第一篇:翻譯-機(jī)械活化法表面改性硅灰石及其特性
機(jī)械活化法表面改性硅灰石及其特性
摘要:采用鈦酸酯改性劑,采用濕法超細(xì)攪拌磨在實(shí)驗(yàn)室硅灰石顆粒表面改性的研究。物理,測(cè)量和評(píng)價(jià)了改性硅灰石的物理化學(xué)性能及應(yīng)用。結(jié)果表明,磨削強(qiáng)度顯著影響改性效果由于機(jī)械力化學(xué)效應(yīng)。硅灰石表面由親水性變成疏水性改性后的。濕磨條件下鈦酸和硅灰石之間的相互作用進(jìn)行了研究。提示:物理吸附和化學(xué)吸附的鈦酸鹽在硅灰石表面共存。聚乙烯的力學(xué)性能(PE)填充改性硅灰石粉末明顯改善。
關(guān)鍵詞:硅酸鹽礦物;改性;表面性質(zhì);球磨;填料
1.簡(jiǎn)介
表面改性,如功能粉體的制備過(guò)程中的關(guān)鍵環(huán)節(jié),是非金屬礦物的一個(gè)重要的現(xiàn)代加工技術(shù)。改性硅灰石已作為填充材料的廣泛應(yīng)用。表面改性硅灰石顆粒呈現(xiàn)親水疏水,使硅灰石填料顆粒再加上有機(jī)基質(zhì),如塑料,橡膠,膠粘劑。填料顆粒的表面改性,顯著提高了基體的力學(xué)性能,增加基體中的負(fù)載,并降低生產(chǎn)成本。
傳統(tǒng)的表面改性技術(shù),包括加熱共混改性和填充改性的方法,已被廣泛應(yīng)用于填料和顏料的處理。然而,它也有一些缺點(diǎn),如弱攪拌強(qiáng)度,材料的低混合程度,和材料之間的不均勻性,特別是,良好的反應(yīng)環(huán)境的缺乏。因此,改性效果差,產(chǎn)品質(zhì)量不穩(wěn)定的[1-3]。因此,有必要尋找一種高效的改性方法。
機(jī)械力化學(xué)表面改性是利用機(jī)械力化學(xué)改性的方法。高強(qiáng)度研磨過(guò)程中發(fā)生的機(jī)械力化學(xué)效應(yīng),固體顆粒撞擊對(duì)方瞬間巨大的機(jī)械力作用下,引起一系列表面的相互作用,如物理,物理化學(xué),結(jié)構(gòu),和表面上的機(jī)械的變化以及在地下區(qū)域[4-5]。機(jī)械力化學(xué)效應(yīng)的結(jié)果在能量?jī)?chǔ)存在礦物表面,提高了表面反應(yīng)活性[ 6 ]。因此,機(jī)械力化學(xué)表面改性增強(qiáng)相之間的反應(yīng),由于礦物顆粒的表面活性增加[7-8]。機(jī)械與活性表面改性的優(yōu)勢(shì)已經(jīng)被許多對(duì)礦物粉體表面改性的研究證明,如SiO2 [ 9 ],[ 10 ]αAl2O3,SiC [ 11 ] [ 2 ]和其他。然而,大多數(shù)這些修改已在干磨系統(tǒng)進(jìn)行的,這需要很長(zhǎng)的時(shí)間和更多的能量
因?yàn)樵S多技術(shù)因素,如顆粒的制劑的懸浮和分散性,改性溫度和紙漿的固體密度的變化,可以很好地控制在一濕磨系統(tǒng),在濕式粉碎系統(tǒng)的機(jī)械力活化表面改性被認(rèn)為是最有效的和有希望的表面改性方法之一。此外,這種方法結(jié)合了表面改性和超細(xì)粉碎一起在研磨設(shè)備,它已經(jīng)在商業(yè)上用于生產(chǎn)精細(xì)和超細(xì)無(wú)機(jī)粉末。因此,濕機(jī)械力活化表面改性是更容易在工業(yè)規(guī)模上得到應(yīng)用。
據(jù)最近的濕化學(xué)機(jī)械表面改性進(jìn)行了研究,采用與硬脂酸鈉[ 12 ]碳酸鈣改性鈦酸鋁,[13-14],[ 15 ],烷基胺甲基膦酸[ 16 ]和[ 3 ],聚合物接枝改性的分別,并在與硬脂酸鈉電氣石改性的改性劑[ 17 ]。
硅灰石微粒鈦酸結(jié)合同時(shí)濕法超細(xì)攪拌磨中的表面改性進(jìn)行描述,并對(duì)各種工藝參數(shù)對(duì)改性產(chǎn)品性能的影響。通過(guò)物理力學(xué)改性硅灰石顆粒作為填充聚合物材料性能測(cè)試評(píng)價(jià)改性效果。研究了鈦酸酯和硅灰石之間的相互作用機(jī)理。
2.實(shí)驗(yàn)
2.1 樣品和改性劑
實(shí)驗(yàn)樣品是來(lái)自中國(guó)吉林省細(xì)硅灰石粉。其主要化學(xué)成分(重量%)是氧化鈣44.86,二氧化硅50.32,氧化鋁0.48,F(xiàn)e2O3的0.31,K 2 O0.064,0.050的Na2O和MgO1.26。樣品的粒度分布(累積百分?jǐn)?shù),%)如下:<1微米,1.6;<2微米,4.7;<5微米,12.8;<10微米,27.5;<15微米,45.1;<20微米,63.8;<30微米,82.4;<40微米,91.3;<50微米,96.7;<60微米,試樣100的中等大小為16.31微米,比表面積0.280平方米·克1,亮度88.40,密度2.85克·cm-3的。在實(shí)驗(yàn)中使用的鈦酸酯偶聯(lián)劑(NT2)為化學(xué)純,所使用的水為蒸餾水。
2.2 測(cè)試與評(píng)價(jià)方法
改性實(shí)驗(yàn)是在一個(gè)容積為0.25 L的超細(xì)攪拌磨機(jī)中進(jìn)行細(xì)磨。這個(gè)過(guò)程是硅灰石通過(guò)細(xì)磨→細(xì)粉,在經(jīng)過(guò)(細(xì)磨+改性劑)→改性硅灰石。
