纳米SiO_2功能化改性石墨烯/热塑性聚氨酯复合材料的制备与性能

采用Hummers法制备了氧化石墨烯(Graphene Oxide,GO),再与经硅烷偶联剂(APTES)偶联改性纳米SiO_2所得的产物(nano SiO_2—NH_2)混合,制备了石墨烯片(Graphene Sheets,GS)接枝纳米SiO_2杂化材料(nano SiO_2-g-GS)。以nano SiO_2-g-GS为填料,热塑性聚氨酯(TPU)为基体,通过熔融共混法制备共混型nano SiO_2-g-GS/TPU复合材料,并对填料和复合材料进行测试和表征。拉伸测试显示nano SiO_2-g-GS的加入对基体TPU有一定的补强作用,使复合材料定伸应力(300%、500%和1 000%)增大。DSC测试显示,与纯TPU相比,nano SiO_2-g-GS/TPU复合材料的结晶温度有大幅升高,填料含量为1wt%时,TPU的结晶温度升高了44℃。形状记忆测试结果显示,随nano SiO_2-g-GS含量增加,nano SiO_2-g-GS/TPU复合材料的形状回复率(Rr)逐渐降低,但形状固定率(Rf)逐渐升高。当nano SiO_2-g-GS质量分数为1wt%时,nano SiO_2-g-GS/TPU复合材料性能最佳。     

添加铜网对片层石墨/Al复合材料热物理性能的影响

使用盐浴法对片层石墨（GFs）进行表面镀Si处理,采用真空热压法制备片层石墨/Al复合材料（Si-GFs/Al）。向Si-GFs/Al复合材料中添加10vol%的铜网,研究了铜网对Si-GFs/Al复合材料热导率和力学性能的影响。使用SEM、聚焦离子束（FIB）和TEM对Si-GFs/Al复合材料的微观结构和微观界面进行表征,并分析了复合材料的断裂机制。结果表明,添加铜网使Si-GFs/Al复合材料内部出现了高聚集定向GFs带,形成高导热通道。当GFs体积分数为30vol%~40vol%时,Si-GFs/Al复合材料的热导率提升了约20%,弯曲强度提升了40%以上。当GFs体积分数为40vol%时,Si-GFs/Al复合材料热导率和弯曲强度同时达到一个优值,分别为512 W/（mK）和127 MPa。      

表儿茶素修饰BN对BN@表儿茶素/环氧树脂复合材料性能的影响

用表儿茶素(EC)作为非共价改性剂,对BN进行表面处理,研究了不同质量分数EC修饰的BN对BN@EC/环氧树脂(EP)复合材料性能的影响。采用FTIR、 XRD、 SEM、 TG等对BN、 BN@EC和BN@EC/EP复合材料的结构和性能进行表征,研究证明EC对BN改性成功,且改性过程中没有对BN的晶型结构产生影响;经EC改性后的BN在树脂基体中的分散性得到改善;SEM测试结果表明,与未改性的BN粒子相比,经EC改性后的BN粒子的团聚程度降低, BN@EC在基体中的分散性更好;经改性的BN@EC在水中的稳定性得到提高;当EC质量分数为10wt%时, BN@EC/EP复合材料的导热性能最好,热导率达1.27 W·m^-1·K^-1,与BN/EP的热导率(0.62 W·m^-1·K^-1)相比提高了106%。最后,分析了EC的加入对复合材料热稳定性能和硬度的影响,结果表明, EC的加入会略微提高复合材料的热稳定性。     

Improved breakdown strength and energy density of polyimide composites by interface engineering between BN and BaTiO3 fibers

Conventionally,interface effects between polymers and fillers are essential for determining the breakdown strength and energy storage density of polymer-based dielectric composites.In this study,we found that interface effects between different fillers have similar behavior.BN and BaTi03 fiber composite fillers with three different interface bonding strengths were successfully achieved by controlling composite processes (BT-fiber/BN ＜ BT-fiber@BN ＜ BT-fiber&BN),and introduced into a polyimide (PI)matrix to form composite films.Considerably enhanced breakdown strength and energy storage density were obtained in BT-fiber&BN/PI composites owing to strong interface bonding,compared to other two composite fillers,which are well supported by the data from the finite element simulation.Specifically,PI composites with only 3 wt％ BT-fiber&BN possess an optimized energy storage density of approximately 4.25 J/cm3 at 4343 kV/cm.These results provide an effective way for adjusting and improving the energy storage properties of polymer-based composites.     

