Preparation, characterization, and in vitro evaluation of nanostructured chitosan/apatite and chitosan/Si-doped apatite composites

Chitosan/apatite (CHI/Ap) composites are attracting great attention as biomaterials for bone repair and regeneration procedures. The reason is their unique set of properties: bioactivity and osteoconductivity provided by Ap and resorbability supplied by CHI among others. Thus, in this study, CHI/Ap and CHI/Si-doped Ap composites were prepared and characterized. Particle size, surface area, in vitro physiological stability, enzymatic biodegradation, and bioactivity were evaluated. Unimodal particle size distribution was obtained for composites with high CHI/Ap ratios while bimodal distribution was present in composites with low CHI/Ap ratio. Physiological stability decreased with Si doping and with the CHI content. Acetylation degree and molecular weight of CHI did not affect in vitro stability. Rate of enzymatic degradation increased with the CHI content in composites. Si-doped Ap composites also showed increased degradation with respect to non-doped ones. The bioactivity of the composites was evidenced by the deposition on their surface of a calcium phosphate layer with Ap morphology after immersion in simulated body fluid. Both, biodegradation and bioactivity were dependent on the molecular weight of the polymeric CHI matrix. These results suggest that the CHI/Ap composites obtained are promising materials for bone regeneration applications.     

Processing and characterization of nanostructured Cu-carbon nanotube composites

Carbon nanotube (CNT) reinforced nanostructured Cu matrix composite with a grain size less than 25 nm has been successfully fabricated via a combination of ball milling and high-pressure torsion. CNTs were found to be homogeneously dispersed into the metal matrix, leading to grain refinement with a narrow grain size distribution and significant increase in hardness.     

聚苯乙烯/纳米金刚石复合微球的制备及性能测定

以纳米金刚石为乳化剂,BPO为引发剂,利用Pickering效应成功合成得到了聚苯乙烯/纳米金刚石复合微球.XRD、TDA-DTA、TEM、BET以及FT-IR分别进行了结构表征.研究结果表明,在聚苯乙烯/纳米金刚石复合微球中,纳米金刚石晶体为立方相,聚苯乙烯为无定形态,颗粒径粒大约为40～70nm,分散较好,比较面积达到230m2/g,该复合材料具有良好热稳定性.进一步的力学系性能测定表明,随着聚苯乙烯/纳米金刚石复合微球添加应用,聚苯乙烯的拉伸强度、断裂伸长率性能得到了明显地改善,但弯曲强度性能有所下降.     

高岭土/钛白复合粉体的制备与表征

借助粉体表面改性的原理及液相化学沉积的包覆工艺,以高岭士为核,利用四氯化钛水解在其表面包覆－层纳米二氧化钛制成高岭土复合钛白,并用TEM、XRD等手段进行了表征。结果表明：复合粉体包覆效果良好800℃煅烧后包覆层二氧化钛主要为锐钛矿型结构,并开始向金红石型转化。     

羟基磷灰石/聚己内酯-壳聚糖复合材料的制备与表征

为提高复合材料的力学性能和生物活性以聚己内酯(PCL) 、壳聚糖(CS) 、羟基磷灰石(HA)为原料,用Hakke流变仪挤出成型制备了不同 HA含量的HA/ PCL-CS复合材料,并对其进行了拉伸性能的测试,考察了复合材料浸渍于模拟体液(SBF)中的生物活性及其在生理盐水中的降解性能,用X射线衍射(XRD) 、傅里叶变换红外光谱(FTIR) 、扫描电镜(SEM) 、接触角测试仪对材料进行了表征。结果表明：复合材料的拉伸强度和断裂伸长率随 HA含量的增加而降低,而杨氏模量随 HA含量的增加而升高;亲水性能随着HA含量的增加而提高; HA/PCL-CS复合材料在模拟体液(SBF)中浸渍 14d后,在表面形成一层弱结晶的碳磷灰石(CHA)覆盖层 , 显示出良好的生物活性; PCL 的分子量随着降解时间的延长而降低,溶液pH值和质量损失率却增大,浸渍28d后,溶液pH值达到9. 54,失重率达到5.86%,显示出良好的生物可降解性。     

