Preparation and Thermal Conductivity of 1,5-Naphthalenediol Modified Epoxy Resin and Boron Ntride Composite
Polymer-based composite materials are widely used in the field of thermal conductivity owing to their low weight,electrical insulation,heat resistance,corrosion resistance,and excellent mechanical properties.Epoxy resin(EP)is essential in the field of thermally conductive composite materials;however,its low intrinsic thermal conductivity limits its application.Therefore,improving the intrinsic thermal conductivity of EP is crucial for developing high-performance thermally conductive composite materials.An improvement in the thermal conductivity of EP composite materials can be achieved by increasing the content of inorganic fillers;however,excessive inorganic fillers also affect the processing performance of the composite materials.Therefore,improving the intrinsic thermal conductivity of EP is important.Generally,the intrinsic thermal conductivity of EP can be improved by introducing molecules with rigid groups.However,in practical operations,limitations often exist,such as polarity differences and inconsistent compatibility between molecules containing rigid groups and EP molecules,which result in complexity in the structural design and synthesis of EP and its composite materials,limiting their practical applications.In this paper,the naphthalenediol-modified EP(NEP)was prepared by the reaction of the strong rigidity naphthalenediol and EP,aiming to improve the"order"of the EP molecular chain.When naphthalene glycol is used as a thermally conductive material,the rigid groups of naphthalene glycol reduce phonon scattering and improve the thermal conductivity of NEP and the corresponding composite materials with thermally conductive fillers.When used as a thermally conductive material,the rigid groups of naphthalenediol reduce the scattering of phonons and improve the thermal conductivity of NEP and the corresponding composites incorporating thermally conductive fillers.Infrared analysis indicated that the 1,5-naphthalene diphenol-modified EP consumed some epoxy groups,indicating the occurrence of a NEP modification reaction.The thermal conductivity of NEP was 0.32W/(m·K),which was 1.68 times that of EP(0.19 W/(m·K)).To determine the effect of the 1,5-naphthalene diphenol content on the thermal conductivity of the NEP and NEP BN composite materials,we conducted tests on the thermal conductivity of the materials at different mass ratios and curing temperatures.The increase rate of the thermal conductivity of the NEP/BN composite material was always greater than that of EP/BN composite material.Specifically,after adding BN filler with a weight ratio of 30％,the thermal conductivity of the NEP/BN composite increased to 1.25 W/(m·K),which was 1.24 times that of EP/BN composite(1.01 W/(m·K))and 6.58 times that of EP.The increase in the NEP and EP/BN composite materials is primarily because the EP modified with a rigid naphthalene ring is more likely to form a thermal conductivity network within the molecule,improving the thermal conductivity of the composite material.Furthermore,the infrared thermal imager recorded the changes in surface color and temperature of the EP(al),NEP(a2),EP BN(a3),and NEP/BN(a4)composite materials over time.After BN was added,the surface color change of the NEP/BN and EP/BN composite materials was significantly faster than that of NEP and EP,and the surface temperature change of all samples became more pronounced with increasing heating time.The mechanism analysis showed that after NEP was heated,phonons were transmitted along the EP naphthalene molecular chain.Because of the relatively complete planar structure of the naphthalene ring,the phonons transmitted here were efficiently transmitted on its surface,reducing the probability of phonon scattering and thereby improving thermal conductivity.This study provides insights into improving the thermal conductivities of modified EP and its composite materials.
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