摘要
利用液滴微流控技术,以活性剂浓度为0.5%的水溶液为连续相,以DAAF的乙酸乙酯溶液为分散相,通过流体聚焦式微通道制备了DAAF/F2602复合微球,研究了两相流速比、分散相浓度以及活性剂种类对DAAF/F2602复合微球的颗粒形貌、粒径以及圆形度的影响,得出了最佳工艺条件,并与水悬浮法进行了对比。研究结果显示,流体聚焦式微通道制备的最佳工艺为悬浮液浓度为4%、两相流速比为16∶1、活性剂为CTAB。2种制备方法所得样品的DAAF晶型均未发生改变,撞击感度均大于100 J,摩擦感度均为0%大于360 N,表明2种样品安全性能良好。其中液滴微流控法所得DAAF/F2602复合微球的粒径为20.22~53.85 μm,小于水悬浮法所得复合粒子的粒径(121~356 μm),且粒径分布更加均匀,热分解峰峰温也延后了6.45 ℃,活化能增加了6.12 kJ·mo
图文摘要
DAAF/F2602 microspheres were successfully prepared by microfluidic technology. The effects of suspension concentration, flow rate ratio, and surfactants on the morphology, particle size, and particle size distribution of microspheres were studied. The morphology and properties of microspheres prepared by liquid drop microfluidics technology were compared with those produced by water suspension technology
炸药粒径、形貌、颗粒比表面积、均一性以及孔隙结构等影响炸药的安全性和爆轰等性
水悬浮
DAAF是一种呋咱类含能化合物,2D层状空间结构可以有效降低外界刺激,具有良好的耐热性、不敏感性、输出能力和较小的临界直径尺
试剂:亚微米DAAF,纯度99.6%,中值粒径130 nm,自
仪器:DX‑2700型粉末X射线衍射仪,中国辽宁丹东浩源公司;JSM‑7900F场发射扫描电子显微镜,捷克斯洛伐克公司;电子光学显微镜,中国深圳市顺华力电子有限公司;ASAP 2020型氮吸附仪,美国Micromeritics公司;DSC‑800差示扫描量热仪,中国英诺精密仪器有限公司;TGA/SDTA851E热失重分析仪,瑞士Mettler Toledo公司;BAM撞击感度测试仪;BAM摩擦感度测试仪。
研究采用液滴微流控平台进行DAAF/F2602复合微球样品的制备。平台由注射泵、注射器、流体聚焦式芯片和恒温磁力搅拌水浴锅组成,如

图1 实验装置示意图
Fig.1 Schematic diagram of the experimental setup
由于所得液滴为水包油(O/W)液滴,所以选择亲水性玻璃材料进行芯片定制加工,通过键合方式对微通道进行闭合,得到流体聚焦芯片。
研究将质量分数为5%的黏结剂F2602加入EA中,并加入DAAF超声搅拌30 min以上,形成均匀的悬浮液作为分散相,质量分数为0.5%活性剂的去离子水溶液作为连续相。通过普通玻璃注射器注入分散相,通过普通塑料注射器注入连续相,同时汇入流体聚焦式微芯片。固定分散相流量为0.15 mL·mi
为进行对比研究,同时采用水悬浮法制备了DAAF/F2602复合粒子。研究将一定质量的氟橡胶F2602溶于乙酸乙酯中,配制成黏结剂质量分数为5%的溶液。将细化后的DAAF炸药颗粒加入装有一定量蒸馏水的广口瓶中,并将水浴锅的温度设置为60 ℃,打开真空系统,设置压力,调节搅拌速度为350 r·mi
采用电子光学显微镜(电子倍数25‑200 X)对2种制备方法所得样品的宏观形貌进行测试。
采用扫描电子显微镜观察极高分辨率下2种制备方法所得样品的表面形貌。
采用X射线衍射仪对原料DAAF、亚微米DAAF、样品
采用差示扫描量热仪对亚微米DAAF、样品
采用热重分析仪对亚微米DAAF、样品
根据GB/T21567-2008、GB/T21566-2008,使用BAM撞击感度测试仪测试亚微米DAAF、样品
采用BET比表面积法,对样品
为分析不同悬浮液浓度对DAAF/F2602复合微球形貌的影响,采用光学显微镜对不同悬浮液浓度下所得样品的宏观形貌进行观测,结果如

a. SC‑3.5%

b. SC‑4%

c. SC‑4.5%

d. SC‑5%
图2 不同悬浮液浓度所得微球样品的光学显微镜图
Fig.2 Optical microscope images of microsphere samples obtained from different suspension concentrations
研究同时对不同悬浮液浓度所得样品SC‑5%~SC‑3.5%进行了SEM测试,结果如

a. SC‑3.5%

b. SC‑4%

c. SC‑4.5%

d. SC‑5%
图3 不同悬浮液浓度所得微球样品的SEM图
Fig.3 SEM images of microsphere samples obtained from different suspension concentrations
Nano Measure是一种粒度分析工具,可以对相关图片的粒度大小、分布的粒度形状,各种尺寸的分布进行快速准确的分

a. SC‑3.5%

b. SC‑4%

c. SC‑4.5%

d. SC‑5%
图4 不同悬浮液浓度所得微球样品的粒径分布图
Fig.4 Particle size distribution of microsphere samples obtained from different suspension concentrations
流速比是影响微球粒径大小的一个重要因素。液滴微流控法可以通过精准调控两相流速比来控制液滴微球的大小。当流速比过小时由于表面张力的影响,炸药颗粒会上浮破裂难以固化形成微球。为分析不同流速比对DAAF/F2602复合微球形貌的影响,采用光学显微镜以及扫描电子显微镜对不同两相流速比所得样品SC‑4%‑1~SC‑4%‑4的宏观与微观形貌进行观测,结果如

