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淀粉三元接枝复合型高吸水性树脂的合成及性能研究 总被引:7,自引:2,他引:5
本研究首次用亚硫酸氢钠和过硫酸铵组成的氧化还原引发剂,N,N-亚甲基二丙烯酰胺为交联剂,使淀粉三元接枝丙烯酸和丙烯酰胺在含有粘土的悬浮液中反应,制得淀粉复合型高吸水性树脂,性能测定发现,该树脂在5min内已吸水超过1000g/g,并且树脂的吸水能力随温度的升高而下降缓慢,该树脂在室温下可吸去离子水1800多倍且具有较好的凝胶强度。中也讨论了淀粉形态,粘土种类,粘土用量和交联剂用量对吸水性树脂性能的影响。 相似文献
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保水剂在沙漠化地区造林绿化中的应用 总被引:3,自引:0,他引:3
保水剂是一种高吸水性树脂,可吸收自身重量的数百倍至上千倍的纯水,并且这些被贮存在保水剂中的水分可以为各种植物根系直接吸收,这一特性决定了保水剂在沙漠化地区造林绿化中的应用前景。 保水剂因原料和合成方法的不同而分为淀粉接枝丙烯酸盐共聚交联物和丙烯酰胺—丙烯酸盐共聚交联物两类。丙烯酸盐聚合交联物吸水能力和速率最强,但耐盐和稳定性较差,寿命短。淀粉是天然高分子,便宜、易于降解,其吸水能力较聚丙烯酸盐差。 相似文献
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采用分级转化策略,首先将糠醛渣中的木质素组分制备成木质素基分散剂(LS),在糠醛渣用量100 g、去离子水用量1 000 g,反应温度70℃、反应时间3 h、氢氧化钠用量6.5 g、亚硫酸钠1.6 g、甲醛0.2 g的条件下得到的木质素基分散剂的分散力为105%。以分离得到的纤维素残渣制备吸水性树脂,探究了反应温度、引发剂过硫酸铵(APS)用量、交联剂N,N′-亚甲基双丙烯酰胺(MBA)用量、复合单体丙烯酸(AA)和丙烯酰胺(AM)总用量对吸水性树脂吸水倍率的影响。在丙烯酸中和度为60%,引发时间0.5 h,复合单体用量9 g,引发剂用量1.3 g,交联剂用量0.05 g,反应温度52℃,接枝共聚反应时间3 h的优化条件下,吸水性树脂的吸水倍率达到64.6 g/g。FT-IR分析表明AM、AA和纤维素残渣发生了接枝反应;SEM表明反应生成了交联网状结构的产物;热重分析说明AA和AM的引入提高了吸水性树脂的热稳定性;XRD表明AA、AM的接枝反应发生在纤维素残渣的骨架上。 相似文献
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木质素磺酸盐与丙烯酸类单体的接枝共聚研究 总被引:2,自引:0,他引:2
研究了木质素磺酸盐粗产品与丙烯酸类单体的接枝共聚反应,对其反应机理进行了评述,并采用红外光谱分析证实了聚合反应的发生。与现有的对纯化木质素磺酸盐的研究结果不同,粗产品的接枝共聚反应可以单纯由过氧化氢引发,原因可能是粗产品中含有的还原性物质起到了亚铁离子的作用。研究表明,合适的引发剂用量应该是木质素磺酸盐干重的1.5%~2.0%,当反应体系中引发剂用量充分时,反应温度和时间对产物粘度的影响不明显。产物的粘度随丙烯酸类单体用量的增加而提高,在相同单体用量下,丙烯酰胺改性产物的粘度高于丙烯酸改性产物,原因是丙烯酰胺聚合物上酰胺基的亲水性比丙烯酸聚合物上羧酸基的亲水性低。 相似文献
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《技术与市场》2001,(3)
原有技术中的吸水材料,如脱脂棉、海绵、纸粉等,其吸水能力仅是自重的10倍~20倍,吸水能力较低。同时,吸水速度较慢,不能重复回收使用。 新型吸水材料高吸水树脂,其吸水能力具突破性,可达自重的几百倍至千倍。它是由高纯丙烯酸、氢氧化钠、植物淀粉、过硫酸钾、去离子水所组成。其具体配方配比为: 高纯丙烯酸:60%,氢氧化钠:27.2%,植物淀粉:9.7%,过硫酸钾:0.2%,去离子水:2.9%。 将高纯丙烯酸和93%分析纯的氢氧化钠称量,在水中进行中和,冷却后加入植物淀粉(如玉米粉)、过硫酸钾,搅拌,通入氮气,加热到40℃(成为半透明浆体),提出后放入陶瓷器皿中,加热到50℃,聚合。冷却,冷却后干燥、粉碎至100目。 高吸水树脂的吸水能力在目前的吸水材料中,是最具有突破性的一种,它吸水后能迅速膨胀,在几分种内就可吸收自身750倍~1000倍的水,从而达到100%的吸水率,将其点滴放水之后,还可以反复使用。吸水后呈现出晶莹剔透状。其吸水能力强的原因是具有亲水集团,且内部为立体网状结构。干燥时,它聚合成一团,当亲水集团遇到水分子时,由于正负相吸的原理层层吸引水分子,达到吸水的目的。 这种高吸水树脂具有以下特点: 1.具有... 相似文献
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对微波法合成羧甲基纤维素-丙烯酸高吸水性树脂的工艺条件进行了研究,主要考察了微波火力、反应时间、加料次序、原料配比、丙烯酸中和度、交联剂用量、引发剂用量等因素对产品吸水能力的影响,得到较好的工艺条件为:羧甲基纤维素(CMC)2g,丙烯酸18g,去离子水50mL,NaOH6.0g,K2S2 O8 0.7g,1g/L的N,N'-亚甲基双丙烯酰胺溶液4mL,微波低火加热2.5min,真空干燥温度60℃,树脂的吸去离子水倍率为738g/g.还测定了树脂对自来水、模拟尿、模拟血和生理盐水的吸液倍率,研究了产品的吸水速率、保水能力和再生性. 相似文献
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《林产化学与工业》2017,(4)
