PETN粒度对其机械感度的影响

用微团化动态结晶方法和溶剂/非溶剂滴加重结晶方法制备出3种粒径的PETN颗粒,采用粒度分析仪和扫描电子显微镜(SEM)对其粒度进行了表征。测定了3种粒度PETN试样的撞击感度(特性落高H50)和摩擦感度(爆炸百分数)值。结果表明,3种粒度PETN撞击感度分别为33.7、28.3和22.9cm,摩擦感度分别为52%、24.8%和40%。撞击感度随粒度的减小逐渐降低,亚微米级PETN最低。摩擦感度随粒度的减小先降低再升高,而且亚微米PETN最敏感。     

机械粉碎法制备纳米HMX及其机械感度研究

采用机械粉碎法制备了纳米HMX,用纳米激光粒度仪和场发射扫描电子显微镜(FESEM)对其粒度分布、颗粒的大小和形貌进行了表征,测试了原料HMX和纳米HMX的摩擦感度、撞击感度和冲击波感度.结果表明,制备的HMX粒径基本小于100 nm;与原料HMX相比,纳米HMX的摩擦感度有较大幅度降低,撞击感度和冲击波感度分别降低107.0％和62.1％,安全性明显提高.     

机械球磨法制备纳米HATO及其性能测试

采用机械球磨法结合真空冷冻干燥技术制备了纳米5,5′-联四唑-1,1′-二氧二羟铵(HATO,又名TKX-50),用激光粒度仪分析其粒度分布,并通过扫描电子显微镜(SEM)观察其颗粒大小和形貌;采用傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)对其晶型、成分及纯度进行分析;采用热重(TG)和差示扫描量热法(DSC)分析其热分解特性,同时测试了工业微米级及纳米HATO的摩擦感度和撞击感度。结果表明,制备的纳米HATO颗粒大小均匀,形貌规则呈类球形,平均粒径小于100nm,且引入的杂质极少;纳米HATO的热分解峰温较工业微米级HATO稍有提前,最大热失重温度降低2.46℃,表观活化能下降2.02kJ/mol,自发火温度提高2.95℃,表明热力学稳定性基本不变,安定性有所提高;纳米HATO的撞击感度和摩擦感度分别为44.5cm和48%,与工业微米级HATO相比分别降低了44%和16%,表明机械感度明显降低,安全性得到提高。     

粒径和晶形对ε-HNIW感度的影响

采用溶剂-反溶剂重结晶工艺制备出3种不同粒径和晶形的ε-型HNIW,用激光粒度仪和偏光显微镜-扫描电镜(SEM)对样品的粒度和形貌进行表征,并测试了撞击、摩擦感度和热分解性能。结果表明,随着粒径的减小,HNIW的撞击感度显著降低,热稳定性缓慢降低,但摩擦感度增加;粒度分布越宽,撞击感度与大颗粒感度值相当,摩擦感度与细颗粒感度值相当;粒径分布窄时,颗粒晶形越规整,撞击和摩擦感度越低,热稳定性越好。影响HNIW撞击、摩擦和热分解的主要因素依次是粒径、粒度分布和晶形。     

球形化TKX-50的制备及性能表征

为提高1,1′-二羟基-5,5′-联四唑二羟胺盐(TKX-50)的流散性、降低机械感度、提高装药密度、增强使用的安全性和可靠性,采用冷却结晶结合超声辅助法制备了球形化TKX-50,探究了溶剂种类、冷却初始温度、降温速率及超声时间对TKX-50晶体形貌的影响;利用扫描电子显微镜、激光粒度仪、傅里叶红外光谱仪、核磁共振仪、X射线衍射仪测定了其结构和形貌;采用差示扫描量热仪测定了其热分解性能;采用撞击感度仪和摩擦感度仪测定了机械感度。结果表明,采用冷却结晶结合超声辅助法,以丙酮与DMSO质量比为1∶4的混合溶液为溶剂,在65℃下配制饱和溶液,自然冷却至室温,将所得样品超声15 min,可制得粒径为171.515μm的球形化TKX-50;球形化后的TKX-50结构未发生变化,摩擦感度为64%,较原料TKX-50提高了24%;撞击感度为16%,较原料TKX-50降低了14%;分解温度为248.22℃,较原料略有提高。     

