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Piezoelectricity in b-phase PVDF crystals A molecular simulation study

Piezoelectricity in b -phase PVDF crystals:A molecular simulation study

GuoDong Zhu *,ZhiGang Zeng,Li Zhang,XueJian Yan

Department of Materials Science,Fudan University,220Handan Road,Shanghai 200433,China

a r t i c l e i n f o Article history:

Received 10July 2007

Received in revised form 9March 2008Accepted 11March 2008

Available online 25April 2008PACS:77.65.Bn

Keywords:PVDF

Molecular simulation Piezoelectricity Dimensional effect

a b s t r a c t

Based on the energy-minimization method in molecular simulation,the origin of piezoelectricity in b -phase PVDF crystals was investigated.Simulation results indicated that under the action of a constant applied voltage,PVDF crystal would be stretched or compressed,dependent on the orientation of dipoles and the polarity of the applied voltage.Our simulation con?rmed that piezoelectricity in polymers would be mostly attributed to the dimensional effect.Piezoelectric coef?cient calculated from our model was well consistent with experimental data,which showed the credibility of this model.

1.Introduction

In 1969,Kawai [1]discovered strong piezoelectricity in poly(vinylidene ?uoride)(PVDF,as abbreviated);in 1971,Bergman [2]and Wada [3]found its pyroelectricity;and soon typical ferro-electric hysteresis loops were also found from the direct polariza-tion measurements using the standard Sawyer-Tower circuit [4].All these discoveries in PVDF family have been regarded as the milestone in organic transducers [5].

Before the discovery of organic ferroelectrics,it is usually be-lieved that piezoelectricity and ferroelectricity are characteristics of crystals and ceramics,and the related mechanism has been intensively studied.However,polymers are mostly semi-crystal-line with coexistence of crystalline phase and amorphous phase,so ferroelectricity and piezoelectricity of polymers are inevitably different from those of inorganic materials.Studies on these polymers have elicited great interest because of their potential applications to transducers,sensors,actuators,and potential ultra-high-density data storage.

A widely accepted mechanism,called a dimensional effect,has been put forward to explain the piezoelectricity and pyroelectricity in polymers,and this mechanism assumes that piezoelectric and pyroelectric activities arise from macroscopic dimensional changes when a sample is deformed,while the moment of constituent molecular dipoles is kept constant.Theoretical considerations by

Broadhurst et al.[6]and Wada and Hayakawa [7]have shown that macroscopic dimensional changes played an important role in the piezoelectric activity of drawn and poled PVDF.Furukawa et al.[8]had examined the contribution of the dimensional effect to the pie-zoelectricity in VDF/TrFE copolymers by experimental measure-ments and theoretical calculations.

In our previous work [9],we introduced the molecular simula-tion method to the study of ferroelectricity in PVDF and illumi-nated the effect of trapped charges on ferroelectric switching process in polymers.In this paper by the molecular simulation method we attempted to study the origin of piezoelectricity in b -phase PVDF crystals.2.Modeling

2.1.Structural parameters of b -phase PVDF

PVDF polymers have four phases:a ,b ,c ,d [10].In this paper b -phase PVDF is simulated,which has the highest spontaneous polar-ization in all these four phases [11].In b -phase PVDF,an all-trans conformation induces the alignment of the CH 2CF 2in zigzag plane and perpendicular to the chain axis (see Fig.1).All chains arrange in a quasi-hexagonal-symmetry structure (Fig.1a).Molecular di-poles associated with positive hydrogen and negative ?uoride atoms are entirely aligned in one direction to generate the largest spontaneous polarization.The lattice constants of such a quasi-hexagonal-symmetry unit cell are a =0.850nm,b =0.491nm,and c =0.256nm [12].The other structural parameters (bond length

*Corresponding author.Tel.:+8602165642872.

E-mail addresses:gdzhu@https://www.sodocs.net/doc/7f2823429.html, ,gawdon@https://www.sodocs.net/doc/7f2823429.html, (G.Zhu).Computational Materials Science 44(2008)

224–229

Contents lists available at ScienceDirect

Computational Materials Science

journal homepage:www.elsevie r.c o m /l o c a t e/c o m m a t s c

and angle)are listed in Table1.The partial atomic charges for b-phase PVDF are directly quoted from Byutner’s calculated values [14]:Q H=0.1807,Q F=à0.2266,Q CH=à0.5202,Q CF=0.6120, where the subscript H and F represent hydrogen atoms and?uo-rine atoms,and the subscript CH and CF represent the carbon atoms bonded with hydrogen atoms and the carbon atoms bonded with?uorine atoms,respectively.2.2.Model and force?eld for our simulation

In this paper we assume that the molecular chains in b-PVDF crystals are rigid and neglect the in?uence of chain torsion on po-tential energy.The model used in our simulation is shown in Fig.2. This model includes a PVDF crystal consisting of5?10molecular chains with quasi-hexagonal symmetry.Each chain is structured by twenty CH2CF2repeat units.The directions of a,b,c vectors are also indicated in Fig.2.The electric?eld(voltage)is set along b axis.Two charge layers in planes are constructed to simulate this applied electric?eld(or voltage),both of which are parallel to the ac plane.The top and the bottom layers were set with the same charge density,but with opposite polarity.In this paper the applied electric?eld(voltage)is de?ned as positive when the top layer is set with a positive charge density.The orientation of dipoles,from negative?uoride atoms to positive hydrogen atoms,was set upward.

In this model,we assume that it is not the dipole moment but the intermolecular spacing in PVDF crystal that changes along b axis direction when the electric?eld(voltage)(simulated by two charge layers)is applied.For a certain applied?eld(voltage),we keep the dipole moment constant and change the value of lattice constant b and plot the dependence on b increment(D b=b–b0) of total potential(W total)in PVDF crystal,consisting of van der Waals potential between molecular chains,interatomic Coulomb potential and electrostatic potential between PVDF crystal and the applied?eld.We regard the corresponding state,in which the new lattice constant b minimizes the total potential,as the new stable state for a certain applied?eld or voltage,the corre-sponding new lattice constant b was marked as b stable,and the

dif-

Fig.2.Model for the simulation of piezoelectricity in b-phase PVDF.

Table2

Parameters of van der Waals potential for b-phase PVDF[14]

Atomic pair A B C

C–C14976.0 3.0900640.80

H–H2649.6 3.740027.36

F–F135782.0 4.5461106.12

C–H4320.0 3.4150138.24

C–F45094.0 3.8181260.77

H–F12300.0 4.1431

53.88

Fig.1.Structure of b-phase PVDF.

