A tung oil-based epoxy resin modifier enhances flexibility and superhydrophobicity

Effect of cross-link density on modification of epoxy resins with reactive acrylic elastomers

The article briefly reviews literature on the modification of epoxy resins and their properties, which are used for its industrial applications. Experimental results on modified epoxy resins are collectively summarized, which focus on the structure, curing, and alternate methods for modification of epoxy resins. The several properties such as thermal stability, adhesive, toughness, and electrical conductivity have been studied during the modifications of epoxy resins, which is useful in the field of electronic encapsulation, blending, composites, and nanocomposites, etc. The review concludes with a brief discussion on the most useful valuable modifications for industrial applications.

Targeting high‐effective modification of flame retardant epoxy resin, elements including phosphorus, nitrogen, and fluorine are simultaneously incorporated into a polymer named as PFNP. A certain amount of amino groups are preserved on PFNP chains to participate in the curing of epoxy resin. The reactive groups and segments contain 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) endowed PFNP with good compatibility in epoxy resin. The proper addition of PFNP improves the mechanical property and Tg values of epoxy resins. The limiting oxygen index values of EP/PFNP increases while the peak heat release rate, heat release capacity, and total heat release values reduce after introduction of PFNP. Samples with contents of PFNP higher than 5 wt% reach UL‐94 V‐0 rating without dripping. Notably, the migration effect of trifluoromethyl (CF3) groups not only increases the water contact angles, but also reduces the dielectric constants of epoxy resins.

Epoxy resins are widely used as high‐performance thermosetting resins for many industrial applications, but unfortunately, some are characterized by a relatively low toughness. In this respect, many efforts have been made to improve the toughness of cured epoxy resins by the introduction of rigid particles, reactive rubbers, interpenetrating polymer networks, and thermoplastics within the matrix. In this work, kaolin as a modifier was added at different contents to improve the toughness of diglycidyl ether of bisphenol A epoxy resin with polyamino‐imidazoline as a curing agent. The chemical reactions suspected of taking place during the modification of the epoxy resin were monitored and evaluated with Fourier transform infrared spectroscopy. The glass‐transition temperature (Tg) was measured with differential scanning calorimetry. The mechanical behavior of the modified epoxy resin was evaluated in terms of the Izod impact strength (IS), the critical stress intensity factor (KIC), and tensile properties at different modifier contents. Scanning electron microscopy (SEM) was used to elucidate the mechanisms of deformation and toughening in addition to other morphological features. Finally, the adhesive properties of the modified epoxy resin were measured in terms of tensile shear strength (TSS). With the addition of kaolin, the reactivity test revealed that the gel time and temperature, exotherm peak, and cure time were reduced. Infrared spectra showed the existence of a chemical reaction between kaolin and the epoxy resin. The presence of kaolin caused a steady decrease in Tg by about 10°C until 15‐phr kaolin was reached prior to leveling off. Most of the tensile properties attained a peak at an approximately 10‐phr kaolin content where the toughening reached its maximum. The modulus increased linearly from 1.85 to 2.7 GPa with increasing kaolin content. For both notched and unnotched specimens, a twofold increase in Izod IS was obtained by the addition of just 10‐phr kaolin compared to the unfilled resin. On the addition of kaolin, the Izod IS varied from 0.85 to 1.53 kJ/m2 for notched specimens and from 4.19 to 8.32 kJ/m2 for unnotched specimens, whereas KIC varied from 0.91 to 2.63 MPa m1/2 with increasing kaolin content. The adhesive properties, evaluated in terms of TSS, increased from 9.14 to 15.02 MPa. SEM analysis revealed that the prevailing toughening mechanism for the epoxy resin under consideration was localized plastic shear yielding induced by the presence of kaolin particles associated with crack pinning. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 861–878, 2001

Modification of epoxy resin using reactive liquid (ATBN) rubber

Development of a method of degradation of poly(ethylene terephthalate) (PET) wastes for the preparation of materials for the synthesis and modification of epoxy resins, development of a method of preparation of epoxy resins, characterization of epoxy resins so prepared, and optimization of the composition of epoxy resins modified with recycled materials were the goals of this work. Therefore, the conditions required for the strong degradation of waste PET by glycolysis reaction were chosen. Glycols with different length of alkyl chain were tested. Composition and structure of the degradation products were determined by GPC and spectroscopic methods (i.e. FT‐IR, 1H‐NMR, and 13C‐NMR). Next, the products of waste PET glycolysis were used as polyhydroxylic reagents for the synthesis of epoxy resins by their reaction with epichlorohydrin. Bis(2‐hydroxyalkyl)‐terephthalate was used as a model compound. The products were applied in the preparation of compositions with Bisphenol A‐based low‐molecular‐weight epoxy resins. It was found that modification of epoxy resins with the products of PET degradation led to the improvement of their tensile and flexural strengths, hardness, and thermal stability. Better results were obtained for the products with longer alkyl fragments. The incorporation of alkylether chains from PET glycolysis not only increased water absorption of the modified resins, but also improved their chemical stability against 10% HNO3, 75% H2SO4, and ethyl acetate. Copyright © 2008 John Wiley & Sons, Ltd.