研磨介質(zhì)是小直徑的玻璃球。每個(gè)實(shí)驗(yàn)加入20g礦物樣本。通過(guò)實(shí)驗(yàn)確定和優(yōu)化工藝參數(shù)。檢測(cè)的樣品是在優(yōu)化的工藝條件下處理的產(chǎn)品。改性后的樣品用丙酮清洗多次為了機(jī)理研究。
在煤油沉淀試驗(yàn)測(cè)定樣品的硅灰石表面改性的效果。沉淀粒子的質(zhì)量在一個(gè)從開(kāi)始到結(jié)束沉淀沉淀盤(pán)是由自組裝沉積建立電子記錄的平衡,和比泥沙質(zhì)量的總質(zhì)量粒子在沉降盤(pán),即沉降率,計(jì)算。較低的沉淀率為樣本,更好的分散顆粒在煤油和更多的顆粒表面的疏水性。因此,粒子的改性效果會(huì)更加增強(qiáng)。
由SA-CP3型沉降粒度分布分析儀島津公司的測(cè)量是地面硅灰石的粒徑分布,日本。用紅外光譜法測(cè)定了NT2對(duì)硅灰石表面的吸附形態(tài)(布魯克ifs-113紅外光譜儀)。
3.結(jié)果與討論
3.1 磨機(jī)械力對(duì)硅灰石的表面改性的強(qiáng)度的影響(1)粒度
所述NT2劑用于修改硅灰石后的試樣進(jìn)行濕式研磨,以一定的尺寸對(duì)于給定的周期。圖1示出研磨時(shí)間和沉降率之間的關(guān)系。研磨時(shí)間上的介質(zhì)尺寸(D50)和的比表面積(SV)的影響地面硅灰石示于圖2。
如圖1,由NT2(1重量%)改性的硅灰石沉淀比率比沒(méi)改性硅灰石(0重量%)顯著降低。由NT2改性的硅灰石沉降率的增加,研磨時(shí)間逐漸降低,并成為穩(wěn)定的(小于20%)后1.5小時(shí)。它表明,硅灰石地與改性劑NT2的改性效果是顯著的,并且研磨時(shí)間1.5小時(shí)是最佳的。圖2示出了最佳的改性條件下硅灰石的粒徑D50=2.58微米,SV =1.223平方米·克1。
研磨時(shí)間對(duì)改性效果的影響
研磨時(shí)間對(duì)硅灰石細(xì)度的影響
NT2用量對(duì)硅灰石(1.5小時(shí))的改性效果的影響示于圖3??梢钥闯龈男孕Ч玫郊訌?qiáng),直到NT2劑量達(dá)到1重量%。超出這個(gè)劑量時(shí),改性效果保持不變。
NT2用量對(duì)改性的影響
改性時(shí)間、影響攪拌轉(zhuǎn)速對(duì)改性效果的影響
(2)改性時(shí)間和混合速度
改性時(shí)間和NT2改性效果以及攪拌磨機(jī)的旋轉(zhuǎn)速度的影響示于圖4。固定條件下:pH為8.0;漿溫度,70℃;礦漿濃度,40%;研磨介質(zhì)礦物喂養(yǎng),5的質(zhì)量比;和研磨時(shí)間修改前,1.5小時(shí)。可以發(fā)現(xiàn),改性時(shí)間和攪拌速度的最佳值是分別為20min和1000轉(zhuǎn)/min。
(3)研磨介質(zhì)與礦物投料的質(zhì)量比
研磨介質(zhì)對(duì)礦物投料的質(zhì)量比是濕超細(xì)粉碎的最重要的技術(shù)因素之一。不同研磨介質(zhì)與礦物投料的質(zhì)量比對(duì)改性的影響示于圖5。其他因素在實(shí)驗(yàn)的相同的那些在上述實(shí)驗(yàn)(圖4),除了改性時(shí)間(20分鐘)和混合速度(1000轉(zhuǎn)/分鐘)。可以看出,硅灰石的改性可以在超過(guò)3的質(zhì)量比時(shí)顯著增強(qiáng),而最佳值是5。
3.2改性的硅灰石的性能(1)物理性質(zhì)
硅灰石在改性前后的物理和物理化學(xué)性質(zhì)示于表1。與非改性硅灰石,改性硅灰石增加水的接觸角相比,改性的硅灰石的接觸角在煤油中減小,在水中增大;吸水率值7,14和21天大大減少;水滲透時(shí)間也大大增加。這表明,硅灰石的親水性表面改性后賦予疏水性。改性也導(dǎo)致增加亮度。
(2)填充硅灰石的聚乙烯的機(jī)械性能
在相同填充率下,填充了非改性和機(jī)械性刺激活化硅灰石粉末的乙二醇的機(jī)械性能列在表2中。熔體流動(dòng)速率反映了在PE矩陣的填料的分散程度,而其拉伸強(qiáng)度,臨界拉伸伸長(zhǎng)率,和卷繞屈服強(qiáng)度明顯填料顆粒與基質(zhì)之間的耦合狀態(tài)。表2表明,相對(duì)于未改性的填料,聚乙烯與機(jī)械性活化改性填料的所有的機(jī)械性能顯著地提高,除了拉伸伸長(zhǎng)。
3.3.NT2和硅灰石之間相互作用的機(jī)理(1)紅外光譜檢驗(yàn)
硅灰石,NT2和由NT2改性的硅灰石的紅外光譜示于圖6。從圖6(a)中可以看出,該硅灰石的特征吸收峰出現(xiàn)之間1086和903厘米-1 [18]。在圖6-b 中NT2在3200-3500cm-1的吸收峰,是因?yàn)?OH振動(dòng)和氫鍵的存在。由P-O-H,P-O-P,和P = O引起1000 cm-1至1300 cm-1的吸收峰。CH 3-和CH 2-的吸收峰出現(xiàn)在2984 cm-1和2934cm-1。在圖6-c中,CH3?和CH2?有非常弱的特征吸收峰在3000cm-1,表明NT2吸附硅灰石的表面上。因?yàn)榧t外樣品通過(guò)丙酮多次清洗,該吸附可以是化學(xué)吸附。
