硅烷偶联剂改性SiC晶须/PVDF复合薄膜的制备及其介电性能研究
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摘要
设计填料为半导体纳米晶须、基体为高分子聚合物是制备具有良好介电性能和力学性能材料的基本要求。首先利用化学改性法将不同硅烷偶联剂修饰在碳化硅晶须(SiC_w)表面,再利用溶液流延法制备改性SiC_w/聚偏氟乙烯(PVDF)复合薄膜。采用直接观察、FT-IR和热重分析对SiC_w的改性效果进行评价,通过SEM观察SiC_w在PVDF中的分布情况,并测试了该复合薄膜的介电性能随温度的变化情况。结果表明:利用本文的试验方法可成功将硅烷偶联剂引入到SiC_w表面;SEM结果显示,利用化学改性法可有效改善SiC_w的团聚问题,使其均匀分布在PVDF基体内;TGA结果表明,添加SiC_w作为填料可有效改善复合材料的热稳定性能,且当采用KH792型硅烷偶联剂时修饰率为6.37%。室温介电性能测试结果表明:添加改性SiC_w可提高复合材料的介电常数,相对纯PVDF提高了近8倍;在0.1wt%KH792-SiC_w/PVDF的介电性能测试中,当f=100 Hz时介电常数εr达到最大值33,介电损耗tanδ达到最小值0.07,且随频率的增加介电常数逐渐减小,介电损耗先减小后又增加;随着温度的增加,介电常数和介电损耗逐渐增加,当f=500 Hz,T=150℃时,εr最大为110,对应tanδ也最大为1.76。
The basic requirement to prepare material which have good dielectric properties and mechanical properties is by using semiconducting nano whisker as filler and polymer as matrix. Firstly,different silane coupling agents were introduced onto Si C whisker( SiC_w) surface by chemical modification,and then modified SiC_w/polyvinylidene fluoride( PVDF) composite membrane was prepared by solution casting method. The modification effect of SiC_w was analyzed by direct observation, FT-IR and thermogravimetric analysis. The distribution of SiC_w in PVDF was observed by SEM,and the dielectric properties were compared under different temperatures. Silane coupling agent can be successfully introduced onto the surface of SiC_w according to observation directly,FT-IR and thermogravimetric analysis results. The modified SiC_w were distributed in the PVDF matrix uniformly by SEM and it illustrated the agglomeration of SiC_wcan be weakened obviously after introducing silane coupling agent into it. It was showed that the addition of SiC_wcan improve the thermal stability of PVDF effectively and the modification ratio is 6. 37% if using KH792 as silane coupling agent. The dielectric properties of the composite membranes were measured at room temperature. It was found that the dielectric constant can be increased to eight times comparing with pure PVDF after addition of modified SiC_w. The composite membrane showed better dielectric properties in 100-2000 k Hz if 0. 1 wt% of KH792-SiC_w was introduced to PVDF. The maximum of εrwas 33 and the minimum of tanδ was 1. 76 at f = 100 Hz. With theincrease of frequency,the dielectric constant decreased while the dielectric loss decreased at first and then increased. The dielectric properties of 0. 1 wt% KH792-SiC_w/PVDF membrane was also measured at20-150 ℃. It was found that the maximum of εrand tanδ was 110 and 0. 07 at f = 500 Hz under the temperature was 150 ℃,respectively. With the increase of temperature,the dielectric constant and dielectric loss increased gradually.
The basic requirement to prepare material which have good dielectric properties and mechanical properties is by using semiconducting nano whisker as filler and polymer as matrix. Firstly,different silane coupling agents were introduced onto Si C whisker( SiC_w) surface by chemical modification,and then modified SiC_w/polyvinylidene fluoride( PVDF) composite membrane was prepared by solution casting method. The modification effect of SiC_w was analyzed by direct observation, FT-IR and thermogravimetric analysis. The distribution of SiC_w in PVDF was observed by SEM,and the dielectric properties were compared under different temperatures. Silane coupling agent can be successfully introduced onto the surface of SiC_w according to observation directly,FT-IR and thermogravimetric analysis results. The modified SiC_w were distributed in the PVDF matrix uniformly by SEM and it illustrated the agglomeration of SiC_wcan be weakened obviously after introducing silane coupling agent into it. It was showed that the addition of SiC_wcan improve the thermal stability of PVDF effectively and the modification ratio is 6. 37% if using KH792 as silane coupling agent. The dielectric properties of the composite membranes were measured at room temperature. It was found that the dielectric constant can be increased to eight times comparing with pure PVDF after addition of modified SiC_w. The composite membrane showed better dielectric properties in 100-2000 k Hz if 0. 1 wt% of KH792-SiC_w was introduced to PVDF. The maximum of εrwas 33 and the minimum of tanδ was 1. 76 at f = 100 Hz. With theincrease of frequency,the dielectric constant decreased while the dielectric loss decreased at first and then increased. The dielectric properties of 0. 1 wt% KH792-SiC_w/PVDF membrane was also measured at20-150 ℃. It was found that the maximum of εrand tanδ was 110 and 0. 07 at f = 500 Hz under the temperature was 150 ℃,respectively. With the increase of temperature,the dielectric constant and dielectric loss increased gradually.
