The impact of polymer matrix blends on thermal and mechanical properties of boron nitride composites

To improve mechanical and thermal properties of a hexagonal boron nitride platelet filled polymer composites, maleic anhydride was studied as a coupling agent and compatibilizer. Injection molded blends of acrylonitrile butadiene styrene (ABS), high-density polyethylene (HDPE), and maleic anhydride with boron nitride filler were tested for thermal conductivity and impact strength to determine whether adding maleic anhydride improved interfacial interactions between matrix and filler and between the polymers. Adding both HDPE and maleic anhydride to ABS as the matrix of the composite resulted in a 40% improvement in impact strength without a decrease in thermal conductivity when compared to an ABS matrix. The best combination of thermal conductivity and impact strength was using pure HDPE as the matrix material. The effective medium theory model is used to help explain how strong filler alignment helps achieve high thermal conductivity, greater than 5 W/m K for 60 wt % boron nitride. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48661.     

Enhancing the Anhydrous Proton Conductivity of Sulfonated Polysulfone/Polyvinyl Phosphonic Acid Composite Membranes With Hexagonal Boron Nitride

Hexagonal boron nitride (h-BN) particles have attracted increasing interest due to mechanical properties, chemical stability, electrical features, thermal stability, and good lubrication property. In this work hexagonal boron nitride were used as inorganic fillers, which increase the mechanical and thermal stabilities of the membrane. The proton conducting polymer membranes were prepared by blending of sulfonated polysulfone, polyvinyl phosphonic acid, and boron nitride. Scanning electron microscopy indicated the homogeneous distribution of hBN nanoparticles in the polymer matrix. hBN increased the proton conductivity and in the anhydrous state the maximum proton conductivity was determined as 7.9 × 10^?3 S/cm at 150°C for PVPA-SPSU-5hBN.     

Synergistic effects of boron nitride sheets and reduced graphene oxide on reinforcing the thermal conduction,SERS performance and thermal property of polyimide composite films

Polyimide (PI) composite films with hybrid fillers containing hBN (hexagonal boron nitride) sheets and rGO (reduced graphene oxide) were successfully fabricated by in-situ polymerization. Herein, hBN sheets and rGO were obtained by ball milling and chemical reduction, respectively. In PI composite films, hBN can be tightly attached onto the surface of rGO via π-π interaction, which can benefit the construction of heat-conduction pathways and reduce boundary of heat resistance. The results show that the addition of rGO and hBN could enhance the thermal conductivity by synergistic effects. Specially, hBN and rGO are at the weight ratio of 1:1 and at the total loading of 33 wt%, thermal conductivity of PI composites can reach up to 1.19 Wm⁻¹ K⁻¹, which is 5.61 times higher than that of pure PI. Thermal property and dynamic mechanical property of composite films were also investigated. Besides, compared with pure PI, mixed fillers have obvious surface-enhanced Raman scattering signals, indicating the synergistic effect of the mixed fillers. Overall, this study gives insights into heat dissipative and high sensitivity analysis components which may be used in the field of high-temperature micro fabrication.     

Enhancement of mechanical and wear resistance performance in hexagonal boron nitride‐reinforced epoxy nanocomposites

Hexagonal boron nitride (hBN), a two‐dimensional nanofiller with good mechanical properties, high thermal conductivity and excellent lubrication properties, has the potential to substantially reinforce polymers to form nanocomposites with advanced properties. In this study, we successfully prepared hBN nanosheets with a thickness of a few atoms by using amine‐capped aniline trimer (AT) as dispersant. Epoxy/hBN nanocomposites were prepared by curing reaction of epoxy E51, Jeffamine D230 and AT‐modified hBN nanosheets, where the hBN contents were 0.5, 1, 2 and 4 wt%. An increase in contact angle of the epoxy/hBN nanocomposites was evident in the presence of hBN nanosheets, implying an increase in the hydrophobic nature of the composites. The as‐prepared composites exhibited enhanced mechanical and tribological performance compared to pure epoxy resin. This effectiveness in improving the mechanical, friction and wear behavior of the epoxy composites could be attributed to the complementary action of excellent mechanical properties, lubrication and thermal conductivity of hBN nanofillers. © 2016 Society of Chemical Industry     

