一步原位气泡拉伸法制备LDHs/PS纳米复合材料及其力学性能分析

采用一步原位气泡拉伸(ISBS)法制备了水滑石/聚苯乙烯(LDHs/PS)纳米复合材料,研究了ISBS对LHDs的分散情况和复合材料机械性能的影响。结果表明:与双螺杆机械分散法相比,ISBS法可以实现LDHs在PS中纳米级均匀分散;通过双螺杆挤出机消泡处理后,分散开的LDHs没有发生明显的再团聚;相同添加量情况下,一步ISBS法制备的复合材料具有更好的机械性能,在一定添加量范围内,材料的冲击强度和拉伸强度随着添加量的增大而增大,均在LDHs质量分数为5%时达到最大值。     

纳米聚丙烯酸酯改性纳米Mg(OH)_2及其在LDPE中的应用

采用纳米聚丙烯酸酯乳液改性纳米Mg(OH)2,通过单螺杆挤出机制备了纳米Mg(OH)2/低密度聚乙烯(LDPE)复合材料,利用红外光谱、扫描电镜、透射电镜等方法对改性前后的Mg(OH)2及Mg(OH)2/LDPE复合材料进行了表征。结果表明:纳米Mg(OH)2表面经纳米聚丙烯酸酯乳液改性后吸附上了一层聚丙烯酸酯;纳米聚丙烯酸酯乳液改性提高了纳米Mg(OH)2的热稳定性,分解温度提高了27℃;改性纳米Mg(OH)2在LDPE基体中分散更为均匀;改性纳米Mg(OH)2的用量为LDPE的15%时复,合材料的拉伸强度比纯LDPE提高了6.5%。     

原位气泡拉伸法制备增韧聚丙烯

将5～30份的纳米碳酸钙(nano-CaCO<,3>)添加至无规共聚聚丙烯(PP-R)树脂中,采用原位气泡拉伸法(ISBS法)将树脂基体中的nano-CaCO<,3>分散,制备出PP-R/nano-CaCO<,3>复合材料.对复合材料进行扫描电子显微镜观察,发现ISBS法可以将nano-CaCO<,3>均匀地分散到PP-R中;通过力学性能测试表明:当nano-CaCO<,3>添加量为20份时,ISBS法制备的复合材料的缺口冲击强度与机械分散法相比提高20.4%.研究结果表明:与传统的机械分散法相比,ISBS法可以将nano-CaCO<,3>更均匀地分散到PP-R中,使nano-CaCO<,3>在PP-R中达到纳米级尺度的分散,进而得到高韧性的聚丙烯复合材料.     

纳米氢氧化镁增强EPDM/PP的力学性能及形态结构研究

采用动态硫化法制备了聚丙烯/三元乙丙橡胶/纳米Mg(OH)2复合材料,通过力学性能测试、差示扫描量热仪(DSC)分析等手段,对纳米氢氧化镁填充EPDM/PP的力学性能以及结晶与熔融特征进行了研究,通过透射电镜考察了纳米Mg(OH)2在EPDM/PP体系中的微观结构.结果显示随着纳米Mg(OH)含量的增加,EPDM/PP的拉伸强度和断裂伸长率都呈先增加然后下降的趋势;与表面未处理的纳米Mg(OH)2相比,经KH560表面处理过的纳米Mg(OH)2在EPDM/PP基体中的分散更加均匀,对EPDM/PP的增强作用更加明显.当经KH560表面处理过的纳米Mg(OH)2质量含量为10%时,纳米复合材料的拉伸强度达到最大值18.5MPa;填充纳米Mg(OH)2后,纳米复合材料的结晶度以及熔融温度都有所下降.红外光谱表明KH560与纳米Mg(OH)2之间形成了化学键.     

LDPE/LLDPE/纳米Mg(OH)2阻燃体系的研究

以LDPE/LLDPE(60:40)共混体系为基础,添加阻燃剂纳米Mg(OH)2,考察聚乙烯/纳米Mg(OH)2共混复合体系的阻燃性能、力学性能以及加工工艺条件.实验表明:随着Mg(OH):份量的增加,发烟量逐渐减少,纳米Mg(OH),添加量大于40%以后,发烟量逐渐趋近于零,说明纳米氢氧化镁在PE阻燃系统中具有优异的抑烟作用;随着阻燃剂纳米Mg(OH),的增加,燃烧级别最后升高至FV-O级.阻燃体系的力学性能随着纳米Mg(OH)2的增加而下降,当纳米氢氧化锾质量含量达到50%时,材料转为脆性.流动性随纳米Mg(OH)2含量的增加而下降.     

