油墨分散体系黏度数学模型研究

油墨是由颜料粒子、连结料和助剂通过研磨混合形成的一种分散体系,表现出极其复杂的流变学性能.油墨分散体系的黏度与颜料粒子的体积浓度及其分散状态、受到的剪切作用等因素有关.本文在实验研究的基础上,通过对实验测试数据进行统计分析、整理、研究,选择适当的变量代换,利用多次分步非线性回归的数学方法,建立油墨分散体系黏度与颜料粒子体积浓度和剪切速率之间关系的数学模型,并进行了分析和检验.油墨分散体系黏度数学模型的数学性质符合典型的分散体系的流变学特征,满足Casson方程.模型黏度曲线与实验测试结果的拟合程度是理想的.     

改性纳米CaCO3水相分散体系流变行为及其流变参数拟合(Ⅰ)——铝锆偶联剂用量对分散体系流变行为的影响

采用铝锆偶联剂对纳米CaCO,进行表面改性,对改性纳米CaCO3水相分散体系的流变数据进行测定,并借助非牛顿流体模型实现流变参数的拟合.结果表明,在低剪切速率下,改性纳米CaCO3水相分散体系的表观黏度随着剪切速率的增大而下降,即剪切变稀,呈现假塑性流体特性;在高剪切速率下,随着剪切速率的增大,分散体系的表观黏度变化很小.呈现近牛顿型流体特性.采用铝锆偶联剂对纳米CaCO3,进行表面改性,可明显改善纳米CaCO3在水相体系中的流动性,使屈服应力、零剪切黏度及极限黏度都明显减小.根据Herschel-Bulkley模型拟合结果,未经表面改性的纳米CaCO3水相分散体系的流动特性指数和屈服应力分别为1.489和2.767 Pa,呈现剪切变稠流动趋势,表明分散体系的不稳定性,部分粒子发牛团聚;而经2.0%铝锆偶联剂改性的纳米CaCO3水相分散体系的流动特性指数和屈服应力分别为0.880和1.250 Pa,呈现明显的假塑性流体特性,分散体系流动性较好.     

剪切黏稠液体的制备及其性能

剪切粘稠液体是一种非牛顿流体,采用SiO2作为分散相微粒,极性溶剂聚乙二醇作为分散介质。用流变仪测量了STF分散体系中SiO2固含量为10%、15%、20%、25%、30%、35%、40%和45%的稳态流变性能以及剪切粘稠性能的可逆性分析,结果表明,随着剪切速率的增加,STF分散体系先出现剪切变稀现象,当剪切速率超过某一临界值时,分散体系的黏度出现急剧增稠现象;在剪切速率由小到大和由大到小变化时,两条扫描曲线基本重合,表明STF分散体系的剪切增稠效应具有可逆性。     

组分间的相互作用对涂料流变性能的影响

研究了重质碳酸钙(GCC)和高岭土体系下,组分间相互作用对涂料流变特性的影响。研究发现,涂料体系剪切流变性和延展流变性没有相关性;相同涂料体积分数下,高岭土体系的延展黏度和剪切黏度均高于GCC体系;与高岭土体系相比,增稠剂与GCC粒子作用效果更加明显;而随着胶乳的加入,模型涂料体系的延展黏度随之降低。     

低酰基结冷胶-果胶复配体系的性能

利用质构仪和流变仪对低酰基结冷胶(low acyl gellan,LA)和果胶复配体系的胶体质构和流变性能进行研究。考察不同种类离子(Ca~(2+)、K~+)、离子浓度(0、2、4、6、8、10、20、40 mmol/L)以及LA和果胶不同质量比(100:0、75:25、50:50、25:75)对复配体系质构特性的影响。结果表明,随着离子浓度的增加破坏应力先增大,当达到临界值后开始减小,二价离子(Ca~(2+))的作用效果要强于一价离子(K~+)。复配胶破坏应力随LA比例降低先增加后减少,质量比在75:25时具有显著协同效应。复配体系的黏度随剪切速率增大而减小;当剪切速率相同时,黏度随LA比例的增加而增加,离子种类和浓度对复配体系黏度的影响与质构特性一致。随着温度的升高,复配体系黏度减小,在相同温度条件下,结冷胶与果胶质量比75:25时,体系的黏度最大。储能模量G’大于相应质量比损耗模量G",且G’和G"随LA比例的增加而增大,说明体系的黏性和弹性随LA比例增加而变大。     

