基于碳量子点荧光恢复的三聚氰胺测定方法

在碳量子点溶液中加入汞离子,量子点的荧光被猝灭,加入三聚氰胺后荧光恢复。据此,建立了基于碳量子点荧光恢复测定三聚氰胺的新方法并应用于实际样品的分析。研究结果表明,在汞离子和碳量子点浓度之比为15∶10000且碳量子点浓度为4.0 g/L、pH值为7.5的实验条件下,方法的线性范围为3.0~60.0mg/L,检出限(3σ/k)为2.2 mg/L。方法应用于实际样品测定时,其回收率为95%~103%。     

Synthesis and Characterization of a Fluorinated Phenolic Resin/phenolic Resin Blend

Fluorine atoms were introduced into the molecular chain of a phenolic resin (PR) by a two-step acid synthesis process to improve its thermal and hydrophobic properties. The successful synthesis of a fluorinated phenolic resin/phenolic resin blend (F-PR/PR) was proven by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance 19F (¹⁹F-NMR). The thermal properties of F-PR/PR were analyzed by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) and the results indicate that the F-PR/PR had good thermal stability. The hydrophobic properties of PR were effectively modified as demonstrated by the water drop contact angles. The flexural and tribological properties of F-PR/PR were also investigated. The fluorine atom, by virtue of its electronegativity, size and bond strength with carbon, can be used to create composites from F-PR/PR with remarkable properties. For comparison, two other resin blends were also synthesized.     

Synthesis and Properties of Polyphenylsilsesquioxane Modified Phenolic Resin by in-situ Polymerization from Phenyltriethoxysilane Precursor

A series of phenolic resin-polyphenylsilsesquioxane (PR-PPSQ) composites were prepared by in situ formation from phenyltriethoxysilane (PTES) precursor during polymerization of the PR. The precursor was firstly hydrolyzed in a solution, and then the sol was added to the PR polymerization system. The structures of the composites were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and solid-state ²⁹Si nuclear magnetic resonance (Si-NMR). The PPSQs were spherical particles with a diameter of about 3 µm and nearly uniformly dispersed in the matrix, as revealed by scanning electron microscopy (SEM). The influence of PTES content on the thermal behavior of the PR was characterized by thermogravimetric analysis (TGA) in nitrogen and air atmospheres. The results showed that the onset temperature and residual weight of the composite containing 20 wt% PTES content were improved by 47°C and 8.4%, respectively, compared to the pure PR. The thermal oxidative stability was also greatly increased; the 50 wt% weight loss temperature rose from 567°C for PR to 601°C. The flexural strength of the composites was improved; in particular, the value of the composite containing 15 wt% PTES content was elevated by 32% (from 41.66 to 55.33 MPa).     

高压下制备的累托石/酚醛树脂复合材料微结构和热性能研究

 采用物理方法在高压下制备了酚醛树脂（PF）/累托石（REC）纳米复合材料,用X射线衍射（XRD）、透射电子显微镜（TEM）及热分析（DSC/TGA）等方法,研究了复合材料的物相、显微结构以及热学性能。结果表明,不通过层间高分子聚合反应,不预先对累托石进行有机化处理,在高压下,由聚合物分子插入粘土层间,可以形成剥离型树脂/粘土纳米复合材料,并且其热学性能发生了较大的改变。     

Effect of the Rubber Components on the Mechanical Properties and Braking Performance of Organic Friction Materials

Vegetable oil modified phenolic resin (PF) mixed with four kinds of rubber modifiers, i.e., styrene butadiene rubber, styrene butadiene 2-vinyl pyridine rubber, nitrile butadiene rubber, and carboxyl nitrile butadiene rubber (CNBR), were used as matrices for organic friction materials. The mechanical and thermal degradation properties of all of the blends were investigated. Friction and braking tests of the organic friction materials based on the different matrices and reinforced with hybrid fibers were carried out. The results showed that the resin was most compatible with CNBR; the CNBR/PF blend possessed much higher impact and toughness, and the friction material based on this blend as a matrix exhibited better friction and braking performance. It was concluded that CNBR, the rubber with the most reactive groups, resulted in better mechanical properties of the friction material, and hence optimized the friction, wear and braking performances.     

