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1.
动态力学分析(DMA)是材料力学分析中常见的一种测试方法,通过在动态的温度和动态的应力下测试材料的力学性能,可以在拉伸、单/双悬臂梁、三点弯曲和剪切模式下测试不同刚性和硬度的材料。本文中的易燃易爆类材料主要指的是高聚物黏结炸药(Polymer bonded explosive, PBX)和作为火箭发动机燃料的推进剂,由于材料的特殊性,要确保测试的安全和精确。推进剂和PBX的常规力学性能测试所需的样品量大,具有一定的危险性,DMA测试所需的样品量少,且安全性高。本文介绍了DMA的测试原理,并综述了DMA在推进剂和炸药中的应用:玻璃化转变温度(Tg)的测定、蠕变测试、应力松弛测试,最后对DMA在易燃易爆类材料的应用进行了展望。  相似文献   

2.
研究了不同环氧度的环氧化反式异戊橡胶(ETPI)/天然橡胶(NR)(质量比15/85)并用胶的力学性能、疲劳性能及动态性能。力学性能测试表明,随ETPI环氧度的增加,拉伸、撕裂强度逐渐降低,100%和300%定伸强度逐渐增大;ETPI环氧度低于20%时,ETPI/NR并用胶硫化胶具有良好的力学性能和动态疲劳性能,与疲劳性能优异的TPI/NR并用胶接近,环氧度高于20%时疲劳性能明显降低;通过动态力学分析仪(DMA)和橡胶加工分析仪(RPA 2000)等测试进一步表明,并用胶的抗湿滑性能随ETPI环氧度增大而增强,滚动阻力随之增大。  相似文献   

3.
用化学镀方法制备了离子聚合物金属复合材料,用扫描电镜观测其形貌以探讨制备过程中Pt金属的形成方式;用能谱仪研究了金属Pt在材料中的分布;用动态热机械分析仪(DMA)测试了材料的部分动态力学性能。以Kerner模型为基础建立了材料的动态力学性能模型,并将模型计算结果与实验结果对比,验证了该模型的可行性。  相似文献   

4.
动态热机械分析仪(DMA)具有高灵敏度、卓越制冷技术、自由旋转测试头、多种形变模式和连续频率温度扫描模式等优点, 能表征材料在交变应力(或应变)作用下的应变(或应力)的响应、蠕变、应力松弛和热机械性能等, 广泛应用于塑料、热固性材料、复合材料、高弹性体、涂层材料、金属和陶瓷等材料的研究和评估。本文简要介绍了DMA进行动态力学行为分析的基本原理和方法, DMA在铁电相变、低频弛豫特性和铁电疲劳研究方面的应用, 以及DMA在铁电/聚合物复合阻尼材料研究中的应用。在对PZT陶瓷和单晶、BaTiO3陶瓷等常用材料的铁电弛豫特性分析中, DMA表现出比介电表征更为敏感的特性。现在DMA已成为研究铁电材料的重要工具之一。  相似文献   

5.
以丁腈橡胶(NBR)为基体,添加受阻酚小分子2,2′-亚甲基双-(4-甲基-6-叔丁基苯酚)(AO-2246)构成杂化体系,在体系中添加片状石墨粉(FGP),研究其对共混物动态力学性能的影响,借助DMA、FTIR和SEM等手段,研究了FGP/AO-2246-NBR共混物的动态力学性能。结果表明:将FGP加入AO-2246-NBR共混物中后,损耗角正切值、动态储能模量及损耗模量均随着FGP含量的增加先增加后减小,当FGP含量达到临界值(质量分数10%左右)时,其动态力学性能损耗角切值、动态储能模量及损耗模量才表现出较好的性能。通过红外光谱分析发现,三元共混物的氢键效应不是决定动态力学性能的关键因素,这与FGP本身的特性及形成的微观结构有关。微观形貌的形成是FGP与AO-2246-NBR共混物间相互作用的结果。  相似文献   

