本文關(guān)鍵詞： PLA超韌 機(jī)械性能 界面相容性 相形態(tài) 增韌機(jī)理　出處：《青島科技大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：聚乳酸(PLA)具有優(yōu)異的可生物降解性、生物相容性、高的機(jī)械強(qiáng)度和易加工性能,被認(rèn)為是目前最具發(fā)展?jié)摿Φ纳锊牧�。但�?聚乳酸的缺口沖擊強(qiáng)度只有2.7kJ·m-2,斷裂伸長率約為3.5%,其自身的脆性大、耐熱溫度低和結(jié)晶速率慢等缺點(diǎn)嚴(yán)重制約著PLA材料在塑料領(lǐng)域的發(fā)展與應(yīng)用。因此,發(fā)展超韌性聚乳酸材料具有重要的理論和應(yīng)用價(jià)值。本文分別以“核殼結(jié)構(gòu)共聚物”、“改性天然橡膠”、“生物彈性體”為增韌劑,通過反應(yīng)性熔融共混,制備了超韌聚乳酸共混物。系統(tǒng)研究了不同增韌劑對聚乳酸共混物機(jī)械性能的影響規(guī)律。通過傅里葉紅外光譜(FT-IR)、熱分析、掃描電子顯微鏡(SEM)等測試方法分別研究了不同增韌劑對PLA共混體系的界面相容性和相態(tài)結(jié)構(gòu)的影響規(guī)律,進(jìn)一步探索超韌PLA共混物的增韌機(jī)理。主要的研究結(jié)論如下:(1)以聚丁二烯(PB)為種子乳液,苯乙烯(St)和甲基丙烯酸縮水甘油酯(GMA)為接枝單體,采用乳液聚合制備得到聚丁二烯-苯乙烯-甲基丙烯酸縮水甘油酯(PB-g-St-GMA)核殼共聚物,FT-IR和透射電鏡(TEM)測試結(jié)果表明合成得到目標(biāo)產(chǎn)物且共聚物的形貌為紡錘型核殼結(jié)構(gòu)。研究了反應(yīng)時(shí)間、引發(fā)劑濃度和乳化劑濃度對聚合產(chǎn)率及產(chǎn)物粒徑的影響,結(jié)果表明:當(dāng)引發(fā)劑濃度為0.5wt%、乳化劑濃度為0.5wt%、反應(yīng)時(shí)間為4h時(shí),聚合物產(chǎn)率可達(dá)到93.5%。(2)研究了PB-g-St-GMA和聚丙烯腈-丁二烯-苯乙烯(ABS)核殼共聚物對PLA共混物的力學(xué)性能和結(jié)晶行為的影響。結(jié)果表明:當(dāng)PB-St-GMA含量為10wt%時(shí),斷裂伸長率達(dá)到10.1%,比純PLA提高了約2倍。少量ABS明顯改善PLA共混物的延展性。當(dāng)ABS含量為6wt%時(shí),PLA共混物的斷裂伸長率達(dá)到118%,比純PLA提高了約23倍,沖擊強(qiáng)度提高約1倍。FT-IR和動態(tài)機(jī)械分析(DMA)測試結(jié)果表明PLA基體的酯基和ABS殼層PSAN的腈基之間產(chǎn)生了極性相互作用,改善了PLA與ABS之間相容性,且少量的ABS作為異相成核劑提高了PLA相的結(jié)晶速率。(3)采用自由基聚合,以GMA為改性單體,通過與天然橡膠(NR)的反應(yīng)熔融共混制備得到了改性天然橡膠(NR-g-GMA),并將NR-g-GMA與PLA進(jìn)行反應(yīng)熔融共混制備了超韌聚乳酸熱塑性彈性體。結(jié)果表明,當(dāng)NR-g-GMA含量為20wt%時(shí),超韌聚乳酸彈性體的缺口沖擊強(qiáng)度和斷裂伸長率高達(dá)73.4kJ·m-2和158.8%,比純PLA提高了26倍和44倍。FT-IR測試結(jié)果表明NR-g-GMA與PLA基體之間發(fā)生的環(huán)氧化反應(yīng)增加了PLA與改性天然橡膠之間的界面粘結(jié)力。超韌聚乳酸熱塑性彈性體的沖擊斷面形態(tài)結(jié)果表明PLA和NR-g-GMA的界面作用很強(qiáng),且發(fā)生大的屈服變形,因而可以大幅度增加PLA的沖擊韌性。(4)采用生物彈性體聚己二酸對苯二甲酸丁二醇酯(PBAT)、乙烯-丙烯酸酯-甲基丙烯酸縮水甘油酯(E-AE-GMA)和PLA的反應(yīng)性熔融共混制備了超韌PLA三元共混物。當(dāng)E-AE-GMA含量為15wt%時(shí),超韌PLA三元共混物的缺口沖擊強(qiáng)度和斷裂伸長率分別高達(dá)61.9kJ·m-2和265.9%,是純PLA的22倍和78倍。采用SEM、DMA、FT-IR等測試手段對超韌PLA三元共混物的相形態(tài)進(jìn)行分析,結(jié)果表明E-AE-GMA的加入有效地改善了PLA/PBAT共混體系的界面粘結(jié)力和相容性。E-AE-GMA在PLA/PBAT/E-AE-GMA三元共混體系中兼具反應(yīng)性增容劑和增韌劑的雙重作用。PLA共混物的SEM結(jié)果表明:PLA基體、E-AE-GMA和PBAT分散相均產(chǎn)生了非常大的應(yīng)力屈服變形,形成了共連續(xù)的沖擊斷面形態(tài)結(jié)構(gòu)。通過對PLA三元共混物的增韌機(jī)理分析表明:PLA基體通過E-AE-GMA的反應(yīng)性增容與PBAT分散相形成強(qiáng)的相界面作用,以及與PBAT、E-AE-GMA之間大的剪切形變對PLA的增韌具有相互協(xié)同作用。
[Abstract]:Polylactic acid (PLA) has excellent biodegradability, biocompatibility, high mechanical strength and easy processing properties are considered to be the most potential biological materials. However, the notched impact strength of poly lactic acid only 2.7kJ - m-2, the elongation is about 3.5%, its own brittleness. Disadvantages of low heat resistance temperature and crystallization rate of slow restricts the development and application of PLA material in the plastic area. Therefore, the development of high tenacity poly lactic acid material has important theoretical and practical value. In this paper, the "core-shell structure copolymer", "modified natural rubber", "bioelastomers" as toughening agent by reactive melt blending, preparation of super toughening polylactic acid blend system. Effects of different toughening agents on the mechanical properties of the blends of poly lactic acid. Through Fourier transform infrared spectroscopy (FT-IR), thermal analysis, scanning electron microscopy (SEM) measurements Test methods of different interface toughening agent on PLA blends compatibility effect regularity and phase structure, to further explore the toughening mechanism of super toughening PLA blends. The main conclusions are as follows: (1) with polybutadiene (PB) as seed emulsion, styrene (St) and glycidyl methacrylate (GMA) as grafting monomer, polymerization