多相剪切增稠液的流变性能

为研究多相剪切增稠液(STFs)的流变行为,以气相二氧化硅(SiO_2)、碳化硅(SiC)为分散相,聚乙二醇(PEG200)为分散介质制备多相剪切增稠液。利用旋转流变仪测试不同质量分数SiC的剪切增稠液的流变性能,分析多相剪切增稠液的稳态以及动态流变行为规律。结果表明:SiC颗粒的加入会使得STFs体系的黏度增加。稳态流变情况下,STFs随着剪切速率的增加呈现先变稀再增稠的现象;随SiC含量的增加,临界剪切速率减小,增稠周期缩短,增稠比增大。动态流变情况下,分散体系中耗能模量(G″)都大于储能模量(G′),以耗能为主;体系主要表现为黏性,模量随着SiC含量的增加有所提高。     

氧化蜡质玉米淀粉的糊流变特性研究

探讨了氧化蜡质玉米淀粉糊流变性、抗剪切能力以及浓度、温度和剪切速率对表观黏度的影响,并与蜡质玉米淀粉糊进行比较.结果表明:氧化蜡质玉米淀粉糊属于非牛顿流体.浓度、温度、剪切速率对流变性均有影响:在同一浓度和剪切速率下,表观黏度随温度的增加而减小;在同一温度和浓度条件下,淀粉糊的表现黏度随剪切速率的增加而减小;在室温、相同剪切速率下,表现黏度随浓度的增加而增大.氧化蜡质玉米淀粉糊属于剪切稀化体系,抗剪切能力较强.     

剪切处理对薜荔籽果胶流变性质的影响研究

以干薜荔籽为原料,水法提取的薜荔耔果胶为研究对象,研究剪切转速和剪切时间对浓度为O.1%的薜荔籽果胶流变性质的影响.结果表明:在相同剪切时间下,薜荔籽果胶溶液的黏度随剪切转速的增大而减小.当剪切转速小于10000 r/min,果胶分子闻弱结合力受到破坏,部分链状分子卷曲成团状,溶液黏度降低,果胶未被降解;剪切转速为13500r/min时,果胶轻微降解;当剪切转速大于20000r/min,果胶分子降解程度较高.在剪切转速17500 r/min下,随着剪切时间的延长,果胶降解的程度越大,黏度越小;当剪切时间为30min时,果胶降解程度达到最大.     

影响NMMO纤维素溶液流变性的因素

研究了体系温度、剪切速率、纤维素质量分数和不同聚合度配比等因素与纤维素/NMMO溶液流变性的关系,尤其是通过聚合度配比这一方法更准确地探讨了聚合度大小对纤维素溶液表观黏度的影响。研究结果表明:浓度为4%的纤维素/NMMO·H2O溶液体系其ΔEη为24.45k J/mo L。不同聚合度的纤维素溶液都属于假塑性流体,存在剪切变稀现象,高聚合度纤维素溶液的剪切变稀现象比低聚合度的更明显。相同浓度但不同聚合度配比条件下,溶液黏度增加与纤维素聚合度增加大致呈比例,但是配比为1∶1的纤维素溶液例外。     

流变助剂对涂料流变性能的影响

研究了CMC对涂布白纸板底涂涂料表观黏度的影响,CMC能保持涂料良好的流动性能和保水性能;而在涂布白纸板画涂涂料中,与CMC相比,加入丙烯酸碱润胀乳液(L255)后,涂料体系的中低剪切速率(10-1000 s-1)表舰黏度增加明显,而在高剪切速率下(大于1000 a-1),随剪切速率增加,涂料表观黏度剪切稀化现象更显著.     

Structural properties of graphene oxide fibers: from graphene oxide dispersion until continuous graphene oxide fiber

Continuous graphene oxide fiber focused for the last seven years have a very large application area such as electronic textiles, photovoltaics, batteries, fuel cells, sensors, filters. This study reports the effect of processing parameters such as time, temperature of the exfoliation together with dispersion preparation methods of graphene oxide on the properties of continuous graphene oxide fibers produced by coagulation bath. Relationship between changing parameters and structural properties of graphene oxide fiber, fiber morphology, roughness, crystalline structure have been discussed. It has been shown that crystalline structures and responses to changing parameters are different when it is an exfoliated state, dispersion state, and fiber state. For example, crystalline sizes and number of layers of GO fiber were higher than those of GO dispersion, while the crystallinity degrees and d-spaces at the GO fiber were always less than that of GO dispersion. Higher exfoliation time leads to an increase of Tex count of fiber, while longer ultrasonic time resulted in lower value compared to both shorter ultrasound time and mechanical homogenization. Shorter ultrasonic treatment and shorter exfoliation time leads to higher electrical conductivity compared to mechanical homogenization. Shorter ultrasonic treatment results in vaguely tendency of an increase of breaking strength.     