预混膜乳化法制备RDX复合颗粒及其性能研究

为了降低黑索今(RDX)的机械感度，以聚叠氮缩水甘油醚(GAP)和乙基纤维素(EC)为黏结剂，采用预混膜乳化法制备了RDX/GAP/EC复合颗粒，并采用扫描电子显微镜(SEM)、X-射线衍射仪(XRD)、差示扫描量热法(DSC)、BAM撞击感度仪和BAM摩擦感度仪对其性能进行表征。结果表明，用200mL乳液制得的模板所得到的RDX/GAP/EC复合颗粒与原料RDX相比，形貌规则较好，球形度比较高，粒径范围270～450μm,晶型未发生改变，活化能提高了20kJ/mol,热爆炸临界温度提高了30℃,撞击感度和摩擦感度能量分别提高了3.5J和48N。     

不同粒度AP的机械感度

采用GJB77A-97标准中601．1及602．1试验方法，研究了粒度（2．7～100μm）对AP撞击感度和摩擦感度的影响。结果表明，随粒度的减小，AP的冲、摩感度升高，认为大颗粒AP破碎时消耗热量、颗粒间的摩擦作用力小、热分解反应发生猝灭使大粒度撞击感度减小，而小颗粒AP晶体上发生的局部摩擦、塑性变形及黏滞流动使其摩擦感度增大。从不同粒度AP在机械作用下发生的物理、化学变化的角度，分析了影响机械感度机理的因素。     

不同粒度HMX的重结晶制备和机械感度研究

采用微团化动态结晶方法和溶剂/非溶剂滴加重结晶方法制备出中位径d50分别为0.472、6.266、36.75μm的HMX颗粒,并采用粒度分析仪和扫描电子显微镜（SEM）对3种试样的粒度进行了表征。测定了3种试样的撞击感度（特性落高H50）和摩擦感度（爆炸百分数）值。测试结果表明,撞击感度随粒度减小逐渐降低,并且在粒度降至亚微米级时降到最低;摩擦感度随粒度减小先升高再降低,而且粒度在10μm～50μm时最为钝感。     

微/纳米HMX粒度级配对TNT基熔铸炸药性能的影响

为了提高TNT/HMX熔铸炸药的装药质量,将HMX进行微/纳米粒度级配后应用于TNT基熔铸炸药中。分别采用场发射扫描电子显微镜(FESEM)和固体密度排水法研究了HMX微/纳米粒度级配对TNT/HMX(质量比为40∶60)熔铸炸药的微观结构与密度均一性的影响;测试了含不同HMX微/纳米粒度级配的TNT基熔铸炸药的抗压强度、抗拉强度、撞击感度、摩擦感度和爆速。结果表明,与采用单一粗颗粒HMX(d_(50)=100μm)所制备的TNT基熔铸炸药相比,当采用质量分数15%纳米级HMX(d_(50)=100nm)、15%微米级HMX(d_(50)=5μm)、70%粗颗粒HMX(d_(50)=100μm)时,制备的TNT基熔铸炸药药柱内部缺陷少,密度均一性好,抗压强度提高200%,抗拉强度提高128%,撞击感度降低45.5%,摩擦感度降低46%,爆速增加32m/s,表明综合性能得到明显提高。     

球形ADN及ADN@AP复合粒子的制备与性能研究

为了改善二硝酰胺铵(ADN)的吸湿性，提高其安全性能，促进其大规模实际应用，采用溶剂-非溶剂法制备球形ADN及ADN@AP复合粒子。通过扫描电镜、X射线衍射仪、红外光谱仪、TG-DSC同步热分析仪、撞击感度仪、恒温恒湿箱对所制备样品的形貌、晶体结构、热分解性能、撞击感度和吸湿性进行表征和测试，并与原料ADN、ADN/AP混合物进行比较。结果表明，ADN@AP复合粒子以ADN为核，AP为壳，形状规则；相比于原料ADN和ADN/AP混合物，ADN@AP复合粒子的反应活化能降低了35.1kJ/mol和10.73kJ/mol,撞击感度降低了100.10%和26.52%,ADN@AP复合粒子相比原料ADN在24h后绝对吸湿率降低了213%,表明复合粒子的热分解性能得到改善，降感降吸湿性效果显著。     