Table1

Parameters of bond length and angle of b-phase PVDF[13]

Bond angle/degree Bond length/nm

H–C–H116.4161C–C0.15242

C–C–C117.8C–H0.10789

F–C–F109.5665C–F0.13457

G.Zhu et al./Computational Materials Science44(2008)224–229225

ference between b stable and b 0was marked as D b stable (=b stable àb 0).The spacing between two layers is synchronously changed with the change of b in order to be consistent with experimental situation.To determine the electric ?eld strength E caused by a certain charge density,a hydrogen atom with n charges is put between the layers,and moves along b axis.The electrostatic potential W 1and W 2,induced by the interaction between the hydrogen atom and the applied ?eld at a certain position r 1and r 2,are calculated.Then electric ?eld strength can be calculated by E ?

W 2àW 121e1T

HyperChem 6.0package is employed in this work,and MM+approximation is chosen for our simulation,in which van der Waals potential can be expressed as

V VdW er T?X i >j A ij exp eàB ij r ij TàC ij

r ij

!e2Twhere r ij is the distance of the i th and the j th atoms,and the coef-?cients of A ,B and C are shown in Table 2.3.Simulation results

3.1.Simulation when the applied electric ?eld was kept constant According to the model shown in Fig.2,if the charge density is unchanged during plotting the dependence of total potential on b increment,the electric ?eld will keep constant.In this section,we studied the change of the stable state at the action of different electric ?eld strength.

Under the free state (E =0),PVDF crystal obtained its energy-minimization at D b stable =0?

A 0

,which was shown in Fig.3a (the black curve).When a ?eld of 130MV/m was applied to the crystal,no evident change was observed and the new stable state still oc-curred at D b stable =0?A

(Fig.3a,the blue curve)1.The same result was obtained when a ?eld of à130MV/m was applied.We compared these three simulation results in Fig.3b.To make the comparison much clearer,the ordinate was indicated as D W ,which was de?ned as D W =W total àW stable ,where W total was the total potential of PVDF crystal corresponding to a certain b increment and W stable was the total potential corresponding to the stable state.For all these three simulation results,the new stable state occurred at D b stable =0?

A 0

.The work of the electric ?eld seemed to only raise or drop the poten-tial curves monolithically but caused no dimensional changes.

3.2.Simulation when the applied voltage was kept constant

The voltage applied to PVDF crystal (V PVDF )could be expressed as V PVDF =E át ,where t was the thickness of PVDF crystal and chan-ged with the change of lattice constant b .In fact,when the electric ?eld was kept constant,V PVDF would change with D b ,which was shown by the black curve in Fig.4.In this section,we would study the dependence of W total on D b when the applied voltage V PVDF kept constant.The constant voltage was obtained by changing the charge density of both layers synchronously with the change

Fig.3.Dependence of W total (a)and D W (b)on D b when the applied electric ?eld was kept constant.

For interpretation to color in Figs.3–6,8,9the reader is referred to the web version of this

article.

Fig.4.The changes of the applied voltage with the change of lattice constant b before and after the

adjustment.

Fig.5.Dependence of W total on D b at the action of a constant voltage of 0.267V.

226G.Zhu et al./Computational Materials Science 44(2008)224–229

lattice constant b.After such an adjustment,the applied voltage could keep nearly constant in our interested range,which could be seen by the red curve in Fig.4.

The dependence of the total potential in PVDF crystal on b incre-ment was simulated when the applied voltage was kept at0.267V, and the curve was shown as blue in Fig.5.As a comparison, W totalàD b curve at the free state was also displayed as black.The result obviously indicated that,under the action of a constant volt-age,the stable state varied and the new potential minimization oc-curred at D b stable=0.032?,that was to say,a positive applied voltage induced the increase of crystal thickness.

We also calculated the change of the new stable state under the action of different applied voltages,which were shown in Fig.6. Fig.6a shows the dependence of total potential W total on b incre-ment,and the existence of positive(negative)applied voltage would increase(decrease)the total potential of crystals.The new stable state also varied according to different applied voltages,as could be clearly observed in Fig.6b.D W–D b curves in Fig.6b shows that a positive voltage had caused the expansion of PVDF crystal along b axis,while a negative voltage had caused the compression. The larger the applied voltage was,the greater the deviation of b stable from b0was.The b increments corresponding to the new stable state at the action of various applied voltages were listed in Table3,in which D t was the thickness change of PVDF crystal, varying with lattice constant b,d33was the piezoelectric coef?-cient,de?ned by D t/V PVDF,and33was the averaged piezoelectric coef?cient obtained by our simulation.The negative sign shown in d33and d33indicated that when the direction of electric?eld was parallel to dipole orientation,PVDF crystal became thinner, as could be seen clearly in Fig.8a.In some papers this phenomenon was also called‘‘negative piezoelectric effect”in order to be distin-guished from that of the inorganic piezoelectrics[15,16].33calcu-lated by our model was aboutà0.461?/V.

In our previous experimental work,based on the atomic-scale resolution of Atomic Force Microscope(AFM),on the surface of fer-roelectric polymer?lms we successfully recorded the local vibra-tions,which were driven by an alternating triangular voltage. Fig.7shows one of such results.Fig.7a indicates the applied trian-gular voltage with amplitude of20V,while Fig.7b shows the simultaneously recorded surface vibrations with amplitude of 0.60nm,so the experimentally piezoelectric coef?cient could be calculated asà0.3?/V,More details on our microscopic experi-mental measurements could refer to Ref.[17].In fact,Li also stud-ied the local vibrations of P(VDF–TrFE)ferroelectric polymers and obtained a piezoelectric coef?cient33ofà0.3toà0.5?/V[18]. Both experimental results were well consistent with our simula-tion result.

We also calculated the new stable state at the action of the ap-plied voltage when the orientation of dipoles was set downward, and the dependence of D b stable on applied voltage for different di-pole orientation were shown in Fig.8a.It was clearly displayed that when the direction of the applied electric?eld(indicated by

the Fig.6.Dependence of W total(a)and D W(b)on D b at the action of different applied voltages.

Table3

Piezoelectric coef?cient simulated by our constant voltage model

V PVDF(V)D b stable(?)D t(?)d33(?/V)d33(?/V)à0.534à0.056à0.224à0.419à0.461à0.267à0.030à0.120à0.449

à0.107à0.012à0.048à

0.448

00.0000.000

0.1070.0120.048à0.448

0.2670.0320.128à0.479

0.5340.0700.280à0.524Fig.7.Local vibrations recorded by AFM on the surface of ferroelectric polymer

?lms.(a)Triangular driving voltage;(b)local surface vibrations.

