【作者】 丁海琴；

【导师】 周伟良；

【作者基本信息】 南京理工大学 ， 材料科学与工程， 2013， 博士

【摘要】 近年来高分子聚合物愈来愈广泛地应用于弹药中,如硝化棉类含能粘结剂和塑料弹带均是典型的高分子聚合物。粘结剂作为发射药的重要组成部分,很大程度上影响着体系的能量性能和力学性能。硝化棉作为含能粘结剂,广泛应用于单基、双基和三基发射药中,但由于NC较高的玻璃化转变温度,低温力学性能较差,限制了发射药的发展和应用。聚叠氮缩水甘油醚(GAP)作为一种新型含能的叠氮类粘结剂,具有氮含量高、机械感度低、热稳定好、玻璃化转变温度低等优点,然而GAP分子链中较大的-CH2N3侧链的存在,使其主链承载原子数少,分子间作用力很小,导致其抗拉强度较低。本文利用聚合物增强原理,在硝化棉和GAP两类含能粘结剂间进行复合改性,以期获得性能互补的含能粘结剂,为发展强而韧的复合含能粘结剂提供基础,满足不同发射药及推进剂的需求。近年来塑料弹带尤其是尼龙66和聚甲醛在各种新式炮弹上得到了广泛应用。钛酸钾晶须的拉伸强度达7000MPa,并具有良好的耐磨性和耐热性,且生产成本低,因此尝试采用钛酸钾晶须改性尼龙66和聚甲醛的力学性能和耐热性能等,以期更好的满足弹带用塑料对强度和尺寸稳定性的需求。针对硝化棉类粘结剂和塑料弹带的改性需求,本课题主要开展以下几方面工作：以4,4’-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬段,聚叠氮缩水甘油醚(GAP)为软段,合成不同硬段质量分数的聚叠氮缩水甘油醚聚氨酯弹性体(GAPE)。DMA分析表明硬段质量分数为33%的GAPE-2的刚性和柔顺性均较佳,低温时自由体积膨胀系数(af)较大,而其低温脆化参数(m)值较小(m=55.6),链段运动活化能为271.0kJ/mol,表明GAPE-2具有较好的低温塑性和韧性且其脆性较小。真密度测试表明随着硬段质量分数由30%增加到36%,GAPE的真密度由1.35g·cm-3增加至1.52g·cm-3、对不同硬段质量分数的GAPE进行力学性能测试,结果显示当硬段质量分数为33%时,GAPE的力学性能较佳,断裂伸长率为360%,特别是抗拉强度为13.3MPa,约比硬段质量分数为30%的GAPE-1的抗拉强度高209%,比硬段质量分数为36%的GAPE-3的抗拉强度高87.3%。通过溶液共混法制得两组不同质量比的GAPE/硝化棉(氮含量=13.5%)、GAPE/硝化棉(氮含量=12.0%)共混试样。采用DMA、力学性能测试、FTIR、真密度等分析手段对共混试样进行表征。GAPE/硝化棉(氮含量=13.5%)共混体系的低温玻璃化转变温度均低于-3℃, GAPE/硝化棉(氮含量=12.0%)共混体系的低温玻璃化转变温度均低于-10℃,硝化棉的低温力学性能得到改善。共混体系均出现2个Tg,GAPE/硝化棉(氮含量=13.5%)共混体系中当GAPE含量为40%时,两相的疋较为靠近；GEPE/硝化棉(氮含量=12.0%)共混体系中当GAPE的含量为30%时,两相的Tg较为靠近,说明此配比下的两相相容性较好。由低温粘弹系数的计算知,这两个配比下材料的低温脆性和柔顺性均较好。当GAPE质量分数为30%时,GAPE/硝化棉(氮含量=12.0%)共混体系的抗拉强度为43.3MPa;而此配比下GAPE/硝化棉(氮含量=12.0%)的断裂伸长率达到33.5%,比硝化棉(氮含量=12.0%)的断裂伸长率7.7%提高了近5倍。同时,当GAPE的质量分数为30%时,GAPE/硝化棉(氮含量=13.5%)的抗拉强度为63.5MPa,断裂伸长率为30.5%。在研究了GAPE对硝化棉的力学性能改性获得一种选用GAPE.硝化棉作为高能高强度复合粘结剂的体系的基础上,选用不同硬段质量分数的GAPE,合成两组不同质量分数的GAPE/硝化棉/硝化三乙二醇的共混体系。采用动态热机械分析仪、力学性能测试仪及TG等技术手段对两组共混体系进行表征。随着两种不同硬段质量分数的GAPE含量增加,试样的抗拉强度和断裂伸长率均出现先增大后减小的趋势,当GAPE-3(硬段质量分数为36%)的含量为5%时,体系的抗拉强度和断裂伸长率均较好,使抗拉强度从24.7MPa提高到32.1MPa,断裂伸长率从37.0%提高到54.4%。同样当GAPE-2(硬段质量分数为33%)含量为5%时,体系的抗拉强度从24.7MPa提高到32.4MPa,断裂伸长率从37.0%提高到58.5%。热失重分析表明：硝化棉/硝化三乙二醇体系的分解温度为127℃,加入GAPE后,热分解温度提前到105℃左右,说明GAPE能够促进硝化棉/硝化三乙二醇体系的热分解过程,降低热分解温度。动态力学性能测试表明：硝化棉/硝化三乙二醇体系中两相玻璃化温度之差为97.7℃,引入GAPE后,两相的玻璃化温度之差缩小,体系的相容性较好。利用NC的葡萄糖的分子链上残余的-OH与含自由-NCO的GAP-MDI预聚物发生化学反应制得GAP/NC依次为30/70、35/65、40/60、50/50的GAP-MDI/NC试样。当GAP的含量为50%时,产物的断裂伸长率为61.7%,高于NC的断裂伸长率7.7%,此时产物的抗拉强度为33.4MPa,低于NC的抗拉强度75.2MPa；动态力学性能测试表明引入GAP-MDI预聚物后,试样高温α峰向低温方向移动,α转变的峰值增大,说明NC的链段柔顺性变好,试样均出现一个低于-9.5℃的低温玻璃化转变温度,表明改性后的NC低温力学性能改善。针对塑料弹带对材料的机械强度、化学稳定性及耐高温性的需求,选用钛酸钾晶须对PA66和POM进行改性。当钛酸钾晶须的含量为20%时,POM的拉伸强度由55.9MPa提高至86.0MPa,提高了53.8%；当钛酸钾晶须的含量为30%时,PA66的拉伸强度由68.2MPa提高至127.6MPa,提高了87.1%。进一步探讨了试样的最佳注射工艺条件,得出当注射温度为210℃、模具温度为90℃、注射压力为55MPa时,钛酸钾改性POM-ZA343的拉伸强度最大为89.1MPa,相比最小值提高了12.9%；当注射温度为315℃、模具温度为60℃、注射压力为60MPa时,钛酸钾改性PA66-ZN262B的拉伸强度最大为127.6MPa,相比最小值提高了35.2%。更多还原

