红外隐身技术用石蜡与MMA接枝改性的研究

以过氧化苯甲酰(BPO)为引发剂,使石蜡与甲基丙烯酸甲酯(MMA)单体接枝共聚.用红外和综合热重法对其结构和热性能进行了分析.研究了反应温度、反应时间、引发剂含量以及单体的用量对接枝率的影响,确定了合成高接枝率产物的优化工艺条件.结果表明,当反应温度为100℃,反应时间为3h,BPO以及单体的用量分别为0.1g和3ml时,接枝率最高.石蜡与MMA的接枝成功拓宽了石蜡的相变温度,其相变潜热最高可提高近50%.最后,分析了接枝共聚物分子结构与其相交温度和潜热的关系.     

低温柔韧型高硬度水性聚氨酯分散体的合成与性能研究

制备了具有核壳结构的水性聚氨酯-丙烯酸酯（WPUA）复合分散体。研究了NCO／OH摩尔比、醇扩链剂、亲水性扩链剂、E-20、MMA等对分散体及涂膜性能的影响,从而确定了最佳合成配方,获得了低温成膜性好、贮存稳定性好、高硬度、耐水性佳的水性聚氨酯分散体及其涂料。     

适用于高阶QAM系统的多模盲均衡新算法

利用QAM信号星座图特点,该文提出了两种含软判决的多模盲均衡算法：MMA+SDD算法和SMMA+SDD算法。两种算法都克服了CMA算法剩余误差大的缺点,在均衡的同时能够克服相位偏转。从仿真结果看,两种新算法的收敛性能和稳态均方误差较CMA+SDD有了进一步提高,其中,MMA+SDD收敛性能最佳,SMMA+SDD的计算复杂度最低。     

手工电弧焊焊工考试是双面焊好还是单面焊好——浅谈我国《锅炉、压力容器焊工考试规则》

本文阐述了单面焊与赋面焊、带垫板的单面焊的不同之处，进而指出焊工考试采用单面焊与实际焊接生产的脱节现象，提出焊工考试时，板状对接应考核双面焊。     

Radiation‐induced graft copolymerization of MMA monomer onto UHMWPE: Adhesion improvement

Graft copolymerization of methyl methacrylate monomer onto ultra high molecular weight polyethylene (UHMWPE) and acid‐etched UHMWPE was conducted using preirradiation method in air in the presence of a Mohr salt and sulfuric acid to improve adhesion to the bone cement. The grafted samples were characterized by Fourier transform infrared (FTIR) spectroscopy, gravimetric method, goniometry, and interfacial bonding strength measurements. The FTIR results showed the presence of ether, carbonyl, and hydroxyl groups for grafted films. The gravimetric results showed that the chromic acid etching and graft copolymerization had a synergetic effect so, the irradiated, then chromic acid etched at room temperature and grafted sample (Rad etch25) had the highest grafting degree. The interfacial bonding strength between UHMWPE and poly methyl methacrylate bone cement was considerably improved by graft copolymerization and chromic acid etching. The surface morphology was studied by scanning electron microscopy. The substitution of polar groups into the backbone of UHMWPE by chromic acid etching and graft copolymerization changed its contact angles with water and methylene iodide and increased its surface energy, as evidenced by contact angle measurements. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of high solids stable translucent nanolatexes of MMA/BA copolymers and MMA/BA/Veova-10 terpolymers with low MFFT using green industrial surfactants

In this study, high solids (∼40 wt%) stable translucent nanolatexes of MMA/BA copolymers and MMA/BA/Veova-10 terpolymers with MFFT ≤ 0 °C were synthesized by a modified semi-continuous microemulsion copolymerization. Ammonium persulfate was used as initiator and a redox system for post-polymerization to reduce the free monomers and achieve over 99.9% conversion. Methacrylic acid or acrylic acid at 1 wt% (calculated on monomers) and a combination of various “green” industrial anionic and non-ionic surfactants free of alkylphenol ethoxylates (APEO-free) at low concentrations (up to 10 wt% on monomers) were used. The resulting latexes were composed of polymer nanoparticles with average diameter size 50–80 nm and low polydispersity index. These friendly to the environment latexes can be potentially used as impregnation primer instead of classic solvent acrylic primers in architectural coatings.     

The development of conventional welding processes in naval construction

In recent years, analysis of the development of joining processes has resulted in the identification of two trends: the refinement and specialization of traditional processes on the one hand, and the development of novel technologies on the other hand. This dual line of trends has sometimes led to points of contact, with the development of the so-called hybrid technologies, involving the use of joining processes based on different physical principles for the creation of a single joint. The scope of this article is to provide a framework view of the state of development of conventional joining technologies with regard to shipbuilding applications.     

甲基丙烯酸甲酯的合成及市场

对目前甲基丙烯酸甲酯的各种合成路线进行了汇总和比较,并对其目前的市场情况进行了阐述分析。     

MMA防水涂料在城际高铁防水中的应用及其存在问题浅析

介绍了MMA防水涂料的制备及相关技术指标,结合在沪宁城际和广珠城际高铁桥面防水中的实际应用,详细阐述了MMA防水涂料的施工工艺以及施工应用中存在的问题,并对这些问题提出了合理的解决方案。     

Hypertension incidence after tap-water implementation: a 13-year follow-up study in the arseniasis-endemic area of southwestern Taiwan

Hypertension is the leading cause of cardiovascular disease worldwide. Long-term arsenic exposure has been linked to increased risk for hypertension; however, little is known whether a previous exposure has lingering effects on hypertension after the exposure being reduced significantly for decades. The study cohort was established in 1990 in an arseniasis-endemic area of 3 villages — Homei, Fuhsin, and Hsinming in Putai Township located on the southwestern coast of Taiwan, where residents were exposed to artesian well water (median level = 700 to 930 μg/L) until early 1970s. The original cohort consisted of 490 non-hypertensive residents over 30-yrs-old and 352 of them were successfully followed up in 2002/03. Arsenic concentrations in the artesian well water consumed by residents during 1960s were used to indicate the previous exposure while urinary arsenic species measured in 2002/3 was used to represent current exposure. Hypertension incidences were 27.4, 65.6, and 69.1, per 1000 person-years for men aged 35-49, 50-64, and 65-74 years, respectively being higher than the corresponding rates of 25.1, 46.1, and 57.2 in a community-based longitudinal study. Cancer was the major cause of the total deaths (17/30 = 57%). Diastolic blood pressure was shown to increase with an increased cumulative arsenic ingestion from drinking water (β = 0.27, p < 0.001). The incidence was increased by 2.43-fold in subjects of As(V) ≥ 2.67 μg/g creatinine as compared to those of As(V) < 1.20 μg/g creatinine (the third vs. first tertile; p = 0.047) after adjustment for conventional risk factors. This study suggests that three decades after cessation of drinking artesian well water, residents of the endemic area are still at increased risk for developing hypertension, particularly those who excrete high amounts of As(V).