可生物降解聚乳酸外文翻译中英文.docx

1、可生物降解聚乳酸外文翻译中英文Thermomechanical and Optical Properties ofBiodegradable Poly(L-lactide)/Silica Nanocomposites by Melt Compounding可生物降解聚乳酸/纳米二氧化硅复合材料的熔融共混法制备以及热力学和光学性质研究Xin Wen,1,2 Ying Lin,1,2 Changyu Han,1 Kunyu Zhang,1,2 Xianghai Ran,1,2Yuesheng Li,1 Lisong Dong11 State Key Laboratory of Polymer Ph

2、ysics and Chemistry, ChangchunInstitute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China2 Graduate School, Chinese Academy of Sciences, Beijing 10080, ChinaReceived 17 January 2009; accepted 4 June 2009 DOI 10.1002/app.30896Published online 7 August 2009 in Wiley InterScien

3、ce ().ABSTRACT: Poly(L-lactide) (PLA)/silica (SiO2) nano-composites containing 1, 3, 5, 7, and 10 wt % SiO2 nano-particles were prepared by melt compounding in a Haake mixer. The phase morphology, thermomechanical properties,and optical transparency were investigated and compared to those of neat PL

4、A. Scanning electron microscopy results show that the SiO2 nanoparticles were uniformly distributed in the PLA matrix for filler contents below 5wt %, whereas some aggregates were detected with further increasing filler concentration. Differential scanning calorimetry analysis revealed that the addi

5、tion of SiO2 Nano-particles not only remarkably accelerated the crystallization speed but also largely improved the crystallinity of PLA. An initial increase followed by a decrease with higher filler loadings for the storage modulus and glasstransition temperature were observed according to dynamic

6、mechanical analysis results. Hydrogen bonding interaction involving CO of PLA with SiAOH of SiO2 was evidenced by Fourier transform infrared analysis for the first time. From the mechanical tests, we found that the tensile strength and modulus values of the nanocomposites were greatly enhanced by th

7、e incorporation of inorganic SiO2 nanoparticles, and the elongation at break and impact strength were slightly improved. The optical transparency of the nanocomposites was excellent, and it seemed independent of the SiO2 concentration; this was mainly attributed to the closed refractive indices betw

8、een the PLA matrix and nanofillers.2009 Wiley Periodicals, Inc.J Appl Polym Sci 114: 33793388, 2009Key words: nanocomposites; polyesters; silicas;transparency通过哈克搅拌机用熔融法制备了含有1，3，5，7，和10的纳米SiO2粒子的聚（L-乳酸）/二氧化硅（SiO2）纳米复合材料。与纯PLA在相形态，热机械性能和光学透明性进行了研究和比较。扫描电子显微镜结果表明，SiO2的纳米粒子以矩阵均匀地分布在添加了5wt以下的PLA，而一些总量进一

9、步增加了填充物的浓度检测。差示扫描量热分析显示，增添了SiO2纳米粒子，不仅显著加快了结晶速度，而且大大提高了聚乳酸的结晶量。根据动态力学分析结果观察到随着填充量的增加，弹性模量和结晶温度都逐渐增加。首次通过傅里叶变换红外分析证明了PLA中SiO2 SiAOH的氢键相互作用。从机械测试中，我们发现，由于无机纳米SiO2团，其拉伸强度和模量的纳米复合材料的值明显提高，断裂伸长率和冲击强度则略有改善。该纳米复合材料的光学透明度非常好，它似乎与SiO2浓度无关，主要是取决于PLA基体与纳米填充物之间封闭的折射率。INTRODUCTIONWith increasing environmental aw

10、areness around the world, the research and development of biodegradable polymers has attracted more and more attention.13 Poly(L-lactide) (PLA), a typical linear aliphatic thermoplastic polyester, has been viewed as the most popular commercial biodegradable material because it is biodegradable,compo

11、stable, and nontoxic to the human body and to the environment; moreover, it can be produced from renewable plant resources (mainly starch and sugar).46 This polymer possesses reasonably good mechanical and optical properties, thermal plasticity, and processability, so it has tremendous market potent

12、ial for packaging materials, fibers, agricultural films, and biomaterials.7,8 However, some of its physical properties, such as its toughness, dimensional stability, melt viscosity, crystallization rate, and gas barrier properties, are still not satisfactory for processing andapplication. Consequent