海藻酸钠/改性氧化石墨烯微孔气凝胶纤维制备与吸附性能

为提升海藻酸钠(SA)/氧化石墨烯(GO)复合纤维对阳离子染料的吸附性能及其力学性能,以轻质碳酸钙作为成孔剂,马来酸酐接枝氧化石墨烯(MAH-GO)微粒作为增强剂,SA作为基体,采用湿法纺丝与冷冻干燥法,经酸性置换制备SA/MAH-GO微孔气凝胶纤维,并对其化学结构、形貌和粒度进行分析,探讨了MAH-GO质量分数对微孔气凝胶纤维断裂强度的影响,采用吸附动力学及吸附等温线模型对吸附实验数据进行拟合分析。结果表明：MAH-GO质量分数为0.5%时,SA/MAH-GO微孔气凝胶纤维的拉伸断裂强度最优,为0.513 cN/dtex,与SA/GO气凝胶纤维断裂强度相比提高了11.51%,其吸附过程符合准二级吸附动力学模型,主要受到化学吸附机制控制,对亚甲基蓝最大吸附量可达2 400.66 mg/g。     

Electro-conductivity,bioactivity and UV protection of graphene oxide-treated cellulosic/polyamide fabric using inorganic and organic reducing agents

Here, graphene oxide (GO) was treated on the cellulosic/polyamide fabric reduced with various inorganic and organic compounds and compared the color changes, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, electrical resistivity, antibacterial/antifungal and ultraviolet protection properties. The graphite oxide was first synthesized using graphite and sonicated to obtain GO. It was then dissolved in distilled water along with cetyltrimethylammonium bromide (CTAB) to prepare a stable solution for long-time adsorbing more and uniform GO on cellulosic/polyamide fabric through exhaustion method. The GO-treated fabric was reduced to reduced graphene oxide (rGO) with inorganic and organic reducing agents including sodium dithionite with and without sodium hydroxide and dopamine hydrochloride at various temperatures. More fabricated GO reduced to rGO at higher temperature using dopamine produced lower electrical resistance. The antimicrobial activities of various samples were tested against two Gram-negative bacteria, E. coli and P. aeruginosa, two Gram-positive bacteria, S. aureus and E. faecalis and one eukaryotic fungus C. albicans. Ultraviolet protection was examined through reflectance spectra showed no UV transmittance from most of the treated fabrics. Further, CTAB was effective to load more GO on the fabric improved electrical resistance and higher antibacterial properties using both reducing agents.     

高效低阻聚丙烯腈/石墨烯纳米纤维膜的制备及其抗菌性能

为了提高聚丙烯腈（PNA）基材料的过滤性能,采用静电纺丝的方法制备了含有不同质量分数石墨烯的PNA /石墨烯纳米纤维复合材料。并对复合材料的过滤效果及抗菌性能进行研究,探讨气流量及孔径分布对过滤效果的影响。研究结果表明：当氧化石墨烯（GO）的质量分数为0.3%时,纺制的纤维平均直径为103nm,复合膜的过滤性能最好;纳米复合材料的过滤效率随气流量的增加而减小,孔径尺寸分布在1.3 ~ 1.7μｍ 之间时最有利于过滤效率的提高;当GO和还原性氧化石墨烯（rGO）质量分数均为0.3%时,PAN /GO 纳米复合材料比PAN/rGO 纳米复合材料的过滤性能好,PAN / GO 和PAN/rGO 纳米复合材料对大肠杆菌的抑菌率分别为32.4%和40.5%,对金黄色葡萄球菌的抑菌率分别为45.8%和56.7%。     

花状氧化石墨烯原位展开共聚聚酰胺6及其功能纤维

为实现复合纤维中石墨烯的分子级分散,从而改善现有石墨烯复合纤维制成率低、强度低、耐用性差等问题,提出了一种原位展开共聚的机制,使得聚酰胺6(PA6)分子接枝的石墨烯片能够均匀分散在体系内,从而批量制备多功能PA6/石墨烯纤维,建立起全新的纤维制备-加工-性能一体化系统,实现了多功能性和高力学性能的兼顾。结果表明：在聚合过程中,花状氧化石墨烯呈现出逐步展开、分散的形貌变化,同时参与聚合反应中;反应结束后,PA6分子均匀接枝在石墨烯片表面,并诱导PA6发生了晶型转变;加入0.1%石墨烯后复合纤维单丝的拉伸强度相比纯PA6纤维提高25.4%,拉伸模量提高49.5%;此外,石墨烯复合PA6面料兼具优异的抗菌、抗病毒、远红外发射、负离子发生、防紫外线等功能,具有广阔的市场前景。     

