共查询到20条相似文献,搜索用时 15 毫秒
1.
Biodegradable nanocomposites of Nanocrystalline Cellulose (NCC) and electrospun poly‐(lactic acid) were prepared via a new mixing technique. Dispersion of hydrophilic NCC in hydrophobic PLA was improved through aqueous mixing and freeze drying of perfectly suspended NCC with PLA nanofibers. Freeze drying produced aerogels with good mechanical integrity. The aerogels were further processed via hot pressing. Resulting composites displayed an improvement in mechanical properties, which was greatest at temperatures below the glass transition temperature of PLA. The optimum compositions were found to be in the 0.5–3% NCC (by weight) range. Experiments performed also showed that due to electrospinning, the crystallinity of the PLA slightly increased and this is accompanied by a decrease in its glass transition temperature. Furthermore, adding NCC to the electrospun PLA matrix did not alter the crystallinity of the final composite. The composites investigated proved their potential to be used in packaging and tissue engineering applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3345–3354, 2013 相似文献
2.
以水稻秸秆经碱解、酸解得到的微晶纤维素(MCC)作为聚乳酸(PLA)的改性材料,通过溶液共混、流延成膜制备了PLA/MCC复合膜,采用傅里叶变换红外光谱仪、差示扫描量热仪、扫描电子显微镜等对其性能进行了表征。结果表明:水稻秸秆中木质素、半纤维素等杂质大部分被有效除去,当NaOH质量分数为5%时,去除率最大,MCC成功制备;当MCC质量分数为8.3%时,可以最大程度改善PLA/MCC复合膜的拉伸性能,MCC与PLA结合最好,而MCC的加入会使复合膜的热稳定性有所降低。 相似文献
3.
4.
采用乙酰柠檬酸三丁酯(ATBC)作为增塑剂增塑聚乳酸,添加改性香蕉纤维和膨胀型阻燃剂(IFR)制备阻燃香蕉纤维增强聚乳酸复合材料.研究结果表明,偶联剂处理纤维的效果最好,使复合材料的拉伸、弯曲强度分别达到57.49MPa、101.80MPa,与扫描电子显微镜(SEM)的结果一致;IFR含量为5份(以聚乳酸为100份计)时综合性能最佳,材料的极限氧指数达到了 32.8%,垂直燃烧实验达到了 V-0 级(UL-94),材料的拉伸和弯曲强度分别为43.97 MPa 和87.95MPa,效果最好.热失重研究结果表明,阻燃香蕉纤维的加入能明显提高聚乳酸的热分解温度和残炭量. 相似文献
5.
6.
7.
将一定质量比聚乳酸(PLA)与聚己内酯(PCL)进行共混,通过熔融纺丝得到PLA/PCL初生纤维,再经过热拉伸后得到PLA/PCL纤维;利用自制模具采用手工编织的方法制备了PLA/PCL管道支架;对PLA/PCL纤维及其支架的结构与性能进行了表征。结果表明:当PLA/PCL质量比为40:60时,PLA/PCL初生纤维的综合力学性能较好;拉伸温度和拉伸倍数对PLA/PCL初生纤维的力学性能影响较大,当拉伸温度为85℃、拉伸倍数为7时,所得的PLA/PCL纤维力学性能最好;在一定温度区间内,PLA/PCL支架的支撑力随着定型温度的升高而升高,合适的定型温度应为其玻璃化转变温度至130℃之间,制备的PLA/PCL支架具有良好的弯曲性、压缩性和支撑性能,能满足支架应用的需求。 相似文献
8.