G.Zhu et al./Computational Materials Science44(2008)224–229227

green arrows)was parallel to the dipole orientation (indicated by the black arrows),PVDF crystal was compressed under the action of applied voltage;while,when the ?eld direction was antiparallel to dipole orientation,crystal was stretched along b axis.In practical situation,this meant that after the ferroelectric polymer ?lm had been polarized by a positive (negative)voltage,a positive driving voltage would make the ?lm thinner (thicker).The red curves in Fig.8a would not occur in experimental measurements because of ferroelectric switching,and the dashed lines indicated ferroelec-tric switching process which would be simulated in our further work.The black and the blue lines revealed butter?y loop struc-ture,which was a characteristic of ferroelectric polymers.As a comparison,a local butter?y loop obtained by microscopic exper-imental measurements [17]was shown in Fig.8b.Both loops showed the same shape indicating the credibility of our simulation results.4.Discussions

Our simulation results indicate that a constant electric ?eld can not induce piezoelectric activity in PVDF ?lms (Fig.3),while a con-stant applied voltage can cause the compression or expansion of PVDF ?lms,dependent on the polarity of the applied voltage and the orientation of molecular dipoles (Figs.6and 8a ).These results are well de?ned and can be simply explained as below.

We plot in Fig.9the dependence on D b of the total potential (Fig.9a),the van der Waals potential between molecular chains and the interatomic Coulomb potential (Fig.9b)and the electro-static potential between PVDF crystal and the electric ?eld (Fig.9c)when the PVDF crystal is at the free state or under the application of a constant voltage.For clarity,the plots of W total àD b dependence under the action of constant voltages shown in Fig.9a have been displayed upwards (for a negative voltage)or down-wards (for a positive voltage)by some scale graduations.

The total potential W total in PVDF crystal under an electric ?eld can be expressed as a function of D b W total eD b T?V vdw eD b TtV el eD b TàE eD b Táp

e3T

where W total eD b Tis the total potential corresponding to a certain D b ,and V VdW eD b Tis the corresponding van der Waals potential between molecular chains,V el eD b Tis the corresponding interatomic electro-static potential in PVDF crystal,and àE eD b Táp represents the inter-action between V el eD b Tthe applied electric ?eld E eD b Tand the total molecular dipole moment p (a constant vector in our model).

The existence of an applied ?eld can not in?uence V VdW eD b T(Fig.9b,the blue curve)and (Fig.9b,the black curve),so Eq.(3)can also be expressed

Fig.9.Dependence on D b of the total potential (a),the van der Waals and the Coulomb potential (b)and the interaction potential between PVDF crystal and the electric ?eld (c)at the free state or under the application of a constant

voltage.

Fig.8.Butter?y loops obtained by our molecular simulation (a)and measured by microscopic experiments (b).

228G.Zhu et al./Computational Materials Science 44(2008)224–229

W totaleD bT?W0eD bTàEeD bTápe4TW0eD bT?V VdWeD bTtV eleD bTe5Twhere W0eD bTrepresents the total potential of PVDF crystal at the free state.

Based on energy-minimization theory,the stable state for a sys-tem is determined when the total potential of this system is min-imized.We deduce the partial derivative of W totaleD bTas

feD bT?oeW totaleD bTT

oeD bT

oeW0eD bTT

oeD bT

oeàD bTápT

oeD bT

e6T

When feD bT=0the system is at a stable state.

At the free state,oeàEeD bTápT

oeD bT=0,a stable state occurs when

D b stable=0?(Fig.9a).

When the electric?eld keeps constant,oeàEeD bTápT

oeD bT=0and a stable

state still occurs when D b stable=0?(Fig.3).

When the applied voltage keeps constant,oeàEeD bTápT–0Fig.9c), dimensional changes will occur in PVDF?lms.

When the direction of electric?eld is anti-parallel to dipole vec-tor,the interaction potential between applied?eld and PVDF crys-tal decreases with the increase of lattice constant b,as is shown by

the black curve in Fig.9c,that is to say,oeàEeD bTápT

oeD bT<0.To satisfy

feD bT=0,from Eq.(6),it can be deduced that the new lattice con-stant b should satisfy oeW0eD bTT?àoeàEeD bTápT>0,and from the W0plot in Fig.9a,it can be concluded that the new lattice constant b at the new stable sate should be larger than b0.So when the direction of applied voltage is anti-parallel to the dipole vector,PVDF crystal is elongated along b axis.Similarly when electric vector was parallel to dipole vector,PVDF crystal was compressed.

Broadhurst[6]and Wada[7]proposed the dimensional effect to explain the origin of organic ferroelectricity.It was believed from the dimensional effect that dipoles in polymers were rigid,molec-ular dipoles retained?xed moment and orientation during the mechanical deformation of samples,and piezoelectric response was attributed to macroscopic dimensional changes.Our simula-tion is well consistent with this macroscopic dimensional effect. Compared to inorganic piezoelectrics which are mostly ionic crys-tals,organic piezoelectrics are mostly molecular crystals,have low-er hardness and elasticity,and easily deform to show negative piezoelectric effect;while piezoelectricity of inorganic materials is mostly attributed to dipole?uctuations because of their higher hardness.This is the essential difference between organic and inor-ganic piezoelectrics.

Organic piezoelectricity comes mostly from the dimensional ef-fect,but perhaps there are some other contributions.Broadhurst [6]calculated the contributions from the dimensional effect,dipole ?uctuations and electrostriction and found about60%of organic piezoelectricity comes from the dimensional effect,while another 10%should be attributed to dipole?uctuations.

5.Conclusion

Based on the energy-minimization method in molecular simu-lation we studied the origin of piezoelectricity in b-PVDF crystal. Simulation results con?rmed that organic piezoelectricity would be attributable to the dimensional effect,which was very different from inorganic piezoelectrics.Piezoelectric coef?cient obtained from our work was well consistent with experimental data,and our model also explained the origin of the negative piezoelectric effect from microscopic scale.

