嵌段聚醚酯共聚物的结晶性能

采用偏光显微镜和光学解偏结晶速率仪研究了嵌段聚醚酯共聚物的结晶形态和等温结晶过程。结果发现,结晶速度Ｋ随聚酯含量增加而增大,随聚醚分子量的增大而增大,交联剂使结晶速度Ｋ减少。嵌段聚醚酯的等温结晶过程可用Ａｖｒａｍｉ方程描述,最快结晶速度Ｋ对应的结晶温度Ｔｍａｘ与聚合物熔点Ｔｍ的关系满足经验式Ｔｍａｘ＝（０．８～０．８５）Ｔｍ。     

聚苯硫醚—聚醚砜嵌段共聚物的红外光谱分析

对实验室合成的聚苯硫醚（ＰＰＳ）－聚醚砜ＰＥＳ）嵌段共聚物的结构进行了红外表征，建立用傅地红外光谱对共聚物组成进行定量分析的方法。发现共聚物中ＰＥＳ的含量随投料经中ＰＥＳ的含量增加而增加，但小于投料中ＰＥＳ含量。     

聚酯—聚醚嵌段共聚物的合成及抗静电性能研究

研究和分析了ＰＥＧ分子量、加料次序、反应时间和温度、物料比例、分散剂和固相缩聚等因素对ＰＥＴ－ＰＥＧ嵌段共聚物分子量和耐水性的影响。合成的嵌段共聚酯醚与ＰＥＴ共混纺丝可以显著改善ＰＥＴ纤维的抗静电性能。     

基于嵌段聚醚酯多元醇的聚氨酯控释机理研究

针对海洋工程设备中弹性基材的防污特殊需求,合成聚乙二醇（PEG）/聚己内酯（PCL）嵌段共聚物PEG/CL_X,并与HDI三聚体固化形成可降解聚氨酯,研究其亲水性能及降解性能,再将PEG/CL_X与氧化亚铜等结合,制备成一系列的海洋防污涂层,研究其控释机理。     

ABA型三嵌段聚合物的可控聚合

以AIBN为引发剂,FeCl3/PPh3为催化剂,在80℃进行丙烯酸丁酯的反向原子转移自由基聚合反应,制备了末端含氯的分子量分布窄的聚丙烯酸丁酯,再以此为大分子引发剂,引发苯乙烯进行原子转移自由基聚合反应,得到两嵌段聚合物。最后在强还原剂和一价铜盐的催化下,进行两嵌段聚合物之间的偶合反应,得到聚丙烯酸丁酯-b-聚苯乙烯-b聚丙烯酸丁酯(PBA-b-PSt-b-PBA)ABA型三嵌段聚合物,PDI为1.127。聚合过程的动力学研究和产物核磁表征,表明该聚合体系为可控聚合,得到了分子量可控、分布窄的聚合物。     

嵌段聚醚氨基硅PEA-b-PS的膜形貌及其表征与性能

以氨值为0.5587mmol/g、数均分子量(-Mn)为2.2×104的聚醚氨基-b-聚硅氧烷(PEA-b-PS)作成膜物质,以氧化单晶硅及棉纤维织物作载膜基质,用原子力显微镜(AFM)等研究了PEA-b-PS的膜形貌和应用性能。结果表明,在氧化单晶硅和棉纤维基质表面,PEA-b-PS均能成膜,宏观上看似平滑的PEA-b-PS膜微观形貌实则呈非均一结构,在PEA-b-PS表面有大量由亲水性聚醚氨基链节所产生的微凸存在。当PEA-b-PS包覆在纤维表面,它不仅能导致处理后棉纤维织物的弯曲刚度明显降低,而且能使织物的静态吸水时间缩短为3.4s。     

聚酯－聚醚嵌段共聚物的合成及抗静电性能研究

研究和分析了ＰＥＧ分子量、加料次序、反应时间和温度、物料比例、分散剂和固相缩聚等因素对ＰＥＴ－ＰＥＧ嵌段共聚物分子量和耐水性的影响。合成的嵌段共聚酯醚与ＰＥＴ共混纺丝可以显著改善ＰＥＴ纤维的抗静电性能。     