Erika Nieddu L. Mazzucco P. Gentile T. Benko V. Balbo R. Mandrile G. Ciardelli 《Reactive and Functional Polymers》2009,69(6):371-379
PurposePerspective applications of nanocomposites in biomedical applications are investigated in this work by producing intercalated dispersions of clays into a biodegradable polymer matrix. Poly(lactic acid) (PLA) was selected being produced from renewable resources and approved by the Food and Drug Administration for medical use.In order to improve PLA mechanical properties and to accelerate its degradation, different layered silicate nanoclays are added: montmorillonites and fluorohectorites, without or with organic modifiers. Preparation, characterization, mechanical properties and biodegradation in blood plasma are evaluated.ResultsNew biodegradable materials were obtained, with improved mechanical properties (Young modulus, Peak stress and Strain at break) and with increased degradation rate (weight loss and lactic acid release). 相似文献
9.
Ersel Ozkazanc Sibel Zor Hatice Ozkazanc Serap Gumus 《Polymer Engineering and Science》2013,53(6):1131-1137
This article reports synthesis of polypyrrole (PPy) and its composites having various amounts of selenium (Se) in the presence of nitric acid in aqueous medium via chemical oxidative polymerization. Samples were spectroscopically characterized using Fourier transform infrared spectroscopy, ultraviolet‐visible spectroscopy, and atomic absorption spectroscopy. Although morphology of the samples was examined by using scanning electron microscopy (SEM), their thermal properties were studied via differential scanning calorimetry (DSC). The alternating current (ac) conductivity and dielectric properties were investigated as a function of temperature. Variation of adsorption free energy obtained from Langmuir adsorption isotherm showed that metal cations were physically adsorbed onto the polymer surface. SEM images showed that filling process significantly changes the morphology of PPy. DSC results indicated that cold crystallization temperature (Tcc) of unfilled PPy decreases with increasing filling level. Dielectric measurements showed that relaxation times for PPy and its composites have decreased linearly with increasing temperature. The conductivity of the PPy, when filled with 1 g of Se, increased ~ four times at room temperature for 1 kHz. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers 相似文献
10.
11.
12.
In this study, polyvinyl alcohol/organically modified montmorillonite (HDA/MMT; organoclay) composite was prepared for the intercalation processes. Firstly, the rheological behavior of aqueous montmorillonite dispersions was investigated as a function of solid content. Hexadecylamine (HDA) was added to the montmorillonite dispersion (2%, w/w) in different concentrations in the range of 5 × 10?4 – 9 × 10?3 mmol/L. The basal spacing of the organoclay (OMMT) was studied by X‐ray diffraction. The FTIR spectra are obtained from the modified montmorillonite products, which revealed the characteristic absorbencies after treatment with HDA. HDA/MMT/PVA composite, which was produced by the reaction of 1 wt % PVA solution with organoclay complex, is characterized by the rheology, electrokinetic, XRD, FTIR, and SEM techniques. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2315–2323, 2006 相似文献
13.
Composites of serpentine and polypropylene (PP) were prepared by twin‐screw extrusion. Serpentine was collected as rocks from the Ankara–Beynam region and ground into powder with an average particle size of about 3 μm for composite production. Both as‐received (rock) and powdered serpentine were characterized. A silane coupling agent (SCA), γ‐aminopropyl triethoxy silane, was used for the surface treatment of serpentine. Mechanical properties of the composites were measured in terms of impact strength, elastic modulus, stress at yield, stress at break, and percentage strain at break. The addition of serpentine was found to have a profound effect on the reinforcement of the PP matrix. Because of the stronger interactions at the interphase induced by SCA treatment, mechanical properties were improved further in comparison with the untreated composites. Similar thermal and morphological behaviors were recorded for the composites with and without surface treatment. Thermal studies showed an increase in both melting temperature and percentage crystallinity of the composites. Scanning electron microscopy analysis revealed that homogeneous distribution of filler was observed at low filler contents, but a certain extent of agglomeration was also seen at high filler loadings. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
14.