Alkylated modified boron nitride nanosheets/polyimide composite films with advanced thermal conductivity and low dielectric constant

Owing to the rapid development of the latest micro-electronic devices, polymer composite materials that combine high thermal conductivity and low permittivity have aroused the interest of researchers. However, it is a huge challenge to balance the above parameters. In this work, hexagonal boron nitride (h-BN) powder was ultrasonically exfoliated to obtain alkylated boron nitride nanosheets (Alkyl-BNNS). Then, a series of polyimide (PI) composites were synthesized with different amounts of Alkyl-BNNS. Attributed to more robust interfacial non-covalent interactions between Alkyl-BNNS and polymer chains to inhibit interfacial polarization, Alkyl-BNNS can be scattered well in PI substrate. Thus, the obtained PI composite behaved a high thermal conductivity of 6.21 W/(mK) and a low dielectric constant (3.23) under the load of 20 wt%. Besides, Alkyl-BNNS/PI composites have efficient thermal management capability, low water absorption, favorable electrical resistance, and prominent tensile strength. Importantly, these composite films are expected to be excellent candidates in the field of microelectronics.     

Enhanced thermal conductivity of boron nitride epoxy‐matrix composite through multi‐modal particle size mixing

Castable particulate‐filled epoxy resins exhibiting excellent thermal conductivity have been prepared using hexagonal boron nitride (hBN) and cubic boron nitride (cBN) as fillers. The thermal conductivity of boron nitride filled epoxy matrix composites was enhanced up to 217% through silane surface treatment of fillers and multi‐modal particle size mixing (two different hBN particle sizes and one cBN particle size) prior to fabricating the composite. The measurements and interpretation of the curing kinetics of anhydride cured epoxies as continuous matrix, loaded with BN having multi‐modal particle size distribution, as heat conductive fillers, are highlighted. This study evidences the importance of surface engineering and multi‐modal mixing distribution applied in inorganic fillered epoxy‐matrix composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Simultaneous improvement of thermal conductivity and mechanical properties for mechanically mixed ABS/h-BN composites by using small amounts of hyperbranched polymer additives

Recently, thermal interface materials (TIMs) are in great demands for modern electronics. For mechanically mixed polymer composite TIMs, the thermal conductivity and the mechanical properties are generally lower than expected values due to the sharply increased viscosity and poor filler dispersion. This work shows that addition of a small amount of polyester-based hyperbranched polymer (HBP) avoided the trade-off in mechanically mixed ABS/hexagonal boron nitride (h-BN) composites. After adding 0.5 wt% HBP, the maximum h-BN content in the composites increased from 50 to 60 wt%. The out-of-plane, in-plane thermal conductivity, and tensile strength of ABS/h-BN with 50 wt% h-BN were 0.408, 0.517 W/mK, and 18 MPa, respectively, and were increased to 0.729, 0.847 W/mK, and 32 MPa by adding 0.5 wt% HBP, while 0.972, 1.12 W/mK, and 29.5 MPa were achieved for ABS/h-BN/HBP with 60 wt% h-BN. The morphological and rheological results proved that these enhancements are due to the improved h-BN dispersion by decreasing viscosity of composites during mixing. Theoretical modeling based on the modified effective medium theory confirmed such results and showed that the interfacial thermal resistance also decreased slightly. Thus, this work demonstrates a facile and scalable method for simultaneously improving the thermal conductivity and mechanical properties of thermoplastic-based TIMs.     

Thermal and electrical properties of aluminum nitride/boron nitride filled polyamide 6 hybrid polymer composites

The effects of boron nitride (BN) and aluminum nitride fillers on polyamide 6 (PA6) hybrid polymer composites were investigated. In particular, the thermal and electrical conductivity, thermal transition, thermal degradation, mechanical and morphological properties and chemical bonds characteristic of the materials with crystal structure of BN and aluminum nitride (AlN) filled PA6 prepared at different concentrations were characterized. Thermal conductivity of hybrid systems revealed a 1.6-fold gain compared to neat PA6. The highest thermal conductivity value was obtained for the composite containing 50 vol% additives (1.040 W/m K). A slight improvement in electrical conductive properties of composites appears and the highest value was obtained for the 50 vol% filled composite with only an increase by 3%. The microstructure of these composites revealed a homogeneous dispersion of AlN and BN additives in PA6 matrix. For all composites, one visible melting peak around 220°C related to the α-form crystals of PA6 was detected in correlation with the X-ray diffraction results. An improved thermal stability was obtained for 10 vol% AlN/BN filled PA6 composite (from 405.41°C to 409.68°C). The tensile strength results of all composites were found to be approximately 22% lower than pure PA6.     