引文
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[21]徐建华,杨文耀.储能聚合物电介质基础[M].北京:科学出版社,2014.
[2]Gillaabb E.Response mechanism of novel polyaniline composite conductimetric p H sensors and the effects of polymer binder,surfactant and film thickness on sensor sensitivity[J].European Polymer Journal,2010,46(10):2042-2050.
[3]Nohria R,Khillan R K,Su Y,et al.Humidity sensor based on ultrathin polyaniline film deposited using layer-by-layer nano-assembly[J].Sensors&Actuators B Chemical,2006,114(1):218-222.
[4]Sohi N J S,Rahaman M,Khastgir D.Dielectric property and electromagnetic interference shielding effectiveness of ethylene vinyl acetate-based conductive composites:Effect of different type of carbon fillers[J].Polymer Composites,2011,32(7):1148-1154.
[5]Rao Y,Wong C P.Material characterization of a high-dielectric-constant polymer-ceramic composite for embedded capacitor for RF applications[J].Journal of Applied Polymer Science,2010,92(4):2228-2231.
[6]李杰,韦平,汪根林,等.高介电复合材料及其介电性能的研究[J].绝缘材料,2003,36(5):3-6.
[7]Ulrich R.Matching embedded capacitor dielectrics to applications[J].Circuit World,2004,30(1):20-24.
[8]马育红,张先宏,杨万泰.聚合物基复合介电材料的研究进展[J].北京化工大学学报(自然科学版),2015,42(3):1-15.
[9]任杰.炭系导电填料填充PVDF/PMMA复合材料结构与性能研究[D].杭州:浙江工业大学,2007.
[10]Tawansi A,Oraby A H,Abdelkader H I,et al.Fe Cl3-Co Cl2,mixed fillers effects on the structural,electrical and magnetic properties of PVDF films[J].Journal of Magnetism&Magnetic Materials,2003,262(2):203-211.
[11]Devi P I,Sivabharathy M,Ramachandran K.Enhancement of dielectric constant in PVDF polymer using dendrite-shaped Pb S nanostructures[J].Optik-International Journal for Light and Electron Optics,2013,124(19):3872-3875.
[12]党宇,王瑶,邓元,等.高性能Ba Ti O3/PVDF介电复合材料及其薄膜电容器应用[J].复合材料学报,2012,29(2):35-39.
[13]卢鹏荐,王一龙,孙志刚,等.高介电常数、低介电损耗的聚合物基复合材料[J].化学进展,2010,22(8):1619-1625.
[14]Wang J W,Shen Q D,Yang C Z,et al.High dielectric constant composite of P(VDF-Tr FE)with grafted copper phthalocyanine oligomer[J].Macromolecules,2004,37(6):2294-2298.
[15]Yin J,Yao D,Xia Y,et al.The effect of modified interfaces on the mechanical property ofβ-silicon nitride whiskers reinforced Cu matrix composites[J].Journal of Alloys&Compounds,2014,615:983-988.
[16]杨萌,罗世凯,邓昭平,等.晶须在聚合物复合材料中的应用[J].材料导报,2014,28(3):51-55.
[17]Shang X,Zhu Y,Li Z.Surface modification of silicon carbide with silane coupling agent and hexadecyl iodiele[J].Applied Surface Science,2016,394:169-177.
[18]李轩科,刘朗,沈士德,等.二元炭质-二氧化硅干凝胶和气凝胶制备碳化硅晶须[J].硅酸盐通报,2000,19(5):23-27.
[19]王永.PVDF/Ba Ti O3复合薄膜的制备及特性研究[D].成都:电子科技大学,2007.
[20]Liu F,Abed M R M,Li K.Preparation and characterization of poly(vinylidene fluoride)(PVDF)based ultrafiltration membranes using nanoγ-Al2O3[J].Journal of Membrane Science,2011,366(1):97-103.
[21]徐建华,杨文耀.储能聚合物电介质基础[M].北京:科学出版社,2014.