新型含杂萘联苯聚醚砜类嵌段共聚物的合成与性能研究

采用连续缩聚法合成氯端基聚醚砜齐聚物,然后与杂萘联苯构成的类双酚合成的羟端基齐聚物进行缩聚反应,合成了新型PPES-PES嵌段共聚物.用IR、DSC、TGA、X-WAXD等方法对聚合物进行了表征,并研究了聚合物的溶解性能.结果表明该嵌段共聚物具有较高的玻璃化转变温度,较好的热稳定性和良好的溶解性能,为非结晶型聚合物,并可浇铸得到透明、韧性高的薄膜.实验还发现聚醚砜组分含量变化对共聚物的热性能影响很大,对杂萘联苯聚醚砜改性效果明显.     

甲基丙烯酸酯嵌段共聚物的合成与表征

研究了ＭＭＡ和Ｃ７～９ＭＡ的阴离子共聚合，得到了Ａ－Ｂ型嵌段共聚物。讨论了嵌段顺序、温度、引发剂及ＰＣ７～９ＭＡ－活性链长对ＭＭＡ嵌段共聚的影响，认为，当第一嵌段单体为Ｃ７～９ＭＡ，Ｔ＝－２０℃，［Ｉ］＝５．０～５．４×１０－２ｍｏｌ／Ｌ，Ｍｎ（ＰＣ７～９ＭＡ－）＜１．６×１０４时，有利于ＰＣ７～９ＭＡ－ｂ－ＰＭＭＡ嵌段共聚物的合成；采用ＧＰＣ、ＩＲ、ＮＭＲ对所得嵌段共聚物进行了表征。     

聚乳酸/改性聚醚酯嵌段共聚物共混体系的结构与性能

采用熔融挤出共混的方法制备了聚乳酸(PLA)/改性聚醚酯嵌段共聚物(CH4132)共混物。利用差示扫描量热分析、动态力学热分析及场发射扫描电子显微镜等研究了共混物的结晶熔融行为、动态力学性能、相形态及力学性能。结果表明,CH4132的添加抑制了PLA的冷结晶能力,而对熔融及熔态结晶行为没有影响;PLA与CH4132具有部分的相容性且相容程度受CH4132含量影响;共混物呈现出以PLA为海、CH4132为岛的典型海岛结构;共混物的拉伸强度、弯曲强度和模量等刚性量随CH4132添加而降低,但体系的断裂伸长率和冲击强度等韧性性质得到了明显改善,在CH4132质量分数为10%时断裂伸长率最大,质量分数为30%时冲击强度为纯PLA的4.5倍。     

Influence of superplasticizer and curing on porosity and pore structure of cement paste

Most concrete produced today contains admixtures. Superplasticizers (SP) are used for the purpose of improving workability and reducing the water to cement ratio; therefore producing more durable concrete. SP cause better dispersion even at high water to cement ratio. Although SP improves the dispersion of particles, it is not quite clear how the addition of SP affect the porosity and pore size distribution of cement paste. The purpose of this study was to examine the influence of one type of SP on porosity and pore size distribution under different curing regimes. Paste specimens with and without SP were prepared at constant water to cement ratio of 0.45. Specimens were cured for 28 days and some for six months. Specimens were exposed to high temperature (45°C) and normal temperature curing (20°C) and also subjected to different relative humidities (100%, 55% and 25%). Curing at high temperature was carried out to simulate temperature in hot climates. Tests on porosity and pore size distribution were conducted using mercury intrusion porosimetry. The results show that the inclusion of SP decreases the total intruded pore volume of paste. The dominant pore diameter, however, does not seem to be affected and the percentage of pores smaller than 100 nm increases in the presence of SP.     

