不锈钢纤维-石墨/ABS-PVDF复合材料相转变与导电特性

以丙烯腈-丁二烯-苯乙烯共聚物（ABS）和聚偏氟乙烯（PVDF）为基体,不锈钢纤维（SSF）和石墨为导电填料,通过熔融法制备SSF-石墨/ABS-PVDF导电复合材料,探究了其导电性能及流变性能。讨论了SSF/ABS-PVDF复合体系中导电填料的分布、导电性能及基体的相转变行为。结果表明:SSF倾向于分布在PVDF相中,当SSF含量为20wt%时,SSF/ABS-PVDF复合材料的电阻率随PVDF比例增加,先降低经历一个平台期后继续降低。PVDF在ABS-PVDF复合基体中含量为30wt%~40wt%和70wt%~80wt%时,SSF/ABS-PVDF复合材料出现相态转变行为。当SSF含量为16.84wt%和25wt%~30wt%时SSF-石墨/ABS-PVDF复合材料出现二次逾渗的现象,且与其动态模量及复数黏度的变化相符合。      

改性石墨烯/高密度聚乙烯复合材料PTC性能研究

以高密度聚乙烯(HDPE)为基体,改性的石墨烯为导电填料,采用熔融法制备正温度系数(PTC)的改性石墨烯/高密度聚乙烯复合材料。通过扫描电子显微镜、热重测试仪以及拉伸测试仪等,观察改性石墨烯/高密度聚乙烯复合材的微观形貌,研究改性石墨烯含量对复合材料热稳定性的影响以及拉伸性能的影响。结果表明:石墨烯在HDPE基体中分散性较好,在室温电阻率同为18.5Ω·㎝条件下,改性前复合材料耐电压冲击为250V,改性后复合材料耐电压冲击为400V,改性后的石墨烯加入HDPE,能够明显地提高复合材料增强耐电压性能,在石墨烯用量同为8.0%(体积百分数)条件下,改性前石墨烯的复合材料拉伸强度为25.6MPa,改性后石墨烯的复合材料拉伸强度为27.7MPa,改性后的石墨烯加入HDPE,能够明显提高复合材料的拉伸强度。     

炭黑/碳纤维/ABS电磁屏蔽复合材料的制备及其性能研究

采用硅烷偶联剂KH550改性炭黑(CB),浓硝酸氧化碳纤维(CF),将表面处理前后的炭黑和碳纤维与丙烯腈-丁二烯-苯乙烯(ABS)树脂通过混炼挤出制备了电磁屏蔽复合材料,考察了炭黑、碳纤维含量及表面处理对复合材料体积电阻率和屏蔽效能的影响。实验结果表明,采用KH550改性炭黑可以达到改性目的,浓硝酸氧化碳纤维后,其表面接上了羰基和羧基。随着炭黑含量增加,复合材料的体积电阻率逐渐下降,且变化规律符合"渗滤效应",在100～1800MHz频率范围内,屏蔽效能逐渐增加,采用1%KH550改性炭黑后,导电性能和屏蔽效能均得到提高。加入碳纤维后,复合材料的导电性能和屏蔽效能均有较大提高,且含量为2%时,分别达到最大值,采用浓硝酸氧化碳纤维后,导电性能得到进一步提高,屏蔽效能提高了1dB左右。     

碳纤维-Ni/尼龙66复合材料的制备与性能表征

为制备低电阻率的尼龙66基复合材料,以碳纤维和镍粉(Ni)填充尼龙66制备碳纤维-Ni/尼龙66高导电复合材料。研究填料表面改性和含量对碳纤维-Ni/尼龙66复合材料导电性能和力学性能的影响。结果表明:KH550改性碳纤维和Ni有助于降低碳纤维-Ni/尼龙66复合材料的电阻率。碳纤维-Ni/尼龙66复合材料的电阻率随着碳纤维和Ni含量的增加而减小,且碳纤维和Ni填充尼龙66的导电逾渗阈值均为20wt%,此时制备的碳纤维-Ni/尼龙66复合材料的电阻率为455Ω·cm,熔融温度为202.2℃。碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度随着碳纤维或Ni含量的增加而先增大后减小。当Ni含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度在碳纤维含量分别为20wt%和10wt%时达到最大值,分别为98MPa和70 MPa;当碳纤维含量为20wt%时,碳纤维-Ni/尼龙66复合材料的弯曲强度和拉伸强度则在Ni含量为30wt%和20wt%时达到最大值,分别为120 MPa和67 MPa。     