13、ly, there is a sustained interest in overcoming these disadvantages without a drastic loss in its general performance to meet various enduse applications.随着世界各地的环保意识的提高，可生物降解聚合物的研究和发展已经吸引了越来越多关注1- 3聚（L-乳酸），一种典型的线性脂肪族热塑性聚酯，已被视为最流行的商业可生物降解的材料，因为它是可生物降解，可堆肥，且对人体和环境无毒，而且，它可以从可再生植物资源（主要是淀粉和糖）获取。这种聚合物具有良好

14、的机械和光学性能，热可塑性强，加工性能好，因此它可以做包装材料，纤维，农用薄膜和biomaterials.，市场潜力巨大。然而，它的一些物理性质，如它的韧性，尺寸稳定性，熔体粘度，结晶率，气体阻隔性能，仍然不理想，因此，在没有克服其综合性能上的缺点，满足各种应用前难以引起人们兴趣。Over the last few years, a new class of mineralreinforced thermoplastics known as nanocomposites has attracted increasing interest for researchers in the field

15、 of polymer and materials science from both academia and industry.911 Fillers as dispersed phases in nanocomposites are nanometer sized, preferably with at least one of its dimensions on theorder of a few nanometers (1100 nm). Because of the small particle size and extremely high surface area, the i

16、ncorporation of nanoparticles into a polymer creates a great amount of interphase and changes the intermolecular interaction of the matrix. As a result, dramatic improvements in the physical and mechanical properties, including stiffness and toughness, thermal stability, gas barrier properties,and e

17、lectrical and thermal conductivity, can be achieved by the incorporation of a few weight percentages of particulate fillers into polymer matrices.On the basis of these advantages of nanocomposites,many excellent studies have been reported on the preparation and properties of PLA nanocomposites.PLA/l

18、ayered silicate nanocomposites have been extensively studied, including some reviews.1214 PLA nanocomposites incorporating hydroxyapatite,carbon nanotubes, calcium carbonate, and titanium dioxide have also been reported.1518 Thecrystallinity, thermal stability and mechanical, gasbarrier,degradation,

19、 and flame-retardant properties of PLA have been greatly improved. Unfortunately,some original properties, such as optical transparency,were lost in these prepared nanocomposites.Fumed silica (SiO2) has also been widely used as a nano-filler the preparation of polymer/SiO2 nanocomposites.1921 It pos

20、sesses advantages of a light mass, low price, rich resource, high strength and modulus, and good thermal stability; more importantly,it has almost the same refractive index as PLA, so it is believed that the outstanding properties are obtained by the preparation of PLA/SiO2 nanocomposites.To this po

21、int, few studies on PLA/SiO2nanocomposites have been reported. Yan et al.22 prepared PLA/SiO2 nanocomposites via two steps: the grafting of L-lactic acid oligomer onto the surface of SiO2 followed melt blending with PLA. The resultingnanocomposites had improved mechanical properties.Subsequently, th

22、e same research group,23 in another study, successfully synthesized plasticizedPLA/SiO2 nanocomposite materials by a solgel process.Recently, Wu et al.24 prepared PLA/SiO2 nano-composites (PLASNs) by the in situ melt polycondensation of L-lactic acid in the presence of acidic SiO2 sol and improved t

23、he dispersion of SiO2 nanoparticles in the final nanocomposites. These methods were positive in improving the performance of PLA, but they often resulted in extra cost and the use of a toxic organic solvent, which is undesired with regard to environmental concerns.When one considers the processing t

24、echnology and cost for preparing PLASNs, direct melt compounding based on commercial raw materials is a more applicable and economical compared with solution blending, solgel processes, and so on. To the best of our knowledge, no detailed investigation on PLASNs has been reported hitherto by this co

25、nvenient method. In this study, PLASNs were prepared by melt compounding in a Haake (Karlsruhe, Germany) mixer. The interaction between PLA and SiO2 was studied by Fourier transform infrared (FTIR) spectroscopy. The effects of SiO2 loading on the phase morphology, microstructure, and thermal and mec

26、hanical properties of the nanocomposites were studied through scanning electron microscopy (SEM), differential scanning calorimetry (DSC),dynamic mechanical analysis (DMA), and mechanical tests. In addition, the dependence of the opticaltransparency on the SiO2 content for the nanocomposites was als