Setting of cement with controlled superplasticizer addition monitored by ultrasonic measurements and calorimetry

The use of ultrasonic measurements to monitor the early hydration of cement based systems is extended during the last decade. Superplasticizers (SPs) affect the rheology just as the hydration process of cementitious systems. With delayed addition, a minor consumption and intercalation of SPs can take place, which enhances their impact.This study presents investigations on cement pastes and mortars with additions of different SPs in varying dosages and addition times. Effects on hydration process, setting and rheological behavior were monitored.The critical as well as the saturation dosage can be reduced significantly with a delayed addition of the SPs. By the application of highly charged SPs, the onset of the acceleration is significantly retarded by delayed addition whereas low charged SPs influence the onset by its concentration. Calorimetric and ultrasonic data determine significant influences on the renewed AFt formation and transformation of AFt to AFm during the deceleration period. A new calculation method was applied which allows a very good location of the initial setting directly from the calorimetric data. A nearly direct correlation was found between the calculated onset of the acceleration and the time of the first inflection point of the ultrasonic velocity.     

Effect of addition time of a superplasticizer on cement adsorption and on concrete workability

The effect of addition time of a naphthalene-based superplasticizer (SNF) on the adsorption behavior on type I Portland cement slurries and on the concrete workability was studied. Test results indicate that the adsorption behavior of SNF on cement particles follows a Langmuir isothermal adsorption model. As the addition time increases, the saturated adsorption amount of SNF decreases sharply at the beginning and then more slowly. In comparison, the concrete workability decreases slightly in the early phase and then falls off abruptly. Most importantly, the transition points in both cases appear to be the same, at about 10–15 min. This strongly suggests that a close relationship exists between the SNF adsorption behavior on cement particles and the workability of concrete. In addition, the optimum addition time of SNF to concrete should be in this period, which corresponds to the beginning of the dormant period of the cement hydration process.     

Modelling flow through unsaturated zones: Sensitivity to unsaturated soil properties

A numerical model to simulate moisture flow through unsaturated zones is developed using the finite element method, and is validated by comparing the model results with those available in the literature. The sensitivities of different processes such as gravity drainage and infiltration to the variations in the unsaturated soil properties are studied by varying the unsaturated parameters α andn over a wide range. The model is also applied to predict moisture contents during a field internal drainage test.     

Crosslinking agents of unsaturated polymers: evaluation of the agent efficiency

We have performed a comparison of efficacy of several curing agents. We have synthesized curing agents with C=C-bonds of allylic, acrylic or peroxide group type, as derivatives of pyromellitic acid: diallylic ester (I), tetraallylic ester (II), di-(2-methacryloyloxyethyl)-pyromellitate (III), tetra-(2-methacryloyloxyethyl)pyromellitate (IV), ditert-butylperoxypyromellitate (V) and tetratert-butylperoxypyromellitate (VI). The possibility to use these agents for curing an unsaturated film-forming copolymer which contains polybutadiene fragments was investigated. The unsaturated curing agents (I–IV) are able to form crosslinked copolymers in the presence of peroxide initiators such as benzoyl peroxide. The gelation process orders as well as the values of the effective activation energies for all curing agents studied have been determined. In the presence of curing agents of methacrylic type (III–IV) the crosslinking proceeds more rapidly than in the presence of allylic esters. Unsaturated curing agents containing carboxylic groups (I, III) promote faster formation of three-dimensional structures than tetra-substituted derivatives of pyromellitic acid. For curing agents of the peroxide type the inverse relation is observed. The hardness of films obtained using carboxylic curing agents is higher than for noncarboxylic ones. Films obtained in the presence of unsaturated curing agents exhibit higher hardness than those obtained in the presence of peroxide agents. Electronic Publication     

PA1212-b-PEG嵌段共聚物的组成对结晶和熔融行为的影响

研究以双端羧基尼龙1212为硬段,以双端氨基聚乙二醇为软段的聚酰胺-聚醚分嵌段共聚物的结晶行为。用偏光显微镜、差示扫描量热法研究了不同组成共聚物的结晶形态、熔融结晶温度的影响。PLM观察到共聚物的结晶形态随硬段分子量的增大趋于完善,软硬段相容性随软硬段分子量增大而变差;DSC扫描表明共聚物的熔融温度随着硬段分子量增大而增大,软硬段分子量较大时软硬段相容性较差。     