LDPE/PEG插层剥离改性氮化硼导热复合材料的制备及其性能

以聚乙二醇(PEG)为插层剂,通过机械球磨法制备了PEG插层剥离改性氮化硼.以低密度聚乙烯(LDPE)为基体,PEG插层剥离改性氮化硼为导热填料,采用双辊开炼、压片成型制备LDPE/PEG插层剥离改性氮化硼导热复合材料,研究了改性氮化硼用量及粒径对复合材料导热性能、力学性能和电绝缘性能的影响.结果表明:随着PEG插层剥...     

环氧树脂/玻纤/BN导热绝缘复合材料制备研究

采用高温模压成型法制备环氧树脂/玻纤/BN导热复合材料,探讨了BN用量对复合材料力学性能、导热性能和电性能的影响,结果表明.当BN用量为10%时,复合材料的冲击强度和弯曲强度较佳;导热性能随BN用量的增加而提高,当BN用量为20%耐.热导率为0.7438 W/mk,此时复合材料仍保持较好的绝缘性能.     

ROMP‐based boron nitride composites

The present work focuses on the investigation of the thermal and dielectric properties of composites obtained by surface‐modified hexagonal boron nitride (hBN) and ring‐opening metathesis polymerization (ROMP) based polymer. A new kind of high performance composites was developed based on using amino silane functionalized hBN (AS‐hBN) and bromine functional group possessing homo and copolymers synthesized via ROMP pathway. Aminosilane capped boron nitride (BN) and bromine bearing polymer backbone enhance the interaction between filler and the polymer chains. The effects of surface‐modified BN (AS‐hBN) and its content on the dielectric properties, and thermal resistance of composites, are systematically investigated and discussed. The resultant composites possess high electrical break over voltages. While all of the ROMP‐based films exhibit low ?′ value in a wide frequency range, in the case of the composite with 20% AS‐hBN and poly(bromooxanorbornene‐co‐cyclooctadiene) (ROMP‐BN‐6) displays very low dielectric constants in around 1.5 up to 1 MHz at 20 °C. This value is significantly lower than that of common polymer dielectrics, which is usually in the range of 3–6. Besides the lowest dielectric constant of ROMP‐BN‐6, it has also the smallest dielectric loss tangent even at high temperatures. Tan δ of ROMP‐BN‐6 is 0.003 and 0.0067 at 10 Hz–1 MHz at 20 °C, respectively. Thermal stability of polymers was also improved by introducing surface‐modified hBN. Polymers bearing 20% AS‐hBN are highly thermally stable up to ～350 °C and gave 25% char yield at 800 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45658.     

High thermally conductive PLA based composites with tailored hybrid network of hexagonal boron nitride and graphene nanoplatelets

Bio‐based polymers and multifunctional polymeric composites are promising for the development of new environmentally sustainable materials and are becoming increasingly popular compared to their oil based counterparts. This research aims to develop new multifunctional bio‐based polymer composites with improved thermal conductivity and tailored electrical properties to be used as heat management materials in the electronics industry. A series of parametric studies were conducted to clarify the science behind the hybrid composites' behavior and their structure‐to‐property relationships. Using bio‐based polymers [e.g., polylactic acid (PLA)] as the matrix, heat transfer networks were developed and structured by embedding hexagonal boron nitride (hBN) and graphene nanoplatelets (GNP) in a PLA matrix. The effects of random uniform thermal hybrid networks of hBN‐GNP on improving the effective thermal conductivity (k_eff) of produced composites were studied and compared. Composites were characterized with respect to physical, thermal, electrical, and mechanical properties for practical application in the electronics industry. The use of high thermally conductive hybrid filler systems, with optimized filler content, was found to promote the composites' effective thermal conductivity to more than 12 times over neat PLA. The thermally conductive composite is expected to provide unique opportunities to injection mold three‐dimensional, net‐shape, lightweight, and eco‐friendly microelectronic enclosures with superior heat dissipation performance. POLYM. COMPOS., 37:2196–2205, 2016. © 2015 Society of Plastics Engineers     

