Effect of hybrid nanofillers on the thermal, mechanical, and physical properties of polypropylene composites

In this study, the effect of single and hybrid nanofillers on the thermal, mechanical, and physical properties of polypropylene composites were carried out. This nanocomposite was compounded using two-roll mill mixing method and the filler content was fixed at 4 vol % loading. The single filler used is synthetic diamond (SD), boron nitride (BN), and carbon nanotube (MWNT). The hybrid system was composed by addition of MWNT into single SD and BN. The prepared samples were characterized by thermal properties, tensile and flexural, and these results were supported by the morphology, void content, and melt flow index values. The result showed that the hybrid composite with combination of BN and SD with MWNT indicate higher thermal conductivity and thermal stability and lower thermal expansion. However, no significant improvements in tensile and flexural strengths were observed due to large formation of agglomeration as being captured by SEM micrographs. Furthermore, the existence of higher percent void content suggests low adhesion and poor compatibility between hybrid filler and matrix. This caused detrimental effect of strength of hybrid composites rather than single filler composites.     

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.     

PA6/CF/EG导电复合材料的制备与性能

采用熔融共混法制备了不同碳纤维/热膨胀石墨(CF/EG)比例的尼龙6/碳纤维/热膨胀石墨(PA6/CF/EG)导电复合材料并研究其性能。结果表明,CF的加入能显著提高复合材料的力学性能;而随着EG含量的提高,复合材料的导电性能和导热性能显著提高,但力学性能在一定程度上得到降低。当CF质量分数为20%时,复合材料具有最优的力学性能,当EG质量分数为20%时,复合材料体积电导率可显著提高至0.262 S/m,热导率可达1.3379W/(m·K)。     

High performance thermoplastic composites: Study on the mechanical,thermal, and electrical resistivity properties of carbon fiber‐reinforced polyetheretherketone and polyethersulphone

High temperature processing thermoplastic polymers, polyetheretherketone (PEEK) and polyethersulphone (PES), were melt blended with carbon fibers (CFs) to make composites. These composites were investigated for their mechanical, thermal, and electrical properties. Mechanical properties that are expressed in terms of storage modulus, loss, and damping were enhanced with the addition of CFs. Thermal properties were determined by DSC and TGA. These methods help to understand the effects of fiber content and fiber–matrix adhesion in the composites. Composites were also tested for their electrical and thermal conductivity because CFs leave the composites thermally and electrically conductive. CFs enhanced the crystallinity of the PEEK appreciably that in turn influenced thermal conductivity, electrical resistivity, and the stiffness of PEEK/CF (composites of PEEK with CFs). PES/CF (composites of PES with CF) shows a different behavior due to the amorphous nature of PES. The work involves one filler and two different matrices, and so it provides an interesting comparison of how matrix morphology can influence the properties of composites. POLYM. COMPOS. 28:785–796, 2007. © 2007 Society of Plastics Engineers.     

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...     

PA6/BN/MgO导热复合材料的制备与性能研究

以聚酰胺6（PA6)为基体,以氮化硼（BN）、氧化镁（MgO）为导热填料制备了PA6/BN/MgO导热复合材料。固定填料含量为50%（质量分数,下同）不变,考察MgO/BN配比的变化对复合材料热导率、力学性能和熔体流动性的影响。结果表明,材料的热导率、拉伸强度和弯曲强度随着MgO/BN配比的增大而减小,冲击强度和断裂伸长率随着MgO/BN配比的增大而增大,材料熔体流动性则呈现了随MgO/BN配比的增大先增大后减小的趋势。     

The synergistic effects on enhancing thermal conductivity and mechanical strength of hBN/CF/PE composite

In this work, a simple and novel method was applied to prepare polymer composites by taking the advantage of melt flow shear force driving orientation of the fillers. By using this method, hexagonal boron nitride/polyethylene (hBN/PE) and hexagonal boron nitride/carbon fibers/polyethylene (hBN/CF/PE) composites were fabricated to be possessed of high thermal conductivity and mechanical properties. A high thermal conductivity of 3.11 W/mK was realized in the composite containing 35 wt% hBN and 5 wt% CF, which was over 1,200% higher than that of unfilled PE matrix. Under this component, the compressive strength and modulus of hBN/CF/PE composite were determined to be 30.1 and 870.9 MPa, respectively, which were far higher than that of unfilled PE accordingly. The bending performance was also somewhat enhanced. Meanwhile, the bulk resistivity of the composite material reached 2.55 × 10¹¹ Ω·cm, which was basically the same as that of pure PE. The novel composites with high thermal conductivity, excellent mechanical properties, and controllable electrical insulation could be a potential thermal management material for electrical and electronics industries.     