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PVDF聚偏氟乙烯

聚偏氟乙烯的晶体结构

聚偏氟乙烯的晶体结构顾明浩1,张　军13,王晓琳2 (11南京工业大学材料科学与工程学院,南京　210009;21清华大学化学工程系,北京　100084) 摘要:介绍了聚偏氟乙烯(PVDF)三种主要的晶体结构:α晶型、β晶型和γ晶型,以及三种晶型之间的相互转换。同时简单介绍了PVDF的其它晶型。探讨了不同环境因素对PVDF三种晶型的影响,并对利用PVDF晶型的多样性拓宽PVDF材料的运用提出分析和展望。关键词:聚偏氟乙烯;晶体结构;α晶型;β晶型;γ晶型引言聚偏氟乙烯(PVDF)因其优良的压电性、焦电性、高机械性、高绝缘性和耐冲击性,应用非常广泛,从简单的绝缘体、半导体到压电薄膜和快离子导体膜,这主要由于PVDF晶型多样性的结果。PVDF常见的晶体结构主要有三种:β(Ⅰ)、α(Ⅱ)、γ(Ⅲ)。其中α晶型最为常见,β晶型因其优良的压电性能受到广泛的关注。γ晶型为极性,一般产生于高温熔融结晶。PVDF三种晶型在不同的条件下产生,又在一定的条件下相互转变,因而PVDF因为晶型晶体结构的不同而显示不同的性能,本文就PVDF三种主要晶型的产生条件和不同环境因素对三种晶型的影响进行了具体阐述。 1　PVDF的主要晶体结构 111　α晶型 α晶型为单斜晶系,晶胞参数为a=01496nm,b=01964nm,c=01462nm[1]。α晶型的构型为TG TG′,并且由于α晶型链偶极子极性相反,所以不显极性[2]。 11111　α晶型的产生　在一定的温度下以适当或较大的降温速率熔融冷却可以得到α晶型的PVDF。在与环己酮[3]、二甲基甲酰胺[4]、氯苯[4]形成的溶液中结晶也可以得到α晶型的PVDF。 11112　结晶温度对α晶型的影响　结晶温度的高低直接影响结晶速度,要得到完善的单晶,结晶温度必须足够高,或者过冷程度(即结晶熔点与结晶温度之差)要小,使结晶速度足够快,以保证分子链的规整排列和堆砌[5]。同时结晶温度对聚合物晶体结构也有影响,在不同的结晶温度下,聚合物大分子链以不同的构型排列,呈现出不同的晶体结构。对于α晶型的PVDF在不同温度的结晶行为,可通过偏光显微镜观察其球晶生长情况,在120℃～160℃结晶,随着结晶温度的升高,球晶数量减少,球晶尺寸增大,球晶的生长速率增加,而成核速率相应减少。当温度从160℃升高到170℃,球晶数量逐渐变小,以致几乎为零,但当结晶温度大于170℃,又出现球晶,是γ晶型。说明当结晶温度高于160℃,α晶型消失,所以PVDF在160℃下熔融结晶,产生α晶型。从220℃熔融,以40℃Πmin降温速率,通过DSC发现结晶峰值温度在130℃,说明α晶型最快结晶温度在130℃[6]。 Pawel等[7]发现PVDF在155℃结晶只有α晶型存在,当结晶温度在160℃以上,α晶型和γ′晶型同时存在(当在高温下,当α晶型转变为γ晶型时,此时的γ晶型称为γ′晶型),在更高的温度下,只有γ晶基金项目:江苏省高校无机及其复合新材料重点实验室资助项目; 作者简介:顾明浩(19812),江苏南通人,男,硕士研究生,主要从事热致相分离法制备聚偏氟乙烯微孔膜的研究; 3通讯联系人.

聚偏氟乙烯PVDF纳米纤维的制备方法

聚偏氟乙烯纳米纤维的制备一、背景聚偏氟乙烯(polyvinylidenefluoride，PVDF)主要是指偏氟乙烯均聚物或者偏氟乙烯与其它少量含氟乙烯基单体的共聚物，属于线性结晶聚合物，PVDF树脂属于热塑性聚合物，呈白色粉末状、粒状。具有优良的耐热和耐化学性、高机械强度和韧性、高耐磨性、卓越的耐气候性、以及对紫外线和核辐射的稳定性。聚偏氟乙烯的结构式聚偏氟乙烯因其具有高机械强度，耐酸，耐碱，压电等优良性质，被广泛的用于电纺纤维制备电池隔膜，传感器，过滤膜等。S.S.Choi等人研究发现，将PVDF基电纺纤维膜应用在锂离子电池中，不仅可以直接作电池隔膜使用，还可以在电解液中活化作为聚合物电解质使用[1]。王永荣用PVDF纳米纤维膜制作了一个压力传感器，每个传感器由三层结构构成，包括柔性上电极、PVDF纳米纤维膜和固定的下电极构成[2]。迪肯大学的Fang等人研制了利用静电纺PVDF薄膜制成的一个能量发电机，通过桥电路将机械力产生的交流电转换成直流电，点亮了电路中的LED灯[3]。武汉理工大学的翟威釆用引入聚氨酯预聚体的方法对PVDF 电纺膜进行粘结改性,使聚氨酯预聚体反应交联后和PVDF形成半互穿性网络,从而提高PVDF 膜的力学性能[4]。二、纳米纤维的制备 2.1仪器和试剂仪器：静电纺丝装置(SS-2535H)；磁力搅拌器；电子天平；扫描电子显微镜(SEM)试剂：聚偏氟乙烯；N,N-二甲基甲酰胺(DMF)，丙酮（市售，分析纯）； 2.2聚偏氟乙烯纳米纤维膜的制备使用静电纺丝装置制备纳米纤维膜。称取一定量的PVDF样品放入100mL磨口锥形瓶，按溶剂的DMF和丙酮按体积比3:2加入锥形瓶内配制成浓度为17%的溶液，水浴加热将其溶解。取5mL配制好的溶液进行静电纺丝。用铝箔作为接收，调节正电压为10KV，负高压1.5KV，喷射距离15cm。液滴在静电力作用下在喷针形成Taylor锥形成射流和纤维。纺丝时间为6~8h后制得聚偏氟乙烯纳米纤维膜。

聚偏氟乙烯的多晶型转化关系的研究进展

聚偏氟乙烯晶体结构及多晶型转化关系的研究进展（兵器工业集团五三研究所，济南250031）摘要：介绍了聚偏氟乙烯(PVDF)两种主要的晶体结构：α晶型、β晶型，同时简要的介绍了PVDF的其它晶型。探讨了不同环境因素下各晶型之间的转化关系。指出PVDF压电材料在多个领域具有广阔的应用前景。关键字：聚偏氟乙烯晶体结构晶型转化 1引言近年来，聚偏氟乙烯（PVDF）在功能高分子材料领域引起人们的特别关注。其原因在于它具有实际应用价值的压电性，热释电性以及复杂多变的晶型结构。 PVDF是由CFCH键接成的长链分子，通常状态下为半结晶高聚物，结晶度约为50%。迄今报道有五种晶型：α、β、γ、δ及ε型[1-2]，它们在不同的条件下形成，在一定条件下（热、电场、机械及辐射能的作用）又可以相互转化[3-6]。在这五种晶型中，β晶型最为重要，作为压电及热释电应用的PVDF，主要是含有β晶型。 2 PVDF多晶型的晶体结构及其形成条件 2.1 α晶型 α晶型是PVDF最普通的结晶形式。其为单斜晶系，晶胞参数为a=0.496nm，b=0.964nm，c=0.462nm[7]。a晶型的构型为TGTG ，并且由于a晶型链偶极子极性相反，所以不显极性[8]。α晶型的ab平面结构示意图，如图１所示。图１α晶的ab平面结构示意图 Fig 1 Projection of poly(vinylidene fluoride) chain onto the ab plane of the unit cell for polymorphic α ________________________________________________________________ ______作者简介：张军英（1978－），女（汉族），在读硕士研究生，主要从事功能材料方面的研究。通讯作者：E-mail： Tel:

