细菌纤维素/肝素复合物的制备与力学性能

采用浸泡和交联法将肝素(Hep)固定在细菌纤维素(BC)上,研究了BC/Hep复合物的结构与力学性能。傅立叶变换红外光谱结果表明,BC结构中出现了Hep的特征吸收峰;扫描电子显微镜和X射线衍射显示,浸泡或交联后,在Hep的作用下,BC的结构变得紧密,结晶度下降,晶粒尺寸增大,其中交联法制备的复合物的结构与结晶性能变化更为明显。拉伸性能实验表明,与纯BC相比,浸泡和交联制备的BC/Hep复合物力学性能增强,交联法制备的复合物力学性能优于浸泡法,Hep溶液浓度为1.5 g/100 m L时其拉伸强度最大,可达到177.82 MPa,与纯BC相比提高了76.3%。     

细菌纤维素增强改性聚碳酸亚丙酯复合材料的制备及性能

将细菌纤维素(BC)作为增强材料加入聚碳酸亚丙酯(PPC)基体中,采用溶液浇铸法制备了PPC/BC复合薄膜材料,研究了BC用量对PPC拉伸性能、热稳定性能及降解性能的影响。结果表明:随着BC用量的增加,PPC/BC复合薄膜的拉伸强度和热稳定性能明显提高,降解速率减慢。     

离子液体法制备再生细菌纤维素纤维

以离子液体(氯化1-甲基-3-正丁基咪唑)溶解高聚合度细菌纤维素(BC),采用湿法纺丝制备再生细菌纤维素(RBC)初生纤维;通过红外光谱分析(FTIR)、广角X射线衍射(WAXD)分析、热失重(TG)分析、扫描电镜( SEM)、单丝强度拉伸等表征了RBC初生纤维的结构和性能.结果表明:该溶剂体系通过10 h的快速搅拌溶...     

G31产细菌纤维素结构表征及其面膜性能测试

以葡糖醋杆菌G31为菌种,用HS培养基发酵制备细菌纤维素(BC),产物湿重产率为320.1 g/L。利用蒽酮比色法、酶水解法初步证明发酵产物为纤维素,采用FTIR、SEM、XRD、CP/MAS 13CNMR、DSC和TG对其结构进行了表征并测试了其性能。结果表明:发酵产物具有超细三维网状结构,属于结晶度为92.42%的纤维素Ⅰ型,具有良好的持水性和拉伸性。分子质量测定结果显示:Mw=5737,属于低相对分子质量BC,其氧气透过率和水蒸气透过率分别为913.55?3.23 cm3/(m2?d?0.1 MPa)和656.15?3.92 g/(m2?d),表明该BC具有更好的锁水能力,为其在面膜领域的应用奠定了基础。     

木醋杆菌生物合成CMC改性细菌纤维素

以椰子水为培养基,添加羧甲基纤维素(Carboxymethyl cellulose, CMC)可制备羧甲基纤维素改性细菌纤维素(CMC-BC)。CMC可促进产物产量：当CMC添加量为0.6% (w/v%)时,产量达到最大（11.41mg/ml）,是纯BC产量(4.73 mg/ml)的2.2倍。采用红外（FT-IR）表征了产物结构,1598cm-1处的吸收峰说明CMC进入了BC中;通过SEM、XRD、TGA研究了产物的微观形态及其性能;并测试了产物的特性粘度与羧甲基化程度。结果显示利用椰子水所制备的CMC-BC缩短了培养时间,增大了产量;并且在CMC添加量较少(0.2-1.8%)时,可改善CMC-BC的性能。     

微晶纤维素增强羟丙基淀粉复合薄膜的性能研究

采用溶液浇铸法制备微晶纤维素(MCC)/羟丙基淀粉(HPS)复合薄膜,探讨不同含量的微晶纤维素对MCC/HPS复合薄膜性能的影响。借助于扫描电子显微镜(SEM)、热重分析(TGA)、万能材料试验机等测试手段对复合薄膜的形貌结构进行表征,并对其热稳定性能、力学性能和水蒸气透过性能进行测试。结果表明,随着MCC含量的增加,复合薄膜的热稳定性能获得改善,拉伸强度先增大后下降,并降低其水蒸气透过性能。当MCC的质量分数为6%时,MCC/HPS复合薄膜的拉伸强度比纯HPS薄膜提高了300%。由此可见,MCC的添加有助于拓宽羟丙基淀粉在包装复合薄膜中的应用范围。     