(2)吸附強(qiáng)度試驗(yàn)
改性硅灰石的表面吸附力,通過(guò)加水洗滌進(jìn)行研究。圖7:改性的硅灰石沉降率比硅灰石的低得多;水洗滌過(guò)的硅灰石沉淀比率比未洗滌的更高。所以洗滌可以去除一些弱吸附的NT2,但不能除去強(qiáng)吸附的端NT2。這意味著化學(xué)吸附和物理吸附硅灰石表面上是共存的。
NT2的硅灰石的表面上吸附模型
NT2 的化學(xué)公式(單烷氧基焦磷酸鈦酸)如以下所示 [1]。NT2 不溶于水,也不與水反應(yīng)。因此,NT2 在修改過(guò)程中是穩(wěn)定的。
硅灰石的化學(xué)式是CaCO3或的Ca3[Si3O9]。Ca-O和Si-O的不飽和鍵上露出硅灰石的劈開(kāi)面可水合以產(chǎn)生一些表面的OH-基團(tuán)[20],如圖8所示。因此,在改性過(guò)程硅灰石和NT2之間的表面相互作用建議如下:(1)端NT2(無(wú)水解)直接參與了反應(yīng),在這之后,鈦和磷的化學(xué)環(huán)境改變;(2)表面的OH-基團(tuán)的硅灰石參加與NT2反應(yīng)。
4.結(jié)論
(1)機(jī)械活化表面改性可用濕超細(xì)粉碎來(lái)強(qiáng)化改性過(guò)程,提高改性產(chǎn)品的填充質(zhì)量,簡(jiǎn)化生產(chǎn)工藝,并降低生產(chǎn)成本。
(2)研磨的細(xì)度和精細(xì)研磨機(jī)械力的強(qiáng)度,改性時(shí)間,攪拌磨機(jī)的旋轉(zhuǎn)速度,和磨礦介質(zhì)對(duì)礦物料的質(zhì)量比,是機(jī)械性活化表面改性的重要因素。一個(gè)中等大小的 2.58 μ m 和
比表面積的 1.223 m2·g?1 改性硅灰石粉末可以通過(guò)優(yōu)化的實(shí)驗(yàn)參數(shù)下的機(jī)械活化表面改性方法獲得。
(3)親水表面的硅灰石改性后呈現(xiàn)疏水性,聚乙烯(PE)填充改性硅灰石粉末后,力學(xué)性能可以得到明顯的改善。
(4)我們可以提出NT2的硅灰石和吸附模型表面上的化學(xué)吸附機(jī)理。
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第二篇:英語(yǔ)論文翻譯演講稿(空心碳納米管用兩親性物質(zhì)表面改性)(小編推薦)
Hello, erverbody!Today I’d like to talk something about Lithium Sulfur Batteries, based on a thesis named “Amphiphilic Surface Modification of Hollow Carbon Nanofibers for Improved Cycle Life of Lithium Sulfur Batteries”.Then, I’ll talk in the light of the four points—overview of thesis,rate capability,cycling performance and voltage profiles of Lithium Sulfur Batteries after Modification.Ok, first, introduce something about Lithium Sulfur Batteries.The advantage of Lithium sulfur batteries is their high specific energy and relatively low cost.However, the major problems of sulfur cathode include low active material utilization, poor cycling performance and low Coulombic efficiency.Think about the question: What caused the loss of electrical contact and capacity decay in Lithium sulfur bactaries? Dissolution of lithium polysulfides has long been understood to be the major problem of sulfur cathode.But now, the experimental results suggest that loss of polysulfides into the electrolyte may not be the sole reason contributing to capacity decay,sulfur
cathode degradation is a multifaceted problem.At the same time, they consider that sulfur cathode degradation requires rational design at different length scales:
(1)Proper functional groups,its chemical moieties need to have good binding strength
