自交联苯丙胶乳纸张涂布剂的合成及其膜性能研究

以苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)、丙烯酸(AA)、丙烯酸羟乙酯(HEA)为原料,通过乳液聚合法合成固含量约为40%的轻度交联苯丙胶乳纸张涂布剂。考察了不同单体用量对乳胶膜机械性能的影响。结果表明,当m(MMA)=11.5%,m(AA)=6.9%,m(HEA)=11.5%,m(St)/m(BA)=1∶2时,乳胶膜呈现良好的机械性能,乳液粒子尺寸较小且分布窄,平均粒径为128.9nm;且聚合物具有良好的耐热性。     

丙烯酸酯乳液及其胶膜的制备和性能表征

采用预乳化半连续自生种子乳液聚合的方法以丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)和苯乙烯(St)为主链,丙烯酸(AA)为功能单体共聚制备丙烯酸酯乳液。研究了预乳化时的相比、种子乳液的含量、反应保温时间、硬单体St与MMA的比例、功能单体用量以及软硬单体比例等对乳液性能的影响。研究结果表明,预乳化油水比为1.8∶1、种子乳液质量为预乳化液的1/3、m(St)/m(MMA)=1∶5.5、AA占单体总量为3%时能得到稳定性好、粒径较小且分布较窄、胶膜吸水率低的乳液。通过拉伸测试、差示扫描量热、红外光谱及凝胶渗透色谱等方法,本实验发现随着软硬单体配比增加,乳胶膜的拉伸强度和玻璃化转变温度(Tg)逐渐下降,断裂伸长率逐渐提高。最终得到了粒径分布在114 nm~290 nm之间,相对分子质量分布指数为1.679的目标产物。     

丙烯酸丁酯-苯乙烯共聚乳液型吸油树脂的合成及性能研究

以丙烯酸丁酯(BA)和苯乙烯(St)为单体,二乙烯基苯(DVB)为化学交联剂,采用乳液合成法制备吸油树脂.通过正交实验得到最佳合成配方,即BA∶ St=2∶1,w(二乙烯苯)=2％,w(过硫酸钾)=1％,w(丁苯橡胶)=O％,二甲苯的吸收率达到8.73g/g.同时探索了单体配比、DVB用量、油品种类对树脂吸油性能的影响...     

两性丙烯酸酯聚合物乳液表面施胶剂的制备及应用

以PVA为分散剂,甲基丙烯酸(MAA),苯乙烯(St),丙烯酸丁酯(BA),甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体,通过无皂乳液共聚反应制备了一种两性聚合物乳液表面施胶剂。讨论了反应条件的变化对乳液稳定性及施胶应用效果的影响,确定了较佳的合成条件:采用种子聚合法,n(DMC)/n(MMA)/n(BA)/n(St)=1∶1.5∶1.6∶2.4,w(KSP)=0.6%,反应温度85℃,反应时间4 h。DSC测量出玻璃化温度为56.8℃;TEM显示乳胶粒呈球状;粒径分析显示乳液平均粒径为107 nm。以2.0%的聚合物乳液进行表面施胶时,可使施胶度达到13 s,拉毛速率达到2.9 m/s。     

无皂硅丙胶乳表面施胶剂的制备及对纸张的增强作用

以γ-甲基丙烯酰氧丙基三甲氧基硅烷(KH570)作自交联单体,聚乙烯醇(PVA)为高分子胶体稳定剂,苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酸(MAA)为单体采用无皂种子聚合制备了稳定性好、性能优异的无皂硅丙乳液表面施胶剂,并优化了合成工艺条件。结果表明,当w(MAA)=2%~3%,软硬单体比例n(BA)/n(St)=2~2.5,w(PVA)=10%~15%,w(KH570)=5%时,无皂硅丙乳液表面施胶剂具有优异的施胶效果;以质量分数为1.0%的聚合物乳液进行表面施胶时,纸张施胶度可达14.5 s,表面强度达3.69 m/s,耐折度3300次。     

