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Toughening of thermoset resin

Some authors have refused to accept the role of interfacial adhesion on the toughening of thermoset resins. Lavita and co-workers [190] reported that non-reactive rubber can toughen BPA-modified epoxy, but the mechanism was not fully discussed. Huang and co-workers [194] showed that when the second phase consists of micron-size rubber particles, the interfacial bonding has only a modest effect on the fracture properties of blends. [Pg.208]

In Chapter 4, toughening of thermoset resins was discussed in a general way. Among the commercially available thermosetting resins, epoxy resins have been the most extensively studied, and toughening technology has been exploited in the field of adhesive and fibre-reinforced composites. This is due to the inherent ductility of the cured epoxy resins and versatile epoxy resin chemistry. In this chapter, the toughening of epoxy resin will be discussed specifically. [Pg.237]

Thermosets are generally used in advanced composites due to their excellent thermal and dimensional stability, high modulus, and good mechanical properties. Because thermoset resins are inherently brittle, however, some applications require improved fracture resistance. Toughening of thermosets has been achieved through various methods, such as incorporation of reactive liquid rubber [1-9], elastomer [10], or rigid thermoplastics [11-25], and IPN formation with ductile component [26]. [Pg.109]

Rowe, E. H., Fractography of Thermoset Resins Toughened with Hycar... [Pg.345]

Developing biphasic materials in order to improve the fracture toughness of thermoset resins is now a common practice. Thermoplastics that have a high glass-transition temperature (Tg) are used as tougheners in preference to low-Tg elastomers because of their insignificant effect on the thermal and modulus properties. [Pg.69]

Two chemically dissimilar polymers will naturally attempt to phase separate and the structure that is formed will reflect the way in which this process occurs and the driving forces associated with the process. Phase separation is used to achieve rubber toughening in thermoset resin systems. Low molar mass CTBN copolymer is soluble in the simple mixtures of monomers used to create amine-cured epoxy resins systems. However, as the molecular mass of the epoxy resin increases so the balance of entropy and enthalpy of mixing of these components changes and a driving force for phase separation is created. [Pg.221]

As an aside, we note that the FDEMS sensor input information can also be used to detect the onset of phase separation in toughened thermoset systems and to monitor cure in thin film coatings and adhesive bond lines. It is particularly important that the FDEMS sensor is also very sensitive to changes in the mechanical properties of the resin due to degradation. As such, it can be used for accelerated aging studies and as a dosimeter to monitoring the composite part during use to determine the knockdown in the required performance properties with time. [Pg.155]

This substantial toughening effect of CTBN on the cycloaliphatic epoxide ERL-4221, coupled with significant increase of the strength of the resin without seriously lowering the heat distortion temperature, is quite unusual for thermosetting systems. [Pg.545]

It was noted in the previous section that the carboxyl end groups on the CTBN elastomer affected the final performance of the material as a toughener since these groups would co-react with the epoxy resin and facilitate stress transfer from the brittle matrix to the phase-separated elastomer. Without this adhesion the particles could debond prematurely, which would lead to poor dissipation of the energy of the growing crack. It has also been noted that excessive adhesion between an epoxy resin and a thermoplastic could be deleterious to the performance (Williams et al, 1997). The process of toughening of a thermoset... [Pg.121]

The importance of the science and engineering of toughened plastics is reflected in the successful series of symposia held on the topic under the auspices of the American Chemical Society. The first, on Rubber-Modified Thermoset Resins, was held in Washington, DC, in 1983 the papers from that conference were published in 1984 as Volume 208 of the Advances in Chemistry Series. The theme of the 1988 symposium, Rubber-Toughened Plastics, was broadened to cover both thermosets and thermoplastics. The papers from that symposium, held in New Orleans, LA, were published in 1989 as Volume 222 of the Advances in Chemistry Series. In 1990 the symposium returned to Washington, DC, and was titled Toughened Plastics Science and Engineering. The papers were published in 1993 as Volume 233 of the Advances in Chemistry Series. [Pg.9]

Linear elastic fracture mechanics studies on toughened brittle plastics at room temperature concentrated on thermosetting resins, which have sufficiently high yield stresses to meet the requirements of Eq. 12.7. There has been increasing emphasis on ductile fracture mechanics in testing the toughened thermoplastics. An alternative approach is to determine the parameter, Jj, which is the quantity corresponding to Gj in linear elastic fracture mechanics, as discussed below. [Pg.881]

Hence a low molecular weight, reactive elastomer is normally used for impact modification of thermosets. The low molecular weight of the mbbery prepolymer aids its easy dissolution or dispersability in the thermosetting resin. The reactive functionality couples the rubber covalentiy to the growing polymer network during the curing reaction. Hence the rubber toughened thermosets may also be considered as co-reacted thermosets and not true blends. [Pg.1109]

A variant of thermosetting has been described in that PPE resins are dissolved in epoxy resins. A variety of polymers can be dissolved in epoxy resins." In order to facilitate the processability of PPE, the PPE is dissolved in an epoxy resin as processing aid. After processing by kneading, the epoxy resin is cured. In contrast to other approaches where the thermoplastic polymer acts as a toughener for the epoxy matrix, the amount of epoxy resin added can be adjusted so that the PPE will form the continuous phase in the final state. [Pg.151]


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See also in sourсe #XX -- [ Pg.326 ]




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