纤维素-聚乳酸共混改性膜材料的性能与制备

聚乳酸纤维是来自天然的可再生原料,具有可持续发展和环境保护的特点,与其他天然纤维相比,PLA纤维是唯一能够熔融加工的生物降解纤维。本文主要介绍了纤维素-聚乳酸混合制备改性膜材料。通过性能分析,认为该膜的断裂伸长率会增加,透光性变化不显著。     

丝素/羧甲基壳聚糖共混膜的结构与性能

利用丝素(SF)与羧甲基壳聚糖(CMCS)共混制取不同比例的SF/CMCS共混膜。研究了CMCS诱导的丝素构象转变行为,测试了共混膜的吸湿性、透湿性和保水性。当CMCS的质量分数为5%时,共混膜中丝素的构象以β-折叠为主;当CMCS的质量分数为10%时,共混膜中丝素的构象由β-折叠向α-螺旋发生转变;当CMCS的质量分数达到15%时,共混膜中丝素的构象向无规卷曲发生转变。当CMCS质量分数小于15%时,共混膜中SF与CMCS具有良好的相容性,溶胀度较小,吸湿性随CMCS含量的增加而迅速降低。     

聚乳酸/碳纳米管共混纤维的制备及其性能研究

将聚乳酸(PLA)切片与硝酸处理过的多壁碳纳米管(MWNTs)按质量比19∶1混合制成PLA/MWNTs母粒,再将PLA切片与母粒按不同比例共混熔融纺丝制得PLA/MWNTs共混纤维,研究了不同工艺条件下纤维的力学性能和抗静电性能。结果表明:添加MWNTs质量分数小于0.8%时,可纺性良好,质量分数达到1.0%时,可纺性变差;最佳工艺条件为纺丝温度194.5℃,纺丝速度875 m/min,拉伸温度80℃;PLA/MWNTs共混纤维的抗静电性随着MWNTs含量的增加而递增,当MWNTs质量分数为0.8%,PLA/MWNTs共混纤维的比电阻为6.55×108Ω·cm,摩擦静电压935 V,衰减静电压672 V。     

静电纺丝PLA/丝素复合纤维膜的结构和性能

以氯仿、丙酮为混合溶剂,制得质量分数为5%的聚乳酸(PLA)纺丝液,经静电纺丝制备PLA纤维膜;以98%的甲酸为溶剂,制得丝素纺丝液,在PLA纤维膜上喷射丝素纺丝液制成PLA/丝素复合纤维膜.采用扫描电镜观察其形貌结构,并测定其微细结构、力学性能、溶失率及生物性能.结果表明:PLA/丝素复合纤维膜呈规整排列的多孔网状结构.与丝素膜相比,PLA/丝素复合纤维膜的丝素蛋白转向β折叠结构,断裂比功提高18倍,水中溶失率降低3倍,更有利于人脐静脉内皮细胞在纤维膜上的生长.     

丝素/聚乳酸静电纺丝的研究

以具有一定生物活性、细胞黏附性能好的丝素蛋白与降解性能优良的聚乳酸复合,以静电纺丝方法形成20%丝素与80%聚乳酸的丝素/聚乳酸共混纤维非织造网。通过扫描电子显微镜研究其形态,X-射线衍射、红外光谱等分析研究其聚集态结构变化。研究表明:丝素/聚乳酸静电纺的纤维直径与电压、接收距离大小和后处理方法有关;不同后处理方法对丝素/聚乳酸静电纺纤维的结晶结构有较大影响。     

聚乳酸共混膜的制备与表征

以聚乳酸(PLA)为膜基材、动物油或植物油为添加剂、二氯甲烷为溶剂,通过流延法制备聚乳酸共混膜。考察添加剂种类、添加剂与PLA的质量比对膜的表面结构与相关性能的影响。结果表明:制备的聚乳酸共混膜具有"海岛"结构;随着添加剂与PLA质量比值的增大,共混膜的"岛径"、接触角、弹性模量、渗析系数和铵根离子的累积渗透量均呈现有规律性的变化,具有良好的可调节性,在包膜缓控释肥料领域具有发展潜力。     

