MMA-粉煤灰漂珠体系凝胶注模成型制备多孔陶瓷

以甲基丙烯酸甲酯(MMA)为单体,粉煤灰漂珠为骨料,采用非水基凝胶注模成型工艺制备多孔陶瓷。考察了MMA含量对浆料性能的影响、MMA预聚合方式对浆料成型的影响以及生坯的排胶与烧结方法,并对多孔陶瓷性能进行了表征。研究表明:微波预聚合可缩短诱导期、加速MMA本体聚合;过高的微波功率和引发剂用量使反应加速,不利于聚合稳定;提高预聚合程度有助于缩短浆料固化时间、降低生坯体积收缩;为保证浆料的流动性及生坯的完整性,应将MMA预聚液含量控制在45wt%~60wt%;生坯(MMA 50wt%)在380℃排胶1h、1050℃烧结2h,得到的多孔陶瓷抗弯强度为40.35MPa,显气孔率为42.03%,平均孔径为1.12μm。     

O/W型微乳液法制备PMMA纳米粒子的研究--(Ⅰ)相图,增容效应,反应动力学

研究了O／W型甲基丙烯酸甲瑟(MMA)、表面活性剂和水的三元微乳液相图。盐类对微乳液增容MMA单体的影响和聚合反应动力学．结果表明．在一定范围内,加入无机盐可以增加微乳液中MMA单体的含量．不同无机盐增容MMA的效果不一样：KBr＞KCl．NaCl＞K2SO4．其增容效采随盐用量增加而提高．聚合反应速率与MMA单体浓度．引发剂浓度和乳化剂浓度的关系为Rp ∝[M]^0.89[I]^0.44[E]^-0.88聚合反应温度提高．聚合速率加快．     

低强度超声波辐照引发MMA的本体聚合

利用功率密度仅有0.25 W/cm2的超声波为辐射源对溶有聚甲基丙烯酸甲酯(PMMA)的MMA物料体系进行辐照引发了MMA的本体聚合。考察了超声波、促进剂、阻聚剂、反应气氛等因素对聚合反应的影响,利用凝胶色谱仪对产物分子量及分布进行了表征。结果表明,该反应为自由基引发聚合,大分子与单体之间的摩擦力是产生自由基的根本原因;超声波频率、辐照时间等对聚合速率有明显影响;产物具有较为规整的分子量分布且几乎不含引发剂残基,可应用于对材料纯度有特殊要求的领域。     

FTIR研究预辐照PMMA／PU IPNs的反应动力学

借助于~(60)Co-γ射线对MMA进行辐照预聚合,用FTIR研究了预聚合MMA/PU IPNs的反应动力学,讨论了反应温度、交联剂含量对IPNs反应动力学的影响。结果表明,IPNs中各组分按互不干扰的机理进行,根据PU反应速率明显快于PMMA网络的事实,提出了PU网络的“笼子效应”。     

新型α-二亚胺中性镍催化剂的合成及催化甲基丙烯酸甲酯(MMA)本体聚合

2,6-二异丙基苯胺经硝化和Schiff碱缩合反应,生成的α-二亚胺配体与无水氯化镍反应制备了中性镍配合物.用FTIR、1H-NMR对中间产物及配合物进行了表征.在甲基铝氧烷(MAO)的助催化作用下,研究了以镍二亚胺为主催化剂对甲基丙烯酸甲酯(MMA)聚合反应的影响因素,考察了聚合温度、n(Al)/n(Ni)值(摩尔比)、聚合时间、n(MMA)/n(Cat)值(摩尔比)等因素对聚合反应的影响,得到的最佳聚合反应条件是:聚合温度为60℃,聚合时间为15h,n(Al)/n(Ni)为600,n(MMA)/n(Cat)为1000.最佳聚合条件下,MMA单体的转化率为65.5%,聚合物的相对分子质量为8.26×104.     

多层核壳结构ACR树脂的合成与性能研究Ⅰ.ACR乳液聚合过程表观动力学

采用聚丙烯酸丁酯(PBA)为种子,分步加入苯乙烯(St)和甲基丙烯酸甲酯(MMA)多步乳液聚合,使形成多层核壳结构的ACR树脂,研究了聚合反应过程的表观动力学,表明PBA种子乳液聚合反应速率与乳化剂浓度的0.89次方成正比.PSt为壳的聚合反应速率与乳化剂浓度的0.5次方成正比.     