preparation of polybutadiene styrene glycidyl methacrylate (PB-g-St-GMA) emulsion with core-shell copolymer, FT-IR and transmission electron microscopy (TEM) test results show that the morphology of the target compound was synthesized and the copolymer for spindle type core shell structure. The effect of reaction time, initiator concentration and the concentration of emulsifier on the polymerization rate and particle size effects, the results show that when the concentration of initiator is 0.5wt%, emulsifier concentration is 0.5wt%, the reaction time is 4h, the polymer yield can reach 93.5%. (2) of PB-g-St-GMA And polyacrylonitrile butadiene styrene (ABS) core-shell copolymer on the effect of PLA blends on the mechanical properties and crystallization behavior. The results show that when the PB-St-GMA content is 10wt%, the elongation rate was 10.1%, higher than that of pure PLA by about 2 times. A small amount of ABS can improve the ductility of PLA blends. When the content of ABS for 6wt%, the elongation of PLA blends reached 118%, higher than that of pure PLA by about 23 times, about 1 times of.FT-IR and improve the analysis of dynamic mechanical impact strength (DMA) test results show that polar interactions between nitrile ester and PLA matrix ABS shell PSAN, improved between PLA and ABS compatibility, and a small amount of ABS as nucleating agent to improve the crystallization rate of PLA. (3) by free radical polymerization, the modified monomer with GMA, with natural rubber (NR) was prepared by melt blending modified natural rubber (NR-g-GMA), and NR-g-GMA The reaction of melt blending with PLA super toughening of polylactic acid thermoplastic elastomer was prepared. The results show that when the NR-g-GMA content is 20wt%, the super tough notched impact strength and elongation at break of polylactic acid elastomer was 73.4kJ m-2 and 158.8% higher than that of pure PLA 26 times and 44 times of.FT-IR test results the epoxidation reaction between NR-g-GMA and PLA matrix increased PLA and interfacial bond strength between natural rubber. The impact section morphology of the polylactic acid thermoplastic elastomers showed that the interface effects of PLA and NR-g-GMA is very strong, and the yield of large deformation, which can greatly increase the impact toughness of PLA. (4) using bioelastomers polyethylene adipate terephthalate (PBAT), ethylene acrylate glycidyl methacrylate (E-AE-GMA) super PLA three binary blends by reactive melt blending process when E-AE-GMA and PLA. The content of 15wt%, notched impact strength and elongation at break of three yuan super toughening PLA blends were as high as 61.9kJ, m-2 and 265.9%, 22 times and 78 times of pure PLA. Using SEM, DMA, FT-IR and other testing methods to analyze the morphology of super tough PLA three blends, the results show that E-AE-GMA to effectively improve the interfacial adhesion of PLA/PBAT blends and the compatibility of.E-AE-GMA blends with the dual role of.PLA reactive compatibilizer and toughening agent in PLA/PBAT/E-AE-GMA three blends SEM results showed that the PLA matrix, E-AE-GMA and PBAT dispersed phase are all produced very big stress deformation, the formation of the morphological structure of cross section. The impact of co continuous toughening mechanism of PLA blends three yuan analysis showed that PLA matrix dispersed by PBAT Reactive Compatibilization and E-AE-GMA phase to phase interface effect, and PBAT, E-AE-GMA Large shear deformation has synergistic effect on Toughening of PLA.

【學(xué)位授予單位】：青島科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：O633.14

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