镀Ag玻璃微珠-膨胀石墨/聚氯乙烯导电复合材料的制备与表征

采用一种无Pd无SnCl₂化学镀Ag新工艺对空心玻璃微珠（HGB）表面进行化学镀Ag,然后通过熔融共混方法制备镀Ag玻璃微珠（Ag-GB）-膨胀石墨（EG）/聚氯乙烯（PVC）复合材料。借助SEM、EDS和XRD测试手段对Ag-GB镀层的表面形貌与结构进行了表征,研究了Ag-GB和EG作为复合填料对Ag-GB-EG/PVC复合材料导电和力学性能的影响。结果表明:预处理的HGB的表面更易于Ag层的沉积,镀覆的镀层更为均匀、致密;Ag-GB表面的Ag层质量分数为81.15%;固定Ag-GB的质量分数为15%,随着EG质量分数的增加,Ag-GB（15%）-EG/PVC复合材料的体积电阻率呈非线性降低趋势,当EG的质量分数达到逾渗阈值12%时,Ag-GB（15%）-EG/PVC复合材料的体积电阻率为2.18×103 Ω·cm,满足抗静电PVC材料的应用要求。添加质量分数为12%的EG,Ag-GB（15%）-EG/PVC复合材料的体积电阻率与单独填充质量分数为50%的Ag-GB时Ag-GB/PVC复合材料的体积电阻率相当,此时其拉伸强度达到最大值。      

碳纳米管/环氧复合材料制备与性能研究

研究了碳纳米管管径、种类、含量以及偶联-三辊研磨-超声处理等工艺条件对碳纳米管/环氧树脂复合材料拉伸强度和电性能的影响。研究结果表明:三辊研磨-超声联用是均匀分散碳纳米管简单而有效的方法。较低的碳纳米管添加量(0.8%～4%)能大幅度提高环氧树脂的剪切强度和导电性能,添加量为3%时,复合材料的综合性能最优,即剪切强度提高了55.19%,表面/体积电阻率下降了8～10个数量级。     

酚醛树脂/TiC/石墨复合材料双极板的性能分析

以改性酚醛树脂(PF)、TiC和石墨粉(EG)作为原料,通过一次模压成型工艺制备一种质子交换膜燃料电池复合材料双极板,并借助扫描电镜表征了复合材料的微观结构。研究了酚醛树脂的含量、成型压力以及TiC的含量对复合材料导电性能、力学性能的影响。实验结果表明:随酚醛树脂含量的增加,导电性能降低,力学性能升高;随成型压力的增大,导电性能和力学性能都呈升高趋势;随TiC含量的增加,力学性能增强,导电性能呈先增大后减小的趋势。当酚醛树脂和TiC质量分数各为10%,成型压力为60MPa时,所得复合材料弯曲强度>36MPa,抗压强度分别>30MPa,体积电导率>150S/cm。     

聚偏氟乙烯/膨胀石墨高介电复合材料的制备及性能

本实验采用溶液共混法制备了聚偏氟乙烯/膨胀石墨(PVDF/EG)复合材料,研究了膨胀石墨(EG)含量对复合材料微观形貌、电学性能、力学性能和热稳定性的影响。结果表明:EG的加入极大地降低了复合材料的体积电阻率(ρ_v),提高了其介电常数(ε_r)和介电损耗(tanδ),在EG质量分数为4%附近复合材料出现了渗流现象。PVDF/EG(5%,质量分数)复合材料的ρv相较于纯PVDF降低了11个数量级,εr提高了约68. 75倍,上升至550。随EG含量的增加,复合材料的拉伸强度和杨氏模量均呈先增大后减小的趋势,当EG质量分数为5%时分别达到最大值58. 31 MPa、910. 09 MPa,比纯PVDF分别提高了27. 76%、70. 10%;而断裂伸长率随EG含量的增加而逐渐减小。复合材料的热稳定性在EG加入量较少时得到明显改善,PVDF/EG(4%,质量分数)复合材料失重5%的分解温度比纯PVDF提高了5. 90℃。     

