摘要
快速发展的增材制造技术为固体推进剂传统浇注成型的柔性化、适应性差等问的解决题提供了有效途径。传统热固性固体推进剂的流平性好,无法逐层沉积成型。因而,为实现热固性固体推进剂的3D打印成型,本研究对其液相组分进行了改性,通过添加少量定型助剂共混改性端羟基聚丁二烯(HTPB),制备得到改性HTPB固体推进剂,并对其的流变特性进行了研究。结果表明,共混改性使黏合剂黏度、表观黏流活化能升高;改性HTPB固体推进剂流变特性符合Herschel‑Bulkley方程,且流动性随温度升高而提高;同时,改性HTPB固体推进剂在室温下具有较高储能模量(>1
图文摘要
The method of blending and modification is used to modify the hydroxyl‑terminated polybutadiene (HTPB) by adding a small amount of styling aids. At the same time, there are no special requirements for the curing parameters and plasticization ratio of propellant formula. It can be well adapted to the performance control means of HTPB solid propellant. Theoretically, this method can be used in 3D printing of various HTPB solid propellants.
增材制造(Additive Manufacturing)技术,又称为3D打印技术,由21世纪80年代的快速成型技术发展而来,以数字模型为基础,通过软件和数控系统将材料按照熔融、光固化、激光烧结、喷射等多种方式逐层堆积成型,最终制造出所设计物品的制造技
热塑性固体推进剂采用熔融挤出成型(Fused Deposition Modelling,FDM)技术实现增材制造,最早由美国普渡大学Creech
紫外光固化推进剂是目前最受研究人员关注的推进剂,它的固化速度快,极适用于增材制造成型。紫外光固化推进剂配方大多已通过增材制造工艺验证,其固含量已提升至85
相对于前2种固体推进剂,热固性固体推进剂有大量实用化经验。然而常规的热固性推进剂为了满足浇注工艺需求,流平性良好,难以适应逐层堆积成型工艺。因此,为了实现热固性固体推进剂的增材制造成型,需要对其液相组分进行改性。Chandru
为不影响推进剂主要性能,不限制推进剂组成,实现热固性HTPB推进剂的3D打印成型,本研究对HTPB预聚物进行改性,基于工艺成熟的HTPB固体推进剂配方,添加少量定型助
原材料:端羟基聚丁二烯(Ⅰ型HTPB),黎明化工研究院;癸二酸二辛酯(DOS),麦克林试剂;定型助剂 RE,实验室自制,其中RE40为(C13.2H24.4O2)n,RE210为(C19.8H37.6O2)n,RE45为(C11.8H21.6O2)n;铝粉(Al,D50= 13 μm),鞍钢实业微细铝粉有限公司;高氯酸铵(AP,D50=130 μm),大连高佳化工有限公司;甲苯二异氰酸酯(TDI),德国拜耳。
仪器:ARES‑G2旋转流变仪,美国TA公司;高温差示扫描量热仪(DSC‑TG),型号:STA 449 F3 Jupiter,德国;FOODB OT‑GD型3D打印机,杭州时印科技公司,

a. picture

b. sketch
图1 桌面级3D打印机
Fig.1 A desktop‑scale 3D printer
改性黏合剂体系的制备:选用3种定型助剂RE40、RE45、RE210,90 ℃下按HTPB∶DOS∶RE质量比为9∶4∶1的比例共混,制备得到改性黏合剂体系
流变特性测试:温度40~70 ℃、剪切速率1
改性HTPB固体推进剂(modified‑HTPB solid propellant)制备:按质量分数HTPB 8%~10%,Al 15%~18%,AP 60%~67%,DOS 4%~6%,RE1%~3%的配方,制备改性HTPB固体推进剂样品Ⅰ;在Ⅰ的配方基础上再加入质量分数为0.3%~0.4%TDI,60 ℃固化5 d后制备得到改性HTPB固体推进剂样品Ⅱ。作为对照,制备未改性的HTPB固体推进剂Ⅲ,各组分与改性HTPB固体推进剂样品Ⅰ相同,RE用等量HTPB替代;在Ⅲ的基础上再加入质量分数为0.3%~0.4%TDI,60 ℃固化5 d后制备得到未改性HTPB固体推进剂Ⅳ。
流变特性测试:采用旋转流变仪对推进剂样品Ⅰ、Ⅲ进行流动扫描测试,测试条件为:25 mm平板,温度65、60、55、25 ℃;采用旋转流变仪对推进剂样品Ⅰ、Ⅲ样品进行动态频率测试,测试条件:40 mm平板,应变率0.1%,温度65、25 ℃。
热分解测试:采用高温差示扫描量热仪对推进剂样品Ⅱ、Ⅳ进行DSC测试,测试条件:N2氛围,升温速率为10 K·mi
为研究共混改性对黏合剂体系流变特性的影响,对改性黏合剂体系(

