【作者】 丁新波；

【导师】 晏雄；

【作者基本信息】 东华大学 ， 纺织工程， 2008， 博士

【摘要】 阻尼材料已经广泛应用于交通工具、产业机械、建筑、家用电器、精密仪器和军事装备等领域的减振降噪。聚合物是一类传统的阻尼材料,是利用其玻璃化转变区内的粘性阻尼部分,将吸收的机械能或声能部分地转变为热能耗散掉,从而达到减振、降噪的目的。通常,高聚物的玻璃化转变温域窄,而高聚物的阻尼性能依赖于玻璃化温度,从而大大限制了高聚物阻尼材料的应用范围。为了获得既具有较高损耗峰,又具有较宽有效阻尼温域的阻尼材料,减少阻尼材料对玻璃化温度的依赖性,本论文主要包括以下四个方面的研究内容:1.高性能有机杂化阻尼材料为了深入了解高分子材料与有机小分子功能添加剂之间形成的杂化材料的阻尼机理,本文以氯化聚乙烯（CPE）为基体材料,并选择了两种化学结构相似的功能小分子添加剂2,2-甲撑双-（4-乙基-6-叔丁基苯酚）（EBP）和2,2-甲撑双-（4-甲基-6-环己基苯酚）（ZKF）,通过热压淬火成型分别制得了CPE/EBP和CPE/ZKF杂化材料。对CPE/EBP杂化材料DSC研究结果发现,CPE和EBP之间是不相容的,在DSC曲线上的20～40℃温域内出现了一个新的玻璃化转变区域,但是EBP除了在-10～0℃温域内有玻璃化转变外,EBP在其他温域并没有出现玻璃化转变。因此,CPE和EBP之间内部作用机理并不同于传统意义上不同组分共混时产生的相分离机理。FTIR研究结果发现,EBP分子上的-OH与CPE分子链上的Cl之间形成的分子间氢键作用而大量聚集,富集成相,并且在淬火处理时被固定下来,产生了相分离,在tanδ-T曲线上表现为两个分离的损耗峰,拓宽了材料的有效阻尼温域。而通过DSC和DMA研究发现,CPE和ZKF之间是相容的,在tanδ-T曲线上只有一个损耗峰,并随着ZKF含量的增加,CPE/ZKF杂化材料的损耗峰大幅度提高,并且损耗峰的位置移向高温方向;FTIR研究发现,一个ZKF分子上的两个-OH与不同CPE大分子链之间同时形成了两个氢键,称为“桥式”氢键作用。在玻璃化转变区域,这种“桥式”氢键的断裂和重建所耗散能量地能量远远大于分子间摩擦引起的能量耗散。因此,在玻璃化转变区域CPE/ZKF杂化材料具有优异的阻尼减振能力。2.有机杂化阻尼材料老化现象的研究及性能优化当杂化材料CPE/EBP和CPE/ZKF在环境温度下自然放置12个月后,杂化材料表面会出现白色析出现象。文中对CPE/ZKF杂化材料的析出机理及析出对杂化材料阻尼性能影响作了研究。通过DSC研究发现,材料表面的白色粉末为无定形态功能添加剂结晶所引起的;对CPE/ZKF杂化材料FTIR和DMA研究进一步发现,在环境温度下放置12个月后,CPE/ZKF杂化材料在3000～3500cm^-1波段内形成的分子间氢键发生了明显的变化,在3208cm^-1处产生的“桥式”氢键消失,这导致了CPE/ZKF杂化材料失去了高阻尼性能。这表明CPE/ZKF杂化材料的阻尼性能是不稳定的。因此,为了进一步研究杂化材料阻尼性能的稳定性,本文研究了三元杂化材料CPE/ZKF/EBP,发现ZKF和EBP对CPE/ZKF/EBP杂化材料的阻尼性能存在协同效应。少量EBP的加入不仅可以进一步提高CPE/ZKF杂化材料的阻尼性能,而且可以通过ZKF/EBP组分来调节杂化材料的损耗峰位置使其处于设计温度。进一步研究发现,柔性大侧基的引入以及氢键网络的形成是ZKF和EBP对CPE/ZKF/EBP杂化材料阻尼性能产生协同作用的根源;另一方面,少量EBP的加入可以减缓CPE/ZKF杂化材料损耗峰高度随退火处理时间延长而下降的趋势,即少量EBP的加入提高了CPE/ZKF杂化材料阻尼性能的稳定性。3.压电导电型宽温域高阻尼减振复合材料由于以无机压电陶瓷为填料形成的压电导电减振复合材料存在玻璃化转变温度附近损耗峰低、机电转换效率低及压电阻尼效果不佳等不足之处,本文中采用具有强介电效果的有机小分子材料ZKF来代替无机压电陶瓷,通过强介电有机小分子材料所具有的分子级别上的压电效应来进一步研究压电导电型阻尼材料。由于在玻璃化转变区域基体材料的粘弹阻尼性能比较明显,压电导电阻尼效果不明显;在橡胶态（60～80℃温域内）发现,当VGCF含量较低时,复合材料内部没有形成导电网络,压电导电阻尼效果不明显;当VGCF含量超过临界值后,复合材料内部形成了一定三维导电网络,复合材料在橡胶态的阻尼减振能力大大提高,在VGCF含量达到16vol.%时tanδ达到了最值,并随着VGCF含量的进一步增加tanδ值下降。由此可见,CPE/ZKF/VGCF复合材料存在明显的压电导电阻尼效应,拓宽了材料的有效阻尼温域,减少了材料阻尼性能对玻璃化温度的依赖性。与CPE/PZT/VGCF复合材料相比,CPE/ZKF/VGCF复合材料不仅在玻璃化转变温域内具有高的损耗峰,而且在橡胶态的压电导电阻尼效果也更明显;另一方面,由于ZKF与VGCF的存在,使复合材料的力学性能得到了进一步优化。4.多层杂化体约束宽温域高阻尼型减振复合材料在对CPE/ZKF杂化材料的研究中发现,随着ZKF含量的增加,CPE/ZKF杂化材料既能大幅度提高阻尼峰高度,又可以调控阻尼峰位置;但是,损耗峰的半峰宽变窄,限制了材料的使用。因此,本文中提出把多层杂化材料叠加通过熔融热挤压技术来制备宽温域、高阻尼多层减振复合材料的设想,从而达到对环境温度的变化引起振动响应的变化。本文从理论上对理想状态下的多层复合材料来拓宽有效阻尼温域进行了分析论证,并进一步对多层复合材料的tanδ_c进行了预测。理论结果与实验结果都表明,可以利用二层杂化材料叠加来有效的拓宽材料的有效阻尼温域,并可以进一步增加复合材料的层数来使“凹谷”区域的tanδ值上升,获得一个较大的最小值区域,即利用多层杂化材料叠加来拓宽材料的有效阻尼温域,无论在理论上和实验上都是切实可行的,为研究和开发“宽温域、高阻尼”减振复合材料提供了新的思路和理论依据。更多还原

【Abstract】 Damping materials are extensively used in various fields such as vehicles, industrial machine, construct and building, home appliances, precise instruments, military equipments and so on. Typical candidate damping materials for the application of passive damping are viscoelastic polymers. Since the mechanical or acoustic vibrating energy is partly converted into Joule’s heat through the viscoelastic damping effect in the vicinity of its glass transition temperature （Tg）, and in turn reduce the vibration and noise. The damping properties of polymers depend on its Tg, but homopolymers usually havenarrow glass transition region. Their applications are limited to some extent. In order to obtain good damping materials with both a high damping peak and a broad temperature range, and reduce the dependence of