【作者】 张兴高；

【导师】 张炜；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2009， 博士

【摘要】 HTPB推进剂是当前和今后相当长一段时间内使用的主要推进剂品种。开展HTPB推进剂贮存老化性能研究,对认识该类推进剂贮存性能规律、分析其老化机理、预估其贮存期具有十分重要的意义。从宏观力学性能、粘合剂基体细观结构、填料/基体界面粘结性能和防老剂H含量等方面,考察了热和热-力耦合作用加速老化条件下HTPB推进剂的贮存性能,分析了热、力作用对HTPB推进剂老化性能的影响,结合HTPB推进剂主要组分的老化特性及组分间的相互作用分析结果,找出了HTPB推进剂贮存性能的关键影响因素,研究了HTPB推进剂的老化机理。预估了HTPB推进剂两类贮存条件下的贮存期,并进行了贮存寿命的可靠性分析。研究结果表明,在热加速老化过程中HTPB粘合剂易被空气中的氧气氧化,发生氧化交联反应,有多种氧化产物产生。防老剂H能够抑制HTPB的氧化。氧化剂AP能促进HTPB的氧化分解。通过理论计算和实验验证,揭示了HTPB粘合剂固化体系的弱键为氨基甲酸酯基团中的C-N键和C-O键。研究了HTPB推进剂中防老剂H的组成及作用机制。研究发现防老剂H是N-N’-二苯基-对苯二胺(DPPD)及其氧化性产物N-N’-二苯基-对苯醌二亚胺(DPBQ)的混合物,并获得了HTPB推进剂贮存过程中DPPD和DPBQ含量的变化规律。证实了在HTPB推进剂中防老剂H与TDI发生反应。研究了防老剂H与HTPB和TDI的竞争反应,在50℃条件下,HTPB/TDI的反应速率是防老剂H/TDI反应速率的12.9倍,即防老剂H仲胺基上的氢不如HTPB羟基上的氢活泼。确定了热和热-力耦合作用加速老化条件下HTPB推进剂老化特性的表征方法和表征参数。宏观力学性能参数包括最大抗拉强度、最大延伸率、断裂延伸率、表面硬度和损耗角正切等;粘合剂基体细观结构参数包括凝胶百分数、交联密度和C-N键相对含量等;填料/基体界面粘结性能参数包括界面张力、粘附功、临界脱粘应力和粘附指数等;同时测定了防老剂H及其氧化产物含量。最终选择最大延伸率、交联密度和粘附功分别作为宏观力学性能、粘合剂基体和填料/基体界面粘结性能的主要特征参量。研究了热和热-力耦合作用下加速老化过程中HTPB推进剂填料/基体界面的粘结性能。在热和热-力耦合作用下加速老化过程中,HTPB推进剂填料与粘合剂基体的粘附功和临界脱粘应力随老化时间的延长而减小,界面张力随老化时间的延长而增大,说明推进剂老化导致了填料/基体界面的脱湿。且热-力耦合作用下加速老化过程中填料/基体界面的脱湿现象比热加速老化过程中填料/基体界面的脱湿现象更严重。说明填料/基体界面的脱湿也是热-力耦合作用下HTPB推进剂的主要老化机理之一。在热加速老化条件下,随老化时间的增加,HTPB推进剂的最大抗拉强度、表面硬度、凝胶百分数、交联密度、DPBQ的含量和粘附指数呈增大的趋势,最大延伸率、断裂延伸率和损耗角正切的α松弛峰值则是降低的趋势,DPPD含量和C-N键相对含量先增加后降低。温度越高,各种性能的变化速率越快。结果表明,热加速老化过程中HTPB推进剂存在粘合剂基体的后固化、氧化交联和降解断链三类反应;在老化的不同阶段,三类反应的影响程度不同。老化初期主要存在后固化反应;老化中期存在氧化交联和降解断链反应,并且两者趋于平衡;老化后期,氧化交联作用强于降解断链作用。在HTPB推进剂的热加速老化过程中,粘合剂基体的氧化交联是主要影响因素。在热-力耦合作用下,随老化时间的增加,HTPB推进剂的最大抗拉强度先降低后增加,凝胶百分数、交联密度、DPBQ含量和C-N键相对含量先增加后降低,最大延伸率、断裂延伸率、DPPD含量和损耗角正切的α松弛峰值降低,表面硬度和粘附指数升高。温度越高,各种性能的变化速率越快。结果表明,热-力耦合作用下加速老化过程中HTPB推进剂粘合剂基体老化初期主要存在后固化反应;老化中期氧化交联作用强于降解断链作用;老化后期,降解断链作用逐渐凸现。但在热-力耦合加速老化过程中,粘合剂基体的氧化交联仍是主要的影响因素,且填料/基体界面脱湿的影响也不容忽视。灰色关联分析法分析结果表明,热和热-力耦合作用加速老化条件下HTPB推进剂宏观力学性能的主要影响参数为交联密度。宏观-细观性能的相关性研究表明:热加速老化条件下HTPB推进剂最大延伸率与交联密度、防老剂H氧化产物含量之间存在相关性,说明最大延伸率的降低主要是粘合剂基体的氧化交联所致。发现热-力耦合作用下HTPB推进剂最大延伸率与交联密度和粘附功存在相关关系,说明氧化交联和填料/基体界面脱湿的作用占主导地位。由此建立了由细观性能评估推进剂宏观力学性能的非破坏性/微破坏性检测方法。获得了热和热-力耦合作用加速老化条件下HTPB推进剂的老化机理。热和热-力耦合作用下HTPB推进剂的老化机理均为粘合剂基体的后固化、氧化交联、降解断链和填料/基体界面的脱湿。热加速老化条件下HTPB推进剂最主要的老化机理是粘合剂基体的氧化交联。热-力耦合作用下HTPB推进剂粘合剂基体的氧化交联、填料与粘合剂基体之间界面的脱湿起主要作用。选择最大延伸率作为老化性能评定参数,预估了HTPB推进剂贮存寿命。以最大延伸率下降30%作为评定参数临界值,预估得到常温(25℃)贮存时HTPB推进剂在单纯热老化条件下和热-力耦合作用下(15%的预应变)的贮存寿命分别为18.0年和13.8年,其可靠度分别为0.9993和0.6217;给定可靠度为0.99下单纯热老化条件下和热-力耦合作用下的贮存寿命分别为20.7年和10.7年。更多还原

【Abstract】 As a primary propellant, HTPB propellant is widely used in solid motor currently and in the future. Therefore, research on the storage properties of the HTPB propellant is significant for understanding the storage properties, analyzing its aging mechanisms and predicting its storage life.The thermal accelerated aging characteristics of the HTPB propellant were investigated in the following four aspects including the macroscopical mechanics properties, the microcosmic structure of binder matrix, interfacial adhesive property of the filler/binder matrix and the content of antioxidant H under thermal and thermal-mechanical coupling aging conditions. The influence of thermal and mechanics on the HTPB propellant were analyzed. The key factors and the aging mechanisms of HTPB propellant were reviewed combining the aging properties and the relationship of the components in HTPB propellant. The storage life of HTPB propellant in the two storage conditions was calculated. The reliability of the storage life was also analyzed.The results show that HTPB binder is easy to be oxidated by oxygen in the air during the storage. During the process, the oxidation crosslinking occurred