聚氨酯弹性体/Mg(OH)2纳米复合材料的制备与表征

将预分散的纳米氢氧化镁[Mg(OH)2]加入聚氨酯弹性体(PUE)反应体系进行原位聚合。由于预聚物粘度的影响,纳米粒子的最大添加量为5%(质量分数)。力学测试表明,所得Mg(OH)2/聚氨酯弹性体纳米复合材料的力学性能较纯PU有较大提高。复合材料置于60℃的水中3周后,拉伸强度保留93%。XRD测试显示复合材料中无明显结晶。氧指数(IO)测定显示,纳米Mg(OH)2的加入,可明显提高复合材料的难燃性能、当其质量分数为5%时,氧指数可达31。     

TPS/LDPE/纳米SiO_2材料结构与性能

以天然高分子木薯淀粉为研究对象,低密度聚乙烯(LDPE)和纳米二氧化硅(SiO_2)为改性材料,甘油为增塑剂,通过熔融法制备了热塑性木薯淀粉(TPS)/LDPE/纳米SiO_2复合材料,研究了复合材料的塑化性能、力学性能、结晶性能、热稳定性和微观结构。结果表明:纳米SiO_2能提高TPS/LDPE复合材料塑化性能,更容易进行加工;随着纳米SiO_2用量的增加,复合材料的拉伸强度降低、断裂应变增加,复合材料的熔融焓、结晶度减小,热降解温度提高;纳米SiO_2的加入使得复合材料的球晶变得更细密,改变了复合材料的晶型;当纳米SiO_2用量为2份(质量份)时在复合材料中分散较好,但随着纳米SiO_2用量的增加会发生团聚现象。     

LDPE/Nano-ATH复合材料性能研究

采用熔融共混法制备了低密度聚乙烯(LDPE)/纳米氢氧化铝(nano-ATH)复合材料,研究了nano-ATH的加入量对复合材料力学性能和阻燃性能的影响,利用扫描电镜分析了nano-ATH在LDPE基体中的分散性。结果表明:随着nano-ATH用量的增加,LDPE/nano-ATH复合材料的拉伸强度稍有下降,但断裂伸长率却急剧下降;nano-ATH的加入,有助于改善LDPE的阻燃性能;随着用量的增加,nano-ATH在LDPE基体中的分散性逐渐变差。     

SBR的纳米级分散对聚丙烯力学性能的影响

利用ISBS方法制备PP/纳米SBR复合材料。通过SEM和力学性能测试,研究了纳米SBR在复合材料中的分散状况,并考察了不同纳米SBR的添加对PP力学性能的影响。结果表明:纳米SBR在基体PP中实现了纳米级分散;且纳米SBR的添加量为7%时,复合材料PP/纳米SBR的力学性能最佳,其中缺口冲击强度提高了80%。     

LDPE/SiO_X纳米复合材料的制备

通过硅溶胶直接法和母料法制备低密度聚乙烯/纳米氧化硅(LDPE/SiOX)复合材料,并研究其工艺方法。通过拉伸试验和扫描电镜对复合材料进行测试和分析。结果表明,采用母料法制备的SiOX含量为2%(质量分数)的LDPE/SiOX复合材料中,SiOx的粒径为(54±10)nm。与纯LDPE相比,该纳米复合材料的拉伸强度提高了2.4N/mm2。     

Mechanical properties of low-density polyethylene/nano-magnesium hydroxide composites prepared by an in situ bubble stretching method

Low-density polyethylene/nano-magnesium hydroxide (LDPE/nano-Mg(OH)₂) composites have been prepared by an in situ bubble stretching (ISBS) method and simple shear method. By means of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), it was confirmed that the ISBS method leads to a high degree of dispersion of the Mg(OH)₂ nanoparticles in the LDPE matrix. Furthermore, no significant re-aggregation of the nanoparticles was observed after removing the bubbles by means of high-speed grinding. The tensile strengths of nanocomposites prepared by means of the ISBS method were higher than those of materials with the same Mg(OH)₂ loading produced by direct blending/extrusion. The tensile strength of the nanocomposites produced by the ISBS method reached a maximum value at an Mg(OH)₂ content of 15 phr. In contrast, the tensile strength of composites prepared by direct blending/extrusion shows a monotonic decrease with increasing Mg(OH)₂ content. The improvement in mechanical properties of nanocomposites associated with the use of the ISBS method can be attributed to a more homogeneous dispersion of smaller nanoparticles.     

Effect of Nano–Magnesium Hydroxide on Mechanical and Flame-Retarding Properties of SBR and PBR: A Comparative Study

Magnesium hydroxide [Mg(OH)₂] is one of the potential inorganic fillers. In this work, nanoparticles (37±5 nm) of the magnesium hydroxide were prepared using matrix-mediated growth and control technique, and their size was confirmed by X-ray diffraction technique. Nano-Mg(OH)₂-SBR and nano-Mg(OH)₂-PBR composites with 2–10% (w/w) filler loading were prepared by compounding on laboratory-scale two-roll mill and a compression molding machine. These composites were tested for tensile and physical properties, and the properties were compared with the composites of commercial Mg(OH)₂. The incorporation of nanofiller improved the properties of nanocomposites.     

