4种保水剂吸水和保水性能的差异性研究

通过室内实验,对比研究了四种保水剂的吸水、保水性能。测试吸水倍率、吸水速率、保水能力及有效持续性等指标,采用评分法对四种保水剂进行综合评价。结果表明:保水剂的吸水倍率与所吸溶液的性质有很大关系。4种保水剂在去离子水中的吸水倍率最高,随着溶液中离子浓度的增大吸水倍率逐渐减小。保水剂颗粒大小对吸水速率有较大影响,对其他指标影响均不大;4种保水剂均具有较强的反复吸水能力。综合分析认为,4种保水剂中,吸水保水性能最优的保水剂为4#保水剂,其成分为聚丙烯酸盐和聚丙烯酰胺共聚体。其次为3#保水剂,再次为1#保水剂,最差的是2#保水剂。     

聚丙烯酸/硅藻土复合保水剂的制备与性能

将硅藻土（DE）与丙烯酸（AA）共混，以N-N亚甲基双丙烯酰胺（MBA）为交联剂，采用溶液聚合一步法制备了PAA/DE复合保水剂，采用红外光谱仪、高级扩展动态流变仪、扫描电子显微镜等对其结构和性能进行了研究。FT IR分析表明DE与PAA间存在较强的界面作用。应变扫描结果表明：复合保水剂中存在网络结构；且随DE用量增加，保水剂的储能模量呈先增加后降低的趋势。DE的加入可以显著提高保水剂的抗压缩性能，同时使保水剂的网络结构变得规整而致密，网壁增厚且网孔尺寸降低，改善溶胀性能；当DE添加量为5wt%时，PAA保水剂的平衡溶胀率（794%）较纯PAA保水剂提高了29.32%，同时抗压缩性能提高了151%。 PAA/DE复合保水剂在室温下具有较好的保水效果，2 h内水分的减少率低于2%， PAA/5 wt% DE保水剂的蒸发平衡时的减少量为33.32%。     

水葫芦基保水剂的制备

利用水葫芦中的纤维素,以过硫酸钾为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,采用复合引发剂体系制备出土壤改良用途的水葫芦基保水剂。考察了单体用量、引发剂用量和交联剂用量对保水剂的吸水吸盐性能的影响。结果表明,以水葫芦为原料,与单体AA进行接枝共聚制备水葫芦基保水剂的最优单体与纤维素的质量比为12∶1,最优引发剂KPS用量为单体质量的0.6%,最优交联剂NMBA用量为单体质量的0.12%,制得的树脂吸水吸盐性能最优。     

稀土与农业

本文简介了稀土农用研究概况、稀土对植物的生理作用、稀土农用的安全性、稀土农用的方法,以及稀土对农业的增产效果等。     

稀土元素日允许摄入量与农用安全性探讨

稀土农用是我国独立开创的稀土应用领域,30年来,取得了巨大的经济效益。然而,作为元素周期表中第ⅢB主族的重金属,稀土元素不是动植物的必需微量元素,其生理效应的机制还不清楚,稀土农用的安全性问题一直受到密切的关注。本文从稀土元素分析方法与人均总膳食摄入量、稀土元素毒理实验方法与日允许摄入量、稀土农用对土壤中稀土元素含量和化学形态的影响、以及稀土农用对食物中稀土元素含量影响的4个方面,对文献报道作了分析、整理和评定,结论是只要对使用的范围、剂量及施用方式进行限制,稀土农用是一种安全的农业增产方式。     

稀土农用研究的现状与前景

本文主要介绍了我国在稀土农用施用技术、稀土土壤学、稀土植物生理、毒理卫生学、稀土农用分析和稀土农用产品及其应用方面的进展和成果。简要介绍了国外开展稀土农用研究的情况并分析了其未取得成果的原因。合理施用稀土可使农作物增产5～15％,并有改善作物品质的作用。经济效益大约是一元投资七元收益。稀土农用的关键技术已获突破,建立一个稀土应用的新领域已成为现实的任务。     

