双向形状记忆聚合物及其复合材料的开发与应用

发布时间：2018-01-13 14:30

本文关键词：双向形状记忆聚合物及其复合材料的开发与应用　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：形状记忆聚合物(Shape memory polymer,SMP)在受到特定的外界刺激后,能由预先固定的临时形状主动回复至初始的永久形状。凭借这一特性,形状记忆聚合物已在航空航天、生物医学等高新领域得到了广泛应用。传统的单向形状记忆聚合物(One-way shape memory polymer,1W-SMP)经赋形(Programming)后可固定一个临时形状,在回复至永久形状后,不经再次赋形则无法主动变回临时形状,其形状记忆过程近似为“一次性”过程。与此不同,双向形状记忆聚合物(Two-way shape memory polymer,2W-SMP)经一次赋形后,可在两个形状间进行多次可逆的形状变化,相比单向SMP,双向SMP使用更为方便可靠。因此,对双向SMP的研究有助于进一步开拓SMP的实际应用。本文选用乙烯-醋酸乙烯酯共聚物(EVA)为原料,以过氧化二异丙苯(DCP)为交联剂,采用热交联工艺,成功制备了双向形状记忆EVA。通过调整DCP的添加量发现,只有DCP加入量达到1.0wt%以上的交联EVA才能表现出双向形状记忆特性。其中,加入3.0wt%DCP的交联EVA在0.1 MPa的恒应力下可逆应变量最大,可达16.7%。加入4.0wt%DCP后,交联EVA具有较为理想的二重形状记忆性能(形状固定率与回复率可分别达到96.6%和97.7%),且在双向形状记忆测试中同样表现良好。为赋予双向形状记忆EVA电刺激响应功能,本文以气相生长碳纤维(VGCF)为纳米填料,通过溶液混合-溶胶化的方法制备了VGCF-EVA复合材料。当VGCF添加量达到15.0wt%时,试样电阻率降至20.4Ω·cm,试样在60 V电压下迅速升温且温度分布均匀,并能够在40 V电压下执行电响应的双向形状记忆。该VGCF-EVA复合材料还具有驱动便捷,形状转变速度快等优点。为进一步探究2W-SMP在智能控制中的实际应用可能,本文利用双向形状记忆EVA为基础材料,经环氧导电银胶涂覆、赋形后制得了智能温控开关。此开关能够在温度达到52.7±2.8°C时主动展开,使电路断开;当温度降至27.3±1.4°C时,开关又能够变形至电路闭合状态。这一智能器件有望应用于智能开关,如限流开关。本文表明,对EVA进行适当交联可赋予其双向形状记忆特性,制得的交联EVA能够在无应力条件下稳定进行多次形状可逆变化;再经加入VGCF导电填料复合改性,EVA基复合材料在保持原有双向形状记忆性能的情况下,兼具有电刺激响应特性;最后,实验证明得到的双向形状记忆EVA经合理的结构设计,有望应用于智能控制领域。
[Abstract]:Shape memory was stimulated by specific external stimuli. The ability to actively return to the initial permanent shape from a prefixed temporary shape. By virtue of this property, shape memory polymers have been used in aeronautics and astronautics. Traditional unidirectional shape memory polymer, One-way shape memory polymer, has been widely used in many fields such as biomedicine. 1W-SMPs can fix a temporary shape after shaping (programming). After returning to a permanent shape, it can't change back to the temporary shape without reforming. The shape memory process is approximately a "one-off" process, unlike the two-way shape memory polymer "Two-way shape memory polymer". 2W-SMP) can be changed several times between two shapes after one shape. Compared with unidirectional SMPs, two-way SMP is more convenient and reliable. The study of bidirectional SMP is helpful to further develop the practical application of SMP. In this paper, ethylene vinyl acetate copolymer (EVA) is used as raw material and diisopropyl peroxide (DCPs) as crosslinking agent. Bidirectional shape memory (DCP) was successfully prepared by thermal crosslinking. Only when the amount of DCP is more than 1.0 wt% can the cross-linked EVA show bidirectional shape memory properties. Under the constant stress of 0.1 MPa, the reversible strain of crosslinked EVA with 3.0wtP was the largest, reaching 16.70.After the addition of 4.0wtP, the reversible strain reached 16.7wtP. The cross-linked EVA has ideal dual shape memory performance (shape fixation rate and recovery rate can reach 96.6% and 97.7 respectively). In order to give the bidirectional shape memory (EVA) electrical stimulation response, gas phase growth carbon fiber (VGCF) was used as nano-filler. VGCF-EVA composites were prepared by solution mixing and solation. The resistivity of VGCF-EVA composites decreased to 20.4 惟路cm when the content of VGCF reached 15.0wt%. The sample is heated rapidly at 60 V voltage and the temperature distribution is uniform, and can perform electric response at 40 V voltage. The VGCF-EVA composite also has a convenient drive. In order to further explore the practical application of 2W-SMP in intelligent control, we use bi-directional shape memory EVA as the basic material and coated with epoxy conductive silver adhesive. The intelligent temperature control switch can be developed when the temperature reaches 52.7 卤2.8 掳C and the circuit can be disconnected. When the temperature drops to 27.3 卤1.4 掳C, the switch can be deformed to the closed state of the circuit. This smart device is expected to be used in intelligent switches, such as current-limiting switches. Proper cross-linking of EVA can endow it with two-way shape memory property, and the crosslinked EVA can make many reversible shape changes under the condition of no stress. The composite modified with VGCF conductive filler has the characteristics of electrical stimulation under the condition of maintaining the original bidirectional shape memory property. Finally, the experimental results show that the bidirectional shape memory EVA is expected to be applied in the field of intelligent control through reasonable structural design.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB381;TB332

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