Fabrication and properties of graphite nanosheets/poly（vinyl chloride） composites

利用超声作用制备纳米石墨微片（nano-Os）,并采用混酸对其进行表面活化,最后通过熔融共混法制备nano-Gs／聚氯乙烯（PVC）复合材料。通过FTIR、SEM对nano-Gs的结构进行表征,并研究了nano-Gs对nano-Gs／PVC复合材料导电性能和力学性能的影响。FTIR分析表明：nano-Gs经混酸处理后表面活性官能团含量明显升高,并与PVC分子链发生一定程度的氢键作用;SEM图片显示：nano-Gs厚度为30-80nm,其微片宽度为4-20μm,在PVC树脂基体中呈无规状均匀分布;导电性能测试表明：随着nano-Gs含量升高,nano-Gs／PVC复合材料的体积电阻率呈非线性降低趋势,最低为10^[3]Ω·cm,nano-Gs的逾渗阈值为10％（质量分数）;力学性能测试表明,随着nano-Gs含量升高,nano-Gs／PVC复合材料的拉伸强度及缺口冲击强度均先升高后降低,nano-Gs质量分数为1％时,复合材料的拉伸强度及缺口冲击强度均达到最大值,相比纯PVC分别升高约14％和38％。     

镀镍碳纤维-碳纤维-玻璃纤维/乙烯基酯树脂导电复合材料的设计制备及其电磁性能

本研究旨在设计制备兼具电和磁功能的新型导电复合材料。采用具有良好导电性的短切碳纤维（CF）与兼具磁性和导电性的短切镀镍碳纤维（Ni-CF）作为功能体,以短切玻璃纤维（GF）作为填料,以乙烯基酯树脂（VER）作为基体,设计制备电磁性能可调控的导电复合材料。分别研究了CF含量对CF-GF/VER导电复合材料体积电阻率的影响、Ni-CF长度对（Ni-CF）-CF-GF/VER导电复合材料体积电阻率的影响,重点研究了Ni-CF含量对（Ni-CF）-CF-GF/VER导电复合材料体积电阻率和磁导率的影响,并初步探索了导电复合材料的电磁屏蔽性能。结果表明：（Ni-CF）-CF-GF/VER导电复合材料体积电阻率在0.35~36.48 Ω·cm范围内可调,磁导率在0.2~0.7内可调。CF和Ni-CF的含量和长度都会对（Ni-CF）-CF-GF/VER导电复合材料电磁性能产生较大影响。制备的（Ni-CF）-CF-GF/VER导电复合材料有望应用于电磁屏蔽领域。     

Preparation of high k expanded graphite/CaCuTi4O12/cyanate ester composites with low dielectric loss through controlling the interfacial action between conductors and ceramics

New composites with high dielectric constant and low dielectric loss, based on expanded graphite (EG), CaCuTi₄O₁₂ (sCCTO) and cyanate ester (CE) resin, were developed by controlling the interaction between EG and sCCTO. Difference from EG, surface modified EG (mEG) has an additional strong chemical interaction with sCCTO, this not only improves the dispersion of fillers, but also enhances the filler-matrix interfacial adhesion, leading to different micro-structures and dielectric properties. Specifically, the percolation thresholds of mEG/sCCTO/CE and EG/sCCTO/CE composites are 3.45 vol% and 2.86 vol%, respectively. When the loading of conductors approaches the percolation threshold, mEG/sCCTO/CE composite has much higher dielectric constant and lower dielectric loss than EG/sCCTO/CE composite. The nature behind these attractive data was revealed by building an equivalent circuit.     