and multiplicate oxidation products formed. The antioxidant H can effectively prohibit the oxidation of HTPB binder. The oxidizer AP can accelerate the oxidation and decomposition of HTPB. By theoretic calculation and experimental validation, the weak bond is C-N and C-O bond of polyurethane in HTPB curing system.The function mechanism and the constituents of antioxidant H were studied in HTPB propellant. It is found that the Antioxidant H is composed of N-N’-Diphenyl-p–phenylenediamine (DPPD) and its oxidation product N-N’-Diphenyl-p-benzoquinone diimines ( DPBQ). The changing rule of the content of them was obtained.It is approved that the antioxidant H can react with toluene diisocyanate(TDI) in HTPB propellant. The competitive reaction of antioxidant H, HTPB and TDI were studied. The results show that the reactive rate of HTPB/TDI is 12.9 times higher than that of antioxidant H / TDI at 50℃. The hydrogen in antioxidant H is less active than that in HTPB.The aging characterization method and parameters were determined under thermal and thermal-mechanical coupling aging conditions. The macroscopical mechanics properties were studied including tensile strength, elongation at maximal and break, surface hardness, the loss factor, etc. The microcosmic structures of binder matrix were studied including the cross-linking density, the gel fraction and the relative content of the C-N bond. The interfacial properties of the filler/binder matrix were studied including the interfacial tension, the work of adhesion, the critical debonding stress and the exponent of conglutination. The content of antioxidant H and its oxidation product were also studied. At last, elongation at maximal, the cross-linking density and the work of adhesion were selected as the main characteristic parameters of the macroscopical mechanics properties, the binder matrix and the interfacial adhesive properties of the filler/binder matrix respectively.The interfacial adhesive property of the filler/binder matrix in HTPB propellant was studied under thermal and thermal-mechanical coupling aging conditions. Results show that the work of adhesion and the critical debonding stress are decreased while the interfacial tension increased along with the aging time. It indicates that the aging makes the interfacial of the filler/binder matrix dewetting. The interfacial dewetting of the filler/binder matrix is more seriously under thermal-mechanical coupling condition than thermal aging condition. It indicates that the interfacial dewetting of the filler/binder matrix is one of the main mechanisms under thermal-mechanical coupling aging condition.Under thermal aging condition, the experimental results show that tensile strength, surface hardness, the gel fraction, the cross-linking density, the content of DPBQ and the exponent of conglutination are increased along with the aging time. The elongation at maximal and break, theαrelaxation peak value of the loss factor are decreased on time duration. The content of the C-N bond and DPPD are increased at first and then decreased. The higher the aging temperature, the larger the changing rate of the aging characteristics. There are three kinds of reaction under thermal aging condition including the continued-curing reaction, the oxidative crosslinking and the degradation. The effect of the three kinds of reaction is different during the aging process. The continued-curing reaction is dominating during the aging initial stages. During the aging metaphase, the oxidative crosslinking and the degradation are existent