Preparation,Characterization, and Properties of Resol-Based Benzoxazine Intermediates and Glass Cloth Reinforced Laminates Based on Their Polymers

A series of multifunctional benzoxazine intermediates (Boz-p-x) with different molecular weights and curing behaviors were synthesized based on resol. Their composition was controlled by adjusting the mole ratio (x) of aniline to phenol; i.e. the content of benzoxazine rings formed was varied. The chemical structures and hydrogen-bonding interaction of the intermediates were confirmed by ¹H nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Their curing behaviors were investigated by differential scanning calorimetry (DSC). The results indicated that the residual phenolic hydroxyl groups in the intermediates formed two kinds of hydrogen bonding and acted as a catalyst in the curing process. The more residual phenolic hydroxyl present, the higher the glass transition temperature was and the faster the curing reaction. Further, glass cloth reinforced laminates based on poly(Boz-p-x)s were prepared. The mechanical properties of the laminates were tested by dynamic mechanical analysis (DMA) and flexural measurements. The poly(Boz-p-8) laminate exhibited the highest glass transition temperature (T _g) and mechanical properties in the laminates. Its T _g was 237°C and its flexural modulus and flexural strength were 26.8 GPa and 597 MPa, respectively. The laminates of poly(Boz-p-6), poly(Boz-p-8), and poly(Boz-p-10) showed good modulus retention at elevated temperature due to more ?OH???N hydrogen-bonding interactions. In addition, poly(Boz-p-x)s exhibited high thermal stability and char yield at 800°C.     

Synthesis and Water Absorbency Properties of Hydrogels Based on Lotus Root Starch

In order to increase the added value of lotus root starch, a new-style hydrogel was prepared by grafting copolymerization by acrylic acid (AA), 2-acrylamide-2-methylpropanesulfonic acid (AMPS), K₂S₂O₈, and N,N′- methylene-bis-acrylamide (MBA) in presence of lotus root starch. The molecular structure was characterized by Fourier transform infrared spectroscopy (FTIR). The different conditions that had an influence on the water absorbency are discussed, such as the ratio of initiator to monomers, the ratio of cross-linker to monomers, the mass ratio of AA and AMPS, the lotus root starch's mass, and the reaction temperature. For the product having the optimal water absorbency of 476 g/g, its water absorption kinetics diffusion model and equation were also researched. The material is friendly to the environment and is suggested to have significant potential to be used in various fields.     

Φ42 mm腔体高岭石-白云石质传压密封介质金刚石合成扩大试验

 高岭石具有良好的流动密封、固体传压及机械加工等物理性能,是传统传压密封介质原料叶蜡石的替代品。采用比纯高岭石更适合作为传压密封介质原料的某地高岭石矿物,经过配料、混料、装模、压制成型以及焙烧等工序,制成了高岭石-白云石质传压密封介质,并对其进行金刚石合成扩大试验。试验结果表明：高岭石-白云石质传压密封介质能够达到与叶蜡石质传压密封介质相当的效果;合成金刚石的单产为19 g,抗压强度不小于160 N的晶粒占32%,晶粒尺寸大于或等于0.30 mm的占82%,合成1 g金刚石的顶锤消耗小于0.5 g,合成过程稳定。     

Synthesis and Characterization of a Fluorescent Water-Borne Polyurethane Based on a Novel Naphthalimide Dye

A waterborne-polyurethane (WPU) dye, based on the fluorescent dye 4-diamino propane-N-allyl-1,8- naphthalimide (WPU-DAN), was synthesized by attaching 4-diamino propane-N-allyl-1,8- naphthalimide (DAN) onto both ends of the polyurethane (PU) chains according to a prepolymer?ionomer process. The synthetic process was confirmed by Fourier transform infrared spectroscopy (FTIR) and UV-visible absorption. The glass transition temperature, molecular weight and average particle sizes were measured. The glass transition temperatures of WPU and WPU-DAN were 46.6 and 49.8°C, respectively. In addition, the particle size distributions of WPU-DAN and WPU were 140 and 134 nm, respectively. The thermal behaviour of WPU-DAN showed improvement compared to WPU. The fluorescence intensity of WPU-DAN was enhanced more than DAN due to the naphthalimide groups attached to the chains, and the fluorescence intensity of WPU-DAN and DAN were increased by increasing temperature. Moreover, the fluorescence intensity of WPU-DAN emulsion was stable during 30 days and no loss of fluorescence intensity occurred for these days.     