聚偏氟乙烯的应用及特性

本文摘自再生资源回收-变宝网（https://www.sodocs.net/doc/7f2823429.html,）聚偏氟乙烯的应用及特性变宝网8月11日讯聚偏氟乙烯在常态下是一种半结晶高聚物，目前已知的有5中晶型，在一定的条件下可以互相转化。一、聚偏氟乙烯的应用 PVDF应用主要集中在石油化工、电子电气和氟碳涂料三大领域，由于PVDF 良好的耐化学性、加工性及抗疲劳和蠕变性，是石油化工设备流体处理系统整体或者衬里的泵、阀门、管道、管路配件、储槽和热交换器的最佳材料之一。 PVDF良好的化学稳定性、电绝缘性能，使制作的设备能满足TOCS以及阻燃要求，被广泛应用于半导体工业上高纯化学品的贮存和输送，采用PVDF树脂制作的多孔膜、凝胶、隔膜等，在锂二次电池中应用，目前该用途成为PVDF 需求增长最快的市场之一。 PVDF是氟碳涂料最主要原料之一，以其为原料制备的氟碳涂料已经发展到第六代，由于PVDF树脂具有超强的耐候性，可在户外长期使用，无需保养，该类涂料被广泛应用于发电站、机场、高速公路、高层建筑等。另外PVDF树脂还可以与其他树脂共混改性，如PVDF与ABS树脂共混得到复合材料，已经广泛应用于建筑、汽车装饰、家电外壳等。

二、聚偏氟乙烯的特性 1、PVDF具有优良的耐化学腐蚀性、优良的耐高温色变性和耐氧化性。 2、PVDF具有优良的耐磨性、柔韧性、很高的抗涨强度和耐冲击性强度。 3、PVDF具有优良的耐紫外线和高能辐射性。 4、PVDF亲水性较差。 5、可射出及押出之氟化树脂（俗称热可塑性铁氟龙）。 6、耐热性佳并有高介电强度。更多聚偏氟乙烯相关资讯关注变宝网查阅。本文摘自变宝网-废金属_废塑料_废纸_废品回收_再生资源B2B交易平台网站；变宝网官网网址：https://www.sodocs.net/doc/7f2823429.html,/tags.html 网上找客户，就上变宝网！免费会员注册，免费发布需求，让属于你的客户主动找你！

聚偏氟乙烯(PVDF)的特性粘度

PVDF聚偏氟乙烯，一种化学品，是石油化工设备流体处理系统整体或者衬里的泵、阀门、管道、管路配件、储槽和热交换器的最佳材料之一。PVDF良好的耐化学性、加工性及抗疲劳和蠕变性，是石油化工设备流体处理系统整体或者衬里的泵、阀门、管道、管路配件、储槽和热交换器的最佳材料之一。采用PVDF 树脂制作的多孔膜、凝胶、隔膜等，在锂二次电池中应用，该用途成为PVDF需求增长最快的市场之一。可用一般热塑性塑料加工方法成型。其突出特点是机械强度高，耐辐照性好。具有良好的化学稳定性，在室温下不被酸、碱、强氧化剂和卤素所腐蚀，发烟硫酸、强碱、酮、醚绵少数化学药品能使其溶胀或部分溶解，二甲基乙酰胺和二甲基亚砜等强极性有机溶剂能使其溶解成胶体状溶液。 PVDF树脂王要是指偏氟乙烯均聚物或者偏氟乙烯与其他少量含氟乙烯基单体的共聚物，PVDF树脂兼具氟树脂和通用树脂的特性，除具有良好的耐化学腐蚀性、耐高温性、耐氧化性、耐候性、耐射线辐射性能外，还具有压电性、介电性、热电性等特殊性能，是目前含氟塑料中产量名列第二位的大产品，全球年产能超过4.3万吨。PVDF应用主要集中在石油化工、电子电气和氟碳涂料三大领域，由于PVDF良好的耐化学性、加工性及抗疲劳和蠕变性，是石油化工设备流体处理系统整体或者衬里的泵、阀门、管道、管路配件、储槽和热交换器的最佳材料之一。其良好的化学稳定性、电绝缘性能，使制作的设备能满足TOCS以及阻燃要求，被广泛应用于半导体工业上高纯化学品的贮存和输送，近年来采用PVDF树脂制作的多孔膜、凝胶、隔膜等，在锂二次电池中应用，目前该用途成为PVDF 需求增长最快的市场之一。PVDF是氟碳涂料最主要原料之一，以其为原料制备