and they tend to balanceable. During the aging anaphase, the oxidative crosslinking exceed the degradation. Oxidative crosslinking is the most important aging factor of HTPB propellant under thermal aging condition.Under thermal-mechanical coupling condition, the experimental results show that tensile strength are decreased at first and then increased during the aging process. The gel fraction, the cross-linking density, the content of DPBQ and the relative content of the C-N bond are increased at first and then decreased. The elongation at maximal and break, the content of DPPD and theαrelaxation peak value of the loss factor are decreased on time duration. The surface hardness and the exponent of conglutination are increased along with the aging time.The higher the aging temperature, the larger the changing rate of the aging characteristics. The results show that the continued-curing reaction of HTPB binder matrix is dominating during the aging initial stages under thermal-mechanical coupling condition. During the aging metaphase, the oxidative crosslinking exceed the degradation. During the aging anaphase, the degradation is arisen gradually. Oxidative crosslinking is the main aging factor of HTPB binder matrix and the interfacial dewetting of the filler/binder matrix can not be slighting under thermal-mechanical coupling condition.Based on the grey correlation analysis, the main factor of macroscopical mechanical properties is the cross-linking density under thermal and thermal-mechanics coupling aging conditions. The study on the correlation of macroscopical-microcosmic properties shows that there is linear relationship between the maximal elongation, the cross-linking density and the content of the oxidation product of antioxidant H under thermal aging condition. The reduction of the maximal elongation is caused by the oxidative crosslinking. It is found that there is correlation between the elongation at maximal and the cross-linking density, the adhesion work under thermal-mechanical coupling aging condition. It shows that the oxidative crosslinking and the interfacial dewetting of the filler/binder matrix are dominant. The method is established to evaluate the macroscopical mechanical property by studying microcosmic property as a Non-Destructive Evaluation (NDE) or Micro-Destructive Evaluation (MDE) method.The aging mechanisms were obtained under thermal and thermal-mechanical coupling aging conditions. The reasons of HTPB propellant performances deterioration under the two storage conditions are the continued-curing reaction, the oxidative crosslinking , the degradation and interfacial dewetting between the filler and the binder matrix. Oxidative crosslinking is the most important aging factor of HTPB propellant under thermal aging condition. Oxidative crosslinking and interfacial dewetting are the main aging factors of HTPB propellant under thermal-mechanical coupling aging condition.Choosing the elongation at maximal as the key aging property,the storage life of HTPB Propellant was predicted. Selecting the changed 30% of the initial value of the maximal elongation as invalidation point, the predicted storage life of the HTPB propellant at room temperature (25℃) are 18.0 years and 13.8 years respectively under thermal and thermal-mechanical coupling aging conditions. The reliability is 0.9993, and 0.6217 respectively. If the reliability is 0.99, the storage life of the HTPB propellant are 20.7 years and 10.7 years respectively under thermal and thermal-mechanical coupling aging conditions.更多还原