In situ ozonation of anthracene in unsaturated porous media

Soil column experiments were conducted to investigate the effect of ozonation duration, contaminant content, particle size, moisture content, OH radical scavenger and soil organic matter on the removal of anthracene by in situ ozonation. In the whole study, the gas flow rate was 100 mL/min and concentration of gaseous ozone was 40 mg/L. The removal efficiency increased with the elapsed time, but the removal rate decreased in the range of 0–90 min. As anthracene content in sand decreased from 50 to 10 mg/kg, the removal efficiency increased from 42.1% to 62.0%, and ozone passed through soil column more rapidly. However, the ozone effectiveness reduced when anthracene content dropped. Small particle size provides a large interfacial area, which led to the high removal efficiency and long ozone breakthrough time in the column. The profile of residual anthracene in soil column varied more greatly at smaller particle size. The removal efficiency reduced when the moisture content rose from 0% to 9.1%. The ozone breakthrough time also decreased with the increasing moisture content. The presence of sodium bicarbonate or humic acid reduced the removal efficiency to some extent. GC–MS was employed in this study to determine 9,10-anthraquinone as the main ozonation product.     

碳分子筛填充聚醚共聚乙酰胺膜渗透汽化分离水溶液中的醋酸正丁酯

将碳分子筛(CMS)引入到聚醚共聚乙酰胺(PEBA)中制备填充膜,采用FTIR、SEM对膜的物理化学结构进行了表征,结果显示CMS与PEBA间未发生化学交联,CMS在膜中分散均匀且与PEBA结合紧密.通过拉伸实验,测定了膜的机械性能.借助溶胀实验,考察了膜在醋酸正丁酯水溶液中的溶胀性能.通过渗透汽化实验,验证了膜的渗透汽化性能,结果表明通量随着温度的升高而增大,分离因子则随温度升高而下降;当料液浓度增大时,醋酸正丁酯的通量和分离因子都显著增大;当CMS填充量为20%时,膜的分离效果最佳,总通量和分离因子分别可达到421.6 g/(m2.h)和590.4.利用Arrhennius方程,关联了通量与温度的关系.另外,还对膜结构与溶液组分的相互作用以及膜中CMS存在通道作用的机理进行了探讨.     

On the problem of cavity expansion in unsaturated soils

The problem of cavity expansion in unsaturated soils is investigated. A unified constitutive model formulated in a critical state framework using the concepts of effective stress and bounding surface plasticity theory is adopted. Consideration is given to the effects of suction and particle crushing in the definition of the critical state and the evolution of the bounding surface. The model accurately captures stress-strain behaviour for a range of load paths encompassing that experienced by soils during cavity expansion. Specifically, the similarity technique is used to solve the cavity expansion problem in speswhite kaolin and Kurnell sand. Eight governing equations are defined and solved simultaneously as an initial value problem including an equilibrium equation for stresses around the cavity. Cylindrical and spherical cavities are considered, as are constant suction and constant moisture content conditions. Substantial differences in the stress-strain response of saturated and unsaturated soils surrounding expanding cavities are observed. The paper highlights the major influence of suction and the importance of accounting for this when using cavity expansion theory to interpret results of the cone penetration and pressuremeter tests.     

A probabilistic solid-porous model to determine the shear strength of unsaturated soils

A probabilistic solid-porous model has been developed to determine the shear strength of unsaturated soils. The probabilistic model was built by analyzing the probability of a certain pore or group of pores of a network to fill or remain filled with water during a wetting or drying process, respectively. This model is used to determine the equivalent stress which represents the stress supported by the solid skeleton of an unsaturated soil and is related to the strength of the material. The probabilistic model is an alternative to the use of computational models and shows some important advantages. The theoretical results of the model are compared with a series of triaxial tests performed at constant suction and constant volume. These comparisons demonstrate that this model is adequate to establish the strength of unsaturated materials.