Comparative Study of the Mechanical and Thermal Properties of Polyamide-66 Filled with Commercial and Nano-Mg(OH)2 Particles

In the present work, polyamide-Mg(OH)₂ nanocomposites were prepared via melt intercalation on a twin-screw extruder. Different particle sizes (24, 20, 11 nm) of Mg(OH)₂ were synthesized by in-situ deposition technique and its shape and sizes was confirmed on transmission electron microscope (TEM). Nano-Mg(OH)₂ was added from 1 to 4 wt% in the polyamide. Properties such as tensile strength, elongation at break, hardness, and flame retardency were studied. These results were then compared with commercial Mg(OH)₂-filled composites. There was propounding effect to be observed on properties of polyamide nanocomposites due to uniform dispersion of nano-Mg(OH)₂ and commercial Mg(OH)₂. Moreover, thermal property like thermal degradation was studied on TGA. Extent of dispersion of nano-Mg(OH)₂ was studied along with microcracks generated during tensile testing using AFM. It was found that nano-Mg(OH)₂ is thermally more stable compared to that of commercial Mg(OH)₂. Besides that, T_g and M.T. are studied on DSC.     

In situ synthesis of hydrophobic magnesium hydroxide nanoparticles in a novel impinging stream-rotating packed bed reactor

Hydrophobic Mg(OH)_2nanoparticles were successfully synthesized via an in situ surface modification method in a novel impinging stream-rotating packed bed(IS-RPB) reactor using oleic acid(C_(17)H_(33)COOH, OA) as a surface modifier, magnesium chloride hexahydrate in the presence of ethanol as a precursor, and sodium hydroxide as a precipitant. The products were characterized by Fourier transform infrared spectroscopy(FTIR), Field emission scanning electron microscopy(FESEM), X-ray diffraction(XRD), and thermogravimetry-differential scanning calorimetry(TG-DSC). Compatibility with organic solutions was determined by sedimentation tests. The prepared nanoparticles exhibited regular hexagonal lamella with an average diameter of 30 nm when OA is added to the reaction system; this result indicates that OA regulates the morphology of the Mg(OH)_2nanoparticles.XRD revealed that the high-purity Mg(OH)_2product presents a brucite structure, and the I_(001)/I_(101) of hydrophobic Mg(OH)_2(0.86) was higher than that of the blank Mg(OH)_2(0.63). FTIR analysis showed that OA bonded to the surface of the Mg(OH)_2. Compared with the blank Mg(OH)_2product, the product obtained through the proposed method possesses excellent hydrophobic properties, including a high water contact angle of 101.4° and good compatibility with liquid paraffin. TG-DSC analysis indicated that the total percentage of mass loss of hydrophobic Mg(OH)_2(40.88%) was higher than that of the blank Mg(OH)_2product(33.18%). The in situ surface modification method proposed in this work presents potential use in the large-scale production of Mg(OH)_2nanoparticles.     

Preparation and properties of LDHs/polyimide nanocomposites

Layered double hydroxides/polyimide (LDHs/PI) nanocomposites were prepared from solution of polyamic acid (polyimide precursor) and LDH-amino benzoate using N,N-dimethylacetamide as a solvent. LDH-amino benzoate (LDH-AB) was obtained by coprecipitation method. The amino benzoate, grafted on the surface of the Mg/Al nanolayers, as a connector improved the compatibility between the inorganic Mg/Al nanolayers and the organic polyimide molecules. The dispersion behavior of Mg/Al nanolayers was investigated by transmission electron microscopy and X-ray diffraction, indicating that the Mg/Al nanolayers were exfoliated in PI matrix to form LDH-AB/PI nanocomposites. The maximum tensile strength and elongation of the LDH-AB/PI nanocomposites were found with the LDH-AB content of 5 and 4 wt%, respectively. The initial tensile modulus of these nanocomposites was increased with the LDH-AB content. These nanocomposites exhibited higher storage and loss moduli compared to those of pure PI. T_g of these nanocomposites increased with the LDH-AB content. Coefficients of thermal expansion (CTE, below and above T_g) of these nanocomposites deceased with the LDH-AB content. The thermal properties of these nanocomposites were enhanced by the incorporation of Mg/Al nanolayers in PI matrix.     