a. SC‑4%‑1

b. SC‑4%‑2

c. SC‑4%‑3

d. SC‑4%‑4
图5 不同流速比所得微球样品的宏观形貌图
Fig.5 Macro morphology of microsphere samples obtained from different flow rate ratios
选择200个以上的DAAF/F2602复合微球,使用Nano Measure对不同两相流速比所得样品进行粒径分析,粒径分布如

a. SC‑4%‑1

b. SC‑4%‑2

c. SC‑4%‑3

d. SC‑4%‑4
图6 不同流速比所得微球样品的粒径分布图
Fig.6 Particle size distribution of microsphere samples obtained from different flow rate ratios
采用质量分数为0.5%活性剂的去离子水溶液作为连续相,研究选择的3种表面活性剂分别为阳离子型表面活性剂CTAB、非离子型表面活性剂PVP、阴离子型表面活性剂SDBS。采用不同活性剂均能制备出球形度较高并且外观规整的微球,结果如

a. SC‑4%‑4‑C

b. SC‑4%‑4‑P

c. SC‑4%‑4‑S
图7 不同表面活性剂所得微球样品的SEM图
Fig.7 SEM of microsphere samples obtained from different surfactants
通过BT‑1600图像粒度分析系
active agent | maximum roundness | minimum roundness | average roundness | span |
---|---|---|---|---|
CTAB | 0.927 | 0.901 | 0.916 | 0.024 |
PVP | 0.942 | 0.666 | 0.907 | 0.034 |
SDBS | 0.941 | 0.861 | 0.915 | 0.029 |
研究根据以上所得最佳条件(悬浮液浓度:4%;两相流速比16∶1;活性剂CTAB)制备出DAAF/F2602复合微球样品

图8 样品
Fig.8 Electron microscope and SEM images of samples 1 and samples 2
采用扫描电镜分别对样品
为了更加直观地观察微球形貌,使用激光扫描共聚焦显微镜拍摄2种样品的3D形貌,测试结果如

a. sample

b. sample
图9 样品
Fig.9 3D morphology of sample 1 and sample 2
为进一步研究2种制备方法所得样品的成分组成,使用X射线衍射仪对样品

图10 原料DAAF、亚微米DAAF、样品
Fig.10 XRD curves of raw DAAF, submicron DAAF, sample
热分解反应是评价炸药性能的重要特征之一。为研究亚微米DAAF、样品

a. submicron DAAF

b. sample

c. sample
图11 亚微米DAAF、样品
Fig.11 DSC curves for submicron DAAF, sample
采用Kissinger
(1) |
samples | Ea / kJ·mo | / kJ ·mo | Ln(A/ | Tp0 / ℃ | Tb / ℃ | ||
---|---|---|---|---|---|---|---|
Kissinger | Ozawa | Starink | |||||
submicron DAAF | 170.00 | 168.34 | 168.28 | 168.87 | 36.90 | 252.89 | 267.33 |
sample | 186.88 | 195.96 | 187.78 | 190.21 | 34.05 | 256.44 | 269.30 |
Sample | 180.81 | 189.76 | 181.71 | 184.09 | 34.71 | 241.99 | 254.57 |
Note: Ea is the apparent activation energy. is the average apparent activation energy. Ln(A/
(2) |
(3) |
(4) |
式中,βi是加热速率,K·mi
由
samples | ΔG / kJ ·mo | ΔH / kJ ·mo |
---|---|---|
submicron DAAF | 79.13 | 163.83 |
sample | 169.16 | 182.47 |
sample | 166.91 | 176.91 |
Note: ΔG is the Gibbs free energy of activation. ΔH is the enthalpy of activation.
在10 ℃·mi

图12 亚微米DAAF、样品
Fig.12 TG curves of submicron DAAF,sample
使用BAM撞击感度测试仪对亚微米DAAF、样品
samples | Ei / J | friction sensitivity / N |
---|---|---|
submicron DAAF | 95 | >360 |
sample | >100 | >360 |
sample | >100 | >360 |
Note: Ei is the impact sensitivity.
通过休止角分析亚微米DAAF、样品

图13 亚微米DAAF、样品
Fig.13 Angle of repose of submicron DAAF, sample
BET计算模型得到的比表面积是目前使用最普遍的方法,通过BET法测试了样品

a.

b.
图14 DAAF/F2602复合微球的N2吸脱附曲线和孔粒径分布曲线
Fig. 14 N2 adsorption‑desorption curve and pore size distribution curve of DAAF/F2602 composite microspheres
(1)液滴微流控法可以通过改变悬浮液浓度调控微球形貌,通过改变两相流速比调控微球大小以及粒径分布,通过改变活性剂调整微球的圆形度。使用该技术可以得到形貌规整,粒径较为均一的微球。
(2)通过液滴微流控法和水悬浮法制备的样品微球的粒径分别为20.22~53.85 μm和121~356 μm。使用液滴微流控法制备微球能够使氟橡胶均匀的包覆炸药颗粒,在表面形成良好的涂层。相比于水悬浮制备的样品,其热分解峰延后了6.45 ℃,活化能增加了6.12 kJ·mo
(3)微流控法以及水悬浮法制备的DAAF样品都具有较好的机械安全性。
(4)亚微米DAAF、微流控法制备得到的复合微球以及水悬浮法制备得到的复合粒子堆积形成的锥角分别为44°,34°,40°,表明液滴微流控法制备的微球具有优异的流散性。
(5)液滴微流控法使亚微米DAAF颗粒聚集呈球,微球内部呈狭缝孔,回滞环为H1型,再次验证使用该技术可制备尺寸均匀的球形颗粒。
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