农用稀土对糯玉米幼苗光合变化和生理指标的分析

为了探明农用稀土对糯玉米幼苗光合和生理指标,采用随机区组排列,研究了农用稀土对糯玉米幼苗叶绿素荧光参数、光合参数、根系活力、植株形态和生物量、MDA和抗氧化酶活性的影响.结果表明,施用农用稀土能显著提高荧光参数Fv/Fm,ETR,NPQ,Fv/F0,Yield,qP最大值分别比对照增加了4.8%,23.9%,45.3%,11.01%,14.8%,26.5%;糯玉米幼苗的光合参数、根系活力、植株形态、生物量、抗氧化酶活性等变化趋势是一致的,在低浓度时,随着农用稀土浓度提高,它们逐渐地提高;到一定浓度后,随着农用稀土浓度升高,它们反而降低;MDA的变化趋势与它们是相反的.     

1,2,4-三唑类化合物的合成及其农用活性研究进展

1,2,4-三唑类化合物是生物活性分子的重要结构单元,具有多种药理活性,特别是在抗真菌、杀虫和除草等农用活性方面得到广泛应用。本文对部分1,2,4-三唑环上的活性位点改性研究及其在农用活性方面的应用进行了总结归纳,期望为后期该类化合物的设计合成及农用活性研究提供参考和借鉴。     

农用稀土施用量、宽窄行配置对鲜食糯玉米产量构成因素及品质的影响

通过田间小区试验,研究了不同稀土施用量、不同宽窄行配置对鲜食糯玉米产量、产量构成要素和品质的影响。结果表明:农用稀土施用量为200 mg.kg-1时,宽窄行配置为70+50 cm时,吐丝进程最快;皮渣比率、可溶性糖含量、籽粒粗淀粉含量、植株全氮含量均比较小;蒸煮品质即风味、气味,糯性等表现最佳。小花总数、受精小花数、结粒数随着农用稀土施用量增加而减少,且宽窄行配置70+50 cm时,为最大。在农用稀土施用量为600 mg.kg-1时,宽窄行配置60+60 cm时,鲜穗产量为最高,达11883.9 kg.hm-2,在农用稀土施用量为800 mg.kg-1时,宽窄行配置70+50 cm时,鲜穗产量为最低,为9355.8 kg.hm-2。     

全国农用稀土毒理研究成果评审会在厦门召开

全国农用稀土毒理研究成果评审会议于1984年10月27～30日在厦门召开,会议由全国稀土农用研究和示范协作网主持,邀请中国预防医学中心卫生研究所、卫生部食品卫生监督检验所、哈尔滨医科大学、北京医学院、上海第一医学院和武汉医学院等单位的有关专家组成评审委员会,出席会议的代表共31人。     

高吸水性树脂

用热力学理论和相转变理论阐明了高吸水性树脂的吸水机理。解释了高分子链上的电荷密度、外界溶液离子强度以及交联度对吸水倍数的影响，并指出了影响吸水速率的因素。介绍了淀粉类、纤维素类、共聚合类、复合类以及可生物降解类高吸水性树脂近30年来的研究状况以及存在的问题，简要介绍了高吸水性树脂的应用。     

Determination of Polyacrylate Super Absorbent Polymers in Air

Abstract

A sampling and analytical method has been developed for measurement of a starch-grafted, cross-linked sodium polyacrylate in air. Also, the method is applicable to measurement of several other polyacrylate super absorbent polymers and involves air sampling with a 37-mm PVC membrane filter, treatment of the sample with 0.07 M cupric acetate solution to form a copper-polymer precipitate, digestion of the precipitate with nitric and perchloric acids, and measurement of the copper content by inductively-coupled plasma-atomic emission spectrophotometry. The interior surface of the front piece of the filter cassette also is analyzed. This analytical method has been compared with a sodium method that currently is used. Detection limits for various super absorbent polymers ranged from 4.4 to 14 micrograms per sample.     

