制样方法对等规聚丙烯连续自成核退火的影响

连续自成核退火法能有效表征等规聚丙烯(i PP)等规指数的分布情况。采用急冷冷压法和自然冷却法制备了双向拉伸聚丙烯(BOPP)薄膜,并分别对其熔融曲线进行了考察。结果表明:两种方法所制i PP的熔融曲线具有明显的差异,采用急冷冷压法制备的BOPP的连续自成核退火法表征成膜稳定性更接近试样的真实情况,能很好地反映试样的等规指数分布并指导产品的实际应用,而采用自然冷却法制备的BOPP的测试结果不能客观反映实际生产中材料的成膜性能,因此,不适合测定i PP等规指数分布。     

注射成型EPDM/PP热塑性硫化橡胶的制备及性能研究

研究了注射成型EPDM／PP热塑性硫化橡胶的配方及共混设备对性能的影响。结果表明：采用双螺杆挤出机制备,硫化剂用量为3份时,制得的EPDM／PP的性能较好;注射成型试样的拉伸性能好于模压成型试样。     

硫酸钙晶须/PVC硬质复合材料性能的研究

采用双辊混炼-模压成型的方法制备了硫酸钙晶须/PVC硬质复合材料,研究了硫酸钙晶须用量对复合材料性能的影响。结果表明:随着硫酸钙晶须用量的增加,试样拉伸强度、弯曲强度逐渐下降,冲击强度、热变形温度先升后降,弯曲弹性模量和维卡软化温度呈升高趋势,且热稳定性明显提高。     

模压与压延成型对PLA/TPEE共混物结构和性能的影响

采用模压和压延两种成型工艺制备了不同配比的聚乳酸/热塑性聚酯弹性体(PLA/TPEE)共混物试样,通过研究两种试样的拉伸性能、微观形貌以及结晶结构等性质,探究不同成型工艺对材料性能影响.扫描电子显微镜观察显示,不同于PLA/TPEE模压试样的"海-岛"状微相结构,压延试样存在大量的TPEE分散相形变和取向结构.拉伸性能...     

高分子增韧剂对硝胺发射药抗冲击性能的影响

为了改善硝胺发射药的抗冲击性能,以一种硝胺发射药(RP5)药片为原料,分别采用低聚合度油状聚叠氮缩水甘油醚(GAP)和一种高聚合度聚氨酯为增韧剂,制备了不同增韧剂含量的硝胺发射药试样。采用落锤冲击试验机和摆锤冲击试验机分别测试了硝胺发射药试样的轴向和径向抗冲击强度。结果表明,径向方向,加入质量分数1%的GAP和质量分数3%的聚氨酯增韧剂均使硝胺发射药试样的抗冲击性能提升约20%;轴向方向,聚氨酯增韧的硝胺发射药试样在低温下的抗冲击性能更优。     

胶/胶界面状态与橡胶疲劳破坏性能的关系

选用胎面胶混炼胶和胎肩垫胶混炼胶,采用模压硫化方式制备了单胶试样以及具有不同粘合界面的试样,通过考察热空气老化时间对试样拉伸性能及疲劳寿命的影响,探讨了胶/胶界面状态与拉伸性能及耐疲劳性能之间的关系。结果表明,在受外力作用时,胶/胶界面能够传递应力,并以界面脱粘和滑动摩擦等方式吸收外力破坏能,阻断裂纹扩展,提高粘合强度和动态疲劳强度;粘合胶界面对改善试样的动静态强度更加有效。     

多羟基聚醚对高能硝胺发射药抗冲击性能的影响

为研究多羟基聚醚改善硝胺发射药抗冲击性能的效果,以一种硝胺发射药(RP5)药片为原料,分别采用不同数均相对分子质量的多羟基聚醚为增韧剂,制备了不同增韧剂含量的硝胺发射药管状试样。采用落锤冲击试验机和摆锤冲击试验机分别测试了硝胺发射药试样的轴向和径向抗冲击强度。讨论了在低温(-40℃)、常温(20℃)、高温(50℃)下,不同类型、不同含量聚醚对高能硝胺发射药抗冲击性能的影响。结果表明,轴向方向上,加入多羟基聚醚的数均相对分子质量为2 118、质量分数为3%时,对硝胺发射药试样的低温增韧效果较优;径向方向上,加入多羟基聚醚的数均相对分子质量为5 618、质量分数为3%时,多羟基聚醚能使试样的径向低温抗冲击性能提升约50%。     

苎麻增强PP复合材料薄板的拉伸性能研究

本文以PP膜作为基体材料，苎麻布作为增强体，制备出具有环境意识的苎麻增强PP复合材料。文章通过对板材拉伸性能的测试以及影响板材拉伸性能的因素的分析，结果表明复合板材拉伸性能受到模压压力、模压温度、苎麻布的前处理等因素的影响。     

浸胶帆布静态粘合力测试影响因素分析

分析浸胶帆布静态粘合力测试的影响因素。结果表明，采用专用切刀一次成型试样、将备测试样放在黑色塑料袋中保存、按照帆布的型号选用合适的胶片厚度和模具、制样过程中减少油性物质的污染、采用耐高温隔离纸、规范试样冷却方式、采用适宜的拉伸角度和拉伸速率，可有效提高测试结果的准确性。     

