交联改性细菌纤维素/肝素复合膜的制备及性能

通过在细菌纤维素(BC)发酵培养液中加入肝素(Hep)原位制备BC/Hep复合膜,并向提纯过后的复合膜加入交联剂1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)与N-羟基琥珀酰亚胺(NHS)进行交联改性,研究了肝素对BC培养液中木醋杆菌生长的影响,以及不同物质的量之比的交联剂对复合膜力学性能、膨胀率和透湿性的影响。结果表明,在BC培养液中加入Hep能够促进木醋杆菌的生长,Hep可提高BC膜的拉伸强度,但降低了膨胀率和透湿性;交联改性后复合膜的拉伸强度进一步得到提高,当EDC/NHS/Hep-COOH的物质的量之比为0.4/0.24/1时,复合膜的拉伸强度较纯BC及未加交联剂的BC/Hep复合膜分别提高了28.28%和15.4%,且膨胀率和水蒸气透过率与纯BC相近,分别为8 274%和(814.10±44.87)g/(m~2·d),可以作为一种理想的创伤敷料。     

细菌纤维素/透明质酸复合材料的生物合成及表征

在培育细菌纤维素(BC)过程中添加不同分子量的两种透明质酸(HA),分别制备出不同的细菌纤维素复合物HA/BC(Mw=3,000)和HA/BC(Mw=300,000)。采用红外光谱、扫描电子显微镜、X射线衍射和热重分析对其结构和性能进行了表征。添加HA后提高了复合物的产量;FTIR结果表明了HA与BC之间存在交联;添加HA增大了BC的热稳定性,而对BC的结晶指数影响不大,且HA/BC(3,000)的性能始终优于HA/BC(300,000);HA(3,000)增大了BC的拉伸强度,而HA(300,000)反而减小了其拉伸强度。结果表明添加小分子量的HA可制备最大热失重温度较高的HA/BC复合物。     

石墨烯/硅橡胶导电复合材料的结构与性能研究

分别采用溶液共混法和机械共混法制备了石墨烯/硅橡胶复合材料,使用扫描电镜(SEM)、X-射线衍射(XRD)、万能拉力试验机和直流电桥对复合材料微观结构与宏观性能的相关性进行了研究。结果表明,与纯硅橡胶相比,石墨烯/硅橡胶复合材料力学性能和导电性能都有明显提高;相比于机械共混法,溶液共混法有助于石墨烯均匀分散和导电网络的形成,其复合材料表现出较好力学性能和导电性能,试样拉伸强度比机械共混法试样拉伸强度高0.7MPa,导电率是后者的10.26倍。     

BC/PVA/PEG增强型复合水凝胶的制备及其表征

通过反复冷冻—溶融法制备了细菌纤维素/聚乙烯醇/聚乙二醇(BC/PVA/PEG)复合水凝胶,并采用扫描电镜、红外光谱、X-射线衍射和拉力测试等手段对水凝胶的结构和性能进行表征。拉伸力学性能测试结果表明,随着PEG的加入,水凝胶的力学性能得到显著增强。     

PP/PA6/OMMT复合材料力学性能与结晶性能的研究

采用3种不同有机改性过的蒙脱土(牌号为DK2,DK3,DK5)熔融插层法制备了PP/PA6/OMMT纳米复合物材料,在此基础上使用1%～7%的DK2的蒙脱土再次制备PP/PA6/OMMT纳米复合物材料,借助力学性能测试和差示扫描量热法(DSC)对体系的力学性能和结晶性能进行了研究。结果表明:使用DK2制备的复合材料的力学性能优于使用DK3和DK5制备的复合材料的力学性能;相对于纯PP,PP/PA6/OMMT纳米复合物材料随OMMT含量的增加,拉伸强度和弯曲强度是先增加后降低,最大下降幅度分别为8.7%和5.3%;冲击韧性一直上升达到9.61kJ/m2。OMMT的加入,对PP/PA6有异相成核的作用,提高PP/PA6的结晶速率和结晶度。     

EP/环氧基苯基多面体低聚硅倍半氧烷复合物的制备及其性能

通过水解缩合反应合成了环氧基苯基多面体低聚硅倍半氧烷(cy-ep-Ph-POSS),并制备了环氧树脂(EP)/cy-ep-Ph-POSS复合物,研究了复合物的热性能、力学性能以及阻燃性能.结果表明:cy-ep-Ph-POSS主要由含有6,8,10个硅原子的多面体低聚硅倍半氧烷结构组成;与纯EP相比,EP/cy-ep-P...     