不同填料复配对尼龙6/石墨烯复合材料导热性能的影响

高分子材料的绝热特性极大地限制了其作为导热材料在工业中的应用。选用多层石墨烯作为导热填料,并分别与导热填料氧化铝(Al_2O_3)和碳化硅(SiC)复配,探究导热填料的复配对尼龙6(PA6)复合材料导热性能的影响。加入质量分数为3%石墨烯时,PA6复合材料的热导率为0.548W·m^-1·K^-1,相比PA6基体提高161%。通过调节石墨烯与Al_2O_3和SiC复配的比例以及复合填料量,PA6复合材料的热导率可控在0.653~4.307W·m^-1·K^-1之间,最高是PA6基体的20倍。为拓展石墨烯在导热材料方面的应用及PA6导热材料在工业上应用提供了有价值的实验依据。     

凝胶注模成型技术制备氧化石墨烯/HA复合材料的研究

以氧化石墨烯和纳米羟基磷灰石(HA)粉体为原料,采用凝胶注模成型技术制备了氧化石墨烯/HA复合材料。研究了有机单体、浆料固相含量和石墨烯含量对氧化石墨烯/HA浆料粘度的影响,观察了陶瓷浆料的凝胶固化过程并测量了固化后生坯的密度和抗压强度,分析了氧化石墨烯含量对烧结后复合材料抗弯强度和断裂韧性的影响,观察了试样断口的显微组织。研究结果表明,有机单体含量为15%(质量分数,下同),固相含量为45%,氧化石墨烯含量为1.5%时,氧化石墨烯/HA浆料的粘度最佳,为362.9mPa·s,浆料的分散性良好,固化后生坯具有较高的密度和抗压强度。随氧化石墨烯含量的增加,复合材料的抗弯强度和断裂韧度均先增加后降低。当氧化石墨烯含量为1.5%时,1 150℃烧结样品的抗弯强度为81.5MPa,断裂韧性为1.52MPa·m1/2,分别比HA基体提高了151.8%和74.7%,因此添加氧化石墨烯后的HA复合材料的力学性能更佳。     

纳米氮化硼增强金属基复合材料的研究进展

在金属中添加陶瓷增强相是调控和改善金属材料结构和性能的重要途径。传统硬质陶瓷增强相难以满足金属材料日益严苛的应用需求。以氮化硼纳米片（boron nitride nanosheet,BNNS）和氮化硼纳米管（boron nitridenanotube,BNNT）为代表的纳米氮化硼具有极大的比表面积和优异的力学性能、热稳定性、化学稳定性等,是制备性能优异的金属基复合材料的理想增强相。系统总结了纳米氮化硼的种类和特征,综述了纳米氮化硼增强金属基复合材料的制备方法,归纳了纳米氮化硼增强Cu、Al、Ti复合材料的研究成果,总结了纳米氮化硼/金属复合材料的力学和摩擦学性能,并揭示了复合材料性能改善的机理。最后,展望了纳米氮化硼/金属复合材料的发展趋势。     