一种降低细菌纤维素分子量的方法

以实验室自行筛选的木醋杆菌(Acetobacter xylinum)为菌种,海南椰子水为主要培养体系,在生物合成过程中向培养基中添加半乳糖醛酸,采用静态培养方法制备了细菌纤维素(BC),对BC的结构和性能进行了研究;结果表明:添加半乳糖醛酸后,BC的产率、持水性能及热稳定性有所下降,而结构特征和结晶性能与不添加半乳糖醛酸的BC差别不大;但产物衍生化后的分子量却降低很大,约10万左右;有望用半乳糖醛酸代替蔗糖为碳源生产低分子量的细菌纤维素。     

聚乳酸/细菌纤维素复合材料制备研究

采用溶液浇铸的方法制备了聚乳酸／细菌纤维素（PLA／BC）复合膜,研究了不同用量的BC对PLA力学性能的影响。将制备的薄膜置于模拟体液与磷酸盐缓冲稀释液中做降解实验,考察了BC对PLA降解性能的影响。结果表明：随着BC用量的增加,改性PLA的断裂伸长率、拉伸强度明显提高,降解速率加快。     

纳米纤维/氧化淀粉/PVA复合膜制备及特性

以甘蔗渣为原料,采用硫酸水解法制备甘蔗渣纳米纤维素。以氧化淀粉(OS)和聚乙烯醇(PVA)为基材,添加甘蔗渣纳米纤维素、增塑剂甘油、交联剂乙二醛制备复合膜。以拉伸强度、断裂伸长率、水蒸气透过率和水溶率为测量指标,研究了甘油、乙二醛、纳米纤维添加量对膜特性的影响。结果表明,随着甘油含量增大,复合膜的水溶率和水蒸气透过率逐渐增大,拉伸强度逐渐降低;添加乙二醛能够提高复合膜的耐水性能,添加量为0. 15 m L/g时,拉伸强度达到最大值(6. 25±0. 16) MPa;适当添加甘蔗渣纳米纤维素增强复合膜的机械性能和耐水性能,当纳米纤维含量为20%时,复合膜的水蒸气透过率达到最小值,为(5. 349±0. 056)×10~(-7)g/(m·h·Pa)。     

添加海藻酸钠对椰子水体系合成细菌纤维素的影响

以椰子水为培养体系,向培养基中添加海藻酸钠,利用木醋杆菌(Ax.)静态培养合成细菌纤维素(BC)。研究发现,培养体系中添加少量海藻酸钠,能显著提高产物的产量,添加量为4 g/L时,产量最大(8.35 g/L),是其他条件相同情况下不添加海藻酸钠时BC产量(3.47 g/L)的2.4倍。采用FTIR、XRD、TGA、SEM对产物进行了表征;并测试了产物的含水率及力学性能。结果表明,海藻酸钠的添加,对产物化学结构无改变,但一定程度降低了细菌纤维素结晶指数;降低了产物含水率和产物干膜的拉伸强度及断裂伸长率。     

Influence of processing condition and HA content on the crystallization behavior of HA‐filled EVA biocomposite

Hydroxyapatite/ethylene‐vinyl acetate (HA/EVA) composites with a HA content of 30 and 50 wt% were prepared by injection molding. The crystallization behaviors of EVA under different injection pressure, annealing temperature, and HA content were investigated. Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscope were used to evaluate the composites. The result of FTIR analysis infers the occurrence of hydrogen bonding between HA and EVA. XRD and DSC analyses show that the increasing injection pressure can accelerate the crystallization rate of EVA but it tends to decrease the crystallization degree slightly, which may be caused by the increase of EVA segmental activity and the loss of EVA crystallization order with the increase of pressure. The EVA crystallization degree can be improved by the annealing process. It is found that HA can induce more nucleation sites of EVA, but the crystallization degree of EVA decreases with the increase of HA content. The large content of HA acts to reduce the mobility of EVA crystallizable chain segments and inhibits the crystal growth of EVA. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Synthesis and properties of HA/ZnO/CNT nanocomposite

The goal of this study was to examine the tribomechanical properties of hydroxyapatite (HA)/ZnO and HA/ZnO/CNT composite ceramics (carbon nanotubes; with different ratios 0.5?wt%, 1.0?wt%, and 1.5?wt%). The composites were synthesized using the hydrothermal method in an autoclave. The structure and morphology of the composites were analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and transmission electron microscope (TEM). The consolidation process was performed by sintering the compounds at 1150?°C under an argon gas atmosphere. The effects of ZnO and CNT on the mechanical properties and wear resistance of the HA-nanoparticle-based ceramic composites were investigated using a Vickers hardness tester, nanoindentation, and reciprocating wear tester equipment. The nanohardness and elastic modulus of the sintered samples increased and the friction coefficient of the sintered samples decreased as the fraction of CNTs increased compared to the pure HA and HA/ZnO compounds. Furthermore, the wear loss of HA/ZnO/CNT composites decreased with the increase in the CNT content compared to the HA and HA/ZnO samples.     