Enhanced thermal conductivity of PE/BN composites through controlling crystallization behavior of PE matrix

In this article, in order to enhance the thermal conductivity of the polyethylene (PE)/boron nitride (BN) composites through controlling the crystallization behavior of the PE matrix, the crystallization and melting behavior of the PE in the PE/BN composites was investigated. When the BN content was more than 10 wt%, an extra weak exothermic peak (T _h) at 130°C was observed. Moreover, after the annealing of the PE/BN composites at 130°C, the extra weak melting peaks (T _mh) of the PE in the PE/BN composites were also observed and shifted to the high temperature with increasing annealing time, which proved that the T _h was induced by PE crystallization. Meanwhile, the results of temperature‐dependent absorbance IR spectra of the PE/BN composites showed that the crystallization peak (729 cm⁻¹) remarkably appeared at 130.2°C, indicating that the crystallization of the PE in the PE/BN composites can occur at 130.2°C. When the annealing time and temperature were 20 min and 130°C, the thermal conductivity of the PE/BN composite was 16% higher than that of the unannealed PE/BN composites. In addition, the results of the wide angle X‐ray diffraction (WAXD) showed that the BN particles had no influence on the PE crystalline form in the PE/BN composites. POLYM. COMPOS., 38:2806–2813, 2017. © 2015 Society of Plastics Engineers     

Enhanced dielectric permittivity and thermal conductivity of hexagonal boron nitride/poly(arylene ether nitrile) composites through magnetic alignment and mussel inspired co-modification

In this work, we present novel hexagonal boron nitride (h-BN)/poly(arylene ether nitrile) nanocomposites with high dielectric permittivity and thermal conductivity. For this purpose, the interfacial adhesion and orientation of nanofillers are the two key factors that need to be considered. Firstly, iron oxide was attached onto the surface of h-BN to obtain magnetically responsive property, which would realize the orientation of h-BN by applying an external magnetic field during the preparation process of PEN composites. Secondly, the magnetic h-BN was further modified by mussel-inspired method with dopamine and secondary functional monomer (KH550). It was found that the alignment of h-BN and improvement of interfacial adhesion resulted in the interesting properties of PEN composites. With addition of 30 wt% modified h-BN, the dielectric permittivity of PEN composites was increased from 3.2 of neat PEN to 16.4 (increased by 413%), and the low dielectric loss was remained. Meanwhile, the thermal conductivity was enhanced to 0.662 W/m K (increased by 140%) at the same loading content. In addition, the resulting h-BN/PEN nanocomposites maintained high mechanical strength and thermal stability even the nanofillers loading content reached 30 wt%. Therefore, the dielectric and thermally conductive h-BN/PEN composites with high mechanical strength and thermal stability have big advantages in the area of energy storage devices.     

Boron nitride-reinforced polysilazane-derived ceramic composites via direct-ink writing

In this study we investigate the use of hexagonal boron nitride (hBN) as a rheology modifier in polysilazane resin to enable direct-ink writing (DIW) of polysilazane-derived boron nitride-reinforced ceramic composites. hBN is shown to effectively modify the flow properties of the resin by imparting strong shear thinning and yield stress behavior, and to reduce the mass loss and shrinkage associated with the polymer-to-ceramic conversion process, when compared with unfilled polysilazane resin. DIW inks are formulated with 40 vol.% hBN and used print flexural specimens and complex structures with high resolution. Mechanical properties of the resulting polymer-derived ceramic composites were evaluated by 3-pt. flexure and Vickers microhardness. The printed composites exhibit flexural strength of 56.4 MPa and microhardness of 111.4 HV2.     

Machinable α-SiAlON/BN Composites

Dense machinable α-SiAlON/BN composites were fabricated by hot-pressing using turbostratic boron nitride (tBN) obtained from nitridation of melamine diborate. The tBN was added to the starting powders, or introduced as a coating that formed in situ on α-Si₃N₄ carrier powders during nitridation, and was subsequently converted to hexagonal boron nitride (hBN) during hot pressing by solution reprecipitation. These composites maintain high strength at 1000°C and their strength/hardness are much higher than similar composites prepared using commercial hBN powder, which yielded a coarser microstructure. Good machinability was achieved despite a flat R curve.     

