【作者】 尹秋英；

【导师】 范力仁；

【作者基本信息】 中国地质大学 ， 材料物理与化学， 2009， 硕士

【摘要】 赋肥与保水功能一体化是保水材料研究发展的方向之一,目前已成为国内外研究的热点。本文所制备的改性磷矿粉复合保水材料就是基于此点,将矿物磷肥通过改性后与保水材料复合,使其同时具有赋磷和保水等功能,以期在农林业获得更广泛的应用,同时带动中低品位磷矿的开发和利用。本文所做的研究工作主要有如下几点:1.研究了磷矿粉的改性,采用的是部分酸化和无机矿物活化相结合的方法,并利用XRD对比分析了改性处理前后矿物的晶体结构变化,阐述了磷矿的改性活化以及释磷机理。2.将改性磷矿粉作为主要添加原料与保水剂复合制备改性磷矿粉复合保水材料,通过一系列的五因素四水平正交实验,研究了改性磷矿粉添加量,丙烯酸中合度,丙烯酰胺、交联剂、引发剂的用量对于复合材料吸液性能的影响,经过极差分析得到最佳实验条件。随后,在正交最优条件的基础上进行了一系列的单因素实验,具体考察改性磷矿粉添加量,丙烯酸中合度,丙烯酰胺、交联剂、引发剂的用量对于复合材料吸液性能的影响,找出最优实验制备条件。3.对比研究了空白样和添加少量改性磷矿粉复合材料样品的保水性能、吸水速率,以及丙烯酰胺用量,改性磷矿粉用量对复合材料溶胀性能的影响。4.重点研究了复合材料的释磷性能:对比分析同一浸泡方法下改性磷矿粉和复合材料的释磷行为,不同浸泡方法下的同一复合材料样品的释磷行为,样品在淋洗柱淋洗下的释磷行为,以及交联剂用量和改性磷矿粉添加量对复合材料释磷行为的影响。5.最后从水势的角度对复合材料的吸水能力进行了较深入的研究:用水凝胶液体交换法测定了复合材料制备条件中不同改性磷矿粉添加量对水势变化趋势的影响,并用不同的拟合方法对复合材料水势曲线进行拟合得到关于复合材料水势的两个经验公式,比较了不同拟合方法对水势的影响,通过水势曲线拟合公式外推得到复合材料各样品在吸水时间为0时的极限水势值。最后探讨分析了复合材料水势、吸液倍率和改性磷矿粉添加量之间的关系。研究所得结论如下:1.通过对比改性前后的XRD图谱发现:通过改性处理后,图谱中除仍保留了磷灰石和石英的特征衍射峰外,磷矿粉主要特征峰峰形钝化,样品中晶相比例减少,无定形态增多,晶粒细化;同时出现了一系列新的特征衍射峰(如CaHPO₄.2H₂O的特征衍射峰（2θ=11.696,20.786,29.161,33,408）和Ca（H₂PO₄）₂.2H₂O的特征衍射峰（2θ=7.595,14.790,22.944,24.165,26.701,29.777）,即磷素在改性处理作用下向有效态转变。2.采用水溶液聚合法,以丙烯酸和丙烯酰胺为合成单体,改性磷矿粉为主要添加原料,过硫酸钾为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,制备出了改性磷矿粉保水复合材料。正交实验分析结果表明,所制备出的复合材料吸蒸馏水时,几个因素的影响顺序如下:改性磷矿粉含量>中和度>丙烯酰胺含量>交联剂的含量>引发剂的含量。取在满足吸蒸馏水、生理盐水倍率分别大于150g/g、30g/g的条件下,磷矿粉添加量最大为最佳工艺条件,即最佳工艺条件是:单体浓度为25%,反应温度为75℃,改性磷矿粉含量40%,中和度70%,丙烯酰胺含量20%,交联剂含量0.04%,引发剂含量0.3%。在正交实验基础上进行的单因素实验结果表明,最佳合成工艺条件为:单体浓度为25%,聚合温度75℃,交联剂用量0.04%,引发剂用量0.50℃,单体中和度65%,丙烯酰胺用量20%,改性磷矿粉添加量40%。复合材料的最高吸蒸馏水量达335g/g,吸0.9%NaCl达32g/g。3.加入一定量的改性磷矿粉可以提高复合材料的保水性能。在恒温60℃的鼓风干燥中。水凝胶在1-3h内失水速率最快,大概失去了50%左右的水分。当时间达到6h后,水凝胶的含水量还为开始时的20-30%左右。在室温下7d时,凝胶的保水率为50%左右,表现出较好的保水性能。所得样品的溶胀特征指数n值都大于1,说明大分子链松弛是控制溶胀速率的主要因素;加入少量的丙烯酰胺可以增加复合材料的吸水速率和溶胀度;改性磷矿粉的加入一方面增大了样品溶胀速率,另一方面降低大分子链松弛对溶胀度的贡献,且随着添加量的增大作用越明显。4.同一浸泡法下改性磷矿粉中水溶性磷素在浸泡一天后释放比例高达36%,其后仍有一定量的磷素释放出来,但是很缓慢;复合材料浸泡一天后磷素释放量为29%左右,其后仍保持较好的持续供磷行为;不同浸泡法下,两种浸泡法下初期磷素释放量基本相同,不换液浸泡法后期磷素释放量基本保持不变,换液浸泡法下,后期表现出较好的持续供磷能力。磷素释放量随交联剂用量的变化有先降低,后增加的趋势,但释放量相差并不大。随着改性磷矿粉用量的增大,磷素释放量也增大。5.淋洗法下改性磷矿粉中磷素在淋洗作用下很快释放出来,前两天就释放了总量的43%左右,其后仍有一定量的磷素释出但比例很小。复合材料的磷素释放速率在初期相对于改性磷矿粉较小,其后则较大,表现出较好的持续释磷性能。复合材料释磷速率有先升后降的趋势,与在浸泡法下得到的释磷曲线趋势并不完全相同,这可能主要是由于不同测试方法所致。在淋洗法下改性磷矿粉添加量不同的一组样品的磷素释放都表现出先升后降的特征,在前期改性磷矿粉添加量小的样品释放速率大,而后期则刚好相反。在测试的时间内,得到的磷素累计释放率是随着改性添加量的增大而变小,而结合上述两图的曲线发展趋势可以看出,随着时间的延长,磷素总释放率差距缩小并趋于接近。6.采用水凝胶液体交换法测定了各个样品在不同吸水时间后的溶液平衡浓度,并换算成相应的水势值。对得到的复合材料在不同改性磷矿粉添加量制备条件下的样品的水势值,采用两种不同的拟合方法得到的复合材料水势的经验公式分别为:ψ=-e^a+bt和ψ=a-bc^t。通过比较曲线拟合的相关系数R发现,第二种拟合方法的准确度更高一些。利用第二种拟合方法得到的曲线拟合公式外推得到的六个在不同改性磷矿粉添加量即添加少量（5%）的改性磷矿粉,可以降低复合材料的水势（59%）,提高吸水能力。但随着改性磷矿粉的添加量继续加大,复合材料的水势升高,吸水能力降低。同时还发现:吸水时间对复合材料的水势和吸水倍率的影响趋势相似,随着吸水时间的延长,复合材料水势逐渐升高,吸水能力降低,吸水倍率则随时间的延长而累计增长;复合材料的水势与吸水倍率存在一定得相关性,即极限水势低的复合材料其吸水倍率也相应较大。更多还原

【Abstract】 Integrating of the function of fertilizer-supplying and water-retention, one of research and development in supperabsorbent plymer materials ,has been the hot spot in home and abroad now.In this paper, the composite prepared by modified phosphate powder and water supperabsorbent polymer is based on this point, having the phosphorus-supplying and water-retention functions with a view to gain a broader application in agriculture and forestry and drive the development and use of middle and low-grade phosphate rock at the same time.In this paper, the main research work are as follows:1. We have a research on modifying phosphate rock with the method of combinating partly acidification and inorganic mineral activation, and use XRD to characterize the crystal structure of minerals and compare the changes before and after modification to expatiate why the modified Phosphate powder can release phosphorus.2.We use the modified phosphate powder as a main added raw materials to supper absorbent polymer to prepare the modified phosphate powder/suppeabsorbent polymer composite. Through a series of five factors and four-level orthogonal experiment,We Study the influence of the addition of modified phosphate powder, neutralization degree of crylic acid and the amount of acrylamide, crosslinker, initiator on absorption properties of the composites, then we get