镁-羟基磷灰石/聚乳酸复合材料的制备及表征

为改善羟基磷灰石(HA)/聚乳酸(PLA)复合材料降解后产生的局部酸性环境,提出Mg-HA/PLA复合材料的新体系,采用溶液共混法结合注塑工艺获得Mg-HA/PLA复合材料。采用扫描电镜、X射线衍射仪分析复合材料的显微相貌及物相组成,电子拉伸试验机测试复合材料的力学性能,模拟体液浸泡分析其降解特性。结果表明,采用溶液共混结合注塑工艺可以制备该复合材料;HA与Mg在PLA基体中未出现明显的团聚;HA、Mg与PLA三者保持各自物相;与5%(质量分数)HA/PLA复合材料相比,1.5%(质量分数)Mg添加对5%(质量分数)HA/PLA复合材料的力学性能影响不明显;Mg-HA/PLA复合材料浸泡4周后的pH值为7.41,而HA/PLA复合材料则为6.95。     

Synthesis and nonlinear optical characterization of nanostructured gold/polymer composites and suspensions

Nanometric gold particles were synthesized by a liquid/liquid phase-transfer reaction. Composites of these particles were prepared by free-radical polymerization of suspensions of the particles in styr ene and methyl methacrylate monomer. Concentrations of 1.0, 1.3, and 4.4 mg/ml were prepared,with no noticeable agglomeration of particles during processing. These composites and toluene suspensions (0.18 mg/ml) showed a linear absorption peak at 530 nm, which is characteristic of nanosized gold. High-resolution electron microscopy measurement showed that the particle diameters varied from 5 to 10 nm. Degenerate four-wave mixing experiments at 532 nm yielded, on 10-micron films, a maximum value of 1.0 × 10⁻¹⁰ e.s.u. for the third-order nonlinear optical susceptibility. The toluene suspension had a susceptibility of 7.7 × 10⁻¹² e.s.u.     

EVA-g-PU/SBR/OMMT复合材料的制备与性能表征

采用熔融共混与熔融插层相结合的方法,制备了EVA-g-PU/SBR/OMMT复合材料.采用x-射线衍射仪(XRD)与透射电镜(TEM)研究了蒙脱土在聚合物基体中的分散状态,用电子万能试验机、摩擦磨损试验机测试了材料的力学性能及耐摩擦磨损性能,并通过扫面电镜分析了材料的磨损机理.结果表明,蒙脱土主要以插层型分布在聚合物基...     

碳纳米管/羟基磷灰石复合材料的制备及表征

以含钴介孔分子筛为催化剂、乙醇为碳源, 采用CVD法制备碳纳米管(CNTs)。通过原位合成法制备一系列不同碳纳米管含量的碳纳米管/羟基磷灰石(CNTs/HA)复合材料。分别采用XRD、FTIR、TEM、N₂吸附-脱附和Raman光谱等分析手段, 对所合成CNTs/HA复合材料的晶相、结构、形貌和比表面积等进行了表征。同时研究了碳纳米管的添加量对所合成CNTs/HA复合材料形貌的影响。XRD与Raman结果表明, 所得CNTs/HA复合粉体中仅有CNTs与HA两种物相, 纯度较高, 结晶度较好; TEM结果显示, CNTs/HA复合材料中CNTs表面均匀包裹着一层纳米级的针状HA晶粒, 两者形成了较强的界面结合, 且当CNTs与HA的质量比为3:17时, CNTs与HA形成最佳结合状态; N₂吸附-脱附表征结果表明, 与HA的比表面积相比, CNTs/HA复合材料具有较高比表面积。     

聚苯乙烯/纳米SiO2复合颗粒制备与表征

为改善二氧化硅(SiO2)纳米粒子与聚合物基体间的亲和性,使SiO2表面功能化,将硅烷偶联剂KH-570引入C=C基团,采用乳液聚合方法在纳米SiO2粒子表面接枝苯乙烯(St)单体,实现了纳米二氧化硅表面的聚苯乙烯(PS)高分子包覆改性,制备了具有核/壳结构的SiO2-PS复合纳米粒子,产物的单体转化率和接枝效率在80%以上.研究了二氧化硅含量和偶联剂用量对聚合反应的单体转化率和接枝效率的影响,探讨了偶联剂的作用机理,利用FT-IR、TEM、TG对SiO2-PS复合粒子的表面结构进行了表征.结果表明,复合粒子具有明显的核壳结构,壳层厚度在20nm左右,乳液聚合过程可有效使二氧化硅的团聚体剥离呈纳米级颗粒.     