不同粒度RDX对DAGR发射药试样抗冲击性能的影响

为了研究黑索金(RDX)粒度对DAGR高能硝胺发射药抗冲击性能的影响规律,以DAGR药片为原料,分别加入用Tyler标准筛筛分的6种不同粒度的RDX,制备成相同RDX含量的试样,通过落锤冲击试验和摆锤冲击试验分别对所制备的发射药试样进行了轴向和径向抗冲击性能测试。研究结果表明,随着RDX粒度的减小,发射药试样的抗冲击性能逐渐增加。通过对试样冲击断面进行亚微观形貌观测,发现试样断裂面中固体填料RDX颗粒与粘结剂基体之间存在相互剥离的现象,断裂面上存在裸露的RDX颗粒及RDX与基体剥离所形成的空穴。     

A new test method to obtain biaxial tensile behaviors of solid propellant at high strain rates

A new test method was proposed and applied for studying the biaxial tensile behaviors of hydroxyl-terminated polybutadiene (HTPB) propellant at high strain rates. The biaxial tensile stress responses of the propellant at room temperature and at different strain rates (0.40–85.71 s^?1) were obtained through the use of biaxial tensile strip samples, a new designed aluminum apparatus and a uniaxial Instron testing machine. A high-speed camera and scanning electron microscop (SEM) were employed to observe the biaxial tensile deformation and the damage of HTPB propellant under the test conditions. The results indicated that strain rate could remarkably influence the biaxial tensile behaviors of HTPB propellant. The effect of strain rate on the characteristics of stress–strain curves, mechanical properties and fracture mechanisms was consistent with that in uniaxial tension. However, the biaxial weakening of HTPB propellant was obvious. The strain at biaxial maximum tensile stress was between 10 and 30 % lower than that at the corresponding uniaxial case. Finally, the correlations between the fracture mechanisms and the mechanical properties of HTPB propellant, stress state and the damage of HTPB propellant were discussed. The damage of the propellant under the biaxial tensile test was less serious than that under uniaxial tension at the same strain rate. In addition, continuously increasing strain rate could change the fracture mechanism of the propellant under the biaxial and uniaxial tensile tests. In this investigation, the dominating fracture mechanism of HTPB propellant changed from the dewetting and matrix tearing at lower strain rate to the particles fracture at higher strain rate.     

丁羟推进剂/衬层粘接界面材料力学性能研究

比较了目前测试推进剂/衬层粘接界面性能的方法。针对丁羟推进剂/衬层粘接界面,采用国内外关于推进剂与金属材料粘接界面性能的微型拉伸试验方法,设计并开展了微型拉伸试验,得出该推进剂材料在粘接界面处的受影响区域范围及相应的材料性能特征。     

基于SEM与数字图像相关的固体发动机黏接界面细观损伤过程分析

为了研究黏接界面细观损伤破坏过程,对其进行了原位拉伸试验,采用扫描电镜(SEM)对试验过程进行了观察,得到了拉伸过程黏接界面细观形貌演化过程SEM图像;采用数字图像相关方法对SEM图像进行了处理,获得了黏接界面原位拉伸过程应变场演化规律。结果表明,黏接界面原位拉伸过程中,外界拉伸应变较小时,损伤主要位于推进剂/衬层界面处,推进剂内部损伤较小;随外界拉伸应变的增大,推进剂内部颗粒脱湿使黏接界面损伤急剧增大,推进剂内部损伤区域不断扩展最终贯穿整个黏接界面是其主要失效模式;SEM与数字图像相关方法结合,可以有效地应用于黏接界面原位拉伸过程变形场的测量,为分析黏接界面细观损伤破坏过程提供了新的方法;原位拉伸过程中,全场的应变随外界拉伸应变的增大而增大,其中εx远远大于εy和εxy;外界拉伸应变从5%增至25%,x方向平均应变εx的极值位于衬层处,从0.07增至1.25;外界拉伸应变从25%增加至28%,推进剂εx急剧增大,黏接界面失效时,推进剂εx约为1.85。     

湿度对HTPB复合推进剂力学性能的影响

通过常温湿度试验,研究了HTPB复合推进剂力学性能随试验时间的变化规律.试验证明,湿度使HTPB推进剂的力学性能大幅度下降;经干燥后,其力学性能能够得到部分恢复.用扫描电镜对常温湿度试验前后推进剂的表面状态和拉伸断口进行了对比分析,结果表明,试验后推进剂表面的AP粒子形状有明显改变,拉伸断口上的AP粒子裸露面增大,粒子脱落坑表面光滑、规整.由此得出HTPB推进剂吸湿后,通过干燥方法不能使其力学性能恢复到原始状态.     