the best experimental conditions after a range analysis analysis.we also set a series of single factor experiment on basis of the optimal conditions of the orthogonal to find the best condition for preparation.3. We have a research on the water retention and water absorbent speed of the composite sapmle added 10% modified phosphate powder with pure sample as a contrast.We also have a stuy on the influence of the amount of acrylamide,modified phosphate powder on swelling performance of the composites.4. We focus our research on phosphorus-release performance of the composite.at first, we find out the difference of phosphorus-release performance between modified phosphate powder and copmsite sample in the same immersion method,then we get the phosphorus-release performance of the same sample in different immersion method.we also stuy the phosphorus-release performance in shower method and the influence of samples with different amount of crossing linker and modified phosphate powder on phosphorus-release performance. 5. Finally, we have a deeply research on the absorbency capacity of the composite from the perspective of water potential. we based on the contrast of mechanism of plant cell and superabsorbent, and research the water potential of the composite which compound with modified and polysodium acrylate and acrylamide. We use hydrogel- liquid- exchange method to test water potential of a series of samples with different amount of modified phosphate powder and use different methods to fitg curve fitting on the water potential of composite materials to get empirical formula.then weahve a comparison to the result of water potential got from different methods of fitting. Through the water potential extrapolation formula, we get the limit of water potential value. at last, we have a discuss on the relation of water potential of composite, fluid absorbency rate and the amount of modified phosphate powder.Study findings were as follows:1 .The char of modified phophate powder still remain the characteristics diffraction peak of apatite and quartz, but the main characteristics of phosphate rock shaped passivation. While the the proportion of crystalline phase reduces, amorphous increases. Crystal size of the sample become smaller.It apears a series of new characteristic diffraction peaks at the same time,such as the characteristic diffraction peak of CaHPO₄.2H₂O（20=11.696, 20.786, 29.161, 33.408） and Ca（H₂PO₄）₂.2H₂O（2θ=7.595,14.790, 22.944, 24.165, 26.701, 29.777 ）. It to say that the role of phosphorus in the modification change to the effective state.2. A modified phosphate powder/superabsorbent polymer composite was synthesized with acrylic and acrylamide as monomer, modified phosphate powder as main added raw materials, K₂S₂O₈ as initiator, and N,N-methylene-bis-acrylamide as crosslinking agent by means of water solution polymerization. The orthogonal experiment results show that the influence of the factors to composite sample on distilled water absorbency as follows: content of modified phosphate powder> neutralization degree of crylic acid >content of acrylamide>content of crosslinker > content of initiator. We choose the optimum conditions under two conditions which meet the absorbency of distilled water, normal saline ratio is greater than 150g/g, 30g/g respectively and the amount of modified phosphate powder added is largest.The optimum conditions are: 25% monomer concentration, reaction temperature is 75℃, content of modified phosphate powder is 40%, neutralization degree of acry acid is 70 percent, 20% acrylamide, content of crosslinker is 0.04%, initiator content is 0.3%.The results of the single factor experiment based on orthogonal experiment show that the best conditions for synthesis is 25% monomer concentration, polymerization temperature at 75℃, 0.04% cross-linker, 0.50% initiator, neutralization degree of crylic acid by 65%, 20% acrylamide, 40% modified phosphatepowder. Composite materials maximum absorption capacity of distilled water and 0.9% NaCl solution are 335g/g and 32g/g respectly.3. The water retention property