its Tg, four sections are mainly included in this dissertation as follows:1. High-performance Organic Hybrid Damping MaterialsIn order to further understand the damping mechanism of an organic hybrid of polymer and a small molecule, the Chlorinated Polyethylene （CPE） is used as the matrix, and two kinds of organic small molecules with similar chemical structure 2, 2’-methylene-bis-（6-tert-butyl-4-ethyl-phenol）（EBP）,2’-methylene-bis-（4-methyl-6-cyclohexyl--phenol） （ZKF） are chosen as the organic additives. Then, two kinds of hybrid materials CPE/EBP and CPE/ZKF are made by hot-pressing and quenching.For CPE/EBP hybrids, differential scanning calorimetry （DSC） shows that, the EBP is incompatible with the CPE matrix, and a novel glass-transition range arises within the temperature range from 20 to 40℃on DSC scanning curves. However, none of glass-transition range of EBP is found on the DSC curves except within that from -10 to 0℃. Therefore, the interactional mechanism between CPE and EBP are different from the conventional polymer blend systems with two or mutli-component. The FT1R results show that, Due to the intermolecular hydrogen bonding interaction between Cl of CPE and the hydroxyl groups of EBP, most of EBP form EBP-rich domains frozen by quenching process, and cause the phase separation. The CPE/EBP hybrids show two loss peaks on tanδ- T curve, which broaden the efficient damping temperature range. For CPE/ZKF hybrids, the DSC and DMA show that, the ZKF is compatible with the CPE matrix, and there is only one loss peak on the tanδ-T curve for all the samples. With increasing the ZKF weight content, the loss peak of the CPE/ZKF hybrids increases dramatically and the loss peak position shifts to higher temperature. The FTIR results show that, a small molecule ZKF formed two hydrogen bonds with two CPE chains at the same time, acted as a bridge. The energy dissipation due to dissociation of the intermolecular hydrogen-bond network is larger than that of due to general friction between polymer chains. Therefore, CPE/ZKF hybrids is a good damping material with a high loss peak near its Tg.2. The Aging Phenomena and the Damping Stability of Organic HybridsWhen the CPE/EBP and CPE/ZKF organic hybrids are aged under the room temperature for twelve months, there is some white powder on the surface of the hybrids. The aging mechanism and the effect of aging phenomena on the damping properties of CPE/ZKF hybrids have been investigated in this section. The DSC results show that, the white powder is caused due to the crystal of EBP. For the aged CPE/ZKF hybrids, the FTIR spectra shows that, there is a evident change of the hydrogen bonding in the region ranging from 3000 to 3500 cm^-1, and the bridge-like hydrogen bond disappeared that is centered at 3208 cm^-1, which results in the loss of the higher damping peak of the CPE/ZKF hybrids. The results show that the stability of the damping properties of the CPE/ZKF hybrids is not well.For further studying the stability of the damping properties of CPE/ZKF hybrids, consequently, the CPE/ZKF/EBP three-component hybrids are investigated, and it is found that there is a synergistic effect between ZKF and EBP on the damping properties of the three-component hybrids. When adding a small quantity of EBP into CPE/ZKF systems, not only the loss peak