丝素/羧甲基壳聚糖共混膜的结构性能探讨

将含有甘油和戊二醛的丝素与羧甲基壳聚糖按一定比例混合,制得丝素/羧甲基壳聚糖共混膜,对共混膜的结构与性能进行了探讨。结果表明:随着羧甲基壳聚糖含量的增加,共混膜的透气率增大,加入交联剂戊二醛有效地改善了共混膜的力学性能,但其透气率有所降低;当丝素与羧甲基壳聚糖的质量比为4/1时,共混膜的断裂强度最大,力学性能较好,共混膜相容性较好,其断面光滑、致密。制备丝素/羧甲基壳聚糖共混膜的较佳条件为:丝素中的甘油质量分数为15%,戊二醛质量分数为0.075%,丝素与羧甲基壳聚糖质量比为4/1。     

GMA接枝聚乳酸对聚乳酸/淀粉共混物性能的影响

首先制备了聚乳酸与甲基丙烯酸缩水甘油酯(GMA)的接枝共聚物(PLA-g-GMA)和丁二酸酐功能化改性淀粉,并利用红外光谱和核磁共振谱对二者的结构进行了表征。进一步通过熔融共混法制备了聚乳酸(PLA)/改性淀粉/PLA-g-GMA三元共混物,并利用转矩流变仪、扫描电子显微镜、差示扫描量热仪和万能拉力试验机等手段研究了接枝物对共混物的流变性能、形貌结构、热性能以及力学性能的影响。结果表明,PLA-g-GMA的加入促进了淀粉在PLA基体中的分布,淀粉粒径最小在0.5μm以下;同时也抑制了PLA的热降解,提高材料的力学性能,尤其是断裂伸长率,最高达到260%;另外也抑制了PLA的结晶。     

丁苯橡胶/聚乳酸共混可降解橡胶的制备及其性能研究

本文通过丁苯橡胶(SBR)与聚乳酸(PLA)熔融共混制备了具有可降解性的SBR/PLA共混橡胶,采用X射线衍射(XRD)与扫描电子显微镜(SEM)对水解前后的SBR/PLA共混橡胶晶体结构与微观形貌进行了表征;研究了SBR与PLA共混比例对SBR/PLA共混橡胶硫化特性、力学性能和降解性能的影响。结果表明:PLA颗粒能较为均匀地分散在SBR基体中,碱性条件下SBR/PLA共混橡胶具有一定的可降解特性。PLA的加入能提高SBR/PLA共混橡胶的降解度,当PLA含量为30 g时,SBR/PLA共混橡胶的力学性能较好,降解程度可达到17.16%。     

贻贝启发蒙脱石-银/聚乳酸抗菌膜的制备及其性能

受自然界贻贝粘附现象的启发,将聚多巴胺(PDA)作为二次反应平台,绿色合成了一种纳米银(Ag NPs)负载蒙脱石(MMT-Ag NPs)复合抗菌颗粒,通过溶剂挥发法将聚乳酸(PLA)和MMT-AgNPs共混,制备了复合抗菌膜(PLA/PDA/MMT-AgNPs)。利用FTIR、XRD、TEM和TGA对MMT-Ag NPs的物质组成、物相结构、微观形貌、热稳定性进行了测定。对所制备的PLA/PDA/MMT-AgNPs复合抗菌膜的微观形貌、物理性能和抗微生物活性进行了考察。结果表明:PDA成功地对MMT进行了改性,PDA改性的MMT仍保持原来的物相结构,Ag NPs在MMT表面成功负载,负载的质量分数达到12.2%。PLA/PDA/MMT-AgNPs复合抗菌膜的拉伸强度显著增强,与PLA膜相比最高增长了32.6%。由于Ag NPs极强的抗菌作用,仅添加少量MMT-Ag NPs的复合抗菌膜就对大肠杆菌和金黄色葡萄球菌表现出了优异的抗菌作用,抑菌率均达到了95%以上。     

