【摘要】：近年來,聚合物材料的研究成為了當(dāng)前國內(nèi)外學(xué)者的研究重點(diǎn),許多研究者致力于開發(fā)新的材料配方、改進(jìn)已有材料,希望能夠合成天然的、具有優(yōu)異特性的仿生材料。因此,本文基于SU-8光刻膠在MEMS領(lǐng)域的廣泛應(yīng)用,運(yùn)用分子動力學(xué)的研究方法,針對SU-8膠及復(fù)合材料的力學(xué)、熱力學(xué)及阻尼性能等進(jìn)行研究。不僅能夠?qū)崿F(xiàn)材料宏觀性質(zhì)的預(yù)測,還有助于從微觀上認(rèn)識和解析出材料宏觀現(xiàn)象產(chǎn)生的機(jī)理。首先,本文結(jié)合分子力學(xué)和分子動力學(xué)的基本理論,分析了適合聚合物材料研究的分子動力學(xué)的力場、系綜、邊界等條件,提出了基于COMPASS分子力場,經(jīng)過分子聚合、能量最小化和退火模擬等構(gòu)建非交聯(lián)和交聯(lián)的SU-8光刻膠模型的方法。計算得到了SU-8膠在室溫條件下的楊氏模量、泊松比等力學(xué)性能參數(shù),并將模擬結(jié)果與實(shí)驗(yàn)結(jié)果對比證明了建立材料模型方法的可行性以及分子動力學(xué)算法的有效性。其次,建立SU-8膠和不同類型碳納米管共混的復(fù)合材料模型,利用分子動力學(xué)的方法研究不同類型的碳納米管對材料力學(xué)性能的影響,結(jié)果表明：碳納米管可以極大的提高材料力學(xué)性能；隨著碳納米管管徑增加復(fù)合材料楊氏模量逐漸減��；同時證明了相對于單壁碳納米管而言,雙壁碳納米管更能顯著改善材料力學(xué)性能。再次,利用分子動力學(xué)模擬研究了SU-8膠的玻璃化轉(zhuǎn)變行為及其主要的影響因素,預(yù)測得到了非交聯(lián)和交聯(lián)SU-8膠的玻璃化轉(zhuǎn)變溫度分別為326.7K和494.8K。著重討論了力場能量項對玻璃化轉(zhuǎn)變溫度的影響,得到非鍵能的改變是影響玻璃化轉(zhuǎn)變的主要因素,有助于深入理解玻璃化轉(zhuǎn)變過程的本質(zhì)和研究材料阻尼性能的微觀機(jī)理。同時,利用動態(tài)機(jī)械分析(DMA)實(shí)驗(yàn)測試得到了不同工藝參數(shù)的SU-8膠玻璃化轉(zhuǎn)變溫度。最后,計算了SU-8膠及復(fù)合材料的氫鍵、徑向分布函數(shù)、自由體積分?jǐn)?shù)和結(jié)合能等相關(guān)參數(shù)。通過計算復(fù)合材料界面結(jié)合能來得到碳納米管和SU-8膠的結(jié)合強(qiáng)度；通過計算SU-8膠的氫鍵和徑向分布函數(shù),可知分子內(nèi)和分子間的相互作用方式；通過復(fù)合材料自由體積的計算,結(jié)合自由體積的變化對玻璃化轉(zhuǎn)變的影響,討論了自由體積和氫鍵等參數(shù)對于材料阻尼性能的影響,為聚合物基阻尼復(fù)合材料的設(shè)計提供參考。
[Abstract]:In recent years, the study of polymer materials has become the research focus of scholars at home and abroad. Many researchers are devoted to the development of new material formulations, the improvement of existing materials, hoping to synthesize natural, excellent properties of biomimetic materials. Therefore, based on the extensive application of SU-8 photoresist in the field of MEMS, the mechanical, thermodynamic and damping properties of SU-8 adhesive and composites were studied by means of molecular dynamics. Not only can the prediction of macro-properties of materials be realized, but also the mechanism of macro-phenomena of materials can be understood and analyzed from the microcosmic point of view. Firstly, combining the basic theories of molecular mechanics and molecular dynamics, this paper analyzes the force field, ensemble and boundary conditions of molecular dynamics suitable for the study of polymer materials, and puts forward the molecular polymerization based on COMPASS molecular force field. Energy minimization and annealing simulation are used to construct non-crosslinked and cross-linked SU-8 photoresist models. The mechanical properties of SU-8 adhesive at room temperature, such as Young's modulus and Poisson's ratio, were calculated. The simulation results were compared with the experimental results to prove the feasibility of establishing the material model and the validity of the molecular dynamics algorithm. Secondly, the composite model of SU- 8 rubber and different types of CNTs was established, and the effects of different types of CNTs on the mechanical properties of the composites were studied by molecular dynamics. The results show that carbon nanotubes can greatly improve the mechanical properties of the materials. As the diameter of CNTs increases, Young's modulus of composites decreases gradually, and it is proved that compared with single-walled CNTs, double-walled CNTs can significantly improve the mechanical properties of the composites. Thirdly, the glass transition behavior of SU-8 adhesive and its main influencing factors were studied by molecular dynamics simulation. The glass transition temperatures of non-crosslinked and crosslinked SU-8 adhesive were predicted to be 326.7K and 494.8K, respectively. The effect of force field energy term on glass transition temperature is discussed emphatically. It is found that the change of non-bond energy is the main factor affecting glass transition, which is helpful to understand the essence of glass transition process and to study the micro-mechanism of damping properties of materials. At the same time, the glass transition temperature of SU-8 adhesive with different process parameters was obtained by dynamic mechanical analysis (DMA). Finally, the hydrogen bond, radial distribution function, free volume fraction and binding energy of SU-8 glue and composites are calculated. The bonding strength between CNTs and SU- 8 adhesive was obtained by calculating the interfacial bonding energy of the composites, and the intermolecular and intra-molecular interaction modes were obtained by calculating the hydrogen bond and radial distribution function of the SU-8 adhesive. Based on the calculation of free volume of composites and the influence of free volume on glass transition, the effects of free volume and hydrogen bond on damping properties of composites are discussed, which provides a reference for the design of polymer-based damping composites.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ317;TB33

【共引文獻(xiàn)】

相關(guān)期刊論文 前10條

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本文編號：2461158