聚磷酸铵制备过程中的预聚合反应研究

以聚磷酸为初始反应原料,尿素为氨化缩合剂,经预聚合和高温固化2个阶段反应制得聚磷酸铵。针对预聚合反应过程中体系随温度变化由液态转化为固态的复杂过程,探讨了升温速率、温度和时间与表观粘度的关系以及反应压力对预聚合过程的影响。在最佳预聚合反应条件下合成的聚磷酸铵聚合度可以达到65.36,氨氮含量和磷含量分别为14.36%和69.84%(均为质量分数)。     

4,4′-偶氮二[4-氰基戊酰(对-二甲基氨基)苯胺]引发苯乙烯聚合及其动力学

以4,4′-偶氮二[4-氰基戊酰(对-二甲基氨基)苯胺](ACPDA)为引发剂,在N,N-二甲基甲酰胺(DMF)中研究了苯乙烯(St)的聚合行为。考察了聚合反应温度、单体浓度和引发剂浓度对聚合物分子量和聚合反应速率的影响,测定了反应级数和聚合反应的活化能。实验结果表明,聚合反应速率随单体浓度、ACPDA浓度的增加和反应温度的升高而加快;聚合物分子量随单体浓度的增大而增大,随ACPDA浓度的增大和反应温度的升高而降低。ACPDA引发St的聚合速率方程为Rp=K[St]1.08[ACPDA]0.51,聚合反应的表观活化能Ea=119.89 kJ/mol。     

4,4''-偶氮二[4-氰基戊酰(对-二甲基氨基)苯胺]引发苯乙烯聚合及其动力学

以4,4'-偶氮二[4-氰基戊酰(对-二甲基氨基)苯胺](ACPDA)为引发剂,在N,N-二甲基甲酰胺(DMF)中研究了苯乙烯(St)的聚合行为.考察了聚合反应温度、单体浓度和引发剂浓度对聚合物分子量和聚合反应速率的影响,测定了反应级数和聚合反应的活化能.实验结果表明,聚合反应速率随单体浓度、ACPDA浓度的增加和反应温度的升高而加快;聚合物分子量随单体浓度的增大而增大,随ACPDA浓度的增大和反应温度的升高而降低.ACPDA引发St的聚合速率方程为Rp=K[St]1.08[ACPDA]0.51,聚合反应的表观活化能Ea=119.89 kJ/mol.     

环糊精和乳化剂共存下苯乙烯的乳液聚合动力学

以过硫酸钾为引发剂,十二烷基硫酸钠为乳化剂,在β-环糊精(β-CD)存在下进行乳液聚合动力学研究,考察了引发剂浓度、乳化剂浓度、β-环糊精浓度以及聚合温度对聚合反应速率的影响,测定了各项反应级数和聚合表观活化能。结果表明,聚合反应速率随引发剂浓度、乳化剂浓度和聚合温度的升高而加快,随β-环糊精浓度的升高先增加后降低,在β-CD浓度≤1.555×10-3 mol/L时,聚合反应动力学关系式为Rp∝[KPS]0.5277[SDS]0.5631[β-CD]0.9987,表观活化能为72.55 kJ/mol。     

Decolorization of methyl orange by ozonation in combination with ultrasonic irradiation

The combination of ultrasound and ozone for the decolorization of azo dye, methyl orange, was studied. The effect of ultrasonic power, ozone gas flow rate, gaseous ozone concentration, initial dye concentration, pH and hydroxyl radical scavenger on the decolorization of methyl orange was investigated. The results showed that the synergistic effect was achieved by combining ozone with ultrasonic irradiation for the decolorization of methyl orange. The synergistic effect was more significant when the system temperature was raised due to the heat effect of ultrasonic irradiation. The decolorization of methyl orange fits the pseudo first order kinetic model. The decolorization rate increased with the increase of ultrasonic power, ozone gas flow rate, gaseous ozone concentration. However, the decolorization rate decreased with the increasing initial dye concentration. Either pH or sodium carbonate has little effect on the decolorization rate, indicating that the low frequency ultrasound enhanced ozonation process for the decolorization of methyl orange is mainly a direct reaction rather than radical reaction.     

Oxidation of methyl methacrylate from semiconductor wastewater by O3 and O3/UV processes

This study investigated the oxidation of methyl methacrylate (MMA) by sole ozonation and ozone/UV treatments. The semi-batch ozonation experiments were proceeded under different reaction conditions to study the effects of ozone dosage and UV radiation on the oxidation of MMA. The experimental results indicated that both the oxidation of MMA by the sole ozonation and O3/UV processes can completely decompose MMA to form the following intermediates within 30 min reaction time. To increase the applied ozone dosage can significantly raise the removal efficiency of MMA. However, the mineralization of MMA via the direct oxidation reaction of molecular ozone was slow, while introducing the UV radiation can promote the mineralization rate of MMA. In addition, the pH value of the oxidized solution in the O3/UV treatment decreased lower than that in the sole ozonation treatment of about 1 unit. The possible scheme of the decomposition pathway of MMA under the ozonation process is proposed in this study. Formic acid and acetic acid were found to be the main ozonated intermediates.     