A new biodegradable blends prepared from polylactide and hyaluronic acid

In this article, the biodegradable polylactide/hyaluronic acid (PLA/HA) composites were prepared by a melt blending method. In addition, the acrylic acid grafted polylactide (PLA-g-AA) was studied as an alternative to PLA. The samples were characterized by a fourier transform infrared (FTIR) spectroscopy, a nuclear magnetic resonance (NMR), a differential scanning calorimetry (DSC), an Instron mechanical tester, and a scanning electron microscopy (SEM). As the result, due to the poor compatibility between PLA and HA, the mechanical properties of PLA/HA composites were worse than PLA. Much better dispersion and homogeneity of HA in the polymer matrix could be obtained when PLA-g-AA was used in place of PLA in the composite. The PLA-g-AA/HA composites could obviously improve the mechanical properties of PLA/HA ones, and the former provided a plateau tensile strength at break when the HA content was up to 20 wt%. Furthermore, the PLA-g-AA/HA was more easily processed than the PLA/HA because the former had lower viscosity than the latter, as they were molten. Biodegradation tests of blends were also studied under the enzymatic environment, and the result showed that the mass of blends reduced by about the HA content within 4 weeks.     

遥爪聚异丁烯的合成

<正>1引言遥爪聚异丁烯的制备生要有2种方法,即聚合物降解法和链引发转移剂法（Inifer）。通过Inifer技术,可以得到末端带有叔氯的遥爪聚异丁烯’“,再由氯端基经有机反应转化为带有不同官能团的遥爪聚异丁烯,如C一C—[2]、羟基[3,4]、浚基”‘和苯基”’等。 Kennedy等“”‘研究表明,采用双端或三端引发剂,可得官能度凡。 2或 3土 0．二的遥爪聚异丁烯。武冠英等”‘研究探讨了合成端氯基遥爪聚异丁烯过程中的环化反应和链转移反应。本文选用双端直链烷烃叔酯为引发剂,三氯化硼为共引发剂,于CHzCI。中合成线性叔氯遥爪聚异丁烯。     

竹炭的改性及对PP废塑料性能影响的研究

首先用硅烷偶联剂γ-氨丙基三乙氧基硅烷(KH550)处理竹炭(BC)得到K-BC,再通过熔融共混制备了一系列的K-BC/聚丙烯废洗衣机料(X-PP)复合材料,通过扫描电子显微镜(SEM)表征了BC的形貌,分析了K-BC含量对复合材料物理性能、尺寸稳定性、热变形温度(HDT)及维卡软化温度(VST)的影响.结果发现,BC...     

A potential trackable bone filler: Preparation and characterization

This study reported the synthesis of fluorescent hydroxyapatite/alginate/carbon quantum dots (HA/Alg/CQDs) nanocomposites via the co-precipitation technique. The N-doped CQDs as a new class of fluorescent materials were prepared by the citric acid pyrolysis method, with an average size around 4 nm. Physical, chemical, and optical properties of the synthesized nanocomposites were investigated by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), UV–visible spectroscopy, and photoluminescence (PL) spectroscopy, respectively. The PL spectroscopy data verified the favorable in vitro luminescent emission of the HA/Alg/CQDs nanocomposites in comparison with HA/Alg and HA samples. The XRD patterns of the prepared samples confirmed the formation of crystalline HA in all composites, possessing a Ca/P ratio around 1.5 as obtained by EDX elemental analysis. The FESEM analysis exhibited HA nanoplates that homogeneously distributed throughout the alginate matrix. Therefore, the synthesized nanocomposites could be regarded as potential trackable drug carriers for hard tissue engineering applications.     