Polyester and multiwalled carbon nanotube composites: characterization,electrical conductivity and antibacterial activity

Poly(butylene terephthalate) (PBT) composites containing multiwalled carbon nanotubes (MWCNTs) were prepared using a melt‐blending process and used to examine the effects on the composite structure and properties of replacing PBT with acrylic acid‐grafted PBT (PBT‐g‐AA). PBT‐g‐AA and multihydroxyl‐functionalized MWCNTs (MWCNTs‐OH) were used to improve the compatibility and dispersibility of the MWCNTs within the PBT matrix. The composites were characterized morphologically using transmission electron microscopy, and chemically using Fourier transform infrared, solid‐state ¹³C NMR and UV‐visible absorption spectroscopy. The antibacterial and electrical conductivity properties of the composites were also evaluated. MWCNTs or MWCNTs‐OH enhanced the antibacterial activity and electrical conductivity of the PBT/MWCNT or PBT‐g‐AA/MWCNTs‐OH composites. The functionalized PBT‐g‐AA/MWCNTs‐OH composites showed markedly enhanced antibacterial properties and electrical conductivity due to the formation of ester bonds from the condensation of the carboxylic acid groups of PBT‐g‐AA with the hydroxyl groups of MWCNTs‐OH. The optimal proportion of MWCNTs‐OH in the composites was 1 wt%; in excess of this amount, the compatibility between the organic and inorganic phases was compromised. Copyright © 2011 Society of Chemical Industry     

Analysis of mechanical,thermal, electrical and EMI shielding properties of graphite/carbon fiber reinforced polypropylene composites prepared via a twin screw extruder

The present research focuses on the preparation of an efficient material that acts as a deterrent to electromagnetic pollution. In this study, graphite and carbon fiber (CF) reinforced polypropylene (PP) composites (GCF) are prepared using a melt processing technique via a twin-screw extruder. The prepared composites were evaluated for mechanical, thermal, DC conductivity, and EMI shielding properties. There is a rise in the tensile strength (4.32%) and thermal stability (6.57%) of composites were recorded as compared to pure PP. The fractured morphology of the composites showed the breakdown of CF, leading to the improvement in the tensile strength of the composites. An increase in electrical conductivity was seen at maximum (GCF4) filler loading indicating 2.31 × 10^?4 S/cm which is much better than the pure PP value (2.07 × 10^?10 S/cm). The maximum value of shielding effectiveness is achieved at the maximum weight percentage of filler loading which is ?44.43 dB with a thickness of 2 mm covering the X-band (8.2–12.4 GHz).     

Synergistic effect of boron nitride and tetrapod‐shaped zinc oxide whisker hybrid fillers on filler networks in thermal conductive HDPE composites

In this paper, in order to investigate and predict the synergistic effect of the tetra‐needle‐shaped zinc oxide whisker (T‐ZnO) and boron nitride (BN) hybrid fillers in the thermal conductive high‐density polyethylene (HDPE) composites, the filler networks were studied through dynamic rheological measurement. Moreover, the crystallinity of the HDPE in the composites, and the thermal and electrical conductivity of the composites were also investigated. It was found that when the ratio of the BN and T‐ZnO in hybrid fillers was 20:10, the HDPE/hybrid fillers composite not only had the highest thermal conductivity but also can maintain the electrically insulating. Furthermore, the gel point of the HDPE/hybrid fillers composites was 11.2 wt%, and it was close to the 10 wt%. Therefore, the synergistic effect of the T‐ZnO and BN hybrid fillers in the HDPE/hybrid fillers composites can be successfully predicted through dynamic rheology date. Simultaneously, the Scanning electron microscope results showed that the T‐ZnO and BN particles can contact each other to form the thermal conductive paths so that the thermal conductivity of the HDPE can be enhanced through addition of the hybrid fillers. In addition, it was also found that the improved thermal conductivity of the HDPE/hybrid fillers composites was not because of a change in the crystallinity of the HDPE in the HDPE/hybrid fillers composites. POLYM. COMPOS., 38:1902–1909, 2017. © 2015 Society of Plastics Engineers     

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.     

The effect of recycling number on the mechanical,chemical, thermal,and rheological properties of PBT/PC/ABS ternary blends: With and without glass‐fiber

The recycling possibilities of poly(butylene terephthalate)/polycarbonate/acrylonitrile–butadiene–styrene (PBT/PC/ABS) ternary blend with and without glass‐fiber content were investigated using repeated injection molding process. In this study, PBT/PC/ABS ternary blends were reprocessed at five times and the results were presented after each recycling process. The recycling possibility of PBT/PC/ABS ternary blend was evaluated by measuring the mechanical, chemical, thermal, and rheological properties. Mechanical properties were determined by the tensile strength, yield strength, strain at break, elastic modulus, impact strength, flexural strength, and flexural modulus. Chemical and thermal properties were evaluated by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and scanning electron microscopy. Rheological properties of the ternary blends were studied by melt flow index measurement. From the results, it was found that mechanical properties of recycled composites were better than virgin PBT/PC/ABS ternary blends. POLYM. COMPOS., 35:2074–2084, 2014. © 2014 Society of Plastics Engineers     