甲基丙烯酸甲酯的微波聚合特性和产物结构

在微波辐射下进行甲基丙烯酸甲酯（MMA）的无乳化剂乳液聚合，发现在微波辐照下MMA聚合速率较加热有较大的提高，微波辐照制备的聚甲基丙烯酸甲酯（PMMA）乳液粒子形状规整，粒径分散系数1．03，达到单分散要求，微波制备乳液的数均分子量与常规加热接近，但分子量分布变窄，微波和热无乳化剂聚合的PMMA的热解过程一致，在200℃－390℃有三个分解峰，与有乳化剂聚合有很大差异，FT－IR，13C－NMR表明无乳化剂聚合的PMMA序列结构以间同为主，微波聚合略微降低PMMA的立构规整度。     

快速升温条件下聚甲基丙烯酸甲酯的燃烧机理

用色谱和质谱研究了快速升温条件下PMMA以及单体MMA在空气和氩气中的不同温度下的热反应，推测了PMMA在空气中燃烧的主要历程。结果表明，在快速升温条件下，PMMA首先降解为单体MMA，而后MMA分解，生成甲醇、甲烷、丙烯、2-甲基丙烯和丙酮等可燃性气态小分子，最后气态小分子与氧反应发生燃烧。在较高温度下，MMA也可直接与氧反应，生成丙酮酸甲酯、甲醛和丙酮，但此反应在PMMA的燃烧历程中处于次要地位。     

The effect of microwave-assisted for photo-catalytic degradation of rhodamine B in aqueous nano TiO2 particles dispersions

The photo-catalytic decomposition of rhodamine B was examined in aqueous nano TiO2 particles dispersions to assess effects of the microwave radiation assisted photo-catalytic process driven by UV radiation. The results of photo-catalytic degradation of rhodamine B showed that the decomposition rate increased with the microwave intensity, UV intensity, TiO2 particle dosages and the circulating fluid velocity. Addition of oxygen gas in the photo-catalytic degradation of rhodamine B increased the reaction rate. The effect of addition of H2O2 was not significant when photo-catalysis was used without additional microwave radiation or when microwave was irradiated without the use of photo-catalysts. When H2O2 was added under simultaneous use of photo-catalysis and microwave irradiation, however, considerably higher degradation reaction rates were observed. This study demonstrates that the microwave irradiation can play a very important role in photo-catalytic degradation.     

单分散间苯二酚-甲醛气凝胶微球的制备工艺

采用T型微流体注射成型技术,以邻苯二甲酸二丁酯、液体石蜡和司班80为油相,间苯二酚/甲醛(RF)溶液为水相,经过溶胶-凝胶、溶剂交换、超临界干燥等过程制备了单分散RF气凝胶微球,并就制备过程中RF溶液与分散剂油相的选择、预聚时间、流速比、搅拌速率、固化温度等影响因素进行了初步讨论.当RF溶液质量分数为10%,60℃预聚1.5 h,间苯二酚与碳酸钠的物质的量之比为100,邻苯二甲酸二丁酯与液体石蜡的质量比为8:1,流速比控制在8～16,搅拌速率为65～90r/min,固化温度为35℃时,制备得到了RF乳液,其粒径分布系数小于2%.     

Magnitude of effect of reaction parameters on 2-chlorophenol decomposition by ultrasonic process.

In the present work, decomposition of o-chlorophenol (2-cp) was carried out using an ultrasonic process. The extent of 2-cp decomposition depends on several parameters such as ultrasound wave energy (ultrasonic amplitude), addition of hydrogen peroxide (H2O2), pH value (H+ concentration), ionic strength, and initial concentration of 2-cp. The experimental results showed that the decomposition of 2-cp was affected by the various reaction conditions. The profiles of 2-cp decomposition fitted well with the first-order kinetic equation. A linear relationship was obtained between the rate constants of 2-cp decomposition and the varying reaction parameters. The magnitude of effect of reaction parameters such as ultrasonic amplitude, H+ concentration, ionic strength, H2O2 and 2-cp initial concentration on 2-cp decomposition were 0.60, 0.48, 0.19, 0.09 and -0.06, respectively.