Investigation on fundamental properties and chemical characterization of water-soluble epoxy resin modified cement grout

L‐leucine was converted to S‐2‐chloro, 4‐methyl pentanoic acid (CMPA) with retention of optical activity. CMPA was reacted with the epoxy resin to form chiral monoester and chiral diester compounds. The modified epoxy resin (MER) was characterized by FTIR spectrophotometer and polarimeter and was analyzed for epoxy content. The MER shows optical activity and the optical rotation increases with increasing concentration of CMPA. DSC studies indicate similar reactivity of the enantiomers of CMPA as well as the recemic mixture. The MER containing different concentrations of chiral modifier was cured with a stoichiometric amount of amine hardener. The cured film (obtained up to 21 mol % of CMPA) exhibits chiral property as well. Dynamic mechanical thermal analysis (DMTA) studies indicate high damping behavior. A shift in tan δ peak toward lower temperature was observed with increasing concentration of chiral modifier. The tan δmax increases up to 14 mol % of CMPA in MER and decreases thereafter. However, storage modulus gradually decreases with an increase in CMPA. Cured film based on two enantiomer‐modified epoxy samples shows different damping behavior. CMPA was also blended with poly(methyl methacrylate) and the blend films were studied similarly. The system behaves in a similar fashion as observed with cured MER films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2523–2529, 2002

Preparation of organic-inorganic hybrid nanocomposites from chemically modified epoxy and novolac resins and silica-attached carbon nanotubes by sol-gel process: Investigation of thermal degradation and stability

PurposeTo reduce the cost of epoxy adhesive without affecting the properties of epoxy adhesive in two pack system.Design/methodology/approachFor effective toughening, adhesion, chemical resistance, etc. various compositions were made by incorporating flow modified solid epoxy resin. The impact, adhesive strengths and some other properties of the unmodified and modified epoxy networks were characterised.FindingsThe modification of epoxy resin using flow modified solid epoxy resin showed significant enhancement of impact and adhesive strengths and chemical resistance over the unmodified one. The optimum results were obtained at 13.66 parts per hundred parts of epoxy resin (phr) of modifier by replacing 4.33 phr of aerosil.Research limitations/implicationsThe modifier, 7004 FM, used in the present context was high molecular weight flow modified epoxy resin. Besides, these results could be obtained from other grades of flow modified high molecular weight epoxy resin. In addition, the efficiency of modification of epoxy resin using this could also be studied.Practical implicationsThe method developed provided a simple and practical solution to removing the costly aerosil without affecting properties such as toughness, adhesive strength and chemical resistance of the cured epoxy.Originality/valueThe method for enhancing toughness, adhesive strength and chemical resistance of cured epoxy was novel and could find numerous applications in surface coating and adhesive.

Vegetable oil-based epoxies

Research on the Durability of Composite Epoxy Resin Modified Repair Mortars Based on Water-Oil Gradient Phase Change: From Macroscopic to Nanoscopic Scales

In this study, carboxyl-terminated polybutylene adipate (CTPBA) was used to modify epoxy resin, and the modified epoxy resin was cured by a room temperature rapid curing agent (T-31). The effects of CTPBA modification on bonding properties and mechanical properties of epoxy resin adhesive at room temperature were carefully studied. Epoxy-terminated prepolymer was synthesized by pre-polymerization and its structure was characterized. Compared with the addition method of direct blending, the bonding properties and mechanical properties of pre-polymerized epoxy resin adhesive were significantly better. Compared with unmodified epoxy resin, CTPBA modification significantly improved the bonding strength. Furthermore, with the increase of CTPBA content, the shear strength of the material increased first and then decreased, and reached the maximum when the addition amount was 40 phr. This shows that the tensile strength of the material decreased with the increase of CTPBA content, and the elongation at break increased with the increase of CTPBA content. Dynamic mechanical analyzer (DMA) test results showed that the addition of CTPBA reduced the glass transition temperature, but broadened the damping temperature range. TG analysis showed that the thermal stability of the modified epoxy resin was good, and compared with pure epoxy resin, the initial temperature of thermal weight loss and the maximum thermal decomposition rate decreased, but the overall thermal stability was not significantly different. In summary, CTPBA modification of epoxy resin is expected to improve the comprehensive mechanical properties at room temperature.

Preparation and characterization of polyurethane composite modified epoxy resin for novel colored anti-skid pavement materials

Adhesion of epoxy-polysulfone (PSF) matrices to glass fibres of 12–30 μm in diameter was studied under both quasi-static and cyclic loadings. A pull-out technique was used for adhesion measurement. It was shown that incorporation of PSF into epoxy resin changed its adhesion to fibres. A maximum was observed in the adhesion strength vs. PSF content dependence at 10 wt% thermoplastic concentration. The results obtained were compared with the data on the epoxy-PSF matrices adhesion to thick steel wire (d = 150 μm) and Nylon-6 fibres (d = 250 μm). Similar values of the adhesion strength increase (22–25%) confirmed that all the changes at the interface were connected primarily with the matrix. A new preferably non-destructive cyclic loading technique was used to test the systems under cyclic loading at varying force amplitudes, frequencies and displacement amplitudes. In this technique the interphase behaviour is characterised by two variables: by the phase angle between the deformation applied to the matrix and the force transferred by the matrix to the fibre, and also by the amplitude of this force. Minimal force amplitudes were observed for the joints with 10 wt% polysulfone. Moreover, phase-angle values for epoxy-10% polysulfone joints were minimal among all the systems investigated. Increase in the number of loading cycles caused much more damage to unmodified epoxy matrix than that to epoxy-polysulfone matrices. Thus, modification of epoxy resin by polysulfone enhanced its adhesion to fibres under both quasistatic and cyclic loadings, especially for epoxy-10% polysulfone matrix. The possible mechanism of the phenomenon observed is discussed.