intensity of the CPE/ZKF/EBP hybrids can be further improved, but also its loss peak position can be lowered to a required temperature region. It is further found that, both the physical bulk side group and hydrogen-bond network should cause the synergistic interaction between EBP and ZKF. On the other hand, the damping stability of the CPE/ZKF hybrids can be improved excellently by adding a small amount of EBP.3. Piezoelectric Composites with a Broad Efficient Damping Temperature Range Due to that, piezoelectric ceramic damping materials are brittle, fragile, and hard, with the result that not only have some difficulty in proceeding technology, but also the electro-mechanical coupling factor is not very good. As a way of improving these inferior properties, the piezoelectric ceramic powder is substituted by the organic small molecule ZKF with strong dielectric behavior, for further studying the piezo-damping properties of CPE/ZKF/VGCF composites by DMA.At the vitrification point, the piezo-damping effect is not obvious, as the mechanical vibration energy converts into thermal energy is higher due to the friction between molecules of CPE matrix. Within the temperature range of 60～80℃, at a low content of VGCF, there are no conductive paths throughout the composites and the piezo-damping effect is not obvious. As the VGCF content exceeds the percolation threshold, a continuous conductive network begin to be formed, the loss factor is increased dramatically, present a peak at 16vol% VGCF content, and finally decreases again. This indicates that the piezo-damping effect really functions in the systems and that the efficient damping temperature region, which reduce the dependence of its Tg.In comparison with CPE/ZPT/VGCF systems, the CPE/ZKF/VGCF composites not only have a high loss peak, but also have an obvious piezo-damping effect. On the other hand, the storage modulus also is great improved due to the present of the VGCF and ZKF.4. Multi-layered Hybrid Composites with a Broad and High Damping RangeFor CPE/ZKF hybrids, with increasing the ZKF content, not only the loss peak height of the hybrids increase dramatically, but also the loss peak position can be adjusted. However, the width of loss peak is narrow for practical applications. Therefore, to obtain good damping materials with a broad and high damping range, we design a novel multi-layered organic hybrid material, which overlap several organic hybrid layers with different ZKF content and corresponding loss peak position by hot-pressing process.In this section, we analyze and discuss the possibility of using the multi-layered hybrid materials to broaden the efficient damping range, and prediction of the damping properties of multi-layered hybrid materials is also studied. The predicted and experimental results show that, it is possible to obtain damping material with broad efficient damping range by two-layered hybrid materials, the value in the middle of two peaks can be improved by increasing the number of layers of the multi-layered hybrids and there is a higher minimum value. Thus, it is feasible in theory and experiment to broaden the efficient damping range by multi-layered hybrid materials, which provides a new approach and solid basis for developing high performance damping materials with a broad and high damping range.更多还原