Ethylene vinyl acetate/expanded graphite nanocomposites by solution intercalation: preparation,characterization and properties

Nanodimensional reinforcing agents are introduced to polymer matrices to improve properties at very low loading. Natural graphite (NG) as such is not reinforcing in nature. But when modified to expanded graphite (EG) by high temperature heat treatment, this may be used as reinforcing nanofiller. In the present study, ethylene vinyl acetate (EVA) was reinforced with EG by solution intercalation, and the composite properties were compared with those of the virgin polymer and NG filled composite. The tensile strength exhibited an improvement of 35% with 4 wt% EG addition, while the modulus at 100% elongation was increased by 150% with respect to the control EVA. Another interesting feature was that unlike the conventional fillers, addition of EG did not reduce the elongation at break, due to the lubricating action of graphite. However, at a high loading of 8 wt%, the tensile strength showed a lower value, due to the agglomeration of graphite platelets. The storage modulus also showed increment with the addition of graphite without much change in the glass transition temperature. In addition to these, the EVA-EG nanocomposites exhibited high thermal conductivity and thermal degradation stability as compared to the virgin polymer. About 4 wt% of EG shifted the temperature of maximum rate of degradation by 14 °C towards higher temperature. These results were well supported by the swelling and morphological studies. The NG filled composite exhibited inferior properties to EVA-EG nanocomposites.     

Preparation and characterization of Nylon-6/exfoliated graphite composite via a combination method of in situ polymerization and thermal expansion

Nylon-6/exfoliated graphite (Nylon-6/EG) composite was prepared via a combination method of in situ polymerization and thermal expansion and characterized via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Otherwise, the resistivity value of Nylon-6/EG composite was measured, and the volume resistivity value was calculated as well as. The characterization showed that Nylon-6/EG composite had the morphology of the graphite worm and was structured by EG and Nylon-6, which covered on the surface of EG. The result exhibited that the volume resistivity of Nylon-6/EG composite would decrease when the dosage of EG increased. When the mass percent of EG was 1%, the the volume resistivity value of Nylon-6/EG composite could reach 2.3 × 10⁶ Ω cm. This shows that the combination method not only is very effective and reliable but also can play an important role in preparing antistatic Nylon-6 composite.     

FG/CS逐层复合保鲜涂膜对三文鱼鱼片品质的影响

目的为了提高复合涂膜对三文鱼鱼片的保鲜性能,获得具有高效长效缓释性能的生物保鲜材料。方法以亚麻籽胶(FG)和壳聚糖(CS)为成膜材料,丁香酚(EG)和月桂精油(LEO)为保鲜剂,采用流延法制备逐层FG/CS+EG/FG+LEO复合涂膜。以三文鱼鱼片为研究对象,评估复合涂膜的保鲜性能。结果 FG/CS+EG/FG+LEO复合涂膜能够显著抑制三文鱼鱼肉中微生物的生长,提高鱼肉持水力,延缓脂肪氧化、蛋白质分解和色差值的变化进程。结论 EG和LEO复配使用具有一定的协同增效作用,同时,多层涂膜组成的缓释体系有效地延长了生物保鲜剂的作用时间,使EG和LEO对鱼片的保鲜效果更好,其中FG/CS+EG/FG+LEO复合涂膜的保鲜效果最优,可使生鲜三文鱼鱼片的货架期从7 d延长至13 d。     

膨胀石墨/石蜡复合材料的制备及热管理性能

石蜡作为相变材料(PCM),膨胀石墨(EG)为导热增强剂,制备不同EG含量的膨胀石墨/石蜡(EG/PCM)复合材料。采用瞬态热线法测量样品的导热系数;把EG/PCM应用于锂离子电池热管理,研究不同EG含量的EG/PCM热管理性能;采用ANSYS软件分析EG/PCM的导热系数对锂离子电池热管理的影响。结果表明:EG的加入大幅度提高了PCM的导热系数,EG含量≥9%时,EG/PCM的导热系数呈各向异性;锂离子电池表面温度随EG含量增加而减小,EG(12)/PCM(88)表现出优异的热管理性能;适当地提高EG/PCM的径向导热系数,有利于提高它的热管理性能。     

Preparation and characterization of polyaniline/exfoliated graphite composite via a combination method of in situ polymerization and thermal expansion

Polyaniline/exfoliated graphite (PANI/EG) composite was prepared via a combination method of in situ polymerization and thermal expansion and characterized, using scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). In the in situ polymerization, PANI/graphite intercalation compounds (GIC) composite was synthesized by GIC and aniline. In the thermal expansion, PANI/EG composite was prepared by PANI/GIC composite. The characterization showed that the morphology of PANI/EG composite was analogous to foam and the surface of PANI/EG composite had many micro-apertures. When PANI/GIC composite was synthesized by 0.80 g of GIC and 2.00 g of aniline, PANI/GIC composite would be exfoliated to PANI/EG composite at 200 °C, which had 75.00 mL·g⁻¹ of the expansion volume and 0.01Ω⁻¹ cm⁻¹of the conductivity.     