27、o investigated.在过去的几年中，纳米复合材料中的一种新型热塑性塑料引起了聚合物学术界和产业界的研究人员的极大兴趣。作为填充物分散在纳米复合材料中的最好状态是纳米尺寸，（1-100 nm）的几个纳米。由于小粒径和极高的比表面积，纳米粒子聚合成团创建了一个界面，形成大量矩阵，改变了分子间相互作用。因此，可以通过在聚合物中按一定百分比添加填充物来显著改善机械和物理性能，包括刚度和韧性，热稳定性，气体阻隔性能，导电性和导热性。在纳米复合材料的这些优势基础上，关于PLA的许多成功的研究已经被报道。聚乳酸/层状硅酸盐纳米复合材料已得到广泛研究，还包括PLA纳米复合材料结合羟基磷灰石，碳纳米管

28、，碳酸钙的评论，二氧化钛也有报道。制备的PLA的结晶度，热稳定性，机械性能，气体阻隔性，阻燃性能得到极大改善。然而，PLA原有的一些性能，如光学透明性则被减弱。气相二氧化硅（SiO2）也被广泛用作制备纳米复合材料中的纳米填料。它拥有轻质量，价格低，资源丰富，强度和模量高，热稳定性好的优势，更重要的是它具有与PLA几乎相同的折射率，所以人们认为通过制备PLA/SiO2纳米复合材料能得到需要的具有优异性能的材料。对于这点，很少有关于PLA/SiO2纳米复合材料的报道。Yan et等通过2步法制备PLA/SiO2纳米复合材料：熔融PLA后在SiO2表面对L-乳酸低聚物接枝。制备产物性能有所改善。随后

29、，同一研究小组在另一项研究中，采用溶胶凝胶法成功地合成PLA/SiO2纳米复合材料。最近，吴等通过在酸性溶胶中进行L-乳酸的缩聚制备PLA/SiO2纳米复合材料，改善了纳米SiO2纳米复合材料分散度。这些方法能有效改善PLA的性能，但会导致成本的增加和有毒有机溶剂的使用，而这会危害到环境。当人们考虑到制备PLASN的加工技术和成本时，处于商业原因，直接熔融混炼比溶液共混，溶胶凝胶法，等等方法更适用且经济。据我们所知，迄今还没有关于通过这种方法制备PLASN的详细的调查报告。在这项研究中，采用熔融法在哈克（卡尔斯鲁厄，德国）混频器混炼制备PLASNs。通过傅里叶变换红外光谱（FTIR）研究了PL

30、A和SiO2之间的相互作用。通过扫描电子显微镜（SEM），差示扫描量热法（DSC），动态力学分析（DMA）和机械试验对PLA/SiO2纳米复合材料的热性能和力学性能的影响，二氧化硅含量对透明度的影响进行了研究。EXPERIMENTALMaterialsThe PLA (4032D) used in this study was a commercial product of Natureworks Co., Ltd. (USA), and had a high optical purity of about 98% L-lactide content. It exhibited a densi

31、ty of 1.24 g/cm3, a weightaverage molecular weight of 250 kDa, a polydispersity of 1.70 (gel permeation chromatography analysis), and a glass-transition temperature (Tg) andmelting temperature (Tm) of 60.48 and 166.40_C(DSC analysis), respectively. The nanosilica (Aerosil 200) was supplied by Deguss

32、a AG (Hanau, Germany). It was hydrophilic pyrogenic SiO2 with a specific surface area of 200 m2/g (99.8% SiO2). The SiO2 nanoparticles were aggregates and had an average primary particle size of 12 nm.本实验中使用的是美国Natureworks公司出产的约含98%乳酸的高光学纯度产品。密度1.24公克立方公分，重量平均分子量为250 kDa，一分散度1.70（凝胶渗透色谱分析），和玻璃化转变温度（Tg）及熔化温度分别为60.48和166.40（DSC分析）。纳米二氧化硅（Aerosil200）购自德固赛股份公司（Hanau，德国）。比表面积为200 m2/g。纳米SiO2的平均粒度约为12nmPreparation of the nanocompositesPLA was mechanically mixed with nanosilica from 1 to 10 wt %. Before blending, PLA and nanosilica were dried in vacuo at 90 and 110_C for 24 h, respectiv