改性纳米BN/甲基乙烯基硅橡胶导热复合材料的制备

以甲基乙烯基硅橡胶（MVSR）为基体,硅烷偶联剂KH550与聚倍半硅氧烷（POSS）结合改性的纳米BN（POSS-g-nBN）为导热填料,经混炼-热压制备POSS-g-nBN/MVSR导热复合材料。结果表明,POSS-g-nBN/MVSR导热复合材料的导热系数（λ）、介电常数（ε）和介电损耗正切值（tanδ）均随nBN用量增加而增大。相同nBN用量下,表面功能化改性有助于进一步提高nBN/MVSR导热复合材料的λ,降低ε和tanδ。当POSS-g-nBN用量为30vol%时,POSS-g-nBN/MVSR导热复合材料的λ为0.92 W（mK）-1,约为纯MVSR的（λ=0.18 W（mK）-1）5倍,也高于相同nBN用量的nBN/MVSR导热复合材料的λ（0.77 W（mK）-1）。相比未改性nBN,POSS-g-nBN更易在MVSR基体内形成导热通路且和MVSR基体具有相对更低的界面热障。当POSS-g-nBN用量为30vol%时,POSS-g-nBN/MVSR导热复合材料的ε和tanδ分别为3.39和0.0049,略低于相同nBN用量的nBN/MVSR导热复合材料的ε（3.43）和tanδ（0.0057）。      

低密度碳空心微球的制备及酚醛树脂空心微球复合材料的性能

以BJO-0930酚醛树脂空心微球为原料,通过酸洗、预氧化、碳化三步工艺,成功制备球形度好、强度高的碳空心微球,并与热固性酚醛树脂复合,热压成型得到轻质酚醛树脂/空心微球复合材料。系统考察了碳化温度、循环酸洗、预氧化等对碳空心微球强度的影响。复合材料的力学性能和隔热性能分别通过压缩性能以及热导率测试进行表征。结果表明:直接碳化得到的碳空心微球破球率高、强度低;通过循环酸洗可以有效去除树脂球的灰分,破球率由28.07%降低至18.03%;进一步预氧化处理可以显著提高碳空心微球的强度,其破球率和等静压破球率分别为10.03%和17.34%;制备得到的酚醛树脂/碳空心微球复合材料具有优异的隔热性能和力学性能,热导率降低至0.115 W·m~(-1)·K~(-1),压缩强度为46.02MPa。     

紫外光辐射固化共混改性环氧树脂复合材料的力学和热老化性能

利用湿法手工铺叠工艺和紫外光固化技术,制备以双酚A环氧树脂E-44与有机硅环氧树脂ES-06共混改性光敏树脂体系为基体的玻璃布增强复合材料,测试并分析比较了复合材料的力学和热老化性能.结果表明,在光敏树脂基体中加入链转移剂以及对光固化后的复合材料进行加压后固化处理,均能显著提高复合材料的性能.采用E-44与ES-06质量比为2:1的共混改性树脂体系制备的复合材料的力学性能和耐热老化性能最佳,其拉伸强度达到146.6 MPa,拉伸模量为19.4GPa,弯曲强度为152.5MPa,层间剪切强度达到16.2 MPa.     

树脂基稀土-铁系超磁致伸缩复合材料的磁致伸缩及其高频磁性能

以粉末粘结、模压成型方法,研制了0-3型的E-44环氧树脂基稀土-铁系超磁致伸缩复合材料。采用电阻应变片技术与Agilent 4294A型动态阻抗分析仪,研究了超磁致伸缩合金/环氧树脂复合材料的磁致伸缩性能及高频磁性能,并对所制备的磁致伸缩复合材料的磁导率、截止使用频率等随频率和树脂体积分数的变化规律进行了系统研究。结果表明:树脂的添加,不仅可以提高复合材料的截止频率和高频磁性能,使其具有良好的高频响应特性,其截止频率达30 MHz以上;而且通过适当选择树脂的体积分数,复合材料仍能保持良好的磁致伸缩性能,当树脂体积分数分别为20%、30%时,磁致伸缩系数分别达808×10-6、821×10-6,而当复合材料中树脂的体积分数为50%时,其磁致伸缩系数仍高达592×10-6。探讨了树脂/磁致伸缩复合材料的磁电耦合机制。      