聚偏氟乙烯的发展与应用

聚偏氟乙烯的发展与应用高倩（北京化工大学理学院应用化学系，北京，20110522）摘要：本文从结构性质到其发展应用全面介绍了聚偏氟乙烯这一物质，重点从石油化工、电子电气和氟碳涂料三个方面来介绍聚偏氟乙烯的应用与发展现状的。关键词：聚偏氟乙烯；应用；氟碳涂料；绝缘介质膜 1、聚偏氟乙烯的结构和性质聚偏氟乙烯（PVDF），是由l，2-二氟乙烯(VDF)单体均聚或共聚而成的线性高分子化合物，聚合度约1500，属于热塑性氟塑料。 PVDF是一种白色粉末状结晶聚合物，密度为1．75～1．789g／cm3，吸水率小于0．04％，玻璃化温度-39℃，脆化温度-62℃以下，结晶熔点约170℃，热分解温度大于316℃，长期使用温度在-40℃～150℃之间。它不耐高浓度强碱和某些胺类化合物；可溶解于二甲基甲酰胺和二甲基乙酰胺等少数几种极性溶剂；在较高温度下可溶解于某些酸类和酯类化合物。 PVDF具有优良的耐化学介质性能，对大多数无机酸、盐类、氧化剂、弱碱以及脂肪酸、芳香族和卤代溶剂等均有优良的抵抗性。它的耐腐蚀性能介于聚四氟乙烯（PTFE）和聚全氟乙丙烯（FEP）之间，特别是对强酸、卤素、卤素化合物及极强氧化剂等具有优异的抵抗力，是化工设备理想的防腐材料。 2、聚偏氟乙烯的应用概述 PVDF应用主要集中在石油化工、电子电气和氟碳涂料三大领域。首先，因PVDF对氯、溴卤素及卤素化合物有极其优异的抵抗特性，及其良好的耐化学性、加工性及抗疲劳和蠕变性，是石油化工设备流体处理系统整体或者衬里的泵、阀门、管道、管路配件、储槽和热交换器的最佳材料之一。PVDF在化工防腐蚀方面的应用，有其它氟树脂无可比拟的优点。同时，聚偏氟乙烯膜介电常数较高，有优良的耐化学品性、耐溶剂性、抗紫外性、耐辐射性和耐候性，同时在氟树脂中它也具有最高的抗张强度和抗压缩强度以及最出色的加工性能，是膜绝缘材料的不错选择。另外，聚偏氟乙烯压电薄膜是一种新型的高分子聚合物型敏感材料，使偏氟乙烯及其共聚物成为目前研究最广泛的铁电聚合物材料，在执行器、传感器、存储器、仿真肌肉及微流控方面具有应用前景。最后，PVDF是氟碳涂料最主要原料之一，由于PVDF树脂具有超强的耐候性，可在户外长期使用，无需保养，该类涂料被广泛应用于发电站、机场、高速公路、高层建筑等；目前在我国以偏氟乙烯为含氟单体和其他含氟单体共聚的涂料用常温固化型氟碳树脂尚未出现，在这方面具有巨大的发展空间。另外PVDF树脂还可以与其他树脂共混改性，如PVDF与ABS 树脂共混得到复合材料，已经广泛应用于建筑、汽车装饰、家电外壳等。 (1)化工领域：采用模压、挤如、注射成型可加工PVDF衬里或全塑阀门、泵、管道、管件、

聚偏氟乙烯(PVDF)

聚偏氟乙烯（PVDF）百科名片 PVDF聚偏氟乙烯，外观为半透明或白色粉体或颗粒，分子链间排列紧密，又有较强的氢键，含氧指数为46% ，不燃，结晶度65%~78%，密度为1.17~1.79g/cm3,熔点为172℃,热变形温度112~145℃,长期使用温度为—40~150℃。基本化学属性： CAS号：24937-79-9 分子式：-(C2H2F2)n- 外观：白色或者透明固体水溶性：不溶于水 1 PVDF聚偏氟乙烯用树脂的特性，除具有良好的耐化学腐蚀性、耐高温性、耐氧化性、耐候性、耐射线辐射性能外，还具有压电性、介电性、热电性等特殊性能，是目前含氟塑料中产量名列第二位的大产品，全球年产能超过4.3万吨。PVDF应用主要集中在石油化工、电子电气和氟碳涂料三大领域，由于PVDF良好的耐化学性、加工性及抗疲劳和蠕变性，是石油化工设备流体处理系统整体或者衬里的泵、阀门、管道、管路配件、储槽和热交换器的最佳材料之一。其良好的化学稳定性、电绝缘性能，使制作的设备能满足TOCS以及阻燃要求，被广泛应用于半导体工业上高纯化学品的贮存和输送，近年来采用PVDF树脂制作的多孔膜、凝胶、隔膜等，在锂二次电池中应用，目前该用途成为PV DF需求增长最快的市场之一。PVDF是氟碳涂料最主要原料之一，以其为原料制备的氟碳涂料已经发展到第六代，由于PVDF树脂具有超强的耐候性，可在户外长期使用，无需保养，该类涂料被广泛应用于发电站、机场、高速公路、高层建筑等。另外PVDF树脂还可以与其他树脂共混改性，如PVDF与ABS树脂共混得到复合材料，已广泛应用于建筑、汽车装饰、家电外壳等。化学结构中以氟一碳化合键结合，这种具有短键性质的结构与氢离子形成最稳定最牢固的结合．因而氟碳涂料具有特异的物理化学性能，不但有很强的耐磨性和抗冲击性能，而且在极端严酷与恶劣的环境中有很高的抗褪色性与抗紫外线性能。 2 PVDF转移膜 PVDF是一种高强度、耐腐蚀的物质，通常是用来制造水管的。PVDF膜可以结合蛋白质，而且可以分离小片段的蛋白质，最初是将它用于蛋白质的序列测定，因为硝酸纤维素膜在Edman试剂中会降解，所以就寻找了PVDF作为替代品，虽然PVDF膜结合蛋白的效率没有硝酸纤维素膜高，但由于它的稳定、耐腐蚀使它成为蛋白测序理想的用品，一直沿用至今。PVDF膜与硝酸纤维素膜一样，可以进行各种染色和化学发光检测，也有很广的适用范围。这种PVDF膜，灵敏度、分辨率和蛋白亲和力在精细工艺下比常规的膜都要高，非常适合于低分子量蛋白的检测。但是使用PVDF膜前，一定要先用无水甲醇预处理，再在transfer buffer中平衡好才可以使用（PVDF膜用甲醇泡的目的是为了活化PVDF膜上面的正电基团，使它更容易跟带负电的蛋白质结合）。经过预处理的PVDF膜在转膜时，可以使用不含甲醇的transfer buffer。而使用NC膜时，有的需要用无水甲醇处理，有的则不必，直接用transfer buffer平衡好就可以了。产品介绍 PVDF是由纯度≥99.99%的偏氟乙烯（VDF）均聚而成的涂料用PVDF可熔性氟碳树脂。有70%PVDF树脂制成的氟碳涂料经喷涂或辊涂等工艺经烘烤制成的漆膜具有无与伦比的超耐候性能及加工性能。完全符合美国建筑材料标准A AMA2605及中华人民共和国行业标准HG/T3793-2005。PVDF不但有很强的耐磨性和抗冲击性能，而且在极端严酷与

PVDF聚偏氟乙烯修订版

P V D F聚偏氟乙烯集团标准化小组：[VVOPPT-JOPP28-JPPTL98-LOPPNN]

