Experimental investigation of the viscoelastic deformation of PC, ABS and PC/ABS alloys

Dynamic Mechanical Analysis (DMA) tests are carried out to investigate the viscoelastic deformation of PC, ABS and PC/ABS alloys with ratio of PC to ABS being 80/20, 60/40, 50/50, 40/60, respectively. Storage and loss moduli and loss angle of PC, ABS and PC/ABS alloys are measured from DMA tests from 30 °C in 160 °C at 1 Hz. Glassy temperature of PC/ABS alloys is determined with loss modulus and loss angle curves. Also, static tests are carried out to measure the relaxation moduli of PC, ABS and PC/ABS alloys. Effect of ABS fraction on the glassy transition temperatures and relaxation moduli of PC/ABS alloys is discussed.     

PC/ABS在高应变率下的压缩大变形

目的对PC/ABS在高应变率下的压缩大变形行为进行实验研究与模拟。方法在应变率为1600~5000 s~(-1),温度为293~353 K的范围内,选用霍普金森压杆获取其在高应变率、高温下的大变形行为;选用DSGZ本构模型,模拟PC/ABS在高应变率下的大变形。结果 PC/ABS大变形行为强烈依赖于应变率和温度,屈服应力随应变率增加或温度降低而升高,大变形行为包括弹性、屈服、应变软化和应变硬化。结论DSGZ本构可准确模拟PC/ABS在高应变率、高温下的大变形行为。     

PC/ABS合金的开发和应用现状

PC/ABS合金是一种优良的工程塑料 ,很有发展前景。文中叙述了该产品的国内外最新生产方法、用途及发展趋势     

Fracture behaviour of PC/ABS resin under mixed-mode loading

Fracture behaviour of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) under mixed-mode loading conditions was studied for several weight fractions of PC and ABS. Mode I and mixed-mode fracture tests were carried out by using compact–tension–shear specimens. At a certain value of mixed-mode loading ratio K _II / K _I a crack of the shear type will initiates at the initial crack tip. Fracture toughness increases under mixed-mode loading with an increase in the mode II component, whereas it reduces with the appearance of a shear-type fracture. Fracture toughness and the appearance of a shear-type fracture depends on the blending ratio of PC and ABS. The transition to shear-type fracture occurs at lower value of K _II / K _I for resins with higher fracture toughness.     

无卤阻燃PC/ABS合金研究进展

综述了近年来国内外PC/ABS合金无卤阻燃改性的研究进展。介绍了PC/ABS合金体系无卤阻燃剂的分类、阻燃机理及存在的一些问题和解决方法。重点阐述了有机磷系阻燃剂及其对PC/ABS合金的阻燃性能、热分解和力学性能等的影响,并指出了今后的研究重点和发展方向。     

玻璃纤维增强阻燃PC／ABS合金性能的研究

研究玻璃纤维增强PC／ABS合金在未加相容剂和分别加入相容剂ABS-g-MAH和AS-g-MAH的力学性能。结果表明，加入相容剂之后合金的拉伸强度和弯曲强度均得到提高，其中AS-g-MAH的增容效果更好。选用符合RoHS标准的卤锑系阻燃剂改性PC／ABS合金，发现合金的阻燃性能在达到UL94V-0级时力学性能略有下降。采用SEM图片观察PC／ABS合金加相容剂以及加纤前后的微观结构，发现微观形貌特征和力学试验结果完全相符。     

高强耐热阻燃PC/ABS塑料合金研究

采用PC和ABS为主要原料,ABS接枝物为相容剂,十溴二苯醚和三氧化二锑为阻燃体系制备PC/ABS塑料合金,利用扫描电镜(SEM)和透射电镜(TEM)对PC/ABS塑料合金微观结构进行研究,并对力学性能、热性能和阻燃性能进行了测试.结果表明,当PC、ABS和ABS接枝物三者比例为54∶2323时,合金的拉伸强度、弯曲强度、缺口冲击强度和热性能与电视机配件中的PPO相当,断裂伸长率为97.3%,弯曲模量为2479MPa,无缺口冲击强度为NB(冲不断),阻燃性达到V-O级,均远优于PPO,可以替代PPO.     

阻燃PC/ABS的热降解动力学

将自合成的一种新型含磷阻燃剂DPWDF与PC/ABS共混;利用热重分析(TGA)法研究了PC/ABS和阻燃PC/ABS在空气氛围中的热稳定性,利用Flynn-Wall-Ozawa方法研究了PC/ABS及阻燃PC/ABS的热降解动力学。结果表明,阻燃剂降低了PC/ABS初始分解温度(IDT)而提高了它的高温残炭量;在转化率70%以前,阻燃PC/ABS的活化能低于PC/ABS,而在转化率70%以后,阻燃PC/ABS的活化能高于PC/ABS。此实验结果体现了该含磷阻燃剂的凝聚相阻燃机理。     

一种新型无卤阻燃剂的合成及其在PC/ABS中的应用

以9,10-二-9-氧杂-10-磷杂菲-10-氧化物(DOPO)、丙烯酸(AA)、N-β-胺乙基-γ胺丙基甲基二甲氧基硅烷(HD-103)和α,ω-二羟基二甲基硅烷(PDMS)为原料,合成出一种新型的集硅、磷、氮于一体的阻燃剂;表征了所合成的中间体及阻燃剂的结构;并将阻燃剂与PC/ABS共混,利用LOI和TGA考察了阻燃PC/ABS的阻燃性及热降解行为.     

