温度和湿度对聚四氟乙烯多孔驻极体膜压电活性稳定性的影响

研究了具有开放性孔洞的聚四氟乙烯(voided polytetrafluoroethylene,PTFE)多孔膜和PP蜂窝膜(polypropylene cellular)的驻极体行为和压电活性的温度效应。研究结果指出：和PP蜂窝膜驻极体相比．PTFE多孔膜驻极体呈现出突出的电荷储存和压电活性的温度稳定性;研究了这类稳定性的驻极体和材料的结构根源。PTFE多孔薄膜驻板体这种压电活性的温度稳定性主要依赖于这类驻极体材料电荷储存及材料的本征性能(如力学性质等)的温度稳定性。实验结果还说明：PTFE多孔膜突出的压电系数温度稳定性使它大大扩展了以包括PP在内的空间电荷型多孔膜研制的压电功能元器件的耐温要求。本文还讨论了环境因素(如相对湿度)对这类功能膜压电活性的影响,分析了环境湿度对压电活性影响的结构根源。     

多孔PTFE/FEP复合驻极体膜的压电性研究

本文报道采用高温熔融粘合工艺和电晕注极方法制备了由多孔PTFE/FEP复合而成的空间电荷驻极体压电膜.根据Kacprzyk等人提出的复合驻极体膜的压电模型,结合等温表面电位衰减和压电系数衰减测量结果,研究了制备工艺对复合膜压电活性的影响.结果表明压电效应的大小不仅取决于捕获在材料中电荷密度的大小,还与被捕获电荷在材料中的存在形式和分布有关.     

微孔结构氟聚合物铁电驻极体的制备及其热稳定性研究

描述了一种微孔结构氟聚合物铁电驻极体的制备方法，利用准静态方法测量了该功能膜的压电系数如，并通过等温衰减和热刺激放电电流谱的测量研究了凼，的热稳定性。结果表明，这类氟聚合物铁电驻极体膜的准静态压电系数d33与热压时间有关；与聚丙烯（PP）压电驻极体膜相比较，氟聚合物压电驻极体膜不但具有更高的压电活性，而且呈现更优良的热稳定性。     

P(VDF-TFE-HFP)/PTFE双层膜的驻极体特性

通过栅控恒压电晕充电,等温表面电位衰减测量．电荷TSD(charge TSD)和热刺激放电(Thermally Stimulated Discharge．TSD)电流谱分析,首次研究了以聚四氟乙烯(PTFE)为基的偏氟、四氟乙烯和六氟丙烯三元共聚物P(VDF—TFE—HFP)构成的双层膜的驻极体性质。TSD电流谱分析说明这种复合驻极体材料是极性驻极体,即体内同时包含有空间电荷和有序取向的偶极电荷。实验结果还指出：通过对双层膜系的PTFE面充电形成的驻极体的空间电荷热稳定性明显优于传统的铁电聚合物驻极体PVDF。适当提高充电温度和充电后的等温老化储存可以改善电荷稳定性,由于该三元共聚物的高弹性柔量(顺度)和双层膜拥有的优良电荷储存能力,其压电活性高于PVDF．     

微孔结构交联聚丙烯驻极体的储电性研究

压电驻极体是以双极性空间电荷驻极体为基体的新一类人工微结构压电功能材料,其压电性能与基体材料的储电性有直接关系.采用等温表面电位衰减测量和开路热刺激放电实验方法,研究了经热压处理的交联聚丙烯(XPP)膜中电荷储存稳定性和电荷动态特性.结果表明,XPP中正电荷的储存稳定性强于负电荷;在老化温度低于90℃时,经过5120min时间老化,正电晕充电样品的表面电位仍然能够维持在初始表面电位的90%以上,而负电晕充电样品却低于86%;热激发脱阱的负空间电荷在驻极体内电场的作用下迁移的过程中大部分被更深的能阱捕获,即脱阱电荷的榆运规律受快再捕获效应控制.     