Reinforced thermal conductivity and mechanical properties of in situ microfibrillar composites through multistage stretching extrusion

To surmount difficulty of the melt processing and deterioration of mechanical properties of polymer composites induced by high fraction of the reinforced fibers and thermal conductive fillers, polyethylene (PE)/boron nitride (BN)/polyamide 6 (PA6) and PE/BN/poly(‐hydroxybenzate‐co‐DOPO‐benzenediol dihydrodiphenyl ether terephthalate) (PHDDT) in situ microfibrillar composites were prepared through multistage stretching extrusion. The experimental results showed that both the tensile and impact strength of the PE/BN/PA6 and PE/BN/PHDDT composites were improved. Meanwhile, the thermal conductivities of the PE/BN, PE/BN/PA6, and PE/BN/PHDDT composites were also reinforced. Based on the equation proposed by Y. Agari, the new modified equations can well predict the thermal conductivity of the composites prepared through multistage stretching extrusion with different number of laminating‐multiplying elements. In addition, it was found that PHDDT can act as a “processing aid” to reduce the viscosity of the PE/BN composites. POLYM. COMPOS., 38:2663–2669, 2017. © 2015 Society of Plastics Engineers     

Electrical conductivity and EMI shielding effectiveness of polyurethane foam–conductive filler composites

The morphological, electrical, and thermal properties of polyurethane foam (PUF)/single conductive filler composites and PUF/hybrid conductive filler composites were investigated. For the PUF/single conductive filler composites, the PUF/nickel‐coated carbon fiber (NCCF) composite showed higher electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) than did the PUF/multiwall carbon nanotube (MWCNT) and PUF/graphite composites; therefore, NCCF is the most effective filler among those tested in this study. For the PUF/hybrid conductive fillers PUF/NCCF (3.0 php)/MWCNT (3.0 php) composites, the values of electrical conductivity and EMI SE were determined to be 0.171 S/cm and 24.7 dB (decibel), respectively, which were the highest among the fillers investigated in this study. NCCF and MWCNT were the most effective primary and secondary fillers, and they had a synergistic effect on the electrical conductivity and EMI SE of the PUF/NCCF/MWCNT composites. From the results of thermal conductivity and cell size of the PUF/conductive filler composites, it is suggested that a reduction in cell size lowers the thermal conductivity of the PUF/conductive filler composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44373.     

Effects of hybrid fillers on the electrical conductivity,EMI shielding effectiveness,and flame retardancy of PBT and PolyASA composites with carbon fiber and MWCNT

The effects of hybrid fillers of carbon fiber (CF) and multiwall carbon nanotube (MWCNT) on the electrical conductivity, electromagnetic interference shielding effectiveness (EMI SE), flame retardancy, and mechanical properties of poly(butylene terephthalate) (PBT)/poly(acrylonitrile-co-styrene-co-acrylate) (PolyASA) (70/30, wt %) with conductive filler composites were investigated. The CF was used as the main filler, and MWCNT was used as the secondary filler to investigate the hybrid filler effect. For the PBT/PolyASA/CF (8 vol %)/MWCNT (2 vol %) composite, a higher electrical conductivity (1.4 × 10⁰ S cm⁻¹) and EMI SE (33.7 dB) were observed than that of the composite prepared with the single filler of CF (10 vol %), which were 9.0 × 10⁻² S cm⁻¹ and 23.7 dB, respectively. This increase in the electrical properties might be due to the longer CF length and hybrid filler effect in the composites. From the results of aging test at 85 °C, 120 h, the electrical conductivity and EMI SE of the composites decreased slightly compared to that of the composite without aging. The results of electrical conductivity, EMI SE, and flame retardancy suggested that the composite with the hybrid fillers of CF and MWCNT showed a synergetic effect in the PBT/PolyASA/CF (8 vol %)/MWCNT (2 vol %) composite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48162.     

