【作者】 韩春苗；

【导师】 刘宇艳；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2013， 博士

【摘要】 形状记忆环氧（Shape Memory Epoxy，SMEP）是一种新兴智能材料，由于具有较好形状记忆性能、力学性能以及广阔应用前景而受到人们的重视，增韧问题在形状记忆环氧的研究和使用中是非常重要的。超支化聚合物（Hyperbranched Polymer，HBP）是近年来另一个新兴的研究热点，用HBP增韧的环氧体系可以在韧性提高同时，体系强度、热性能等只受轻微影响，且改性剂与基体间的反应性易调节。针对以上背景，本文提出了“脂肪族超支化聚醚改性形状记忆环氧及其性能研究”这一课题，合成了超支化聚合物“聚3-乙基-3-羟甲基氧杂环丁烷（HBPO）”及其不同支化度和端基接枝比例的产物，并用其增韧SMEP，研究了HBPO含量、固化工艺、支化度、端基改性比例等因素对SMEP体系性能的影响和原因，分析了固化机理，给出了体系增韧机制。首先合成了高支化度的HBPO，采用1H-NMR、定量13C-NMR、GPC等方法对其化学结构、支化度、分子量、分散系数等进行表征之后，用HBPO增韧形状记忆环氧-酸酐（SMEP-AA）体系。通过变温红外方法在线监测SMEP-AA体系的固化过程，给出了HBPO/SMEP-AA体系的固化机理。然后，确定出HBPO/SMEP-AA体系的两种固化工艺，研究了HBPO含量和固化工艺对体系力学性能、玻璃化转变温度和形状记忆性能的影响，并从宏微观角度分析了性能变化的原因。研究发现，10%-HBPO-1-GX体系具有最佳的增韧效果，断裂伸长率、断裂功和拉伸强度与未改性体系相比分别提高了70%、147%、40%，增幅明显，Tg稍有下降，HBPO的加入对SMEP-AA体系形状固定率和形状回复率没有影响，形状回复速率在合适的HBPO含量下可以得到提高，解决了SMEP材料在使用中高韧性与高强度及良好耐热性能难共存的技术难题。改性体系均相，反应程度提高，自由体积尺寸和含量减小。根据微观结构分析，提出了该体系的增韧机理，很好地解释其增强增韧的原因以及与其他HBP增韧环氧体系的差别，认为在改性体系中形成了以HBPO为中心的三维交错区域，该区域在受力时发生的强迫变形和相关变化是体系增强增韧的主因。合成了不同支化度的HBPO，进行了结构、支化度和分子量表征后，用其增韧SMEP-AA体系。首先探讨了支化度降低对HBPO/SMEP-AA体系固化机理的影响，接着研究了支化度变化对体系性能的影响。结果表明随着HBPO支化度的降低，改性体系的韧性、强度和模量都呈下降趋势，Tg值略微降低，体系形状固定率和形状回复率不受影响，但形状回复温度有所下降，回复过程的温度跨度增加，回复速率减小。通过微观结构分析得知，随着HBPO支化度的降低，HBPO/SMEP-AA体系相容性下降，反应程度略有减小，自由体积尺寸和含量增加，界面相互作用减弱，体系中难以形成有效的三维交错区域，导致HBPO/SMEP-AA体系性能下降。合成了端羧基不同接枝比例的HBPOS，进行了结构、端羧基接枝比例和分子量表征后，用其增韧SMEP-AA体系。首先探讨了端羧基接枝对HBPOS/SMEP-AA体系固化机理的影响，接着研究了HBPOS接枝比例对体系性能的影响。结果表明随着HBPOS端羧基接枝比例的增加，改性体系的韧性和强度均呈下降趋势，Tg值先增后减，体系的形状固定率和形状回复率不受影响，但回复过程的温度跨度明显增加，形状回复速率减小。微观结构分析的结果表明，随着HBPOS端羧基接枝比例的增加，HBPOS/SMEP-AA体系相容性逐渐变差，反应程度略有提高，自由体积尺寸和含量增加，界面相互作用减弱，体系断面微观结构发生改变，由于存在较大位阻而难以形成三维交错区域，使得HBPOS/SMEP-AA体系性能下降。使用HBPO增韧形状记忆环氧-胺（SMEP-AM）体系，通过变温红外在线监测固化过程，给出了HBPO/SMEP-AM的固化机理。研究了HBPO/SMEP-AM体系性能随HBPO含量的变化规律，结果表明改性体系的韧性和强度都随着HBPO含量的增大而先增后减，加入5wt.%-HBPO体系具有最佳的增韧效果，其断裂伸长率、断裂功、拉伸强度和Tg值与未改性体系相比分别提高了38%、77%、29%和3℃，HBPO的加入对SMEP-AM体系的形状固定率和形状回复率没有影响，形状回复速率在合适的HBPO含量下得到提高。微观结构研究发现，HBPO/SMEP-AM不是均相体系，HBPO的加入使体系反应程度明显增加，孔穴增韧和基体剪切变形抽丝增韧是HBPO/SMEP-AM体系的增韧机理。更多还原