6.
UP/GF/LCPU原位混杂复合材料动态力学性能   总被引:1,自引:0,他引:1  
为了改进不饱和聚酯树脂在高低温和交变应力下力学性能和热稳定性较差的缺点,利用自行合成的端基含有活性基团的热致性液晶聚合物(LCPU)对不饱和聚酯(UP)/玻璃纤维(GF)复合材料改性,用DMA测试了共混物的动态力学性能,用扫描电镜(SEM)对材料断面的形态结构进行了研究.结果表明,加入一定量的LCPU,复合材料的动态力学性能得到一定改善,材料的冲击强度和弯曲强度得到明显的提高,其中冲击强度最大提高了16%,弯曲强度最大提高36%,弯曲模量最大提高61%,材料的应力-应变行为得到改善,而LCPU的含量对材料的硬度影响不大;LCPU的加入对提高材料的断裂能具有一定的作用.  相似文献   

7.
以1,4-丁二醇(BDO)为扩链剂,采用熔融预聚二步法合成了不同硬段含量的聚叠氮缩水甘油醚聚氨酯弹性体(GAPE)。运用动态热机械分析仪(DMA)研究其动态力学性能,得到GAPE的储能模量、损耗模量、损耗因子,进而运用时温叠加原理,合成频率跨越十几个数量级范围的主曲线,并计算出WLF方程的粘弹系数C1g和C2g,以及链段运动活化能、低温脆化参数。结果表明,硬段质量分数为33%的GAPE-2在-50℃储能模量达到6000MPa,而其低温脆化参数和活化能也较低,分别为55.6和271.0 kJ/mol,是一种刚性好、韧性高、脆性低的弹性体。  相似文献   

8.
针对动态热机械分析仪(DMA)较少应用于含能材料的现状,将DMA测试应用于固体推进剂材料的研究文献进行综述,并提出了DMA在固体推进剂领域的应用方向。  相似文献   

9.
运用动态硫化法制备EPDM/PP橡胶,研究了其流变行为、结晶及动态力学性能。利用扫描电镜观察了硫化EPDM/PP橡胶熔融共混后EPDM颗粒在PP基体中的分散情况。动态力学性能(DMA)和拉伸性能测试的结果显示橡塑比为40/60时,EPDM/PP橡胶的综合性能最为优异。研究了硫化EPDM/PP橡胶在黏性弹性区域的振荡剪切行为。DMA结果显示橡塑比提高导致储能模量与tanδ下降。流变行为表明,复合黏度随交联密度的增加而增加,弹性变形优于黏性流动。硫化过程使EPDM颗粒细化导致PP分子链结晶受阻。  相似文献   

10.
对具有良好液晶聚合物微纤结构的聚丙烯/热致液晶聚合物/玻璃纤维 (PP/TLCP/GF) 混杂复合材料,使用静态拉伸和动态力学分析 (DMA) 的方法研究了材料的力学性能。拉伸实验结果表明,混杂复合材料的拉伸强度和模量随着PP和TLCP挤出后的牵伸速率增大而上升,并且含有增容剂PP-g-MAH的体系,力学性能更优异。DMA测试结果表明,混杂复合材料的动态模量E'随着体系中玻纤的含量增加而增大;当体系中加入增容剂后,复合材料的刚性得到进一步提高。但无论是否使用了增容剂PP-g-MAH,当体系中玻纤含量高于20%后,模量随玻纤含量增大的趋势变缓。当体系中增强相的含量增加,以及加入增容剂使增强相与基体的界面粘结得到改善后,PP基体的损耗因子 (tanδ) 峰值都有一定的减小。  相似文献   

11.
采用环保型水切割胶粉及力化学改性胶粉(MRP)与天然橡胶(NR)复合制备胶粉-NR复合胶,并探讨了胶粉用量对复合胶力学性能和动态性能的影响。通过红外和热失重分析确定了胶粉的主要成分为NR和丁苯橡胶(SBR),且改性后胶粉大分子链结构未发生明显变化。通过橡胶加工分析仪研究了胶粉用量及改性对复合胶加工性能的影响。采用炭黑分散仪研究并观察了胶粉在NR中的分散情况。结果表明,胶粉改性后与NR的相容性提高,二者界面结合力增大,MRP-NR复合胶加工性能改善。炭黑分散结果表明,胶粉用量越多,其分散性越差,改性后胶粉的分散性提高,MRP-NR复合胶的力学性能最优,拉伸强度为27.9 MPa。  相似文献   