Thermal conductivity of polypropylene composites with hybrid fillers of boron nitride and vapor‐grown carbon fiber

High thermal conductivity fillers of boron nitride (BN) and vapor‐grown carbon fiber (VGCF) were used alone or incorporate to prepare polypropylene (PP) composites. The effects of filler content, particle size and shape, and single vs. hybrid BN/VGCF fillers were investigated with respect to the thermal conductivity of the PP composites. The thermal conductivity of PP/BN composites depended upon the content and particle size of the BN. Increased content and length of VGCF had the effect of increasing the thermal conductivity of the PP composites. Hybrid fillers were created with a mixture of medium‐sized BN and long‐length VGCF; hybrid BN/VGCF fillers enhanced the thermal conductivity of PP composites with a lower total content compared with PP composites containing only medium‐sized BN particles. POLYM. COMPOS., 37:936–942, 2016. © 2014 Society of Plastics Engineers     

Preparation and characterization of thermally conductive thermoplastic polyurethane/h‐BN nanocomposites

Polyurethane nanocomposites are versatile engineering polymers with unique properties. In this study, nano hexagonal boron nitride containing thermoplastic polyurethane elastomers were prepared via melt blending and hot‐pressing techniques. The nanocomposites were characterized using Fourier transform infrared, differential scanning calorimetry, thermal gravimetric analysis, tensile tests, and thermal conductivity measurements. The surface morphology of the TPU/h‐BN composites was characterized by scanning electron microscopy. The optical properties of the composites were determined by UV transmittance measurements and as the amount of h‐BN increased, optical transparencies decreased dramatically. Nanocomposites displayed higher E‐modulus values and lower elongation at break values than the pure TPU elastomer. Char yields of TPUs increased with increasing h‐BN percentage. Moreover, thermal conductivity of the composite materials improved with the incorporation of h‐BN. POLYM. COMPOS., 35:530–538, 2014. © 2013 Society of Plastics Engineers     

Electrical and thermal conductivity and tensile and flexural properties of carbon nanotube/polycarbonate resins

Adding conductive carbon fillers to insulating thermoplastic polymers increases the resulting composite's electrical conductivity. Carbon nanotubes (CNTs) are very effective at increasing composite electrical conductivity at low loading levels without compromising composite tensile and flexural properties. In this study, varying amounts (2–8 wt %) of CNTs were added to polycarbonate (PC) by melt compounding, and the resulting composites were tested for electrical conductivity (1/electrical resistivity), thermal conductivity, and tensile and flexural properties. The percolation threshold was less than 1.4 vol % CNT, likely because of CNTs high aspect ratio (1000). The addition of CNT to PC increased the composite electrical and thermal conductivity and tensile and flexural modulus. The 6 wt % (4.2 vol %) CNT in PC resin had a good combination of properties for electrical conductivity applications. The electrical resistivity and thermal conductivity were 18 Ω‐cm and 0.28 W/m · K, respectively. The tensile modulus, ultimate tensile strength (UTS), and strain at UTS were 2.7 GPa, 56 MPa, and 2.8%, respectively. The flexural modulus, ultimate flexural strength, and strain at ultimate flexural strength were 3.6 GPa, 125 MPa, and 5.5%, respectively. Ductile tensile behavior is noted in pure PC and in samples containing up to 6 wt % CNT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal conductivity of boron nitride‐filled thermoplastics: Effect of filler characteristics and composite processing conditions

The thermal conductivity of boron nitride (BN)‐filled poly(butylene terephthalate) (PBT) was investigated as a function of particle size, aspect ratio, surface area, surface chemistry, and concentration of BN as well as composite processing methods and conditions. In the low filler concentration region, a larger BN surface area resulted in lower thermal conductivity of the composites as a result of phonon scattering at interfaces. In the high filler concentration region the ease in forming filler networks, as reflected by the aspect ratio of BN, played a more dominant role. A percolation‐like behavior was observed when BN networks were formed while the thermal conductivity at close vicinity of the percolation threshold was not completely governed by the scaling law of classic percolation theory. High shear force employed in extrusion was effective in dispersing BN agglomerates into fine platelets while also inducing PBT degradation. When a low screw speed was used in extrusion followed by injection molding, the samples exhibited significantly lower thermal conductivity, which may be attributed to flow‐induced orientation of BN platelets in the direction perpendicular to the heat flow, relatively low concentration of filler at sample surfaces (skin‐core effect), and agglomeration of the BN platelets. POLYM. COMPOS. 26:778–790, 2005. © 2005 Society of Plastics Engineers     

石墨和碳纤维改性聚酰亚胺复合材料的导热性能

以石墨、碳纤维(CF)、聚酰亚胺(PI)三元复合材料为研究对象,考察了CF体积含量对PI三元复合材料导热性能的影响,并采用了拟二元体系模型探讨了石墨和CF填充PI复合材料的协同效应。结果表明,CF的加入可以提高复合材料的力学性能：拉伸强度呈现先升高后降低的趋势,当CF含量为11.8 %（体积分数,下同）时,拉伸强度可达66.37 MPa;弯曲强度随着CF体积含量的增而增加,当CF含量为24.6 %时,弯曲强度可达103.3 MPa。复合材料热导率呈非线性增长,表明石墨和CF间存在协同效应;当CF含量为34.1 %时,环境扫描电子显微镜分析表明,CF与石墨能很好地搭接,增大了传热面积,复合材料热导率可达0.512 W/(m·K),约是其计算值的2倍。