【Abstract】 Polymers have been applied more and more extensively in ammunition in recent years. Nitrocellulose (NC) binder and plastic belt just are the typical polymers. Binder is a key part in gun propellant, to a great extent, whcih affects the energy performance and mechanical properties of gun propellant. Nitrocellulose (NC) binder has been widely used in single-base, double-base and tri-base gun propellants, while the cryogenic mechanical properties of NC are relatively not good due to its high glass transition temperature, which limits its application in gun propellant. Glycidyl azide polymer (GAP) which is a novel energetic binder being is considered as the key component of gun propellants due to its insensitivity and high energy. The pendant azide group of GAP main chain results in low mechanical properties of gun propellants, so it is necessary to improve the mechanical properties of GAP binder. In this paper, NC and GAP were modified by the reinforcing mechanism of polymers in order to obtain the complementary of energetic binder which hopes to meet the demands of gun propellant and propellant. Recently, plastic belt especially PA66and POM have been widely used in new kinds of projectiles. The tensile strength of potassium titanate whisker reaches to7000MPa, and it also shows well wear resistance, heat resistance and low cost. So in this paper, potassium titanate whisker is tried to modify PA66and POM. The main work is as follows:Gap-based polyurethane elastomer (GAPE) with different hard segment contents were synthesized with4,4’-Diphenylmethane diisocyanate (MDI),1,4-butylene glycol(BDO) as hard segments and GAP as soft segments. The results showed that with33wt%of hard segment, the stiffness and flexibility of GAPE-2were better. The αf of GAPE-2at low temperature was larger. What’s more, the low-temperature fragility parameter and activation energy of GAPE-2were lower, respectively,55.6and271.0kJ·mor-1. As the mass fraction of hard segment increased from30%to36%, the density GAPE increased from1.35g-cm-3to1.52g·cm-3. With33wt%of hard segment, the tensile strength of GAPE-2was up to maximum13.3MPa, which was equivalent to about209%higher than that of GAPE-1with30wt%of hard segment and87.3%higher than that of GAPE-3with33wt%. And the breaking elongation of GAPE was better.Two series of blends of GAPE/NC (WN=12.0%),GAPE/NC(WN=13.5%) were prepared by solution mixing. The properties of the blends were analyzed by means of true Density, FTIR spectroscopy, dynamic mechanical analysis (DMA) and tensile testing. The Tg at low temperature of GAPE/NC (WN=13.5%) was below-3℃. The Tg at low temperature of GAPE/NC (WN=12.0%) was below-10℃. The mechanical properties of NC at low temperature were improved. When the