PVDF聚偏氟乙烯，分子式：-(C2H2F2)n-，英文缩写poly(vinylidenefluoride)，主要是指偏氟乙烯均聚物或者偏氟乙烯与其他少量含氟乙烯基单体的共聚物，它兼具和通用树脂的特性，除具有良好的耐化学腐蚀性、耐高温性、耐氧化性、耐候性（可在户外长期使用）、耐辐射性能外，还具有压电性、介电性、热电性等特殊性能，化学结构中以氟一碳化合键结合，这种具有短键性质的结构与氢离子形成最稳定最牢固的结合。P V D F亲水性较差。PVDF膜在处理前是疏水性的膜，经过甲醇处理后，PVDF膜就成了亲水性的了。这个你在实验中也应该看到了。所以，只要用甲醇处理PVDF膜30s左右就可以完全的把PVDF膜从疏水性状态转变成亲水性的了，时间延长后效果都是一样的。同时，用肉眼观察，膜表面是否还有白色的点状或者块状区域存在，没有了再浸泡到transferbuffer中15min。用过millipore、Pall-Gelman、osmonics的PVDF膜，都是在甲醇中浸泡1-2MIN。millipore公司的膜说明书都说的是在甲醇中浸泡1-2min。 PVDF膜可以结合蛋白质，而且可以分离小片段的蛋白质，最初是将它用于蛋白质的序列测定，因为在Edman试剂中会降解，所以就寻找了PVDF作为替代品，虽然PVDF膜结合蛋白的效率没有硝酸纤维素膜高，但由于它的稳定、耐腐蚀使它成为蛋白测序理想的用品，一直沿用至今。PVDF膜与硝酸纤维素膜一样，可以进行各种染色和化学发光检测，也有很广的适用范围。这种PVDF膜，灵敏度、分辨率和蛋白亲和力在精细工艺下比常规的膜都要高，非常适合于的检测。但是使用PVDF膜前，一定要先用无水甲醇预处理，再在transferbuffer中平衡好才可以使用（PVDF膜用甲醇泡的目的是为了活化PVDF膜上面的正电基团，使它更容易跟带负电的蛋白质结合）。经过预处理的PVDF膜在转膜时，可以使用不含甲醇的transferbuffer。电转液中SDS增加蛋白的水溶性，促进蛋白在电转液中泳动。若不加SDS，蛋白会沉淀在胶上，但SDS过多会影响蛋白与膜的吸附。甲醇能使SDS与蛋白分离，甲醇浓度越高SDS与蛋白分离越快，但高浓度的甲醇对蛋白会有固定作用，不利于蛋白从胶里跑出来。一般来说甲醇的浓度为20%，但PVDF膜截留marker上交联的小分子颜料的能力很差，可考虑提升甲醇的浓度至25%（它对普通蛋白的转膜影响不太，颜料截留更多）；大蛋白转印可考虑降低甲醇浓度，另外SDS必须添加。甲醇的另一个作用是降温，旧的电转液由于电解质的消耗和甲醇的挥发，电转时电流或电压变化更快、温度升高也更快，因此可考虑增加额外的甲醇；这点对半干转缓冲液的意义较大，因为半干转缓冲液消耗很慢，缓冲液放置的时间较久，甲醇挥发比较严重，可临时少量补加。转移后效果的鉴定1．染胶用考马斯亮兰染色经destain脱色后，看胶上是否还有蛋白来反映转移的效果。2．染膜有两类染液选择，可逆的和不可逆的。可逆的有ponceau-sred、FastgreenFC、CPTS等，这类染料染色后，色素可以被洗掉，膜可以用做进一步的分析用。但是不可逆的染料，如考马斯亮兰、indiaink、Amido.black10B等，染色后膜就不能用于进一步的分析。

聚偏氟乙烯膜(PVDF)亲水性改善方法的研究进展

聚偏氟乙烯膜（PVDF）亲水性改善方法的研究进展摘要：聚偏氟乙烯(PVDF)有价格低廉、化学和热稳定性好、机械强度高等优点，但PVDF分子链上氟原子对称分布导致了材料表面的表面能低、疏水性强，在含油废水分离过程中污染严重，从而制约了PVDF分离膜的应用，因此需要对膜材料表面进行亲水化改性处理。对于聚偏氟乙烯膜的改性主要有物理和化学两种方法，然后可用接触角、膜的纯水通量等测试对其亲疏水性表征。关键词：聚偏氟乙烯，亲水性，接触角 1、聚偏氟乙烯简介[1] PVDF由偏氟乙烯单体CH2=CF2经悬浮聚合或乳液聚合得到，它是一种成膜性能较好的聚合物材料，使用诸如二甲基甲酞胺(DMF)、二甲基乙酞胺(DMA C)和N-甲基毗咯烷酮(NMP)等极性溶剂溶解。从PVDF分子结构分析，整体符合一般聚烯烃分子碳链的锯齿构型，氟原子替代氢原子，因为氟原子电负性大，原子半径很小，C-F键长短，其键能达到50kJ.mol-1，整个分子链呈柔性使聚合物具有一定的结晶性，表现为突出的热稳定性，熔点为170℃，热分解温度在316℃以上，连续在150℃高温以下暴露2年内不会分解。由于氟原子对称分布，整个分子显示非极性，聚合物表面能很低，仅为25J.m-3。通常太阳能中可见光---紫外光部分对有机物起破坏作用，光子波长在200--700nm之间，而C-F键能接近220nm光子在总数中所占比例极少，所以氟材料耐环境气候性好。由于性质稳定的氟原子包围在碳链四周，使PVDF具有很好的化学稳定性，在室温条件下不易被酸、碱和强氧化剂及卤素腐蚀。因PVDF能溶于一些强极性溶剂中，且具有很好的可纺制性能，它可以被用来纺丝制备中空纤维膜。聚偏氟乙烯在1961年首先在建筑领域被商品化，迄今数十年的使用中PVDF树脂的优良性能得到广泛的证明，在X射线平板印刷术、光纤、涂料等方面己被广为应用。近些年来含氟聚合物又作为一种性能优异的膜材料，在膜分离工程领域的研究应用成为人们热点关注对象。 PVDF相对于聚醚砜(PES)、聚丙烯睛(PAN)等其它膜材料，PVDF膜的特点是疏水性强，是膜蒸馏和膜吸收等分离过程的理想材料。但是，同样因其强疏水性而导致在含油废水分离时污染严重、通量减小，制约了其在此领域应用。对