a. scatter diagram of viscosity‑temperature

b. shear rate‑stress curve
图2 改性前后黏合剂体系的流变特性
Fig.2 The rheological properties of binders before and after modified by different modified resins
一般而言,黏合剂的表观黏度‑温度关系符合Arrhenius方
Note: A is pre‑exponent factor. Eη is apparent viscous flow activation energy.
由于推进剂中含有大量固体填料,推进剂的流变特性与黏合剂的流变特性差异明显,为了解改性HTPB固体推进剂的流变特性以及它能否满足3D打印成型工艺,对改性HTPB固体推进剂Ⅰ和未改性HTPB固体推进剂Ⅲ进行了流变测试,结果分别如图

a. shear rate‑stress curve

b. shear rate‑apparent viscosity curve
图3 不同温度下改性HTPB固体推进剂的流变曲线
Fig.3 The rheological curve of the modified‑HTPB solid propellant at different temperature

a. shear rate‑Stress curve

b. shear rate‑Apparent viscosity curve
图4 未改性HTPB固体推进剂的流变曲线
Fig.4 The rheological curve of the HTPB solid propellant
固体推进剂往往表现出非线性Bingham流体特
在发生流动畸变前,推进剂的剪切应力与剪切速率遵从幂定律,即与呈现线性关系(
Note: τy is yield stress. K is viscosity coefficient. n is non‑Newtonian index.
然而,通过拟合得到的屈服值是在物料流动后外推得到的最小切应力,而物料由固态行为向液态行为转变的临界应力为真实屈服值,这两者不一定连
在油墨直写打印中(Direct‑Ink‑Write,DIW),需要物料具备较高的储能模量G′(>1

a. 25 ℃

b. 65 ℃
图5 不同温度下改性HTPB固体推进剂(Ⅰ)的动态频率曲线
Fig.5 The dynamic frequency curve of the modified‑HTPB solid propellant at different test temperature

a. 25 ℃

b. 65 ℃
图6 不同温度下未改性HTPB固体推进剂(Ⅲ)的动态频率曲线
Fig.6 The dynamic frequency curve of the HTPB solid propellant at different test temperature
由

a. the printing depositing

b. the sample after curing
图7 改性HTPB固体推进剂3D打印试验照片
Fig.7 The pictures of 3D printing of the modified‑HTPB solid propellant
propellant
燃烧性能是固体推进剂最重要的性能之一,为研究共混改性对推进剂的燃烧性能影响,开展热分解测试,对比使用改性粘合剂前后固体推进剂的热分解特性差异,观察共混改性对推进剂的热分解特性带来的影响,进而判断改性HTPB固体推进剂的基本燃烧性能。为此制备固化成型的改性HTPB固体推进剂Ⅱ、未改性HTPB固体推进剂Ⅳ,进行了DSC测试,结果如