12.
Strain rate is not only an important measure to characterize the deformation property, but also an important parameter to analyze the dynamic mechanical properties of rock materials. In this paper, by using the SHPB test system improved with high temperature device, the dynamic compressive tests of sandstone at seven temperatures in the range of room temperature to 1000 °C and five impact velocities in the range of 11.0–15.0 m/s were conducted. Investigations were carried out on the influences of strain rate on dynamic compressive mechanical behaviors of sandstone. The results of the study indicate that the enhancement effects of strain rates on dynamic compressive strength, peak strain, energy absorption ratio of sandstone under high temperatures still exist. However, the increase ratios of dynamic compressive strength, peak strain, and energy absorption ratio of rock under high temperature compared to room temperature have no obvious strain rate effects. The temperatures at which the strain rates affect dynamic compressive strength and peak strain most, are 800, and 1000 °C, respectively. The temperatures at which the strain rates affect dynamic compressive strength and peak strain weakest, are 1000 °C, and room temperature, respectively. At 200 and 800 °C, the strain rate effect on energy absorption ratio are most significant, while at 1000 °C, it is weakest. There are no obvious strain rate effects on elastic modulus and increase ratio of elastic modulus under high temperatures. According to test results, the relationship formula of strain rate with high temperature and impact load was derived by internalizing fitting parameters. Compared with the strain rate effect at room temperature condition, essential differences have occurred in the strain rate effect of rock material under the influence of high temperature.  相似文献   

13.
The work describes the manufacturing and dynamic characterization of nickel wire-based metal rubber (MR) solids. The storage modulus and the loss factor of the nickel MR samples are measured over a frequency range between 0.1 Hz and 200 Hz, and at different levels of dynamic force and strain using a dynamic mechanical analyzer (DMA) technique. A sensitivity analysis about the effect of different static and dynamic testing parameters is initially carried out to identify suitable testing protocols for this metal porous material. DMA testing is then carried out over three different batches of samples (5 specimens each) with variable relative densities to identify the correlation between storage modulus and loss factors with frequency and dynamic force and strain levels. The results are discussed using a mechanical theoretical model relating the mechanical properties of MR solids to the contact states of the wire composing the microstructure. A comparison with analogous results obtained from cyclic tests at 1 Hz from a conventional tensile machine is also performed. The results from this benchmark highlight the necessity to use dynamic-based testing protocols to efficiently implement nickel-based metal rubber for vibration damping and energy absorption designs and applications.  相似文献   

14.
Blends of natural rubber (NR)/epoxidised natural rubber (ENR) were prepared and their morphology, transport behaviour and mechanical properties have been studied. Ebonite method was used to study the blend morphology. Transport behaviour of pentane, hexane, heptane and octane was studied in the temperature range 27–60 °C. Different transport parameters such as rate constant, diffusion and permeation coefficients, and sorption coefficient have been calculated. Temperature dependence of diffusion has been used to estimate the activation parameters. The improved performance of NR/ENR blends has been established from the mechanical studies of unswollen, swollen and deswollen samples.  相似文献   

15.
The purpose of this study is to investigate the static and dynamic mechanical properties of polydimethylsiloxane (PDMS) and the mixture of PDMS and carbon nanotubes. The PDMS/CNT nanocomposites were stirred by an ultrasonic instrument to prevent agglomerations. The tested specimens of nanocomposites were manufactured by using the thermoforming method at 150 °C for 15 min. A micro tensile tester was adopted in this testing system with a maximum load of 500 mN and a crosshead extension of 150 mm. The static elastic modulus can be calculated by means of a tensile test and the average elastic modulus of pure PDMS is 1.65 MPa. In addition, the Nano Bionix tensile tester was also used to perform the dynamic mechanical analysis. Its dynamic frequency range is from 0.1 Hz to 2.5 KHz. The dynamic properties of PDMS/CNT nanocomposites such as storage and loss modulus can be obtained by this system. The storage modulus increased with the CNT content and also with the higher frequencies. Finally, the nanoindentation measurement system was employed to characterize the mechanical properties of PDMS and PDMS/CNTs. The measurement results of elastic modulus by a nanoindentation test have the similar trend with the results obtained by the tensile test method.  相似文献   

16.
The microstructure and mechanical property of improved press-hardened steel with hot pressing combined dynamic partitioning (HP-DP) treatment are presented. Microstructure of the steel subjected to HP-DP treatment is featured by multi-martensite phases and the retained austenite (RA) phase with carbon content gradient. Compared with conventional hot-pressed samples, the HP-DP samples show better tensile property especially ductility. The effect of HP-DP parameters on the evolution of RA and mechanical property is then discussed. Finally, hot pressing of a double U-shaped part using both 22MnB5 steel sheet and the developed HP-DP steel sheet was carried out with exact control of part temperature at the end of hot pressing followed by air cooling.  相似文献   