石墨烯整理蚕丝织物的导电性能

为获得耐水洗和高导电的纺织材料,采用原位还原法将氧化石墨烯(GO)用于蚕丝织物的导电整理。探究了GO 质量浓度、GO 溶液pH 值、还原剂用量、超声时间和十二烷基苯磺酸钠质量浓度等对蚕丝织物导电性能的影响,分析了还原氧化石墨烯(rGO)导电蚕丝织物的导电耐久性,并借助扫描电子显微镜对织物形貌进行表征。结果表明：在GO 质量浓度为15 g/ L,GO 溶液pH 值为5,还原剂质量浓度为5 g/ L,超声时间为30 ~ 60 min 时,采用原位还原法还原吸附GO 并烘干的蚕丝,其表面电阻值降低至1. 372 kΩ/ cm,导电性优良;蚕丝表面被GO 完全覆盖,经20 次水洗或机械摩擦后蚕丝织物依然保持较好的导电性能。     

Effects of Granule Size and Size Distribution on Rheological Behavior of Chemically Modified Potato Starch

The effects of granule size and size distribution on rheological behavior of hydroxypropylated and phosphate cross‐linked potato starch (HPS) were studied by steady and dynamic viscoelasticity measurements. The rheological behavior of starch dispersions was strongly influenced by granule size and granule‐to‐granule interaction. Average granule size of HPS dispersion at high concentration was smaller than that at low concentration. Time dependence of viscosity was quite different depending on shear rate; thixotropy at low shear rates and antithixotropy at high shear rates. At higher concentrations, HPS dispersion showed a non‐Newtonian behavior, and it tended to a Newtonian behavior when concentration was lowered. Yield stress and creep recovery of HPS dispersion at higher concentrations was more pronounced than those at lower concentrations.     

氧化石墨烯基材料吸附重金属离子的研究进展

废水中所含的重金属离子对自然环境和人体健康造成了极大危害。在众多处理方法中,基于氧化石墨烯(GO)基材料吸附重金属离子的方法受到研究者关注。梳理近年来的研究文献,重点论述GO、不同GO基纳米复合材料、磁性氧化石墨烯(MGO)基纳米材料及还原氧化石墨烯(rGO)基材料的合成方法、重金属离子吸附概况等,通过结构表征及吸附热力学和动力学机理分析,为进一步研究、设计氧化石墨烯材料及处理重金属离子奠定基础。     

Fabrication of electrically conductive and improved UV-resistant aramid fabric via bio-inspired polydopamine and graphene oxide coating

Abstract

This study presents the fabrication of woven aramid fabric (AF) with integrated properties, especially with improved surface activity, UV resistance, electrical conductivity and thermal properties. A biomimicry surface functionalization with polydopamine (PDA) and a further modification by graphene oxide (GO) coating of the AF was demonstrated. The surface properties of AF were changed by repeated reduce graphene oxide (rGO) coating process. The scanning electron microscope (SEM) results showed that the rGO sheets were successfully formed on the surface of AF, and the deposition of GO/rGO was proven by X-ray photoelectron spectroscopy (XPS). The electrical conductivity was ascertained by the electrical surface resistance value of the AF. A low surface resistance value of 6.43 K?cm^?1 was obtained after five times of modification, resulting in an excellent conductivity. The ultraviolet protection factor (UPF) value of the modified AF increased to 73 in comparison to 37 for the original AF.     

棉秆皮纤维素/氧化石墨烯纤维的制备及其力学性能和吸附性能

为提高纤维素基纤维的强力及其对阳离子染料亚甲基蓝的吸附能力,利用超声分散和湿法纺丝法,制备了含有不同质量分数氧化石墨烯(GO)的棉秆皮纤维素/GO纤维。借助透射电子显微镜、扫描电子显微镜、傅里叶红外光谱仪分析了棉秆皮纤维素/GO纤维的形态和结构,探讨了GO质量分数对纤维断裂强力和吸附量的影响,并对吸附实验数据进行拟合分析。结果表明:随着GO质量分数的增加,纤维的断裂强力先增大后减小;GO质量分数为0.4%时,纤维断裂强力最优为31.12 cN,与未添加GO的纤维相比断裂强力提高了84%;纤维对亚甲基蓝的吸附量随着GO质量分数的增加而增加,吸附过程符合准二级吸附动力学模型和Langmuir等温吸附模型,属于单分子层的吸附,吸附过程为自发的放热反应。