紫外线对多孔聚四氟乙烯驻极体压电性能的影响

将恒压电晕充电的多孔聚四氟乙烯(polytetrafluoroethylene,PTFE)驻极体置于不同强度的紫外线下,研究紫外线对多孔PTFE驻极体压电活性的影响,探讨多孔PTFE医疗产品采用紫外消毒的可能性.研究结果指出(1)常温下,多孔PTFE驻极体的准静态压电系数d33随充电时间的延长而增加,并呈现出线性区、非线性区和饱和区三个区间,多孔PTFE驻极体的压电活性主要依赖于这类材料的电荷储存能力.(2)医用紫外线辐照对多孔PTFE的准静态压电系数d33的影响甚微.(3)多孔PTFE驻极体的d33随紫外辐照时环境湿度的提高而有下降,环境湿度越大,d33的下降越多.(4)紫外线辐照适合聚四氟乙烯医用驻极体产品的消毒.     

单层及多层PP蜂窝膜驻极体的压电性

经压力膨化处理后,以正逆压电系数d33测量研究了一种经无栅电晕充电的国产商用聚丙烯蜂窝膜(cellular PP,商品名PQ50)驻极体的压电性.经过优化工艺参数压力膨化处理后的PQ50蜂窝膜呈现600pC/N以上的准静态压电系数,这一量值约为PVDF相关系数的40倍.而通过将单层PQ50蜂窝膜驻极体粘贴形成合理的多层结构,得到的复合膜系压电系数d33高达2010pC/N,约为PZT压电陶瓷相应系数的3倍.从而为拓宽这类新一代的非极性孔洞聚合物压电功能膜应用领域,推动其应用进程提供了一定的理论和技术依据.     

P(VDF/CTFE)共聚物薄膜的驻极体行为

通过不同条件下的正负电晕充电,等温表面电位衰减测量,热刺激放电（TSD）电流谱分析和热脉冲技术,首次研究了偏氟乙烯（VDF）和三氟氯乙烯（CTFE）共聚物P（VDF／CTFE）的驻极体性质,结果指出：共聚物驻极体的空间电荷热稳定性明显优于PVDF;TSD谱分析说明这种材料驻极体也是极性驻极体,即体内同时包含有偶极和空间电荷。本文还对样品的正负电晕充电后的电荷储存稳定性做了对比;研究了材料的能阱分布,确定了样品在不同温度电晕充电时平均电荷重迁移规律。     

聚偏氟乙烯及其共聚物基压电复合材料的研究进展

聚合物压电材料聚偏氟乙烯(PVDF)及其共聚物P(VDF-TrFE)、P(VDF-HFP)是一类典型的具有压电性的有机高分子材料,它们由于具有良好的力学性能、耐腐蚀性、生物相容性以及易于加工等特点而受到研究人员的广泛关注.但相对于传统无机类压电陶瓷材料来说,聚合物压电材料的压电常数仍相对较低,因此提升这类聚合物压电材料...     

压电陶瓷/聚合物复合材料的制备工艺及其性能研究进展

本文首先介绍了压电材料的种类和基本性能,然后介绍了在不同的应用背景下压电陶瓷／聚合物复合材料的十种连通方式,综述了这类压电材料的制备工艺,较全面地总结了前人对这类压电材料的性能研究工作,展望了这类压电材料的应用前景和发展方向     

Comparison and electrical modeling of new polymeric cellular electrets

A new family of cellular polymers-that, upon appropriate charging, reveals interesting piezoelectric properties-has been developed recently. Its major characteristic is thermal stability up to high temperatures, which broadens the potential field of application. These materials become electrets upon charging under high levels of electric field. Investigation of charging mechanisms is fundamental to reach optimization of electret and piezoelectric properties. This paper presents results and considerations relevant to contact charging of these new materials, pointing out the relation between partial discharge and space charge formation, as well as time and temperature stability of electret properties. The concepts of threshold for partial discharge inception and space charge accumulation, the modeling of avalanches in cavities, and the rate of charge generation are exploited trying to explain charging mechanism and, therefore, they provide useful indication for optimization of material manufacturing.     