【Abstract】 Shape memory epoxy (SMEP), a new type of smart material attracts more attentions in recent years because of its outstanding shape memory performance and excellent mechanical property as well as broad application prospects. Toughening research is important for the basic study and practical application of SMEP. Hyperbranched polymer (HBP) is another recent emerging research hotspot. HBP modified epoxy can be effectively toughened along with slight impact on the strength and thermal properties. Moreover, the reactivity between HBP and epoxy matrix can easily be adjusted. In this thesis, hyperbranched polymer “poly-3-ethyl-3-(hydroxymethyl)oxetane (HBPO)” with different degree of branching and HBPO with different proportion of carboxyl grafting were synthesized and used for toughening SMEP. The effects of HBPO content, curing method, degree of branching and proportion of carboxyl grafting on properties of SMEP systems were investigated. The curing mechanism and toughening mechanism were studied.First, HBPO with high degree of branching was synthesized and characterized by1H-NMR, quantitative13C-NMR and GPC methods. The curing mechanism of HBPO/SMEP-AA system was studied through variable-temperature FT-IR method. Two curing methods were chosen for preparation of HBPO/SMEP-AA systems. Then, the effects of HBPO content and curing method on mechanical property, Tg and shape memory property of SMEP system were investigated. The system10%-HBPO-1-GX prepared with the second curing method the best toughening performance with elongation at break, work of fracture and tensile strength increased by70%,147%and40%respectively. Tg value slightly decreased compared with the unmodified SMEP system. Incorporation of HBPO had no effect on SMEP’s shape retention ratio and shape recovery ratio, whereas improved the shape recovery rate. Thus, good toughness, high strength and good heat resistance were concomitantly achieved. It was revealed that HBPO/SMEP-AA was a homogeneous system with higher extent of reaction, smaller free volume size and lower free volume content. Microstructural analysis revealed a toughening mechanism of HBPO/SMEP-AA system which well explained the observed simultaneous improved toughness and strength, and the difference between HBPO/SMEP-AA and other HBP modified epoxy systems. With this toughening mechanism, three-dimensional staggered fields centered in HBPO formed in the modified system. A series of HBPO with different degree of branching were synthesized and characterized. The effects of HBPO’s degree of branching on curing mechanism and properties of HBPO/SMEP-AA system were investigated. The results showed that, with lower HBPO’s degree of branching, toughness, strength and modulus of the modified system all reduced, Tg slightly decreased, shape retention ratio and shape recovery ratio unaffected, but the shape recovery temperature lowered, temperature range during recovery process became larger, and the recovery rate reduced. The microstructural analysis revealed, with lower HBPO’s degree of branching for HBPO/SMEP-AA system, poorer compatibility, slightly reduced extent of reaction, larger free volume size, higher free volume content and weaker interfacial interaction. Three-dimensional staggered fields were hard to form and to function effectively in HBPO/SMEP-AA system modified by HBPO with low degree of branching, and that’s what made properties reduced.A series of HBPOS with different proportion of carboxyl grafting were synthesized and characterized in detail. The effects of carboxyl grafting on curing of HBPOS/SMEP-AA and HBPOS’s proportion of carboxyl grafting on properties of this system were investigated. The results showed that, with increased HBPOS’s proportion of carboxyl grafting, toughness and strength of the modified system both reduced, Tg value first increased and then slightly decreased, shape retention ratio and shape recovery ratio of modified system unaffected, but temperature range during recovery process larger, and the shape recovery rate reduced. The microstructure analysis revealed that, with increased HBPOS’s proportion of carboxyl grafting, HBPOS/SMEP-AA system got poorer compatibility, slightly improved extent of reaction, larger free volume size, higher free volume content, weaker interfacial interaction and a gradually changed fractograph. Three-dimensional staggered fields were hard to form in HBPOS/SMEP-AA system because of intense steric effect of HBPOS.HBPO was used for toughening SMEP-AM system. The curing mechanism of HBPO/SMEP-AM system was studied through variable-temperature FT-IR. Then the effect of HBPO content on properties of HBPO/SMEP-AM system was investigated. The results showed that, with increased HBPO content, toughness and strength of the modified system first increased and then decreased. The modified system with5wt.%HBPO content achieved the best toughening performance, with elongation at break, work of fracture, tensile strength and Tg value increased by38%,77%,29%and3℃respectively. The shape retention ratio and shape recovery ratio of modified system were unaffected, and the shape recovery rate of SMEP could be improved at an appropriate HBPO content. The microstructural analysis revealed that HBPO/SMEP-AM was a heterogeneous system and its extent of reaction was highly improved after incorporation of HBPO. The toughening mechanism of HBPO/SMEP-AM system was found to be cavitation and matrix shear deformation.更多还原