Metal ion permeation properties of silk fibroin/chitosan blend membranes

Silk fibroin/chitosan (SF/CS) blend membranes were prepared and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy. It was found that SF and CS were compatible in the blend membranes and that the membranes were dense without microscopic phase separation. Swelling experiments showed that the swelling ratio of the blend membranes increased with CS content and reached the highest value when CS content was 70 wt%. Experiments indicated that the permeability coefficient of K⁺ through the blend membrane was 2–4 times higher than that of pure CS membrane, and 10 times higher than that of pure SF membrane. The permeation rate of K⁺ increased linearly with CS content in the blend membrane for the lower concentration feeding solution. For different metal ions, the permeability through SF/CS blend membranes was in the sequence K⁺ > Ca²⁺ > Cd²⁺ > Pb²⁺ > Cu²⁺ > Ni²⁺. Copyright © 2006 Society of Chemical Industry     

Production of silk sericin/silk fibroin blend nanofibers

Silk sericin (SS)/silk fibroin (SF) blend nanofibers have been produced by electrospinning in a binary SS/SF trifluoroacetic acid (TFA) solution system, which was prepared by mixing 20 wt.% SS TFA solution and 10 wt.% SF TFA solution to give different compositions. The diameters of the SS/SF nanofibers ranged from 33 to 837 nm, and they showed a round cross section. The surface of the SS/SF nanofibers was smooth, and the fibers possessed a bead-free structure. The average diameters of the SS/SF (75/25, 50/50, and 25/75) blend nanofibers were much thicker than that of SS and SF nanofibers. The SS/SF (100/0, 75/25, and 50/50) blend nanofibers were easily dissolved in water, while the SS/SF (25/75 and 0/100) blend nanofibers could not be completely dissolved in water. The SS/SF blend nanofibers could not be completely dissolved in methanol. The SS/SF blend nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and differential thermal analysis. FTIR showed that the SS/SF blend nanofibers possessed a random coil conformation and ß-sheet structure.     

Physical properties of silk fibroin/chitosan blend films

Silk fibroin/chitosan blend films were examined through IR spectroscopy to determine the conformational changes of silk fibroin. The effects of the fibroin/chitosan blend ratios (chitosan content) on the physical and mechanical properties were investigated to discover the feasibility of using these films as biomedical materials such as artificial skin and wound dressing. The mechanical properties of the blend films containing 10–40% chitosan were found to be excellent. The tensile strength, breaking elongation, and Young's modulus were affected by the chitosan contents of the blend films, which were also related to the density and degree of swelling. The coefficient of water vapor permeability of the blend films increased linearly with the chitosan content, and the values of 1000–2000 g m^?2 day^?1 were comparable to those of commercial wound dressings. Silk fibroin/chitosan blend films had good oxygen and water vapor permeabilities, making them useful as biomaterials. In particular, the blend film containing 40–50% chitosan showed very high oxygen permeability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 928–934, 2001     

纳米二氧化钛/丝素复合膜的制备及其光催化甲基橙的研究

制备了纳米二氧化钛/丝素复合膜,并用原子力显微镜、X射线能谱和红外光谱对复合膜进行了表征,以甲基橙为例,考察了复合膜的光催化行为。结果表明复合膜制备方法合理,当纳米二氧化钛与丝素质量比为0.1%时,其以粒径50nm左右均匀分散于复合膜中,复合膜与普通丝素膜仅存在细微的构象差异,复合膜表现出较优异的光催化性能,甲基橙降解率可达91%,符合Langmuir Himshelwood模型。     

Structural and physical properties of silk fibroin/alginate blend sponges

Silk fibroin/alginate blend sponges were examined through IR spectroscopy, X‐ray diffractometry, and differential scanning calorimetry to determine the structural changes of silk fibroin. The effects of fibroin/alginate blend ratios on the physical and mechanical properties were investigated to discover the feasibility of using these blend sponges as biomedical materials such as wound dressings. The compressive modulus of silk fibroin was increased up to 30 kPa, from 7.1 kPa, by blending with alginate. Thermal crystallization behavior of fibroin induced by heat treatment was restricted by blending with alginate. In spite of that, the structural characteristics of fibroin were not changed by incorporation with alginate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2174–2179, 2004     