Piezoelectricity in Multilayer Black Phosphorus for Piezotronics and Nanogenerators

Recently, piezoelectric characteristics have been a research focus for 2D materials because of their broad potential applications. Black phosphorus (BP) is a monoelemental 2D material predicted to be piezoelectric because of its highly directional properties and non-centrosymmetric lattice structure. However, piezoelectricity is hardly reported in monoelemental materials owing to their lack of ionic polarization, but piezoelectric generation is consistent with the non-centrosymmetric structure of BP. Theoretical calculations of phosphorene have explained the origin of piezoelectric polarization among P atoms. However, the disappearance of piezoelectricity in multilayer 2D material generally arises from the opposite orientations of adjacent atomic layers, whereas this effect is limited in BP lattices due to their spring-shaped space structure. Here, the existence of in-plane piezoelectricity is experimentally reported for multilayer BP along the armchair direction. Current–voltage measurements demonstrate a piezotronic effect in this orientation, and cyclic compression and release of BP flakes show an intrinsic current output as large as 4 pA under a compressive strain of −0.72%. The discovery of piezoelectricity in multilayer BP can lead to further understanding of this mechanism in monoelemental materials.     

孔洞结构聚丙烯铁电驻极体薄膜的压电性研究

为了提高孔洞结构聚丙烯(cellular PP)铁电驻极体的压电性能,采用高压气体膨化技术对材料进行了改性处理,并利用准静态和干涉仪测量方法,对经处理的cellular PP铁电驻极体薄膜的压电效应进行了研究.结果表明:气体膨化工艺能够明显提高cellular PP铁电驻极体薄膜的压电活性:这种突出的压电活性源干膨化膜杨氏模量Y的降低和电极化能力的提高;压电系数d33随频率的增加呈现下降趋势:从0.01 Hz下的1200 pC/N降低到共振频率附近的350 pC/N;对于不同参数处理的样品,它们的共振频率在150～400 kHz;大多数样品的d33在0.2～10 kPa的范围内没有明显的变化,但是高于10 kPa,d33随之下降;cellular PP铁电驻极体薄膜d33的热稳定性与非孔洞型PP驻极体薄膜的电荷储存热稳定性相当.     

2D Electrets of Ultrathin MoO2 with Apparent Piezoelectricity

Since graphene, a variety of 2D materials have been fabricated in a quest for a tantalizing combination of properties and desired physiochemical behavior. 2D materials that are piezoelectric, i.e., that allow for a facile conversion of electrical energy into mechanical and vice versa, offer applications for sensors, actuators, energy harvesting, stretchable and flexible electronics, and energy storage, among others. Unfortunately, materials must satisfy stringent symmetry requirements to be classified as piezoelectric. Here, 2D ultrathin single-crystal molybdenum oxide (MoO₂) flakes that exhibit unexpected piezoelectric-like response are fabricated, as MoO₂ is centrosymmetric and should not exhibit intrinsic piezoelectricity. However, it is demonstrated that the apparent piezoelectricity in 2D MoO₂ emerges from an electret-like behavior induced by the trapping and stabilization of charges around defects in the material. Arguably, the material represents the first 2D electret material and suggests a route to artificially engineer piezoelectricity in 2D crystals. Specifically, it is found that the maximum out-of-plane piezoresponse is 0.56 pm V⁻¹, which is as strong as that observed in conventional 2D piezoelectric materials. The charges are found to be highly stable at room temperature with a trapping energy barrier of ≈2 eV.     

主客体掺杂的分子偶极聚合物驻极体材料的空间和偶极电荷的性质研究

以主客体掺杂型DR1／PMMA（分散红1号／聚甲基丙烯酸甲脂）体系为例，通过表面电位等温衰减研究了材料极化后空间电荷的脱阱及异性电荷的补偿导致的衰减行为，由开路和短路的热刺激放电及电光效应实验探讨了样品内空间和偶极电荷的性质。     

聚酰胺压电性研究进展

回顾了压电聚合物的历史,探讨了不同结构形态聚合物的压电机理,详细综述了脂肪族聚酰胺压电性能的研究历史和现状,讨论了芳香族聚酰胺及聚酰胺复合薄膜的压电性,最后进一步指出了聚酰胺压电性能的研究方向。