单轴拉伸下γ′-聚偏氟乙烯的相变研究

Study on the phase change ofγ′-polyvinylidene fluorideunder uniaxial stretching

通过固-固相转变的方式制备得到纯的γ′-聚偏氟乙烯(PVDF)薄膜.在此过程中,探究了十六烷基三甲基溴化铵(CTAB)浓度和退火温度对相变效率的影响.发现更高的CTAB浓度以及更高的退火温度有利于离子偶极作用的增强,加快相变效率.此外,研究γ′-PVDF薄膜的结晶温度对机械性能的影响.结果表明,室温结晶的γ′-PVDF样品具有最大的断裂伸长率.此后,以室温结晶的γ′-PVDF薄膜作为初始样品进行拉伸实验.结果表明,经过单轴拉伸,γ′同样能够发生向β的相转变.并且使得样品的介电常数增大;同时,更大的牵伸倍数有利于获得更多的β相.在600%的牵伸比下,相变效率能够达到93.1%.并且更大的牵伸倍数能够进一步增强样品的介电性能.

Pureγ′-polyvinylidene fluoride(PVDF)film is prepared by solid-solid phase transformation.In this process,the effects of the concentration of cetyltrimethylammonium bromide(CTAB)and annealing temperature on the phase transition efficiency were investigated.The findings revealed that higher CTAB concentration and higher annealing temperature facilitated the enhancement of ionic dipole interactions,leading to an accelerated phase transition efficiency.Additionally,the influence of crystallization temperature on the mechanical properties ofγ′-PVDF films was studied.The results showed thatγ′-PVDF samples crystallized at room temperature exhibited the highest fracture elongation.Subsequently,theγ′-PVDF films crystallized at room temperature were used as initial samples for the stretching experiment.The results indicated that,through uniaxial stretching,γ′-PVDF also underwent a phase transition towardsβ-phase.Furthermore,it resulted in an increase in the dielectric constant of the samples.Simultaneously,a larger stretching ratio is beneficial for obtaining a greater amount of theβ-phase.Under a strain ratio of 600%,the phase transition efficiency can reach 93.1%.Moreover,larger strain ratios can further enhance the dielectric performance of the sample.