17.
The dynamic mechanical behaviour of bitumen (BIT) modified with styrene/butadiene/styrene block copolymer (SBS) were investigated. Dynamic mechanical analysis (DMA) were performed in the temperature range –80 to 60 °C. The primary viscoelastic functions were determined at the traffic frequency, 5 Hz. The BIT+SBS blends were investigated in creep fatigue regime at temperature 10, 20, 30, 40 and 50 °C. Dynamic mechanical behaviour of BIT+SBS blends depends on their morphological characteristics, number of phases, phase compositions and phase content in blend, as well as time and temperature. The curves of primary viscoelastic functions, storage modulus (E′), loss modulus (E′′) and loss tangent (tg δ) vs. temperature of polymer modified bitumen differ from unmodified bitumen and indicate the presence of the swollen polybutadiene and polystyrene phases in bitumen phase. The curve E′ vs. temperature of polymer modified bitumen show the rubbery plateau. With the increment of SBS content the rubbery plateau is shifted to high temperatures. At the constant load the creep values of BIT-SBS blends increase and those of creep modulus decrease over a period of time. These effect are more pronounced in samples with higer content of SBS. The time-temperature correspondence principle was applied to create master curves for the reference temperature 10 °C for the creep modulus of BIT + SBS blends. The data were analysed using WLF and Arrhenius equations. Electronic Publication  相似文献   

18.
In this work, effect of ZnO nanoparticles doped graphene (Nano-ZnO–GE) on static and dynamic mechanical properties of natural rubber composites were studied. Nano-ZnO–GE was synthesized by sol–gel method and thermal treatment. With the incorporation of nano-ZnO–GE into the matrix, the mechanical properties of NR nanocomposite significantly improved over that of NR composite containing with 5 phr of conventional-ZnO. The results demonstrated that the presence of nano-ZnO on the surface of graphene sheets not only conduces to suppressing aggregation of graphene sheets but also acts as a more efficient cure-activator in vulcanization process, with the formation of excellent crosslinked network at low nano-ZnO–GE content. This work also showed that NR/Nano-ZnO–GE nanocomposites exhibited higher wet grip property and lower rolling resistance compared with NR/Conventional-ZnO composite, which makes nano-ZnO–GE very competitive for the green tire application as a substitute of conventional-ZnO, enlarging versatile practical application to prepare high-performance rubber nanocomposites.  相似文献   

19.
Determination of the mechanical properties of materials under the combined effects of high-temperatures and high strain-rates has been an important and challenging issue. A strategy has been proposed and evaluated recently towards this purpose in which a heating cell with accurate temperature control is synchronized with the split Hopkinson pressure bar (SHPB) system. This strategy allows pre-heating the specimen to desired temperatures before arrival of the stress wave and provides an experimental technique for the measurement of dynamic mechanical properties of materials at high-temperatures. Since its advent, this method has gained increasing interest in the community of dynamic mechanical testing owing to its ease of manipulation. However, a couple of critical problems should be addressed to validate the experimental results. Among the problems, a crucial one is associated with the temperature change in the heated specimen upon its contact with the relatively cold bars. In this paper, experiments were designed to determine the influence of cold-contact-time (CCT) on the temperature variation within the specimen. The experiments were conducted on Ti700 alloy at strain-rates of ∼104 s−1 and at temperatures from 20 to 800 °C. The results show that the CCT does have a strong effect on the experimental results. Based on the experimental results and our analyses, we believe that the data can faithfully reflect the material behavior if CCT is shorter than 50 ms. While in most systems without the heating cell being synchronized with the SHPB system, the typical CCT is about 500 ms, and therefore the experimental data cannot be taken as representing the material behavior.  相似文献   

20.
硅烷偶联剂KH550对NR硫化胶热氧老化性能的影响   总被引:1,自引:0,他引:1  
研究了硅烷偶联剂KH550对NR硫化胶老化过程中的交联密度和力学性能的影响。结果表明,加入KH550可以减缓交联密度和损耗因子tanδ的变化,有效抑制NR硫化胶的热氧老化,同等老化条件下物理力学性能要好于无KH550填充的NR硫化胶。随着KH550用量的增大,上述硫化胶性能变化的趋势增强。  相似文献   

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