mass fraction of GAPE was30%, the blends of GAPE/NC (WN=12.0%) exhibited good compatibility. When the mass fraction of GAPE was40%, the blends of GAPE/NC (WN=13.5%) exhibited good compatibility.What’s more, the low-temperature brittleness and flexibility of the two ratio were better. When the mass fraction of GAPE was30%, the tensile strength of GAPE/NC (WN=12.0%) was43.3MPa and its elongation was33.5%, which was5times more than that of NC. When the mass fraction of GAPE was30%, the tensile strength of GAPE/NC (WN=13.5%) was63.5MPa and its elongation was30.5%.Based on the modification of the mechanical properties of the nitrocellulose by GAPE, two blends of GAPE/TEGN/NC were prepared by solution mixing. With the GAPE content increasing, the tensile strength and the elongation of samples increased first and then decreased. When the mass fraction of GAPE-3(with36wt%of hard segment) was5%, the tensile strength of the blends increased from24.7MPa to32.1MPa and the elongation of the blends increased from37.0%to54.4%. When the mass fraction of GAPE-2(with33wt%of hard segment) was5%, the tensile strength of the blends increased from24.7MPa to32.4MPa and the elongation of the blends increased from37.0%to58.5%. TG showed that the decompostion temperature of GAPE/TEGN/NC was105℃while the decompostion temperature of TEGN/NC was127℃. This suggested that GAPE could promote the thermal decomposition process and reduce the temperature of thermal decomposition. The DMA analysis showed that the compatibility got better with GAPE adding.The polyurethane prepolymer was synthesized based on diphenylmethane4,4’-diisocyanate (MDI) and GAP, and then the prepolymer was grafted onto NC, the graft-polymer was gained. Experiments showed when the mass fraction of GAP was50%, the ε of the graft-polymer could increase to61.7%. It was obviously higher than the ε of NC. The DMA analysis indicated that the chain flexibility increased. What’s more, The lower Tg was-9.5℃, it illustrated that the mechanical properties at low temperature were improved.In order to meet the requirements of the mechanical strength and dimensional stability of plastic belts, potassium titanate whisker were used to modify PA66and POM. When the mass fraction of potassium titanate whisker was30%, the tensile strength of POM increased from55.9MPa to86.0MPa, increased by53.8%and the tensile strength of PA66increased from68.2MPa to127.6MPa, increased by87.1%. When injection temperature was210℃, mold temperature was90℃and injection pressure was55MPa, the tensile strength of ZA343was89.1MPa. When injection temperature was315℃, mold temperature was60℃and the injection pressure was60MPa, the tensile strength of ZN262B was127.6MPa.更多还原