图8 未改性与改性HTPB固体推进剂(Ⅱ,Ⅳ)的DSC曲线
Fig.8 The DSC curves of HTPB solid propellant(Ⅱ) and modified HTPB solid propellant(Ⅳ)
(1)对HTPB预聚物的共混改性,提高了黏合剂的表观黏流活化能及其黏度,使改性黏合剂具有了更明显的温敏特性,其中使用RE210改性的黏合剂呈现出线性Bingham流体特征。
(2)改性HTPB固体推进剂药浆流变行为符合Herschel‑Bulkley方程,其黏度、屈服值随温度变化较大,具有良好的温敏特性。改性HTPB固体推进剂在25 ℃下具有G′>G″且G′>2×1
(3)改性HTPB固体推进剂的第二个放热峰温度比HTPB固体推进剂的放热峰温度低13.1 ℃,其他热分解过程没有明显区别,推测黏合剂的共混改性不会给推进剂燃烧带来负面效果。
(4)改性HTPB固体推进剂实现了3D打印成型。
参考文献
卢秉恒, 李涤尘.增材制造(3D打印)技术发展[J].机械制造与自动化,2013,42(4):1-4. [百度学术]
LU Bin‑heng, LI Di‑chen. The development of additive manufacturing(3D Printing) technology[J]. Machine Building & Automation, 2013, 42(4):1-4. [百度学术]
杨伟涛, 肖霞, 胡睿, 等. 增材制造技术在火炸药成型中的研究进展[J]. 火炸药学报, 2020, 43(1):1-11. [百度学术]
YANG Wei‑tao, XIAO Xia, HU Ruiet al. Developments of additive manufacturing technology in propellants[J]. Chinese Journal of Explosives & Propellants, 2020, 43(1): 1-11. [百度学术]
蔺向阳, 屈明和, 曹宇鹏, 等. 一种基于紫外光固化的固体推进剂3D打印成型方法:中国,CN107283826A[P], 2017. [百度学术]
LIN Xiang‑yang, QU Ming‑he, CAO Yu‑peng, et al. A UV‑curable solid propellant‑based 3D printing molding method,CN107283826A[P]. 2017. [百度学术]
MCCLAINMS, GUNDUZIE, SONSF. Additive manufacturing of ammonium perchloratecomposite propellant with high solids loadings[J]. Proceedings of the Combustion Institute, 2019, 37(3):3135-3142. [百度学术]
MCCLAINMS, AFRIATA, RHOADS J F, et al.Development and characterization of a photo polymeric Binder for additively manufactured composite solid propellant using vibration assisted printing[J]. Propellants Explos.Pyrotech., 2020, 45: 1-12. [百度学术]
张亮, 刘晶, 张哲, 等.增材制造技术以及在火炸药研究中的现状与发展[J]. 爆破器材, 2016, 45(4):118. [百度学术]
ZHANG Liang, LIU Jing, ZHANG Zhe, et al.Additive manufacture technology and its research status and development in propellant and explosive industry[J]. Explosive Materials, 2016, 45(4): 118. [百度学术]
岳婷. 双端官能化聚丁二烯液体橡胶的合成及其紫外光固化研究[D]. 北京:北京化工大学, 2014. [百度学术]
YU E‑ting. Synthesis of Double End‑functionalized Liquid Polybutadiene Rubber and Research of UV Curing[D]. Beijing:Beijing University of Chemical Technology, 2014. [百度学术]
崔敏. 复合固体推进剂热塑成型及3D打印成型基础研究[D].长沙:湖南大学, 2019. [百度学术]
CUI Min. Basic Research on Thermoforming and and 3D printing of Composite Solid Propellant[D]. Changsha: Hunan Unicersity, 2019. [百度学术]
张婷婷, 李磊, 许壮志, 等, 光固化固体推进剂浆料及其制备方法和成型方法[P]. CN201811545989.9. [百度学术]
ZHANG Ting‑ting, LI Lei, XU Zhuang‑zhi, et al. Light‑cured solid propellant slurry and its preparation and molding method[P]. CN201811545989.9. [百度学术]
BROWN C B. Experimental Characterization and Numerical Modeling of Additive‑ Manufactured Composite Solid Rocket Propellant with Anisotropic Density[D]. Colorado: Colorado School of Mines, 2019. [百度学术]
TREVOR S E, BRAD J, RANIA Z, et al. Additive Manufacturing of Small Scale Rocket Grain Cartridges with Uniformly Distributed Aluminum Particles. [C]// 52nd AIAA/SAE/ASEE Joint Propulsion Conference, Salt Lake City, 2016:4507. [百度学术]
CREECHM,CRANDELLA,EISENHAUEEN, et al.3D printer for paraffin based hybrid rocket fuel grains [C]//53rd AIAA Aerospace Sciences Meeting,Kissimmee, Florida,5‑9 January 2015. [百度学术]
王伟,李伟,王芳, 等.增材制造研究用巧克力型推进剂设计与制备[J].化学推进剂与高分子材料, 2017,15(5):71-74. [百度学术]
WANG Wei, LI Wei, WANG Fang, et al.Design and preparation of chocolate‑type propellant used for additive manufacturing research[J]. Chemical Propellants & Polymeric Materials, 2017, 15(89): 71-74. [百度学术]
蔺向阳, 曹宇鹏, 樊黎霞, 等. 一种固体推进剂的增材制造方法:中国,CN106346774A[P]. 2017. [百度学术]
LIN Xiang‑yang, CAO Yu‑peng, FAN Li‑xia, et al. A material augmentation method for solid propellant fabrication:China,CN106346774A [P].2017. [百度学术]
CHANDRUR A,BALASUBRAMANIAN N, OOMMENC, et al. Additive manufacturing of solid rocket propellant grains[J]. Journal of propulsion and power, 2018, 34(4):1090-1093. [百度学术]
王伟, 付晓梦、史钰, 等. 一种温敏时变的固体推进剂:中国,CN110963866A[P]. 2019. [百度学术]
WANG Wei,FU Xiao‑meng,SHI Yu,et al.A temperatur‑ e‑sensitive and time‑dependent solid propellant:China.CN110963866A[P]. 2019. [百度学术]
M H SUMMERS, J C DANFORTH, D G GARRETT. Solid propellant additive manufacturing system. US20200024210A1[P]. [百度学术]
王伟, 李伟, 付晓梦, 等. 一种热固型复合固体推进剂及其制备方法:中国, CN109438149A[P], 2019. [百度学术]
WANG Wei, LI Wei, FU Xiao‑meng, et al. A Thermosetting composite solid propellant and its preparation method:China,CN109438149A[P], 2019. [百度学术]
庞爱民, 马新刚, 唐承志. 固体火箭推进剂理论与工程[M]. 北京: 中国宇航出版社,2014. [百度学术]
PANG Ai‑min, MA Xin‑gang, TANG Cheng‑zhi. Solid rocket propellant theory and engineering[M].Beijing: China Aerospace Press, 2014. [百度学术]
唐汉祥. 推进剂药浆流变特性研究[J]. 固体火箭技术,1994,(3):28-34. [百度学术]
TANG Han‑xiang.Study on the rheology of propellant slurry[J]. Journal of Solid Rocket Technology, 1994,(3):28-34. [百度学术]
LI Long‑yu, LIN Qian‑ming, TANG Miao, et al. Advanced polymer designs for direct‑ink‑write 3D printing[J]. Chem. Eur. J., 10.1002/chem.201900975. [百度学术]