersion-compression test, and Hamburg wheel tracking test)

Bitumen Binders Modified with Sulfur/Organic Copolymers

With the continuing growth of waste sulfur production from the petroleum industry processes, its utilization for the production of useful, low-cost, and environmentally beneficial materials is of primary interest. Elemental sulfur has a significant and established history in the modification of bitumen binders, while the sulfur-containing high-molecular compounds are limited in this field. Herein, we report a novel possibility to utilize the sulfur/organic copolymers obtained via the inverse vulcanization process as modifiers for bitumen binders. Synthesis and thermal characterization (TGA-DSC) of polysulfides derived from elemental sulfur (S8) and unsaturated organic species (dicyclopentadiene, styrene, and limonene) have been carried out. The performance of modified bitumen binders has been studied by several mechanical measurements (softening point, ductility, penetration at 25 °C, frass breaking point, adhesion to glass and gravel) and compared to the unmodified bitumen from the perspective of normalized requirements concerning polymer-modified bitumen. The interaction of bitumen binder with sulfur/organic modifier has been studied by means of FTIR spectroscopy and DSC measurements. The impact of the modification on the performance properties of bitumen has been demonstrated. The bitumen binders modified with sulfur/organic copolymers are in general less sensitive to higher temperatures (higher softening point up to 7 °C), more resistant to permanent deformations (lower penetration depth), and more resistant to aging processes without intrusive deterioration of parameters at lower temperatures. What is more, the modification resulted in significantly higher adhesion of bitumen binders to both glass (from 25% up to 87%) and gravel surfaces in combination with a lower tendency to form permanent deformations (more elastic behavior of the modified materials)

Influence of Modified Epoxy Resins on Peroxide Curing, Mechanical Properties and Adhesion of SBR, NBR and XNBR to Silver Wires. Part I: Application of Monoperoxy Derivative of Epoxy Resin (PO)

The research was aimed at checking the effect of monoperoxy derivative of epoxy resin (PO) on the possibility of rubber crosslinking and a subsequent adhesion of the modified rubber to silver wires. Three of the commonly industrially used rubbers were selected for the study: styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR) and carboxylated acrylonitrile-butadiene rubber (XNBR), together with the popular, commercially available Epidian 6 epoxy resin, subjected to the functionalization. An improvement in the adhesion of rubbers to silver wires was observed when using the modified resin. In some cases, an improvement in the mechanical properties of the rubber was observed, especially when the resin was used for crosslinking together with dicumyl peroxide (DCP). Crosslinking synergy between dicumyl peroxide and the modified resin could be observed especially in the case of PO applied for peroxide curing of SBR and NBR

Microwave-Assisted Synthesis of Modified Glycidyl Methacrylate–Ethyl Methacrylate Oligomers, Their Physico-Chemical and Biological Characteristics

In this study, well-known oligomers containing ethyl methacrylate (EMA) and glycidyl methacrylate (GMA) components for the synthesis of the oligomeric network [P(EMA)-co-(GMA)] were used. In order to change the hydrophobic character of the [P(EMA)-co-(GMA)] to a more hydrophilic one, the oligomeric chain was functionalized with ethanolamine, xylitol (Xyl), and L-ornithine. The oligomeric materials were characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy, scanning electron microscopy, and differential thermogravimetric analysis. In the final stage, thanks to the large amount of -OH groups, it was possible to obtain a three-dimensional hydrogel (HG) network. The HGs were used as a matrix for the immobilization of methylene blue, which was chosen as a model compound of active substances, the release of which from the matrix was examined using spectrophotometric detection. The cytotoxic test was performed using fluid extracts of the HGs and human skin fibroblasts. The cell culture experiment showed that only [P(EMA)-co-(GMA)] and [P(EMA)-co-(GMA)]-Xyl have the potential to be used in biomedical applications. The studies revealed that the obtained HGs were porous and non-cytotoxic, which gives them the opportunity to possess great potential for use as an oligomeric network for drug reservoirs in in vitro application