聚偏氟乙烯树脂的合成方法

聚偏氟乙烯树脂的合成方法 1 概述聚偏氟乙烯(PVDF)是偏氟乙烯(VDF)的均聚物或VDF与其他少量含氟乙烯基单体的共聚物，相对分子质量为400×103-600×103。由于结构中同时存在乙烯基和二氟乙烯基，因此PVDF同时具有通用树脂和氟树脂的特性，存在较强的耐腐蚀性、耐高温性、耐氧化性及耐气候性。已经成为氟树脂中除聚四氟乙烯(PTFE)外使用最广的第2大品种。此外，PVDF还存在某些独特的性质：1)压电性，PVDF通常状态下为非极性α晶体，此时总偶极矩为O，不显示压电性，但在低温下拉伸可得β晶体，存在极强的压电性；2)介电性，在6～60Hz下介电常数可达6～8，电容量增量较大； 3)成型性，PVDF结晶熔点约为170℃，分解温度在316℃以上，较广的温度范围使其容易采用热塑性塑料的方法进行加工。 2 PVDF树脂的合成 PVDF树脂的主要合成方法包括乳液聚合、悬浮聚合、溶液聚合及超临界聚合，而乳液聚合和悬浮聚合是主要的工业化生产手段。 2.1乳液聚合法 VDF的乳液聚合实际上属于沉淀聚合，主要包括VDF单体溶解在水相中、稀水溶液聚合、PVDF从水相中沉淀出来在乳化剂的作用下形成乳胶粒3个步骤。聚合过程中加入的成分除了常规乳液聚合中的单体、水、引发剂和乳化剂外，还要加入链转移剂和石蜡。 VDF乳液聚合中的去离子水电导率要小于3μS／cm．不仅维持体系的稳定，而且保证树脂的性能和色泽，其用量一般为单体质量的5-6倍。所用的引发剂分为无机过氧化物和有机过氧化物，无机过氧化物主要为过硫酸盐类，有机过氧化物引发制备的PVDF高分子链为非离子端基，稳定性较强，最常用的为过氧化二碳酸二异丙酯(IPP)，用量一般为单体质量的0．15％～1％。乳化剂多为含氟化合物，最经典的是如全氟辛酸及盐类(PFOA)，用量一般为单体质量的0．1％～0．2％，降低了液滴之间的表面张力，防止单体液滴或乳胶粒的凝聚，但是由于具有持久的环境稳定性和高的生物累积性，被联合国列入持久性有机污染物(POPs)清单，予以禁用，其最新替代品主要集中在6种，即采用C4或C6含氟整理剂、纳米型含氟整理剂、复配型含氟整理剂、丙烯酸氟烃酯类树脂和PTFE等。链转移剂能够在不影响聚合稳定性和反应速率的条件下通过调节用量控制其相对分子质量和相对分子质量分布。在聚合过程中，链转移剂用量过大时，熔体质量流动速率增大，特性黏度减小，PVDF相对分子质量降低；链转移剂用量过小时，虽然相对分子质量较高，但聚合反应不平稳，过程难以控制，聚合时间短．生产效率低下，常用的包括醇类、酯类、酮类及卤代烷烃，一般用量为单体质量的l％～3％。石蜡则可以起到稳定PVDF胶束的作用，避免凝聚和粘釜现象的发生。以C 6F 13 I和IC 4 F 8 I为链转移剂的条件下通过碘转移成功进行了VDF和三氟甲基丙烯酸(TFMA)的无皂乳液共聚，发现在不同配比下(TFMA、VDF摩尔比0：1～0．5：0．5)制备共聚产物的相对分子质量与理论值极为接近，相对分子质量分布最高为2.95，同时加入少量的TFMA能够提高聚合过程及制备乳液的稳定性。

聚偏氟乙烯(PVDF)压电膜

聚偏氟乙烯（PVDF）压电膜是本世纪70年代在日本问世的一种新型高分子压电材料。到目前为止，世界上只有少数先进国家生产。锦州科信电子材料有限公司以清华大学为技术依托，成功地实现了PVDF压电膜国产化批量生产。它具有独特的介电效应、压电效应、热电效应。与传统的压电材料相比具有频响宽、动态范围大、力电转换灵敏度高、机械性能强度高、声阻抗易匹配等特点，并具有重量轻、柔软不脆、耐冲击、不易受水和化学药品的污染、易制成任意形状及面积不等的片或管等优势。在力学、声学、光学、电子、测量、红外、安全报警、医疗保健、军事、交通、信息工程、办公自动化、海洋开发、地质勘探等技术领域应用十分广泛。产品主要有金、银、铝三个品种，膜厚30—500μm，产品形状、面积大小，可根据用户需要确定，是制作改进压力动态传感器和超声、智能探测的新型换能材料。性能及特点： PVDF压电膜具有较高的化学稳定性、低吸湿性、高热稳定性、高抗紫外线辐射能力、高耐冲击、耐疲劳能力，其化学稳定性比陶瓷高10倍，在80℃以下可长期使用。PVDF压电膜质地柔软、重量轻，与水的声阻抗相近，匹配状态好，应用灵敏度高；PVDF压电膜在厚度方向的伸缩振动的谐频率很高，可以得到较宽的平坦响应，频响宽度远优于普通压电陶瓷换能器；电容值高，可以采用低淙胱杩沟囊瞧髯鞯推到邮铡?SPAN lang=EN-US>PVDF压电膜优点如下： (1) 良好的工艺性。可用现有设备进行加工； (2) 能制作大面积的敏感元件； (3) 频带响应宽(0～500MHz)； (4) 声阻抗接近于人体组织和水，所以可用于医疗诊断的敏感装置结构中； (5) 具有高冲击强度(可使用于冲击波的传感器中)； (6) 耐腐蚀性(在活性介质中使用时这种性能是必需的)； (7) 相对介电常数较低；相应较高的压电常数值d33(约比其它压电材料高一个数量级以上)和热信号灵敏度(p/ε)值； (8) 与压电陶瓷相比有更低的导热性；并能制得更薄的薄膜； (9) 柔软坚韧(PVDF的柔顺系数约为PzT的30倍,并且轻(比重只有PzT的1/4左右)；能制成所需的各种较复杂的形状(锥形、穹顶形等)，可使用在需要具有特殊定向的元件中。总的来说：PVDF压电膜比石英、PzT等具有压电常数大，频响宽，机械强度好，耐冲击，质轻，柔韧，声阻抗易匹配，易加工成大面积，不易受水和一般化学品的污染、价格便宜等特点。它不仅在许多领域中可替代压电陶瓷材料使用，而且还可以应用在压电陶瓷材料不能使用的场合。因此它是一种极有发展前途的换能性高分子敏感材料。 PVDF压电膜品种技术规格： 1、感观要求：项目指标色泽有金属光泽，基本一致

PVDF聚偏氟乙烯

P V D F聚偏氟乙烯 Revised final draft November 26, 2020

Piezoelectricity in b-phase PVDF crystals A molecular simulation study

PVDF聚偏氟乙烯

聚偏氟乙烯的晶体结构

聚偏氟乙烯PVDF纳米纤维的制备方法

聚偏氟乙烯的多晶型转化关系的研究进展

聚偏氟乙烯的应用及特性

聚偏氟乙烯(PVDF)的特性粘度

聚偏氟乙烯的发展与应用

聚偏氟乙烯(PVDF)

PVDF聚偏氟乙烯修订版

聚偏氟乙烯膜(PVDF)亲水性改善方法的研究进展

聚偏氟乙烯树脂的合成方法

聚偏氟乙烯(PVDF)压电膜

PVDF聚偏氟乙烯

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