Simultaneously improving the thermal conductive and flame retardant performance for epoxy resins thermosets by constructing core‐shell‐brush structure and distributing of MWCNTs in brush intervals

Abstract

Fire safety and thermal dissipation performance of epoxy resins thermosets were critical for its application in key fields such as electronic devices. The simultaneous improvement of flame retardant and thermal conductivity properties were still a challenge. Herein, ammonium polyphosphate (APP) was firstly encapsulated with 5-wt% epoxy resins based on APP and then surface grafted with polyurethane polymer chain, and the resulting APP with core-shell-brush structure was constructed. Finally, the multiwalled carbon nanotube (MWCNT) was assembled in the intervals of polymer brush on APP surface, and the prepared filler was defined as MF-APP. Its chemical structure and morphologies were characterized and confirmed. The wettability of MF-APP was evaluated by water contact angles tests (WCA) and MF-APP exhibited hydrophobic property with the WCA of 138°. When 9-wt% MF-APP was incorporated into EP thermosets, the thermal conductive value of EP/MF-APP achieved 1.02 Wm −1 K −1 , and the MWCNTs concentration was only 1.8 wt% in thermosets.Compared with the previous work, the prepared EP/MF-APP thermosets exhibited outstanding thermal conductive efficiency because of the homogeneously distribution of MWCNTs. Moreover, the samples fulfilled UL-94 V-0 grade during vertical burning tests with the limiting oxygen index of 30.8%. As a result, the thermal conductivity and flame retardancy of EP thermosets were simultaneously enhanced with a relatively low addition amount of MF-APP, which would bring more chance for wider application of EP thermosets in key fields. KEYWORDS core-shell-brush structure, epoxy resin, flame retardancy, thermal conductivity 1 | INTRODUCTION Epoxy resin (EP) has been widely used in electronic and electrical industries, especially in printed circuit board (PCB) because of its exciting properties such as corrosion resistance, electrical insulation, and high strength. 1-3 With the development of electronic devices toward miniaturization and integration, a large number of heat fluxes in electronic equipment are generated during operation process. It is crucial for the devices that the produced heat can be effectively dissipated. However, EP thermosets exhibit low intrinsic thermal conductivity of 0.1 to 0.4 Wm −1 K −1 . 4-6 Besides, the fire risk is a significant drawback of the EP thermosets. Considering the public safety and the requirement of electronic devices, the simultaneous improvement of thermal conductivity and flame retardancy for the EPs thermosets is becoming an urgent problem and has attracted a lot of attention over the years.To enhance the thermal conductivity, the traditional highly thermally conductive fillers (~5000 Wm −1 K −1 ) such as aluminum oxide, 7,8 whiskers, 9 nanosilica, 10 and aluminum nitride 11 are generally incorporated into the polymeric material. However, the high loading amount (about 30%-60% by volume) is required to fulfill the thermal conductivity (>1 Wm −1 K −1 ). Besides, the high addition amount of filler would deteriorate the processing and the mechanical properties...

The design of a metal–organic framework with flame-retardant performance and bionic hydrophobic surface inspired by the lotus leaf

“…7b and d, the addition of S-Fe-MOF effectively inhibits the release of toxic gas in the combustion process of the PS composite. 23 The peak carbon monoxide production rate (PCOPR) and peak carbon dioxide production rate (PCO 2 PR) of PS/S-Fe-3.0 are 0.051% and 0.392%, respectively, which are significantly lower than those of the pure PS. 24 To further reveal the combustion behavior of the PS composite, the char residue after combustion was observed via SEM and a digital camera (Fig.…”

A facile strategy to construct multifunctional microencapsulated urea ammonium polyphosphate for epoxy resins towards satisfied fire safety, thermal stability and compatibility

“…However, it is worth noting that APP is hygroscopic and has poor compatibility with polymers, which easily leads to the precipitation of substances and the reduction of flame-retardant efficiency. 9 To resolve above problems, many studies have focused on the modification technology of APP. At present, the modification methods of APP mainly include supermolecular selfassembly modification, 10 coupling agent modification, 11 microencapsulation 12 and surfactant modification.…”

“…Ammonium polyphosphate (APP), as a common phosphorus‐based flame retardant, can provide a superior acid source when applied to intumescent flame‐retardant systems. However, it is worth noting that APP is hygroscopic and has poor compatibility with polymers, which easily leads to the precipitation of substances and the reduction of flame‐retardant efficiency 9 . To resolve above problems, many studies have focused on the modification technology of APP.…”

Strategy for Constructing Epoxy Composites with High Effective Thermal Conductive Capability Based on Three-Dimensional Cellulose and Multiwalled Carbon Nanotube Network

“…With the rapid development of high-power electronic devices and electrical equipment, heat sinking has become a crucial concern and restrained the miniaturization and high integration of electronic products. Therefore, it is urgent to seek high-performance thermal management materials. − Over the past decade, epoxy resin (EP) composites were widely used as substrates and packing materials in the field of electronic packing and devices due to their unique chemical stability, excellent electrical insulation, and good design freedom. , However, the pristine EP possesses a relatively low thermal conductivity (TC, 0.2 W·m –1 ·k –1 ), which is far from satisfying the cooling requirements of contemporary electronic devices for high integration, miniaturization, and multifunction. − Recently, a wide variety of thermal conductive fillers have been used to enhance the TC of EP composites, such as carbon nanotubes (CNTs), graphene nanosheets, boron nitride (BN), aluminum nitride, and carbon nitride . Nevertheless, addition of a large amount of thermal fillers is required to achieve a satisfied TC of composites, but the mechanical properties of thermosets will be deteriorated.…”

“…1−3 Over the past decade, epoxy resin (EP) composites were widely used as substrates and packing materials in the field of electronic packing and devices due to their unique chemical stability, excellent electrical insulation, and good design freedom. 4,5 However, the pristine EP possesses a relatively low thermal conductivity (TC, 0.2 W•m −1 •k −1 ), which is far from satisfying the cooling requirements of contemporary electronic devices for high integration, miniaturization, and multifunction. 6−8 Recently, a wide variety of thermal conductive fillers have been used to enhance the TC of EP composites, such as carbon nanotubes (CNTs), 9 graphene nanosheets, 7 boron nitride (BN), 6 aluminum nitride, 10 and carbon nitride.…”