退火对聚碳酸酯注塑制品力学及动态力学性能的影响

本文研究了聚碳酸酯（Lexan OQ2720）注塑制品退火后的力学及动态力学性能的变化。结果表明，制品的应力集中情况有明显改善，力学性能除断裂伸长率外都产生了较高提升，拉伸强度提高了14.86%，弯曲强度提高了12.7%，弯曲模量提高了21.27%，冲击强度提高了17.93%；动态力学分析结果表明，，注塑制品的内部存在应力。经退火后，注塑制品内部取向、缠结的分子链得到充分松弛，制品储能模量随温度的变化呈线性规律，内部链段的状态稳定，热变形温度得到了提高。而未退火试样的储能模量随温度变化起伏不定，内部链段的状态比较活跃。动态频率对制品中应力有一定响应能力，响应频率范围约为30-60Hz，随着频率扫描温度的升高，由于应力集中降低，频率对应力响应能力不断降低。     

硬质多孔聚氨酯脲抛光垫材料的制备及性能研究

采用浇注机浇注的方法制备了可作为抛光垫材料使用的硬质多孔聚氨酯脲弹性体,借助万能拉力机、DMA、DSC等手段对材料性能进行表征。实验结果表明:调整硬段含量在一定范围时,可获得不同性能、多种抛光需求的抛光垫;与2,4–TDI相比,2,6–TDI的增加有助于与MOCA形成规整的硬段结晶,阻尼峰向高温处移动,但由于产物是完全线性结构,材料的储能模量反而有所降低;KEL值(能量损耗因子)用于表征材料的抛光性能时,少量的交联有助于获得较好的抛光效果。     

固体催化剂力学性能研究

本文评述了固体催化剂力学性能研究的进展,介绍了催化剂强度失效和数据统计关联等力学基础,给出了固体催化剂力学研究体系。并指出催化剂力学研究的目标是形成催化剂填充床力学可靠性模型。     

Influence of the grafting topology of hydrophobic silica surfaces on the mechanical properties of silicone high consistency rubbers

Silica‐filled rubber materials exhibit stress softening and hysteresis under cyclic loadings. These phenomena are usually associated with both the Payne and Mullins effects. To better characterize these properties, five model silicas were produced and used in industrial‐like high consistency rubber (HCR) formulations: the native (hydrophilic) silica and four chemically modified silicas for which both the content of surface silanols and the nature of the grafted silicone chains differ. Silica ? polydimethylsiloxane HCR elastomer with constant silica content and optimal dispersion was tested via static (uniaxial tensile tests, cyclic and monotonic) and dynamic tests. The Payne and Mullins effects as well as the ultimate properties were evaluated as a function of particle surface treatment. It was found that the Payne amplitude decreases with the content of grafted chains, whereas the Mullins effect and ultimate strain decrease with an increase in molar mass between crosslinks. Finally, the ultimate strength is optimal as long as silica is surface treated, albeit independent of surface grafting topology. © 2015 Society of Chemical Industry     

聚甲基丙烯酸甲酯／不饱和聚氨酯共聚物的力学性能

报道了ＰＭＭＡ／ＵＳＰＵ共聚物的力学性能。研究结果表明，ＵＳＰＵ对ＰＭＭＡ具人显著的增韧必增强作用。共聚物的模量－组成关系符合Ｄａｖｉｅｓ模型，表明共聚物中ＰＭＭＡ相和ＵＳＰＵ相之间呈互为连续的形态。     

TPI结晶性对DCP硫化TPI胶料性能的影响

研究了反式-1,4-聚异戊二烯（TPI）结晶性对不同用量过氧化二异丙苯（DCP）硫化的TPI性能的影响。结果表明,拉伸前后TPI试样的XRD曲线上结晶峰有明显不同。TPI预拉伸冷冻试样的拉伸性能与冷冻前后原始试样的差异明显。随着DCP用量的增加,500mm/min和50mm/min拉伸速率下测得的拉伸强度之间的差异变得越来越小;同一压缩率时,试样的压缩强度不断降低。在tanδ-温度曲线上,随着交联密度的提高,TPI低温损耗峰的tanδ值不断增大,而其高温损耗峰的tanδ值呈下降趋势。     