纳米ZnO/纤维素纳米晶/聚乙烯醇复合膜的制备及性能

采用球磨法制备的纤维素纳米晶(CNC)及市售纳米ZnO对聚乙烯醇(PVA)进行改性,改善了PVA膜的力学性能,并且,赋予其抗菌性,测试复合膜的力学性能、水蒸气透过性能及抗菌性能。结果表明,加入CNC后,提高了PVA膜的力学性能和阻湿性能,加入纳米ZnO后,复合膜对金黄色葡萄球菌具有一定的抗菌性能,并且,能进一步提高复合膜的拉伸强度,但是,降低了复合膜的阻湿性能。当CNC的添加量为3%、纳米ZnO∶CNC=2∶1(摩尔比)时,复合膜综合性能较好,拉伸强度为73.7 MPa,与纯PVA膜相比,提高了77.2%;断裂伸长率为3.8%,与纯PVA膜相比,提高了46.1%;水蒸气透过系数为3.44×10^-13 g·cm/(cm²·s·Pa),与纯PVA膜相比,提高了11.7%。     

细菌纤维素/聚乙烯醇复合材料的制备及性能

采用浸渍法向细菌纤维素(BC)中引入聚乙烯醇(PVA),对BC/PVA复合材料的结构、光学性能及力学性能进行研究。当浸渍液中PVA浓度为20 g/L时,力学性能及光学性能测试表明,复合材料在保持BC超高力学强度的同时光学性能较纯BC显著提高,透光率最高可达90.74%,可见光区最多提高24.26%。扫描电子显微镜及X射线衍射表明,大量自由PVA渗入BC网络结构,复合材料层状结构淡化,结晶度下降。     

石墨烯/热塑性硫化胶复合材料的制备及热电性能（英文）

通过熔融共混方式制备了石墨烯(Ge)/聚丙烯母粒,然后采用动态硫化的方法与丁基橡胶共混制备Ge/热塑性硫化胶(TPV)复合材料,研究了Ge/TPV复合材料的相态结构、热电性能和力学性能。结果表明,丁基橡胶交联颗粒以微米级长条状分散在聚丙烯母粒基质中,Ge表面褶皱明显,片层厚度较薄,均匀分散在聚丙烯母粒相和橡塑两相界面中。丁基橡胶交联颗粒能够排斥Ge,从而提高Ge/TPV复合材料的热电性能。与纯TPV相比,Ge/TPV复合材料(Ge质量分数2%)的交流电导率增加了1个数量级,介电常数增加了1.6倍,热导率增加了44.2%。Ge/TPV复合材料的热电性能及力学性能因Ge的存在而大幅提高。     

氟橡胶/丁腈橡胶共混物的相态结构及性能

在六氟异亚丙基二酚(BAF)硫化体系和硫黄硫化体系的交联作用下,采用熔融共混法制备了氟橡胶(FKM)/丁腈橡胶(NBR)共混物,研究了共混物的硫化特性,考察了两组分不同配比对共混物的相态结构、物理机械性能和动态力学性能的影响.结果表明,BAF硫化体系和硫黄硫化体系可使FKM与NBR形成各自独立的交联体系;当FKM/NBR(质量比)为80/20时,共混体系具有最完善的两相共连续形态,共混物的拉伸强度和撕裂强度达到最大值,且只存在1个玻璃化转变温度,其值低于纯FKM.改善了耐低温性能.     

纳米ZnO改性PLA/PBS及其发泡体系的性能

采用熔融共混法制备了纳米氧化锌(ZnO)填充聚乳酸/聚丁二酸丁二酯(PLA/PBS)复合材料。研究了ZnO质量分数对复合材料的力学性能、结晶性能以及动态流变性能的影响。结果表明,随着ZnO含量的增加,复合材料的力学性能和结晶度先升高后降低,当ZnO质量分数为0.5%时,复合材料的拉伸强度和冲击强度分别达到最大值40.99 MPa和8.82 k J/m~2,比未添加ZnO时分别提高了6.3%和28.2%,同时结晶度达到24.4%。动态流变性能测试表明,ZnO的质量分数为0.5%时,复合材料的损耗模量和储能模量均为最大值,反映出此时复合材料内部氢键和交联网络最完善,协同作用效果达到最佳状态,因此力学性能也最优。在ZnO质量分数为0.5%的基础上,采用超临界二氧化碳发泡法对复合材料进行间歇发泡,结果显示添加ZnO的发泡材料泡孔密度比未添加的高出一个数量级,泡孔尺寸分布更加集中,体积膨胀率更高。     