膨胀石墨-碳纤维/尼龙三元导热复合材料制备

以尼龙6（PA6）为基体,膨胀石墨（EG）和碳纤维（CF）作为导热填料,采用熔融共混法制备了EG/PA6、CF/PA6和CF-EG/PA6导热复合材料。重点研究当固定导热填料（CF和EG）填充量为40wt%时,CF与EG不同的填充比例对CF与EG的接触方式及CF-EG/PA6复合材料的导热性和力学性能的影响。结果表明,相比单一CF填充,EG的加入有利于CF-EG/PA6复合材料热导率的增加;CF:EG质量比是25:15时的EG-CF/PA6三元复合材料,热导率可以达到2.554 W/（m·K）,是PA6的8倍,拉伸强度提高了125.34%,弯曲强度提高了119.8%,同时具有优异的耐热性。SEM结果表明,纤维状CF与蠕虫状EG片层在适当的填充比例下可以形成"面接触"的三维网络结构,这种三维网络结构不仅显著增大EG-CF/PA6复合材料的热导率,而且明显提高了其力学性能和耐热性能。为研制填充型导热高分子材料提供了一条新思路。      

Preparation and Thermal Characterization of Nitrates/Expanded Graphite Composite Phase-Change Material for Thermal Energy Storage

Molten nitrate is widely used as thermal storage medium in the solar thermal power plants for its appropriate phase-change temperature, high heat storage density and low cost, etc. But its low thermal conductivity, heat absorbing and releasing rate limited its application. Expanded graphite (EG) can compensate the low thermal conductivity of nitrate. In this study, binary nitrates at the weight ratio of 4:6 for \(\hbox {LiNO}_{3}:\hbox {KNO}_{3}\) were prepared using static mixed melting method. EG with the mass fraction of 5 %, 10 %, 15 %, 20 % and 30 % was used to enhance the thermal conductivity. The compound of nitrates/EG was prepared using the ultrasonic smashing method. The thermal conductivity of binary nitrates, EG and nitrates/EG composite was measured by the transient plane heat source technique (TPS). The thermal behaviors were analyzed with a differential scanning calorimeter (DSC). Results showed that the addition of EG significantly enhanced the thermal conductivity, e.g., the thermal conductivity of 10 wt% EG composite phase-change material (PCM) is 8.5 \(\hbox {W}(\hbox {m}{^{-1}} \hbox {K}{^{-1}})\) to 9.5  \(\hbox {W}(\hbox {m}{^{-1}}\hbox {K}{^{-1}})\), which is about eight times larger than that of binary nitrates. To observe the combination morphology, pure EG, nitrates/EG composite PCM and binary nitrates were characterized using scanning electron microscope (SEM). The thermal reliability of the binary nitrates and the composite PCM was determined by DSC. Thermal cycling test showed that both binary nitrates and nitrates/EG composite material have good thermal reliability.     

可膨胀石墨改性APP/PER/EN防火涂料热降解行为

采用可膨胀石墨 (EG) 对APP/PER/EN防火体系进行改性,制备成一种新型EG改性APP/PER/EN防火涂料。运用示差热分析 (DTA) 、热重分析 (TG) 、扫描电镜分析 (SEM) 、能谱分析 (EDS) 和隔热性能试验分析研究APP/PER/EN防火涂料和EG改性防火涂料的热降解行为、残余炭体元素含量、成炭率和隔热性能。EG改性防火涂料的APP-PER-EN之间的化学反应膨胀过程与可膨胀石墨物理膨胀过程作用温度范围接近,能产生很好的协同配合作用。膨胀石墨提高了APP/PER/EN防火涂料炭质层的成炭率、抗氧化性和热稳定性。EG添加量过高 (≥15%) 会造成燃烧后期炭质层脱离基材。10% EG (质量分数) 添加量能有效提高APP/PER/EN防火涂料的隔热防火性能。