Structure and physical properties of silk fibroin/polyacrylamide blend films

This article deals with the characterization of blend films obtained by mixing silk fibroin (SF) and polyacrylamide (PAAm). The DSC curves of SF/PAAm blend films showed overlapping of the main thermal transitions characteristic of the individual polymers. The exothermic peak at 218°C, assigned to the β‐sheet crystallization of silk fibroin, slightly shifted to a lower temperature by blending. The weight‐retention properties (TG) of the blend films were intermediate between those of the two constituents. The TMA response was indicative of a higher thermal stability of the blend films, even at low PAAm content (≤25%), the final breaking occurring at about 300°C (100°C higher than pure SF film). The peak of dynamic loss modulus of silk fibroin at 193°C gradually shifted to lower temperature in the blend films, suggesting an enhancement of the molecular motion of the fibroin chains induced by the presence of PAAm. Changes in the NH stretching region of silk fibroin were detected by FTIR analysis of blend films. These are attributable to disturbance of the hydrogen bond pattern of silk fibroin and formation of new hydrogen bonds with PAAm. The values of strength and elongation at break of blend films slightly improved at 20–25% PAAm content. A sea–island structure was observed by examining the air surface of the blend films by scanning electron microscopy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1563–1571, 1999     

Preparation of nanosize cadmium sulfide particles with a silk fibroin membrane and their photocatalytic activity

We present a novel method for the synthesis of nanosize CdS particles with a silk fibroin membrane, which were characterized with UV spectrometry, X‐ray diffraction (XRD), and atomic force microscopy. The UV spectra showed a clear blueshift in the absorption edge for the CdS particles prepared at different concentrations. XRD showed the prevailing crystal were the cube ZnS crystals formed. The particle sizes were calculated from the band gaps with the effective mass approximate model, suggesting that they were dependent on the concentration of the precursors. Meanwhile, nanosize CdS had good photocatalytic activity throughout the photocatalytic degradation experiments. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2162–2166, 2006     

新型丝素复合膜的微结构表征及热稳定性

基于丝素的高分子复合材料可以广泛地应用于组织工程、生物医药和半导体材料等领域。通过物理-共混技术制备了一种新型生物高分子丝素/聚乳酸复合膜。利用扫描电镜、傅里叶红外光谱、拉曼光谱、X射线衍射和热分析技术对其形貌、结构和相态组分以及热稳定性进行了表征,探究了不同比例复合膜的微结构、相互作用机理和热稳定性。结果表明：随着丝素含量的增加,复合膜中的β-折叠含量增多,α-螺旋和无规卷曲含量减少,玻璃化转变温度提高;由于丝素与聚乳酸间的相互作用,提高了复合膜的热稳定性。     

Study on the properties of the electrospun silk fibroin/gelatin blend nanofibers for scaffolds

Silk fibroin (SF)/gelatin blend nanofibers membranes as scaffolds were fabricated successfully via electrospinning with different composition ratios in formic acid. The formation of intermolecular hydrogen bonds and the conformational transition of SF provided scaffolds with excellent mechanical properties. FTIR and DTA analysis showed the SF/gelatin nanofibers had more β‐sheet structures than the pure SF nanofibers. The former's breaking tenacity increased from 0.95 up to 1.60 MPa, strain at break was 7.6%, average fiber diameter was 89.2 nm, porosity was 87%, and pore diameter was 142 nm. MTT, H&E stain, and SEM results showed that the adhesion, spreading, and proliferation of human umbilic vein endothelium cells (HUVECs) and mouse fibroblasts on the SF/gelatin nanofibers scaffolds were definitely better than that on the SF nanofibers scaffolds. The scaffolds could replace the natural ECM proteins, support long‐term cell growth, form three‐dimensional networks of the nanofibrous structure, and grow in the direction of fiber orientation. Our results prove that the addition of gelatin improved the mechanical and biological properties of the pure SF nanofibers, these SF/gelatin blend nanofiber membranes are desirable for the scaffolds and may be a good candidate for blood vessel engineering scaffolds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009