Synthesis and Properties of Semicrystalline Copolyimides Based on 4,4′-Diaminodiphenylether and 1,3-Bis(4-aminophenoxy) Benzene

Copolyimides were prepared from 4,4′-diaminodiphenylether (4,4′-ODA), 1,3-bis(4-aminophenoxy) benzene (TPER), and pyromellitic dianhydride (PMDA) through a three-step imidization process with different monomer compositions. The copolymerization disrupted the molecular regularity and decreased the intermolecular interaction of the polyimide chains. The X-ray diffraction (XRD) results indicated the prepared copolyimides showed the same semicrystalline character, but had various crystallinity and crystal forms. The copolymerization also changed the crystal morphologies of the polyimides. With increasing TPER ratio, the copolyimides started to form spherulites and hedrites, which then tended to grow more perfectly as the TPER ratio was further increased. The solubility of the copolyimides and their dependence on the crystallnity and the chain flexibility was investigated. These copolyimides exhibited excellent thermal and thermo-oxidative stability.     

基于Schiff碱反应的新型碳量子点制备及其影响因素研究

通过简便水热合成方法,以戊二醛(GA)与3-氨丙基三甲氧基硅烷(APTMS)的Schiff碱反应制备了新型碳量子点。该碳量子点为直径2~7 nm的球体,激发波长为350 nm时,最大发射峰位于400 nm,量子产率为13.6%。实验表明,碳量子点的最佳制备条件是APTMS与GA的量比为1∶2,在180℃下加热8 h。碳量子点在p H=6.0磷酸缓冲液中的荧光强度最大,且荧光强度随测定温度(273~303 K)的升高而降低。     

基于密度泛函理论的外电场下双酚A型环氧树脂分子的结构及特性

采用密度泛函m062x的方法在6-31g(d)基组上对双酚A型环氧树脂分子进行优化得到了它的稳定结构,并且研究了不同外电场(0-0.013 a.u., 1 a.u.=5.142×10~(11) V/m)作用下双酚A型环氧树脂分子的分子结构、电偶极矩和分子总能量,偶极矩、极化率、前线轨道的能级和成分,原子之间的键能和红外光谱的变化.研究表明:随着外加电场的增大,双酚A型环氧树脂分子从倒V型结构逐渐变成线性结构,总能量降低,偶极矩和极化率都升高,且双酚A型环氧树脂分子的稳定性随着外加电场的增大而降低;最高占据轨道能级随着外加电场的增大而增大,沿逆电场方向分子链端表现出亲核反应活性,最低空轨道能级随着外加电场的增大而减小,沿电场方向分子链端表现出亲电反应;位于分子两端环氧基团上的C-C,C-O容易发生断裂,进而破环了双酚A型环氧树脂分子的稳定性;分子红外光谱在高频区的吸收峰出现了明显的红移现象.     

菲并咪唑衍生物蓝光材料的合成、光物理性质及理论计算

合成了两个蓝光材料2-苯基-1H-[9,10-d]菲并咪唑(Phen-PI)和2-吡啶-1H-[9,10-d]菲并咪唑(PyriPI),光物理分析表明Phen-PI和Pyri-PI的最大发射峰分别位于371.5 nm,388.5 nm和403.5 nm,相对量子效率分别为0.383和0.528,激发态衰减寿命分别为3.87 ns和3.68 ns。通过密度泛函理论(DFT)对化合物的前线分子轨道成分和能级分布分析表明,当把Phen-PI中的苯基被吡啶环取代后,Pyri-PI的HOMO能级和LUMO能级分别下降0.09 e V和0.23 e V,同时Pyri-PI的HOMO轨道和LUMO轨道的能级差比Phen-PI减少0.14 e V,在理论层面上解释了Pyri-PI发射光谱的红移。