纳米Ag链的制备及其在聚氨酯基柔性导电复合材料中的应用

针对柔性聚合物基导电复合材料的导电性差和柔性差这2个关键问题,分别从导电填料的柔性化及降低填料含量2方面着手,以脱氧核糖核酸（DNA）大分子链作为模板,制备了大小均一、链状排列的柔性纳米Ag链及纳米Ag链填充的聚氨酯基柔性导电复合材料。利用SEM对纳米Ag链/Ag包Cu粉/聚氨酯导电复合材料的界面结构进行了表征,探讨了纳米Ag链/Ag包Cu粉/聚氨酯导电复合材料导电性及柔性的机制。研究发现:保持导电填料总质量分数为76%、纳米Ag链的质量分数为4%时,纳米Ag链/Ag包Cu粉/聚氨酯导电复合材料的电阻率及形变前后的电阻变化比值达到最佳值,分别为2.13×10-4 Ω·cm和3.6;当以纳米Ag链为单一填料时,制得的纳米Ag链/聚氨酯导电复合材料具有优异的柔性;泡沫法制备的纳米Ag链/聚氨酯导电复合材料可以在低填料质量分数时达到更高的导电性,当纳米Ag链质量分数为60%时,方阻为56 Ω/sq,低于共混法制备的填料质量分数为65%时的纳米Ag链/聚氨酯导电复合材料（98 Ω/sq）。      

Liquid crystalline texture and hydrogen bond on the thermal conductivities of intrinsic thermal conductive polymer films

Polymer-dispersed liquid crystal(PDLC)films comprising polyvinyl alcohol(PVA)and liquid crystal monomer(LCM)were successfully obtained by the method of solution casting&thermal compress-ing.LCM was distributed orderly in PVA matrix by hydrogen bond interaction,to form PVA-LCM interpenetrating-layered networks.When the mass fraction of LCM was up to 35 wt％,the corresponding in-plane thermal conductivity coefficient(λ∥)of PDLC film was significantly increased to 1.41 W m-1 K-1,about 10.8 times that of neat PVA(0.13 W m-1 K-1).High intrinsic λ//values of PDLC films were mainly attributed to the formed microscopic-ordered structures from ordered stacking of LCM,ordered arrangement of PVA chains,and their hydrogen bond interaction.This work would offer a new way to design and prepare novel intrinsic high thermal conductive polymers.     

Ice‐Templated Assembly Strategy to Construct 3D Boron Nitride Nanosheet Networks in Polymer Composites for Thermal Conductivity Improvement

Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D‐BNNS) network using ice‐templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m⁻¹ K⁻¹), a low thermal expansion coefficient (24–32 ppm K⁻¹), and an increased glass transition temperature (T_g) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates.     

无机填料对PVC/CPE/CB复合材料导电性能的影响

研究了具有不同粒子形态的无机填料(球形的纳米二氧化硅、片状的滑石粉和纤维状的玻璃纤维),以及不同粒径的碳酸钙(纳米碳酸钙、超细碳酸钙)对聚氯乙烯(PVC)/氯化聚乙烯(CPE)/导电炭黑(CB)复合材料导电性能的影响。电性能测试和扫描电镜形态结构分析结果表明,添加纤维状填料比球形和片状填料更有利于复合材料导电性能的保持;粒径较小的纳米碳酸钙对复合材料的导电性能影响较小。当炭黑含量为12phr时,添加15phr纳米碳酸钙后复合材料的电阻率仅为6.04×106Ω.cm。     

The synergy of a three filler combination in the conductivity of epoxy composites

Epoxy resin filled with carbon materials including graphite nanoplatelets, carbon blacks and carbon nanotubes was synthesized via a liquid mixing method. It was suggested that the conductivity of the composite filled with three fillers was much higher than that filled with only one or two carbon fillers. While the percolation threshold was 1 wt.% and 0.5 wt.% respectively for the composites filled with pure graphite nanopatelets and graphite nanoplatelet/carbon black (mass ratio of 9:1), it was only 0.2 wt.% for the nanocomposites filled with graphite nanoplatelets/carbon black/carbon nanotubes (mass ratio of 7:1:2). The synergistic conductive effect among the three carbon fillers was investigated in detail.     