为有效利用野生淀粉资源,利用过硫酸铵(APS)引发丙烯酸(AA)和野豌豆淀粉的接枝聚合反应,采用静态一锅法制备了凝胶型淀粉基高吸水性树脂(VS-SAP)。研究了不同反应条件对产物吸水性能的影响,并探讨了起泡剂用量和加入时间对产物平衡和实时吸水性能的影响,结果表明:较佳制备条件为淀粉0.3 g,纯水24 mL,NaOH 0.80 g,APS 30 mg,N,N'-亚甲基双丙烯酰胺(MBA)6 mg,AA 3.6 mL,在65℃反应30 min后添加NaHCO_3 0.5 g/g(以淀粉质量计),继续反应4.5 h,在此条件下合成的VS-SAP得率为95.7%,其对纯水、自来水、生理盐水和人工尿液的吸液率分别为2 589、604、101和104 g/g,浸泡1 h吸自来水可达257 g/g。傅里叶变换红外光谱(FT-IR)结果显示丙烯酸成功地接枝到淀粉分子链上;碘显色试验结果显示产物仍然保留了淀粉的部分分子链结构;热重和扫描电镜结果显示起泡剂NaHCO_3的加入使产物热稳定性提高,形貌更加疏松、粗糙。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
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本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):131-138
The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):472-479
Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken. 相似文献
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Srisuda Thippayarugs Banyong Toomsan Patma Vityakon Viriya Limpinuntana Aran Patanothai Georg Cadisch 《Agroforestry Systems》2008,72(2):137-148
In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic
or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts
(stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea
(Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content
as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest
N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized
to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea,
largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for
N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant
components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N
released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures
were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality
components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in
the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols.
Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest
age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its
components are mixed. 相似文献
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A. Rigueiro-Rodríguez M. R. Mosquera-Losada E. Gatica-Trabanini 《Agroforestry Systems》2000,48(3):245-256
The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste
disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization,
(2) milk sewage sludge at 40 kg N ha−1 target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two
pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha−1. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1); (2) Lolium perenne L. var. Tove (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea
(Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m2, with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect
on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage
sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but
affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral
systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献