Jing Sun Jian Li Anrong Huang Juan Li Shanshan Luo Min Shi Chengtao Gao Zhu Luo 《应用聚合物科学杂志》2024,141(9):e55011
In situ microfibrillar poly(lactic acid) (PLA)/polyolefin elastomer (POE) composites (MFCs) with and without compatibilizer POE-g-GMA were prepared using a multistage stretching equipment. The results showed that the distribution of PLA inside the POE matrix for the MFCs without compatibilizer was in the form of microfibrils, and most of the PLA microfibrils were well-oriented and arranged in the matrix. Further, the high PLA content was more likely to form longer PLA microfibrils in MFCs. With the increase in the amount of POE-g-GMA for (PLA/POE, 20/80) system, the length of PLA microfibrils significantly decreased, whereas the average diameter increased. The addition of 2 wt% POE-g-GMA increased the tensile strength and elongation at the break of POE-20-2 by 52.7% and 53.5%, respectively, and the crystallization temperature increased by about 4°C. 相似文献
15.
《Journal of the European Ceramic Society》2006,26(9):1687-1693
Using a mica-crystallizing glass powder in which a large amount of mica crystal was precipitated and a larger amount of MgF2 component was contained as the raw materials of mica, machinable alumina/mica composites were obtained at 1400 °C. In the firing process, magnesia component in the mica crystals reacted with alumina to form spinel at 1150–1200 °C. The reaction made the mica crystals melt. However, the mica crystals were precipitated again during the cooling. Because a larger amount of MgF2 component was contained in the mica-crystallizing glass powder, the nucleation of the mica crystals was caused during the cooling by the residual magnesium and fluorine in the liquid phase and succeedingly the mica crystals were precipitated. The precipitated mica crystals grew to anisotropicaly larger size than alumina grains, which lowered the bending strength and Vickers hardness and little heightened the fracture toughness. 相似文献
16.
17.
以环氧树脂为基体,苯乙烯-丙烯腈-丁二烯(ABS)树脂为增韧剂,制备了环氧树脂/ABS复合材料,讨论了增韧剂对复合材料的热性能和机械性能的影响。结果表明,ABS的添加可提高复合材料的断裂韧性。扫描电镜结果显示,基体的剪切屈服和橡胶颗粒的微孔洞是ABS增韧环氧树脂的主要增韧机理。 相似文献
18.
19.
Graphite oxide (GO)/polypyrrole (PPy) composites (GPs) and 1,5-naphthalene disulfonic acid (1,5-NDA) doped GPs (1,5-NGPs) have been successfully synthesized via in situ polymerization of pyrrole on GO. The conductivity of 1,5-NGPs is as high as 7 S/cm, seven orders of magnitude higher than that of pristine GO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results show PPy “dressed” on the surface of GO layers, while Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirm the interaction between GO and PPy. The results of thermogravimetric analysis (TGA) and heat treatment at 1000 °C show that the “dressed” PPy on the surface of GO layers in GPs and 1,5-NGPs has effectively prevented the deflagration of GO. 相似文献
20.
Zhengke Wang Qiaoling Hu Xiaoguang Dai Hao Wu Youxiang Wang Jiacong Shen 《Polymer Composites》2009,30(10):1517-1522
Cellulose fiber/chitosan biodegradable rod (CF/CS rod) with layer‐by‐layer structure, good mechanical properties, and excellent X‐ray developing capability was successfully constructed via in‐situ precipitated method. As the ratio of CF to CS was 0.2/20 (wt/wt), the bending strength and bending modulus arrived at 124.1 MPa and 4.3 GPa, respectively, were significantly improved compared with pure CS rod. TGA indicated that the thermal stability of CS rod could be enhanced by mixing with CF, but fiber and matrix are partially compatible. SEM made clear that fibers were randomly dispersed in the CS matrix to connect layers of CS rod that can endure stress. FTIR spectra illuminated that small amount of Schiff base was formed due to the chemical reaction between fibers and CS matrix, which could enhance the mechanical combining stress of the interface. Thus, CF/CS rod has great potential to be used as internal fixation of bone fracture. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers 相似文献