SiC颗粒-SiC晶须混杂填料/双马来酰亚胺树脂导热复合材料的制备与性能

以双马来酰亚胺树脂(BMI)为树脂基体,二烯丙基双酚A(DABA)为增韧剂,γ-缩水甘油醚氧丙基三甲氧基硅烷(KH-560)表面改性的SiC颗粒-SiC晶须(SiCP-SiCW)为复配导热填料,浇注成型制备SiC_P-SiC_W/BMI导热复合材料,分析研究SiC形状、用量、质量比及表面改性对SiC_P-SiC_W/BMI导热复合材料的导热性能、介电性能、力学性能和热性能的影响。结果表明,当改性SiC_P-SiC_W用量为40wt%且SiC_P∶SiC_W质量比为1∶3时,SiC_P-SiC_W/BMI导热复合材料具有最佳的综合性能,导热系数λ为1.125W(m·K)~(-1),介电常数ε为4.12,5%热失重温度为427℃。     

AlN/玻璃复合材料的相分布对导热性能的影响

以热压烧结方法在850～1000℃的低温下制备了Al/玻璃复合材料,通过组成变化研究了复合材料热导率的变化规律,利用SEM、TEM、XRD等方法观察了AlN/玻璃复合材料的显微结构和相组成与分布,讨论了复合材料的显微结构和相组成对热导率的影响,结果表明:AlN/玻璃复合材料的热导率随玻璃相的减少而增加,低温烧结的复合材料的热导率可以达到10W/m·K以上,材料的相分布对热导率的影响表现为:当玻璃相减少,AlN晶粒相互接触时,有利于热导率的提高;当材料内部以AlN晶相为主时,材料出现晶体的导热特征,即热导率随温度的升高而下降。     

Insights into heat management of hydrogen adsorption for improved hydrogen isotope separation of porous materials

Separating high-purity hydrogen isotopes from their mixture still remains a huge challenge due to almost the identical physicochemical properties.Much importance has been attached to tune microstructure of porous materials,while heat management during hydrogen isotope separation tends to be ignored.Herein,a porous material 5A molecular sieve(5A)is mixed with graphene(GE)under ball grinding to enhance its thermal conductivity for hydrogen isotope separation.The thermal conductivity increases from 0.19 W m-1 K-1 of neat 5A,0.75 W m-1 K-1 of 5A/GE2(2 wt％GE)to 1.23 W m-1 K-1 of 5A/GE8.In addition,introducing GE into 5A promotes hydrogen adsorption and D2/H2 adsorption ratio.5A/GE2 shows the highest D2 adsorption capacity(5.40 mmol/g)and the largest D2/H2 adsorption ratio(1.07)among the composites.It also displays a high efficiency of heat transfer that contributes to a low energy consumption due to the shortened cycle time during hydrogen isotope separation.This work offers new insights into material design for improved hydrogen isotope separation,which is greatly crucial to scientific and industrial applications,such as fuel self-sustaining in fusion reactors.     

原位合成TiB_2/ZL205A复合材料的组织及流动性

采用原位合成法制备了TiB_2/ZL205A复合材料,对所合成复合材料的物相、TiB_2颗粒形貌及分布、流动性进行了研究。结果表明:TiB_2/ZL205A复合材料主要由α-Al、Al_2Cu和TiB_2组成,TiB_2颗粒呈多边形或卵圆形,平均颗粒尺寸500nm左右,大部分沿晶界分布,少量分布在晶粒内部。TiB_2/ZL205A复合材料的流动性与浇铸温度及TiB_2质量分数的关系均可用指数阻尼模型进行描述。当浇铸温度由710℃提高到750℃时,7wt%TiB_2/ZL205A复合材料的流动性提高了30.4%;当浇铸温度在750℃以上时,7wt%TiB_2/ZL205A复合材料的流动性随浇铸温度的提高而提高的速率降低。与基体合金相比,在730℃浇铸时,3wt%TiB_2/ZL205A复合材料的流动性降低了21.8%,7wt%TiB_2/ZL205A复合材料的流动性降低了36.4%。