of the composite can be improved by adding a certain amount of modified phosphate powder. The hydrogel loss about 50% water at the first 3 hours in the blast drying at 60℃,but the water content of hydrogels also around the 20-30% at 6 hours.When put at room temperature, the hydrogel can retain 50% water at 7 days. The swelling characteristics index values of samples are greater than 1,which is to say that relaxation of macromolecular chains is the main factors controlling the swelling ratio. Addiing modified phosphate powder to composite can increase the swelling speed, as well as reduce the contribution macromolecular chain relaxation to swelling ratio, and the influence can be amplifed by addition more modified phosphate powder to composites.4. Modified phosphate powder can release phosphorus as much as 36% in one day and there is still a certain amount of phosphorus released but very slow while the composite phosphorus-release is about 29% after soaking in a day in the same immersion method,and it remains the performance of phosphorus-release well.The amount of phosphorus released by the same ocmposite sample is about the same in two different immersion method. The amount of phosphorus remain the same in later in the liquid unchanged immersion method while it keep increasing in the liquid changed immersion method. With the amount of cross-linking agent changes, the amount of phosphorus released begin to reduce at first and become bigger later, but there is no big blank in the amount of phosphorus of the different samples.5.The modified phosphate powder can leacha large part of phosphorus under the shower method, the amount of phosphorus reach about 43% at the two days and there is still a certain amount of phosphorus released but very little. The phosphorus release speed of composite materials is slower than modified phosphate powder at the first days, then become faster than the modified phosphate powder, Which is different to the result got from the immersion method mainly due to different testing methods.The phosphorus-release rate of the samples which content less modified phosphate powder is bigger than the sample s content more at first while it become inverse in later. We received the total of phosphorus-release rate is smaller with the addition of modified phosphate powder increasing in the test of time, while combinatiing to the development trend of the two curves of the map can see that the total of phosphorus-release rates will tends to close the gap with the time extented.6.We use hydrogel- liquid- exchange method to test the value of equilibrium concentration of the samples soaked for different time, and converted the value into the corresponding water potential value.We use two different fitting method to the values of the samples which content different amount of modified phosphate powder to get the empirical formula.The two empirical formulas areψ=-e^a+bt andψ=a-bc’.By comparing the correlation coefficient R of the two fitting curves,we find that the second fitting method is accurater than the first one. The limit water potential value of the six samples content different amount of modified phosphate powder calculated by extrapolation with the second empirical formulas are as follows:That is to say adding a small amount （5%） of modified phosphate powder to composite materials can reduce the water potential （59%）,and increase the water absorbency capacity. However, the water potential of composite materials increase and water absorption capacity began to reduce with the addition of modified phosphate powder continued to increase. We also find that the absorbent time have the similar inluency on water potential and water absorbency of the composites at the same time. with the suction time goes, water potential of the composites become bigger and water absorption capacity becomme weaker while water absorbency ratio become bigger. there must be relevant relationship between the water potential and water abosrbency ratio. Composites which have the least water potential can absorbentnthe largest amount of water.更多还原