一种细菌纤维素/姜黄素复合材料的制备及表征

采用原位吸附法，将细菌纤维素（Bacterial Cellulose，BC）浸渍在不同浓度的姜黄素乙醇溶液中，经超声震荡，使BC对姜黄素吸附饱和，获得不同浓度下的BC/姜黄素复合材料。采用SEM、FTIR、XRD及水接触角测量仪等对BC/姜黄素复合材料性能进行测试表征。测试结果表明，原位吸附法成功地将姜黄素固定在BC材料中，随着姜黄素乙醇溶液浓度的提高，BC中吸附姜黄素的量增加，同时将试样置于潮湿环境下，吸附姜黄素的试样具有抗霉变特性，是一种具有应用前景的包装材料或组织工程材料。     

Preparation and characterization of titanate nanotubes/carbon composites

Titanate nanotubes/carbon composites(TNT/CCs) were synthesized by allowing carbon-coated TiO₂ (CCT) powder to react with a dense aqueous solution of NaOH at 120 °C for a proper period of time. As-prepared CCT and TNT/CCs were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectrometry. The processes for formation of titanate nanotubes/carbon composites were discussed. It was found that the TiO₂ particles in TiO₂-carbon composite were enwrapped by a fine layer of carbon with a thickness of about 4 nm. This carbon layer functioned to inhibit the transformation from anatase TiO₂ to orthorhombic titanate. As a result, the anatase TiO₂ in CCT was incompletely transformed into orthorhombic titanate nanotubes upon 24 h of reaction in the dense and hot NaOH solution. When the carbon layers were gradually peeled off along with the formation of more orthorhombic titanate nanotubes at extended reaction durations (e.g., 72 h), anatase TiO₂ particles in CCT were completely transformed into orthorhombic titanate nanotubes, yielding TNT/CCs whose morphology was highly dependent on the reaction time and temperature.     

Preparation and characterization of dense nanohydroxyapatite/PLLA composites

Synthetic bone graft substitutes based on PLLA have been largely studied during the past decade. PLLA/hydroxyapatite composites appear as promising materials for large bone defect healing. In this study dense PLLA/nano-hydroxyapatite composites were prepared by hot pressing. Dense samples were investigated rather than porous scaffolds, in order to shed light on possible correlations between intrinsic mechanical properties and nano-hydroxyapatite concentration. Hydroxyapatite deagglomerated by wet attrition milling, and further dispersed into chloroform was used (median diameter = 80 nm). Particle size distribution measurements and transmission electron microscopy show evidence that particle size and dispersion are maintained throughout the successive steps of composite processing. Mechanical properties were tested (uni-axial and diametral compression tests) as a function of nano-hydroxyapatite content. Increasing concentrations of nano-hydroxyapatite (0, 25 and 50 wt.%) increase the Young's modulus and the mechanical strength of the composite; at the same time, the failure mechanism of the material changes from plastic to brittle. Young's modulus over 6 GPa and uniaxial compressive strength over 100 MPa have been achieved. These values expressed in terms of intrinsic tensile and shear strengths indicate that 50 wt.% nano-hydroxyapatite containing samples develop properties comparable to those of cortical bone. PLLA/nano-hydroxyapatite composites are thus promising candidates to develop bioresorbable porous bone substitutes showing superior mechanical performance.     

Preparation and characterization of conducting polycaprolactone/chitosan/polypyrrole composites

A novel processing method was developed to produce conducting polycaprolactone/chitosan/polypyrrole composite membranes. Results obtained from infrared and X-ray spectra as well as thermal dynamic measurements demonstrated that there were pronounced interactions between polycaprolactone and chitosan components, and composite membranes had partially miscible microstructures. It was found that some composite membranes showed conductivity transitions at a polypyrrole load of around 2 wt.%, and significantly enhanced conductivity for these composite membranes was already achieved in overall interval of polypyrrole loads compared to those membranes composed of a single component and polypyrrole particles. The tensile properties of composite membranes both in dry and wet state were examined, and the results revealed that the tensile mechanical properties of hydrated composite membranes could be well maintained if weight ratios of polycaprolactone to chitosan were selected as appropriate values.     