Bacterial cellulose/collagen composite: Characterization and first evaluation of cytocompatibility

The novel bacterial cellulose (BC)/collagen composites were prepared by immersing wet BC pellicle excreted by Acetobacter xylinum in collagen solution followed by freeze‐drying process. The product looks like a foam structure. The morphology of BC/collagen composite was examined by scanning electron microscope (SEM) and compared with pristine BC. SEM images showed that collagen molecules was not only coated on the BC fibrils surface but also could penetrate inside BC and hydrogen bond interactions were formed between BC and collagen. The prepared BC/collagen composite was also characterized by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and mechanical test. With the incorporation of collagen in the BC, no changes happened in the crystal structure but the thermal stability was improved. Tensile test results indicate that the Young's Modulus and tensile strength have a big increase while the elongation at break has a slight decrease. The cytocompatibility of composite was preliminarily evaluated by cell adhesion studies. The tests were carried out using 3T3 fibroblast cells. The cells incubated with BC/collagen scaffolds for 48 h were capable of forming cell adhesion and proliferation. It showed much better cytocompatibility than pure BC. So, the prepared BC/collagen scaffolds are bioactive and may be suitable for cell adhesion/attachment suggesting that these scaffolds can be used for wound dressing or tissue‐engineering scaffolds. Therefore, these results suggest that these novel BC/collagen scaffolds may have the potential to be sued for some biomedical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Hydroxyapatite nanoparticles (HA) reinforced polymer blend based on chlorinated nitrile rubber (Cl-NBR) and chlorinated ethylene propylene diene monomer rubber (Cl-EPDM) were prepared. Resulting blend composites were analyzed with regard to their rheometric processing, crystallinity, glass transition temperature (T_g), mechanical properties, oil resistance, AC conductivity, and transport behavior. The decrease in optimum cure time with the addition of HA is more advantageous for the development of products from these blend nanocomposites. The XRD, FTIR, and SEM confirmed the attachment and uniform dispersion of HA nanoparticles in the Cl-NBR/Cl-EPDM blend. The good compatibility between polymer blend and nanoparticles was also deduced by the formation of spherically shaped HA particles in the blend matrix determined by TEM analysis. DSC analysis showed an increase in T_g of the blend with the filler loading. The addition of HA particles to the blend produced a remarkable increase in tensile and tear strength, hardness, AC conductivity, abrasion, and oil resistance. The diffusion of blend composites was decreased with an increase in penetrant size. The diffusion mechanism was found to follow an anomalous trend. Among the blend composites, the sample with 7 phr of HA not only showed good oil and solvent resistance but also a remarkable increase in AC conductivity and mechanical properties.     

葡糖醋杆菌G31产细菌纤维素的结构表征及性能测试

以葡糖醋杆菌G31为菌种,用HS培养基发酵制备细菌纤维素（BC）。利用蒽酮比色法、酶水解法初步证明发酵产物为纤维素,采用FTIR、SEM、XRD、CP/MAS 13C-NMR、DSC和TG对BC的形貌和结构进行表征并对其进行性能测试。结果显示：发酵产物具有超细三维网状结构,属于结晶度为92.42%的纤维素Ⅰ型,具有良好的持水性和拉伸性。同时对其分子量进行测定,Mw为5737,属于低分子量BC,其氧气透过率和水蒸气透过率分别为913.55?3.23 cm3/m2?24h?0.1MPa和656.15?3.92 g/m2?24h,表明该BC具有更好的锁水能力,为其在面膜领域的应用奠定了基础。     

Amphiphilic PLGA-PEG-PLGA triblock copolymer nanogels varying in gelation temperature and modulus for the extended and controlled release of hyaluronic acid

Different compositional parameters of poly(_D,L-lactic-co-glycolic acid)-b-poly(ethylene glycol) triblock copolymers (PLGA-PEG) were varied to analyze their effect on gel formation and mechanical properties. Parameters such as hydrophilic/hydrophobic ratio (PLGA/PEG ratio), lactic acid/glycolic acid ratio (LA/GA ratio), PEG molecular weight (PEG Mw), polymer solution concentration, copolymer molecular weight (Mw), and polydispersity index (PDI) were studied in this work. For copolymers with PEG Mw of 1500 Da, gelation temperature (34–37 °C) was affected by _D,L-LA/GA ratio and Mw; while modulus was affected by LA/GA ratio, Mw, and Mn. Based on the parametric study, an injectable, thermoresponsive hyaluronic acid (HA) delivery platform was designed for ocular applications. PLGA-PEG copolymers with _D,L-LA/GA ratio of 15/1, PLGA/PEG ratio of 2/1, PEG Mw of 1500 Da, and Mw of about 6 KDa gelled at 35 °C, were optically transparent, had a modulus less than 350 Pa and were used for HA release studies. This work also demonstrates, for the first time, an extended and controlled release of HA, beyond 2 weeks, from injectable hydrogels modified with a noncovalent interacting agent, poly(L-lysine). Smaller PLL chains slowed down the HA release kinetics, while larger PLL chains produced a release profile similar to the nonmodified hydrogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48678.