高吸水性树脂的合成与应用

综述了高吸水性树脂的研究、发展状况。并指出了高吸水性树脂研究中存在的问题。     

Application of Polyvinyl Alcohol (PVA)/Carboxymethyl Cellulose (CMC) Hydrogel Produced by Conventional Crosslinking or by Freezing and Thawing

Hydrogels for this study were prepared from a mixture of PVA and CMC using three different techniques, i.e., freezing and thawing, electron‐beam irradiation or combined freezing and thawing and electron beam irradiation. A comparative study between the three techniques was carried out in terms of gel fraction (%) and swelling (%). It was found that the physical properties of the hydrogel were improved when the combination of freezing and thawing and irradiation were used rather than just freezing and thawing, or irradiation only. The effects of temperature and soil fertilizers on swelling (%) were examined to evaluate the usefulness of the hydrogel as a super absorbent in the soil. It was found that the swelling ratio increased as the composition of CMC increased in the blend. Hence, the blend having the composition 80/20 (CMC/PVA) was used as a super absorbent in the soil for agriculture. Moreover, the water retention increased in the soil containing this hydrogel. Thus, this type of hydrogel can be used to increase water retention in desert regions.     

高吸水性树脂溶胀热力学及吸水机理

分析了高吸水性树脂吸水的热力学本质，探讨了Flory公式的意义，通过简化的Flory公式得到吸水率与外部溶液离子强度的简单关系。同时，对高吸水性树脂在与水的相互作用以及溶胀过程进行了探讨，并以此为基础解释了一些吸水、保水现象。     

Plasma Polymers Applied to Chemical Sensing

The paper describes attempts to apply plasma polymers to the development of chemical sensors. The plasma polymers were used as membranes to coat conventional conducting polymer sensors, as stand-alone chemiresistive sensors and as absorbent coatings on quartz crystal microbalances. The plasma polymers were derived from combinations of pyrrole and three silicon containing monomers. In the chemiresistive sensors, conductivity was induced in the polymer matrix by doping with iodine. The paper describes the experimental polymerization conditions, the physical characteristics of the polymers, and the application of the different polymers to sensing common volatile analytes.     

超高吸水性聚丙烯酸钠的制备

以聚-γ-巯丙基硅氧烷作为引发剂,将丙烯酸和少量交联剂对二乙烯基苯,在四氯化碳和氢氧化钠水溶液中进行共聚,可得到吸水量400倍以上的超高吸水性聚丙烯酸钠。如果同时加入二氧六环,没有交联剂对二乙烯基苯,也可以得到吸水量将近400倍的超高吸水性聚丙烯酸钠。     

Novel nanocomposite super absorbent polymers reinforced by clay nanosheets

Super absorbent polymers (SAPs) are of great significance in industry and personal care, etc. The study aims to introduce novel nanocomposite SAPs that are able to uptake very high water content while maintaining excellent strength. The polymers are synthesized by in situ polymerization with the presence of exfoliated montmorillonite (MMT) and trace amount of crosslinkers. SEM images show macroporous structures of these nanocomposites, while TEM images demonstrate excellent distribution of the MMT nanosheets in the polymer matrix. The effect of clay content on the equilibrium water uptake has been systematically investigated. More importantly, the highly swollen nanocomposite SAPs show very high tensile strength (up to 550 kPa), which is much higher than those reported in literature and used in the market. These SAPs with high water uptake and strength may find applications in agriculture and oil fields.     

高吸水性树脂的SEM研究方法

高吸水性树脂是一种新型高分子材料,是交联型高分子电解质。它能吸收比自身重几百倍至几千倍的水;一旦吸水成水凝胶后,即使加压也很难把水分离出来。因此,它可应用于工农业生产、医疗卫生和日常生活等方面,近年引起人们极大关注。有些学者研究其吸水机