以松香为功能单体的苯乙烯丙烯酸酯乳液(SAE)表面施胶剂的制备及表征

利用低黏度阳离子淀粉(CS-8)的乳化、分散作用,采用无皂乳液聚合的方法,以苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)为主要原料,引入松香作为功能单体,合成了核壳型阳离子苯乙烯丙烯酸酯乳液(SAE)。讨论了其合成影响因素,并优化了合成工艺条件;用扫描电子显微镜(SEM)、红外光谱仪、激光粒度仪和电荷密度测定仪(PCD)对产物进行了表征。研究表明,当w(CS-8)=8%,w(APS)=0.5%,w(松香)=2%时,所制SAE无皂乳液性能优异,施胶效果良好。在SAE制备过程中添加松香作为功能性单体,能明显改善经SAE表面施胶后纸页的抗水性能。     

预乳化半连续法聚丙烯酸酯核壳乳液的制备与性能

以甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)为主单体,丙烯酸(AA)和丙烯酸羟丙酯(HPMA)为功能性单体,采用预乳化、半连续法种子乳液聚合方法合成了一种硬核软壳聚丙烯酸酯乳液。文中研究了核壳质量比、核和壳中软硬单体BA/MMA质量比对乳液及涂膜性能的影响。通过激光粒度仪、透射电镜、差示扫描量热分析、动态力学分析等手段对乳液粒径及表面形貌、涂膜的玻璃化转变温度、力学性能进行了分析,并对漆膜的硬度、附着力、吸水率等进行了检测,结果表明,核壳质量比为5∶5、核中m(BA)∶m(MMA)为0∶50、壳中m(BA)∶m(MMA)为24∶26时,储存模量可达到3500 MPa,漆膜硬度为2H,附着力为1;乳胶粒有明显的核壳结构,粒径在100 nm左右。     

交联剂对聚硅氧烷/丙烯酸酯乳液性能的影响

采用阳离子开环乳液聚合法制备了含有双键的聚硅氧烷乳液(PSiO)。以丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)等为主要单体,乙氧基化三羟甲基丙烷三丙烯酸酯(EO9TMPTA)为交联剂合成了一系列聚硅氧烷/丙烯酸酯(PSiOA)乳液。采用傅里叶红外光谱和透射电镜表征乳液的结构形态。考察了EO9TMPTA用量对PSiOA乳液的稳定性、粒径、流变行为和对乳胶膜的吸水率、拉伸性能等各项性能的影响。结果表明:随着EO9TMPTA用量的增加,乳液凝聚率、黏度增大,胶膜的热稳定性、耐水性等综合性能得到了较大提高。当m(EO9TMPTA)=3g时,综合性能达到最佳,拉伸强度为5.62MPa,断裂伸长率为653%。     

无溶剂阴离子聚氨酯/丙烯酸酯乳液的制备及其膜性能研究

采用原位聚合法,以异佛尔酮二异氰酸酯(IPDI)、聚己内酯二元醇(PCL)、二羟甲基丁酸(DM-BA)、甲基丙烯酸羟乙酯(HEMA)、甲基丙烯酸缩水甘油酯(GMA)、甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)等为主要原料制备得到了无溶剂阴离子聚氨酯-丙烯酸酯(WPUA)复合乳液,并系统地研究了n(NCO)/n(OH)(R值)、亲水扩链剂DMBA和硬单体MMA的用量对WPUA乳液及其膜性能的影响。结果表明,WPUA乳胶粒呈核-壳结构,当R=1.2,m(DMBA)=3.1%,m(MMA)=26.6%时,所得的WPUA乳液粒径较小且分布窄,平均粒径为98.98nm,乳胶膜呈现良好的物理机械性能,拉伸强度为17.02MPa,断裂伸长率为109%,吸水率低至6.9%。     

含氟丙烯酸酯复合乳液的制备及性能

含氟丙烯酸酯性能优异,目前以丙烯酸六氟丁酯(HFBM)单体合成水性含氟丙烯酸酯乳液的报道较少。以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)为主要单体,HFBM为功能单体,采用预乳化工艺合成了含氟丙烯酸酯复合乳液,优化了乳液合成条件(复合乳化剂配比、引发剂用量、含氟单体用量),并用红外光谱和热重分析研究了优化条件合成乳液的结构和其所成乳胶膜的热稳定性。结果表明:复合乳化剂中m(十二烷基硫酸钠)∶m(曲拉通X-100)=3∶2,引发剂(过硫酸钾)用量为1.0%,含氟单体用量为9%时,合成的含氟丙烯酸酯复合乳液性能最好,具有较大的单体转化率和较小的凝胶率,乳胶膜有较大的拉伸强度;HFBM被成功地引入聚合物链段结构中,并使聚合物的热稳定性大幅提高。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.