(2)The contact surface area between sulfur and the electrolyte should be minimal
(3)Sulfur should be evenly distributed in the electrode
Following the guiding principles mentioned just now, they investigated the effect of adding amphiphilic polymers in modifying the interface between sulfur and the hollow carbon nanofiber.They decided to chose polyvinylpyrrolidone(PVP)due to its simple molecular structure and availability.And then, talk about the electrochemical performance of sulfur cathode after surface modification.First, its rate capability.Figure(a)shows the rate capability performance of the modified sulfur cathode.AtC/5, a specific capacity of around 1180 mAh/g was achieved.The specific capacities were
around 920 mAh/g and 820 mAh/g atC/2 and 1C, respectively.Then, its cycling performance.Figure(b)shows the comparison of cycling performance at C/2 with and without the PVP modification.The red line represents modified electrode and black line represents unmodified electrode.Instead of the rapid initial decay generally observed in the unmodified electrodes, the first few cycles of modified electrodes showed a slight increase in specific capacity from 828 to 838 mAh/g.The amphiphilic polymers provide anchoring points that allow lithium sulfides to bind strongly with the carbon surface.Subsequent cycles showed very stable performance,with less than 3% decay over the first 100 cycles.The capacity retention was over 80% for more than 300 cycles of charge/discharge, with Coulombic efficiency at around 99%.Now, talk about its voltage profiles.Figure(c)shows the voltage profiles of the first, 10th, 50th and 200th cycles at C/2.The first discharge shows a small initial plateau, probably due to the reaction between sulfur and the electrolytes.The voltage profiles from
the 10th cycle onward are quite similar to each other.The hysteresis between the charge and discharge cycles also decreases significantly during cycling, which could be due to the mitigation of electrode resistance during cycling.In summary, Interfacial modification of carbon with amphiphilic polymers helps stabilize the discharge products and improve the cycling performance.We demonstrated that the modified sulfur cathode could achieve stable performance of more than 300 cycles with 80% capacity retention.Thank you!