Synergistic effects of hybrid fillers on the development of thermally conductive polyphenylene sulfide composites

The future of integrated circuits with three‐dimensional chip architecture hinges on the development of practical solutions for the management of excessive amounts of heat generation. This requires new polymer–matrix composites (PMCs), with good processibility, high effective thermal conductivity (k_eff), and low but tailored electrical conductivity (σ). This article explores the synergy of hybrid fillers: (i) hexagonal boron nitride (hBN) platelets with different sizes and shapes; (ii) hBN platelets with carbon‐based fillers promoting the k_eff of the polyphenylene sulfide (PPS) composites. It explores the promotion of interconnectivity among the fillers in the PPS matrix, leading to higher k_eff, by the uses of hybrid fillers. It discusses using carbon‐based fillers as secondary fillers to tailor the PMCs' σ. Finally, it presents the effects of hybrid fillers on the PMCs' coefficient of thermal expansion. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of Interfacial Interaction on Morphology and Properties of Polyethylene/Boron Nitride Thermally Conductive Composites

In this study, polyethylene-g-maleic anhydride was utilized to enhance interfacial interaction between boron nitride and polyethylene. Moreover, KH550 was used as a surface treatment agent to improve interfacial interaction between boron nitride and polyethylene. It was found that surface functionalization of boron nitride particles and the addition of polyethylene-g-maleic anhydride can promote dispersion of boron nitride particles with reduced aggregation, resulting in the improvement of both tensile and impact strength of polyethylene/boron nitride composites. Compared to surface functionalization of boron nitride particles, the addition of polyethylene-g-maleic anhydride was much effective to enhance thermal conductivity of polyethylene/boron nitride composites and drop effectively rheological percolation threshold and gel point of polyethylene/boron nitride composites.     

Influence of hBN content on mechanical and tribological properties of Si3N4/BN ceramic composites

Silicon nitride materials containing 1–5 wt% of hexagonal boron nitride (micro-sized or nano-sized) were prepared by hot-isostatic pressing at 1700 °C for 3 h. Effect of hBN content on microstructure, mechanical and tribological properties has been investigated. As expected, the increase of hBN content resulted in a sharp decrease of hardness, elastic modulus and bending strength of Si₃N₄/BN composites. In addition, the fracture toughness of Si₃N₄/micro BN composites was enhanced comparing to monolithic Si₃N₄ because of toughening mechanisms in the form of crack deflection, crack branching and pullout of large BN platelets. The friction coefficient was not influenced by BN addition to Si₃N₄/BN ceramics. An improvement of wear resistance (one order of magnitude) was observed when the micro hBN powder was added to Si₃N₄ matrix. Mechanical wear (micro-failure) and humidity-driven tribochemical reaction were found as main wear mechanisms in all studied materials.     

The electrical and thermal properties of polyimide/boron nitride nanocomposite films

In the paper, the polyimide (PI)/boron nitride (BN) nanocomposites were prepared by in situ polymerization and exhibited enhanced electrical property and thermal stability. The structure of synthesized PI was confirmed by scanning electron microscopy, energy dispersive spectrometer, and Fourier transform infrared. The influence of doping concentrations on the relative permittivity, electrical conductivity, loss tangent, corona-resistant lifetime, and thermal stability of PI composites was investigated. Results showed that the relative permittivity of PI/BN composites increases after doping BN nanoparticles. It was noteworthy that both the electrical conductivity and loss tangent of PI composites were enhanced in low frequency (0–3000 Hz) and the situations were shifted in high frequency (>3000 Hz). It was observed that the corona-resistant lifetime of PI/BN composite with 20 wt% BN increases more than eight times. Moreover, significant improvements in the thermal stability of PI composites were achieved by addition of only a small amount of BN. The decomposition temperatures at 5 and 10% weight loss were 518.7 and 551.6 °C for 15 wt% doped PI/BN composite, respectively, which increases by 37.3 and 40.5 °C compared to those of pure PI. The resulting properties expand further the application range of polyimides.