碳纤维-氧化石墨烯/环氧树脂复合材料的制备及表征

采用改进的Hummers法制备了五种具有不同氧化程度的氧化石墨烯（GO）。借助元素分析、X射线光电子能谱及FTIR红外光谱测试对所制备GO的组成及结构衍变进行了表征。利用光学显微镜对不同GO在固化剂异佛尔酮二胺（IPDA）中的分散状态进行观察,并将分散效果最佳的GO试样用于改性碳纤维/环氧树脂（CF/EP）复合材料。结果表明,随着氧化剂用量及反应时间的增加,GO的氧化程度也随之增加。在氧化程度较低时,GO表面官能团主要以羰基、羧基和酚羟基为主。随着氧化程度的不断提高,GO表面官能团主要为醚、环氧和醇羟基结构。GO在IPDA中的分散状态与其氧化程度密切相关,氧化程度最低和最高的GO均出现明显的聚集现象。另外,GO表面在分散过程中可被IPDA化学改性。在EP基体中加入分散效果最佳的GO（0.2wt%）后,与CF/EP复合材料相比,CF-GO/EP复合材料的弯曲强度、层间剪切强度和Ⅱ型层间断裂韧性分别提高了14%、17%和14%。     

Preparation and characterization of conducting polyaniline/silica nanosheet composites

A series of polyaniline/silica nanosheet composites (PANI/SNS) with different contents of the silica nanosheets derived from vermiculite via acid-leaching were prepared via the in situ chemical oxidation polymerization. The PANI/SNS composites were characterized with Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and electrical conductivity measurement. It is interesting that the electrical conductivities of the PANI/SNS composites increased with the increasing of the contents of the silica nanosheets added because of the moisture absorption. It was confirmed by the TGA analysis.     

可膨化石墨/低密度聚乙烯导电复合材料的制备及性能研究

选用可膨化石墨(EGP)和低密度聚乙烯(LDPE)制备了一种导电复合材料,并系统研究了LDPE/EGP复合材料的电学、力学性能以及正温度系数(PTC)效应.实验结果表明,随着EGP用量的增加,复合材料的拉伸强度升高,弹性形变减少,为保证复合材料的力学性能,EGP的最大填充量应低于40%.加入一定比例的EGP后,纯LDPE电阻率降低了近6个数量级.随着EGP含量的增加,复合材料的PTC强度先增加后降低.当EGP含量介于30%～35%之间时,复合材料的PTC强度达到最大值,最大值约为5.85.选择合适的热处理温度和密炼时间,可获得具有较高PTC强度的复合材料.     

丝素蛋白/羟基磷灰石复合材料的制备及性能表征

为了改善羟基磷灰石( HAP) 的脆性和新骨诱导性, 采用共沉淀法合成HAP , 盐溶法制备丝素蛋白(SF) , 在胶体状态下将HAP 和SF 复合得到了SF/ HAP 复合材料。采用扫描电镜(SEM) 、X 射线衍射(XRD) ,傅立叶红外光谱( FIR) 对复合材料结构和化学组成进行了分析, 在模拟体液中检验了复合材料的生物活性, 并对其抗压强度进行了测定。结果表明: HAP 与SF 在纳米尺度进行了复合, 复合材料中SF 主要以β-折叠构象存在,酰胺Ⅴ红外特征峰消失,β-折叠构象的其他峰发生了移动, 表明HAP 与SF 间存在化学结合; 模拟体液中浸泡18 天后, 复合材料表面形成了片层状的HAP ; 与纯的HAP 晶体比较, 复合材料结构稳定, 具有较好生物活性和骨诱导性, 其抗压强度可达63 MPa , 可望成为理想的骨组织替换和工程支架材料。      

Preparation and characterization of carbon nanotubes/aluminum matrix composites

2024Al matrix composite reinforced with 1 wt.% carbon nanotubes (CNTs) was fabricated by cold isostatic pressing, followed hot extrusion techniques. The microstructure characteristics and the distribution of carbon nanotubes in the aluminum matrix were investigated. The mechanical properties of the composite were measured at room temperature. Experimental results showed that CNTs were distributed homogeneously in the composite, and the interfaces of Al–CNTs bonded well. The grain size of the matrix was as fine as 200 nm, and with a small amount of CNTs additions, the elastic modulus and the tensile strength were enhanced markedly over those of the 2024Al matrix fabricated under the same process. The reasons for the increments could be due to the extraordinary mechanical properties of CNTs, the bridging and pulling out role of CNTs in the Al matrix composite.