NEPE推进剂拉伸断裂行为研究

通过单向拉伸力学性能实验,考察了不同测试温度和不同拉伸速率条件下NEPE推进剂力学性能的变化情况。采用扫描电镜(SEM)和原位拉伸SEM观察了推进剂拉伸断面形貌。结果表明,在低温测试条件下,NEPE推进剂最大伸长率较常温条件下显著降低,最大抗拉强度较常温和高温条件下显著升高,NEPE推进剂的破坏主要表现在黏合剂的撕裂和固体颗粒的断裂;在高温、慢拉伸速率的测试条件下,推进剂断裂时结构被破坏的程度较大,NEPE推进剂的破坏首先发生在固体颗粒堆积处,再到黏合剂网络结构。推进剂断裂的过程是推进剂拉伸取向与裂纹扩展之间的竞争过程。     

Experiments on the transition deflagration-detonation of propellants

In the course of testing a new storage concept for granular propellants, the transition deflagration-detonation has been investigated on a porous nitrocellulose propellant, on a nitroglycerin flake propellant and on a single-perforated nitrocellulose propellant without surface treatment. Test charges weighed from 1 kg to 770 kg and the temperatures ranged from 10°C to 71°C. The test containers consisted of steel, of wood or of a combination of both steel and wood. Temperature coefficients have been established in the order of −0.6%/°C for the critical height of bed for detonation.     

An Advanced GAP/AN/TAGN Propellant. Part II: Stability and Storage Life

A solid rocket propellant based on glycidyl azide polymer (GAP) binder plasticized with nitrate esters and oxidized with a mixture of ammonium nitrate (AN) and triaminoguanidine nitrate (TAGN) and including non‐lead ballistic modifiers, was formulated. The propellant was designed so as to produce non‐acidic and non‐toxic exhaust products while still providing reasonably good burning rate and impulse. This propellant was characterized with respect to thermal and chemical stability and storage life by a variety of test methods. The data indicate that the propellant exhibits good stability and is suitably safe for prolonged storage. Characterization data for this propellant with regard to processing parameters, tensile properties, and ballistic performance are presented in a companion paper.     

HTPB推进剂的低温力学性能

通过低温和低温恢复常温单轴拉伸试验,考察了低温条件下HTPB推进剂力学性能的变化情况,用SEM扫描电镜观察了推进剂拉伸断面形貌,分析了所得HTPB推进剂的拉伸应力-应变曲线和力学性能特性。结果表明,在低温拉伸条件下,HTPB推进剂主要表现为基体撕裂和颗粒脆断,而在低温恢复常温拉伸条件下,主要以"脱湿"破坏为主。推进剂的低温拉伸曲线具有明显的屈服现象发生,说明推进剂的屈服现象与低温有关。推进剂在低温和低温恢复常温条件下的最大抗拉强度、弹性模量和延伸率等力学性能呈现出不同的变化规律。     

Evaluation of Mechanical Properties of Solid Propellants in Rocket Motors by Indentation Technique

It is essential to evaluate the mechanical properties of propellants in a solid propellant rocket motor (SPRM) for structural integrity and its performance evaluation before the flight test. Conventionally, uni‐axial tensile testing on an universal testing machine (UTM) is used to evaluate the mechanical properties of solid propellant carton which is cast along with SPRM. Propellants in rocket motors experience various types of loading during storage, transportation, and environmental conditions over the period of time before actual flight whereas the propellant carton doesn’t experience the same as it is stored in magazine. At present, the mechanical properties of propellant cast in a carton are considered to be the mechanical properties of propellant in a rocket motor, which is not truly representative. Therefore, a non‐destructive indentation technique has been used to establish a method for evaluating the mechanical properties of solid propellants in rocket motors based on hydroxyl terminated polybutadiene. The test results obtained using the penetrometer indentation technique was analyzed comprehensively and compared with UTM results. The mathematical correlations were also developed using least square method and established by conducting the penetrometer indentation test on similar propellant composition. Further, the developed correlation was used to evaluate the mechanical properties of propellant in flight SPRM by penetrometer indentation technique.     

Preparation and Properties of a nRDX‐based Propellant

The incorporation of nano‐scaled cyclotrimethylene trinitramine (nRDX) in nitrocellulose (NC)‐based propellants poses processing problems when following conventional methods. Hence, a new preparation method containing a pre‐dispersion process was developed, by which 30 mass % RDX (290 nm) was incorporated in the propellant. Meanwhile, the corresponding 290 nm, 12.85 μm and 97.76 μm RDX‐based propellants were prepared for comparison using a conventional method. The morphology, structure, ballistic and mechanical properties of the prepared propellants were characterized by scanning electron microscopy (SEM), density analyzer, closed vessel (CV), uniaxial tensile tester and impact tester. The results indicate that the nRDX particles were uniformly dispersed in the NC/NG/TEGDN matrix using the novel method, while agglomerated and recrystallized into large particles with the conventional method. The propellant density increased with decreasing RDX particle size. In particular, the 290 nm RDX‐based propellant exhibited a higher burning rate and lower average pressure exponent (α =0.958) compared to the 12.85 μm RDX‐based propellant (α =1.043). The tensile strength, elongation at break and impact strength of the RDX‐based propellant at −40 °C, 20 °C and 50 °C were dramatically improved by using 290 nm RDX with the novel method.