Preparation and optical properties of transparent epoxy composites containing ZnO nanoparticles

Polymer nanocomposites are usually made by incorporating dried nanoparticles into polymer matrices. This way not only leads to easy aggregation of nanoparticles but also readily brings about opaqueness for nanocomposites based on functionally transparent polymers. In this letter, transparent ZnO/epoxy nanocomposites with high‐UV shielding efficiency were prepared via two simple steps: first, in situ preparation of zinc hydroxide (Zn(OH)₂)/epoxy from the reaction of aqueous zinc acetate (Zn(Ac)₂·2H₂O) and sodium hydroxide (NaOH) at 30°C in the presence of high‐viscosity epoxy resin; second, thermal treatment of the as‐prepared Zn(OH)₂/epoxy hybrid into ZnO/epoxy composites. Optical properties of the resultant ZnO/epoxy nanocomposites were studied using an ultraviolet–visible (UV–vis) spectrophotometer. The nanocomposites containing a very low content of ZnO nanoparticles (0.06 wt %) possessed the optimal optical properties, namely high‐visible light transparency and high‐UV light shielding efficiency. Consequently, the as‐prepared ZnO/epoxy nanocomposites are promising for use as novel packaging materials in lighting emitting diodes technology. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

氢氧化镁阻燃硅橡胶的制备及性能

分别采用未处理氢氧化镁、有机硅处理氢氧化镁、硬脂酸处理氢氧化镁为阻燃剂,制备阻燃硅橡胶,研究了氢氧化镁种类对硅橡胶阻燃性能、力学性能、电性能的影响;通过扫描电镜观察阻燃硅橡胶的拉伸断面形貌,并通过热重分析对硅橡胶的阻燃机理进行初步探讨。结果表明,采用经有机硅处理的氢氧化镁为阻燃剂时,硅橡胶的阻燃效果优于采用其它两种氢氧化镁为阻燃剂的硅橡胶;有机硅处理氢氧化镁对硅橡胶的力学性能和电性能损害较小。添加60份有机硅改性氢氧化镁时,硅橡胶的极限氧指数达到36%,拉伸强度为6.4MPa,撕裂强度为32.9kN/m,邵尔A硬度为51度,体积电阻率和表面电阻率分别为5.8×1015Ω.cm和4.1×1015Ω,介电常数和介质损耗因数分别为3.43和2.34×10-2。有机硅处理氢氧化镁在硅橡胶中分散较均匀,界面结合紧密,孔洞较少。     

聚丙烯／纤维级Mg（OH）2／P复合材料研究

以聚丙烯（PP）为基料,通过与纤维级Mg(OH)2、红磷（P）以及其他助剂改性制备阻燃材料。实验结果表明：当PP、纤维级Mg(OH)2和P的比例为100：95：5时,共混体系的阻燃性能和力学性能均能满足使用要求,通过与PP／球状Mg(OH)2/P体系对比,发现PP／纤维级Mg(OH)2/P体系的拉伸性能优异。     

Mechanical,optical, and electrical properties of cellulosic semiconductor nanocomposites

Photoluminescent cellulose fibers were prepared by impregnation of bleached bagasse pulp with the different cadmium and zinc sulfides nanostructures, namely, CdS, ZnS, CdS/ZnS, ZnS/CdS (Core/shell nanostructures), CdS/ZnS/CdS and ZnS/CdS/ZnS multilayered nanostructures. The prepared cellulosic nanocomposites were characterized regarding strength properties (tensile strength, tensile energy absorption, and burst resistance), optical properties (fluorescence emission), thermal stability, and dielectric properties. The strength properties of paper sheets nanocomposites impregnated with different nanoparticles solutions were noticeably decreased in spite of the very low loading of the fibers with the semiconductor nanoparticles. The decrease in tensile index, tensile energy absorption, and burst index of paper sheets nanocomposites are found to be ranged from 12–27, 13–36, and 11–38 %, respectively. The different paper sheets nanocomposites showed fluorescence emission different from the as prepared polyethyleneimine‐stabilized nanoparticles. Thermogravimetric analysis results showed that: the semiconductor nanoparticles did not affect the onset degradation temperature of cellulosic fibers but it caused faster termination of the main degradation step. The dielectric loss and the dc‐conductivity of cellulosic fibers increased as a result of impregnating the fibers. The nature of the nanoparticles and the properties of the interphases strongly influenced the dielectric properties of the cellulosic/semiconductors nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

EVA／Al（OH）3纳米复合材料性能的研究

采用熔融共混挤出法制备了EVA／Al(OH)3纳米复合材料。用TEM、SEM分析了Al(OH)3粉体改性前后在EVA树脂中的分散性与相容性。研究了表面处理对复合材料阻燃与力学性能的影响，并对Al(OH)3阻燃机理进行了探讨。结果表明：采用钛酸酯偶联剂对粉体进行表面改性可有效改善其在树脂中的分散与结合情况，复合材料阻燃级别提高到UL94 V-1级，拉伸性能得到改善。