Electret properties of cycloolefin copolymers

Sessler, G. M.; Yang, G.M.; Hatke, Wilfried

doi:10.1109/ceidp.1997.641113

Cited by 16 publications

(5 citation statements)

References 4 publications

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“…These results agree with [26] and seem to be consistent with the higher value of TI measured for COC. Therefore, spacecharge measurements support a much better temperature-time stability of COC in comparison with expanded cellular PP.…”

Section: Space-charge Measurementssupporting

confidence: 90%

Charging properties and time-temperature stability of innovative polymeric cellular ferroelectrets

Montanari¹,

Fabiani²,

Ciani³

et al. 2007

IEEE Trans. Dielect. Electr. Insul.

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After appropriate mechanical and electrical treatments, some cellular polymers become able to retain space charge for a long time, i.e. they acquire electret behavior. The electrical treatment consists of charging under high levels of DC electric field. The mechanical treatment, based on the application of stretching forces to cellular polymer slabs that were before expanded under pressurized gas, affects the cavity size and shape, and therefore also the effectiveness of the charging process itself. An investigation of charging mechanisms, as well as of mechanical treatment, is therefore fundamental for optimizing the ferro-and piezo-electret properties. The aim of this paper is to discuss the effect of the physical dimension of the cavities on the charging behavior of cellular ferroelectrets and to focus on the time-temperature stability for two families of polymeric cellular ferroelectrets based on polypropylene (PP) and on a cyclo-olefin copolymer (COC). Emphasis will be given to the stretching process and in particular to the expansion rate applied during the manufacturing process (which affects the radial dimension and the height of the cavities, respectively). Space-charge and partial-discharge measurements as a function of time and temperature are the main tools to infer the influence of the cavity size on charging and stability characteristics. . In 1988, he was awarded an ITG-Preis by the Informationstechnische Gesellschaft im VDE. In 1989, he received a Silver medal from the Stiftung Werner-von-Siemens-Ring. In 2001, he was awarded the first Technologietransfer-Preis by the Technologie-Stiftung Brandenburg and the Prof.-Adalbert-Seifriz-Preis by the Verein Technologie-Transfer Handwerk for his technological collaborations with small industrial companies. The main research areas of Prof. Gerhard-Multhaupt are polymer electrets and ferroelectrets, in particular the mechanisms of space-charge storage and dipole polarization in dielectric polymers and polymer composites, their ferro-, pyro-and piezoelectrical properties, and their applications in sensors and actuators, as well as the nonlinear optical properties of polymers, and more recently also the physics of musical instruments. He is a

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Section: Space-charge Measurementssupporting

confidence: 90%

Charging properties and time-temperature stability of innovative polymeric cellular ferroelectrets

Montanari¹,

Fabiani²,

Ciani³

et al. 2007

IEEE Trans. Dielect. Electr. Insul.

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“…In a previous study, a COC polymer was found to have better machining properties and better stability to store charge storage [2]. The experiment set-up was carried out using 22cm x 22cm samples of 35/-lm thickness as the COC samples.…”

Section: Experimen Tal Set-upmentioning

confidence: 99%

Method to optimize charge distribution in electret films using multiple needle discharges

Chen

Liao

et al. 2011

2011 - 14th International Symposium on Electrets

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The purpose of this paper was to find the optimal parameters of moving multiple needle corona discharges by looking at the transport velocity and the distance of the needles.The parameters were then used to symmetrically arrange the discharge needles for large-scale mass production. A corona discharge method is typically used to perform charge injection in the creation of electret films.A static single needle corona discharge method typically leads to a non-uniform space charge distribution in electret films. Since obtaining uniformly injected charge distribution and uniform efficiency of large-area electret films have become important research topics recently, methods such as moving multiple needle corona discharges have been developed to improve production efficiency and uniformity in the spatial charge distribution of electret films for industrialapplications. An automated control system was developed using VB (Visual Basic) to create a virtual instrument to perform the corona discharges and to measure the surface potential. Several important processing parameters were identified to enable us to obtain uniform spatial charge distribution in newly created electret films. I. BACKGROUNDIn a previous study conducted by our research group, we found that the optimal parameters of a static multiple needle corona discharge included such parameter information as the exposed length of the needle, spacing of the needles, suitable distance between the needles and plate electrode, etc.[1] The parameters were applied to produce large-scale electret loudspeakers. However, as a static discharge method has been identified to have low production efficiency, a moving multiple needle corona discharge method can circumvent such limitation and allow us to achieve large scale mass production. II. EXPERIMEN TAL SET-UPIn our set-up, both the moving velocity and the spacing of the needles in the moving corona discharge method were varied to tailor to the fmal spatial charge distribution in the electret films. At the beginning, a needle experiment was set up in a large-scale moving X-Y plane to establish and identify the optimal surface potential distribution and the discharge region under a fixed temperature and relative humidity environment. In most situations, a surface potential decay (SPD) measurement technique is extensively employed to investigate the spatial charge distribution of electret materials due to their reliability and low cost. The parameter for a single needle grid plate electrode system was determined with respect to a set of different sample moving velocities. The decay of an average surface potential at different sample moving speeds are detailed. The spacing of the needles in our 978-1-4577-1025-4/11/$26 . 00 ©2011 IEEE mUltiple needle corona discharge method provides us with an effective operating parameter to obtain uniform surface potential distribution in electret films for large-scaleproduction. In a previous study, a COC polymer was found to have better machining properties and better stability to store char...

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“…An electret is a dielectric material that traps quasi-permanent space charges induced by an external charging process [1]. The cyclic olefin copolymer (COC) is an ethylene and norbornenebased copolymer which has good electret properties and glass transition temperature when compared to polypropylene (PP) [2,3]. Its advantages include low cost, low water absorption, good electrical insulation, and easy solubility in toluene to form a solution.…”

Section: Introductionmentioning

confidence: 99%

Use of 2-(6-mercaptohexyl) malonic acid to adjust the morphology and electret properties of cyclic olefin copolymer and its application to flexible loudspeakers

Tseng

Leu

et al. 2010

Smart Mater. Struct.

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Recent uses of flexible electret loudspeakers in futuristic applications have garnered much interest for these novel loudspeakers. In this paper, a novel thin film processing method was developed to improve the performance of an electret diaphragm. This paper discusses the relationship between the charge storage and the additive concentration. A cyclic olefin copolymer (COC) thin film containing an additive such as 2-(6-mercaptohexyl) malonic acid was prepared using a spin-coating process. Furthermore, attention was directed towards the processing conditions which were found to have an important role and are related to the self-assembly and micelle formation behavior of the additives in the COC. In the present study, thin films of 13 μm thickness were charged by a corona method. Compared with a reference thin film of pure COC, results indicated that when a 3497 mg kg −1 additive was added to the COC matrix, the obtained surface potential was 71% higher. Thus, the results show that a COC + additive thin film leads to a much improved charge storage. It appears to be an inexpensive and relatively easy way to form a thin structure for developing novel flexible electret loudspeakers.

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Electret properties of cycloolefin copolymers

Cited by 16 publications

References 4 publications

Charging properties and time-temperature stability of innovative polymeric cellular ferroelectrets

Charging properties and time-temperature stability of innovative polymeric cellular ferroelectrets

Method to optimize charge distribution in electret films using multiple needle discharges

Use of 2-(6-mercaptohexyl) malonic acid to adjust the morphology and electret properties of cyclic olefin copolymer and its application to flexible loudspeakers

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