Development of a novel PPTA/cellulose composite insulation paper with low dielectric constant and improved mechanical properties by BTCA crosslinking

This study investigates the effect of 1,2,3,4-butane tetracarboxylic acid (BTCA) crosslinking treatment on the electrical properties of poly-p-phenylene terephthalate (PPTA)/cellulose insulation paper to prepare a novel composite insulation paper with low dielectric constant and good electrical performance. Three-layer PPTA/cellulose composite paper crosslinked by BTCA under various conditions, composite paper without crosslinking, directly mixed composite paper, and conventional Kraft paper are prepared. The morphology and surface chemical composition of the paper samples are characterized. Dielectric, mechanical, and thermal properties are investigated. Results show that the BTCA concentration of 0.2 mol L⁻¹ with a 180°C curing temperature is the relatively superior crosslinking condition to prepare a novel composite with low dielectric constant and good comprehensive performance. The dielectric constant and loss of the novel composite paper decrease to 3.21 and 0.392 at 50 Hz. The tensile strength of the BTCA crosslinked three-layer PPTA/cellulose composite paper (thickness: 130 μm) has reached 10.01 kN m⁻¹, increased by 41.6% than the directly mixed composite paper. The novel BTCA crosslinked composite paper also shows improved thermal stability. The BTCA crosslinking proves to be a promising method to improve the dielectric properties and electrical performance of the PPTA/cellulose composite paper.     

Effect of the cellulose of Agave tequilana Weber onto the mechanical properties of foamed and unfoamed polypropylene composites

Morphology, mechanical properties and crystallinity of foamed and unfoamed composites polypropylene (PP) and cellulose from Agave tequilana were studied. The PP–cellulose composite with PP–g-MA as coupling agent was obtained using a twin-screw extruder. Foamed composite was obtained by blending the composite with a blowing agent and moulding by compression. The morphology of the foamed composite, observed by SEM, shows that the bubble diameters were smaller when cellulose content increased. Young's modulus and impact of foamed and unfoamed PP/PP–g-MA composites were higher than the pure PP matrix, and they increase with the cellulose content. An increment of the crystallization percent was observed with respect at XRD analysis. This indicates that the cellulose acts as a nucleation agent, favouring the crystallization in the composites.     

Crystallisation,mechanical properties and rheological behaviour of PLA composites reinforced by surface modified microcrystalline cellulose

Microcrystalline cellulose chemically modified by 3-isocyanatopropyl triethoxysilane (K-MCC) was incorporated as reinforcement into a polylactic acid (PLA) matrix to prepare PLA/K-MCC composites by melt blending. X-ray diffraction showed that PLA's crystalline structure was not affected by the added K-MCC, but its degree of crystallinity increased somewhat. Differential scanning calorimetry indicated that, when 5?wt-%K-MCC was added to PLA, the crystallisation of PLA improved greatly, and the degree of crystallinity reached a maximum of 39.4%, which exceeded that of pure PLA. Mechanical testing revealed that the tensile strength, modulus and heat distortion temperature of PLA also increased significantly after modified MCC was added, and the optimum mechanical properties of the composite were obtained. Dynamic rheological tests revealed shear thinning behaviour in the PLA/K-MCC composites. With increasing shear rate, more obvious shear thinning was observed because of more homogeneous dispersion of K-MCC with fewer hydroxyl groups in the PLA matrix.     

Effects of fiber surface chemistry and roughness on interfacial structures of electrospun fiber reinforced epoxy composite films

This work reported the effect of surface chemistry and roughness of electrospun fibers on fiber/matrix interfacial structures and the resultant macroscopical properties of composite films. Three types of fibrous mats composed of ultrafine fibers, that is, cellulose acetate (CANM), polyurethane (PUNM), and cellulose acetate/polyurethane composite (CAPUNM) were fabricated through electrospinning. CA fiber surfaces were rough with many hydroxyl groups; PU fiber surfaces were smooth, whereas CAPU composite fibers exhibited cocontiuous structure with rough surfaces. The fiber‐reinforced epoxy composite films were prepared by the solution impregnation method. The fractured surfaces of the composites were analyzed by scanning electron microscopy. Severe interfacial debonding and fiber pullouts were observed for PUNM/epoxy composites, while strong interfacial adhesion was formed for CANM/epoxy and CAPUNM/epoxy composites. The interfacial structure played important roles in the visible light transmittance of the composite films. For example, CANM/epoxy films showed the best optical property, whereas PUNM/epoxy films displayed the poorest light transmitting property and were translucent. The interfacial structure also affected the mechanical properties of the composites. The mechanical strength of fibrous mats followed an increasing order of CANM < CAPUNM < PUNM, but the mechanical strength of the composite films was in a reverse order, that is, CANM/epoxy > CAPUNM/epoxy > PUNM/epoxy. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

