Thermal, electrical, and mechanical properties of talc‐ and glass microsphere‐Reinforced Cycloaliphatic epoxy composites

Abstract

Cycloaliphatic epoxy (CE) is used in high voltage and temperature applications because of its high glass transition temperature and resistance to ultraviolet, ozone, and hydrothermal aging mechanisms. Fillers can be used to increase the tensile modulus and thermal conductivity (TC) without a corresponding increase in electrical conductivity (1/electrical resistivity [ER]), which would be detrimental in a high voltage environment. In this study, two fillers were examined in a CE system: talc and glass microspheres (MS). Up to 20 wt% talc/CE and up to 40 wt% glass MS/CE composites were fabricated and tested for ER, TC, and tensile properties. As desired, all composites remained electrically resistive. Composite TC increased with increasing filler content from 0.15 W/m‐K for the neat epoxy to 0.25 W/m‐K for 20 wt% talc and for 40 wt% glass MS. This TC increase could be helpful to dissipate heat in high voltage and temperature applications. Tensile modulus increased from 2.7 GPa for the neat epoxy to 3.6 GPa for 20 wt% talc/CE and to 5.2 GPa for 40 wt% glass MS/CE composites. Increasing the tensile modulus is useful in the newly developed Polymer Core Composite Conductors that are used to transmit power. POLY COMPOS., 39:E1581–E1588, 2018. © 2017 Society of Plastic Engineers

Accelerated hygrothermal aging of Talc/Cycloaliphatic epoxy composites

“…Figures 5 and 6 show that the addition of talc increases flexural modulus for all aging times, from 3.2 GPa for the neat epoxy to 4.1 GPa for the 20 wt% talc/ epoxy composite. This is expected for reinforcement in epoxy [3,6,18,19] and for talc in polymers in general [13,20,21]. The trend from these data indicates that higher talc content leads to higher flexural modulus, but other studies with similar filler and epoxy systems indicate that there may be an optimal amount of talc above 20 wt% after which the modulus decreases [10,19,22,23].…”

“…In all tables, the mean is reported ± standard deviation, with n = sample size. Samples containing 5 and 15 wt% talc were fabricated for a previous paper on talc/epoxy properties . The 5 and 15 wt% talc samples were not aged or otherwise tested in this article.…”

“…At all aging levels, the addition of talc decreased the flexural strength by about 30 MPa for 20 wt% talc. In polypropylene, talc has been shown both to increase and to decrease the strength, possibly depending on interface quality [8,9,18]. The talc used in this study was not treated to improve the interface, so it is expected that adding talc would decrease the strength.…”

Thermo‐mechanical properties of epoxy composites filled with inorganic particulate fillers for robust solder mask application

“…For 15 wt% talcfilled epoxy composite, the drop in tensile strength can be ascribed mainly to the randomly oriented talc filler, which is in accordance with the findings from other researchers. 39 Another study obtained an improvement in tensile strength due to induced filler orientation during processing, which enhances the anisotropic properties of the epoxy composite. 57 For 15 wt% BN-filled epoxy composite, a drop in tensile strength is evident due to the filler agglomeration and the poor interfacial adhesion between the BN filler and epoxy matrix.…”

Latent Curing, Chemorheological, Kinetic, and Thermal Behaviors of Epoxy Resin Matrix for Prepregs

“…The incorporation of reinforcing fillers into epoxy resins leads to the facile fabrication of advanced materials due to the combined advantages of fillers and epoxy. Epoxy resins can be compounded with talc, mica, silica, fibrous matter, graphene, or carbon nanotube, or impregnated with reinforcing fibers such as glass fiber, aramid fiber, and carbon fiber (CF). − Among various filler-embedded polymer composites, fiber-reinforced polymer matrix composites (PMCs) are preferable for use in specific applications owing to their outstanding specific stiffness and strength, high thermal and electrical conductivities, and low coefficient of thermal expansion, especially in the fiber-dominated direction. − Uniaxially directional CF-embedded epoxy prepregs ( PRE -im PREG nated materials) maximize the described properties owing to unidirectional orientation at a high CF volume fraction. − …”