Methods for studying the mechanical and tribological properties of hard and soft coatings with a nano-indenter

This study illustrates the capabilities of a nanoindentation/nanoscratch tester to assess mechanical and tribological properties of coating films. Properties such as hardness, elastic modulus, mar and scratch resistance, and critical force for cracking can be accurately measured. Operation of the Nano-Indenter is described in detail. A scanning probe microscope (SPM) is shown to be a valuable supplement to the Nano-Indenter. Well-characterized thermoset acrylic clearcoats and thermoplastic latex films were studied. For the first time, operating parameters are described for measurement of relatively soft coatings, such as films cast from a latex with a glass transition temperature (T_g) of 8°C. Thus, the method is made available for study of most types of coatings. The method can easily discriminate between coatings with different T_gs and crosslink densities. Once operating parameters are established, it takes about 10 minutes for an indentation test and 10 minutes for a scratch test with the Nano-Indenter, and with further automation this time could be reduced. Each indentation test accurately measures hardness and elastic modulus as a function of depth within the coating, and each scratch test provides additional insight into the material’s behavior. The method is sensitive to small changes in polymer composition and formulation, and results are highly reproducible. Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 12–14, 2003, in Philadelphia, PA.     

铝合金无铆钉自冲铆接仿真研究

文章主要针对无铆钉自冲铆接成形工艺进行研究,运用有限元分析软件LS-DYNA对不同压边力条件下无铆钉铆接接头成形后回弹性能的影响以及接头拉伸力学性能的影响进行分析,研究接头的失效模式,确定该模型在考虑回弹和力学性能的条件下得到最佳的压边力。     

Mechanical properties of functionally graded carbon black–styrene butadiene rubber composites: Effect of modifying gradation and average filler loading

The mechanical properties of functionally graded polymeric composites (FGPCs) with varying carbon black loading and the effect of stacking sequence in styrene butadiene rubber (SBR) matrix were studied. For a given average amount of nanofiller, the modulus of FGPCs for any given stacking sequence of layers is higher when compared with its uniformly dispersed polymeric composites (UDPCs) counterpart. Tensile strength, elongation at break, and tear strength either increase or decrease depending on the stacking sequence and average loading of the filler in FGPCs. In addition, the smoother gradation (i.e., lesser difference in the amounts of CB content in adjacent layers) and a wide gap of difference in CB content in a stack has a profound effect on the modulus and tensile strength of FGPCs. Dynamic mechanical analysis shows lesser damping in FGPCs than UDPCs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The effect of fiber concentration on mechanical and thermal properties of fiber‐reinforced polypropylene composites

A novel composite material consisting of polypropylene (PP) fibers in a random poly(propylene‐co‐ethylene) (PPE) matrix was prepared and its properties were evaluated. The thermal and mechanical properties of PP–PPE composites were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) with reference to the fiber concentration. Although, by increasing PP fiber concentration in PPE, no significant difference was found in melting and crystallization temperatures of the PPE, the storage, and the tensile and flexural modulus of the composites increased linearly with fiber concentrations up to 50%, 1.5, 1.0, 1.3 GPa, respectively, which was approximately four times higher than that for the pure PPE. There is a shift in glass transition temperature of the composite with increasing fiber concentration in the composite and the damping peak became flatter, which indicates the effectiveness of fiber–matrix interaction. A higher concentration of long fibers (>50% w/w) resulted in fiber packing problems, difficulty in dispersion, and an increase in void content, which led to a reduction in modulus. Cox–Krenchel and Haplin–Tsai equations were used to predict tensile modulus of random fiber‐reinforced composites. A Cole–Cole analysis was performed to understand the phase behavior of the composites. A master curve was constructed based on time–temperature superposition (TTS) by using data over the temperature range from −50 to 90°C, which allowed for the prediction of very long and short time behavior of the composite. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2260–2272, 2005