碳酸钙对聚乳酸/酯化纤维素复合材料性能的影响

采用熔融共混工艺制备了聚乳酸(PLA)/酯化纤维素/CaCO3复合材料,通过力学性能测试、热重分析、凝胶渗透色谱和红外光谱分析,研究了CaCO3对复合材料力学性能和热稳定性的影响。结果表明:CaCO3能够与酯化纤维素相互作用,并在一定程度上改善复合材料的力学性能,提高复合材料的热稳定性,减缓PLA的热降解。     

Poly(L‐lysine)/microcrystalline cellulose biocomposites for porous scaffolds

The need for tissue engineered scaffolds is growing due to a shortage in organ donation, potential immunoreactions to allotransplants, and high cost associated with transplantation. The main focus of this research is concerned with material selection and processing which are key for a successful design of any tissue engineered structure. This work investigates the possibility of reinforcing a weak polypeptide [poly(L ‐lysine)] with a stronger polysaccharide (cellulose) and processing the resulting composite into a porous structure. As the main processing parameters, the effect of pH on the secondary structure of the polypeptide and the effect of the hydrolysis conditions on the properties of commercially available microcrystalline cellulose (MCC) were studied. The significance of the cellulose content as well as the scaffold fabrication conditions on the properties of the composite system was assessed. Overall, PLL/MCC composites showed a lower crystallinity compared to the PLL alone while further hydrolyzed MCC particles (HMCC) showed surface erosion and resulted in a crystallinity increase when incorporated into a composite structure. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Shear‐induced crystallization of injection molded vetiver grass‐polypropylene composites

Vetiver grass was used as an alternative filler in polypropylene (PP) composites in this study. Chemical treatment of vetiver grass by alkalization was carried out to obtain alkali‐treated vetiver grass. It was shown that alkali‐treated vetiver grass exhibited higher thermal stability than untreated vetiver grass. Injection molding was used to prepare the composites. The microstructure of injection molded samples showed a distinct skin layer due to shear‐induced crystallization. It was found that normalized thickness of shear‐induced crystallization layer of the composite was lower than that of neat PP. The effect of vetiver particle sizes on shear‐induced crystallization and physical properties of the composites were elucidated. Furthermore, the effect of processing conditions on shear‐induced crystallization, degree of crystallinity, gapwise crystallinity distribution, and mechanical properties of the composite were investigated. It was shown that injection speed and mold temperature affected the normalized thickness of shear‐induced crystallization layer and degree of crystallinity of the composites. However, processing conditions showed insignificant effect on the mechanical properties of vetiver fiber‐PP composites. The degree of crystallinity showed no distribution throughout the thickness direction of the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Covulcanization of LLDPE/EMA blends using dicumyl peroxide

The effect of dicumyl peroxide (DCP) content on the gel fraction, mechanical, dynamic mechanical, and thermal properties of linear low‐density polyethylene (LLDPE)/ethylene‐co‐methyl acrylate (EMA) blends were studied. Gel content of the blends increases with increasing DCP content, and EMA is more prone to crosslinking than LLDPE. Wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC) were used to study the effect of DCP crosslinking on percent crystallinity and crystalline structure of the blends and individual components. At lower level of DCP loading, crosslinking process does not have significant effect on the crystalline structure of the LLDPE, which was confirmed from the percent crystallinity and lattice distance value. However, at higher DCP content, percent crystallinity decreases significantly. At lower EMA concentration (<50%), percent crystallinity and lattice distance remain unchanged up to 2 wt % of DCP. For EMA contents of more than 50 wt %, increasing DCP content reduces the crystallinity of the blends and increases the lattice distance. The highest level of mechanical and dynamic mechanical properties was observed for 60/40 LLDPE/EMA blends at 2 wt % DCP. Addition of LLDPE‐g‐MA (3 wt %) as a compatibilizer enhances the properties of the vulcanizates. Blends crosslinked with DCP up to 0.3 wt % can easily be reprocessed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011