Constitutive modeling of nitrogen-alloyed austenitic stainless steel at low and high strain rates and temperatures

In this paper, microstructures-based constitutive relations are introduced to simulate the thermo-mechanical response of two nitrogen-alloyed austenitic stainless steels; Nitronic-50 and Uranus-B66, under static and dynamic loadings. The simulation of the flow stress is developed based on a combined approach of two different principal mechanisms; the cutting of dislocation forests and the overcoming of Peierls–Nabarro barriers. The experimental observations for Nitronic-50 and Uranus-B66 conducted by Guo and Nemat-Nasser (2006) and Fréchard et al. (2008), respectively, over a wide range of temperatures and strain rates are also utilized in understanding the underlying deformation mechanisms. Results for the two stainless steels reveal that both the initial yielding and strain hardening are strongly dependent on the coupling effect of temperatures and strain rates. The methodology of obtaining the material parameters and their physical interpretation are presented thoroughly. The present model predicts results that compare very well with the experimental data for both stainless steels at initial temperature range of 77–1000 K and strain rates between 0.001 and 8000 s⁻¹. The effect of the physical quantities at the microstructures on the overall flow stress is also investigated. The evolution of dislocation density along with the initial dislocation density contribution plays a crucial role in determining the thermal stresses. It was observed that the thermal yield stress component is more affected by the presence of initial dislocations and decreases with the increase of the originated (initial) dislocation density.     

一种新型含硅阻燃剂的合成及在PC/ABS中的应用

以9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)、丙烯酸(AA)、N-β-胺乙基-γ胺丙基甲基二甲氧基硅烷(HD-103)和α,ω-二羟基二甲基硅烷(PDMS)为原料,合成出一种新型的集硅、磷、氮于一体的阻燃剂;表征了所合成的中间体及阻燃剂的结构;并将阻燃剂与PC/ABS共混,利用LOI和TGA考察了阻燃PC/ABS的阻燃性及热降解行为。     

不锈钢纤维(SSF)和镍碳复合纤维(NCF)填充PC/ABS导电塑料性能影响分析

本文介绍了采用不锈钢纤维(SSF)和镍碳复合纤维(NCF)填充PC/ABS注塑成型新型轻质复合导电塑料,着重阐述了填充纤维后对复合材料的屏蔽效能、力学性能等的影响。     

纳米CaCO3复合微粒增韧增强PC/ABS合金

经甲基丙烯酸甲酯和丙烯酸丁酯双单体聚合包覆的纳米碳酸钙形成了核壳结构增韧复合微粒。在双螺杆挤出机中采用二次挤出法制备出PC/ABS/纳米碳酸钙复合材料。研究纳米碳酸钙复合微粒对PC/ABS合金力学性能的影响表明:添加适量纳米CaCO3复合微粒,PC/ABS合金的缺口冲击强度和拉伸强度都得到提高。纳米CaCO3复合微粒具有无机纳米颗粒和弹性体双重协同增韧的作用,其表面的聚合物分子链与基体树脂起到嵌段增容作用。     

阻燃改性对PC/ABS合金热降解行为的影响

采用氧指数、水平垂直燃烧、红外光谱和热重分析4种方法对两种市售PC/ABS合金PC-345和PC-510的燃烧性能和热降解过程进行了研究。研究发现,与未经改性的PC-345相比,经过阻燃改性的PC-510氧指数有所提高,垂直燃烧测试中可以在30s内自熄,燃烧等级提高到UL-94V-1级。红外光谱研究发现PC-510在温度低于700℃时,保持了PC/ABS原有的结构。热降解动力学分析结果表明,PC-510最大分解温度比PC-345有所升高,尤其在高加热速率下表现得更明显,聚合物达到相同分解程度需要的能量增加,材料热稳定性得到提高。     

无卤阻燃PC/ABS的制备及燃烧性能

以齐聚磷酸酯(BDP)作为添加型阻燃剂制备了阻燃PC/ABS塑料合金,采用锥形量热仪(CONE)、扫描电镜(SEM)及热裂解-气相/质谱法(Py-GC/MS)等对材料的燃烧性能和阻燃机理进行了研究.结果表明,阻燃剂BDP对PC/ABS有良好的阻燃效果;BDP的加入使PC/ABS燃烧残留物上产生大量的致密微孔,同时由Py-GC/MS分析表明BDP的加入降低了PC/ABS可燃性降解产物的生成,裂解产物中含有三苯基磷酸酯(TPP),说明BDP在塑料合金降解过程中分解生成TPP发挥阻燃作用.     

Characterization and constitutive modeling of aramid fibers at high strain rates

The quasi-static and rate-dependent mechanical properties of aramid yarns are presented together with a study on different methods of securing yarn specimens in tensile tests. While capstans were found to be suitable for quasi-static tests, they either were not strong enough or had too high inertia for dynamic tests in a Split Hopkinson Pressure Bar setup. Instead, specially designed clamps were used. A viscoelastic material model to describe the mechanical behavior of the yarns, including failure, is also presented. The material model was employed in the computational simulation of ballistic penetration of woven aramid fabrics. Comparison of the simulations and actual ballistic tests showed that predictions of the energy absorbed by the fabric were in good agreement with the experiments.     

ABS/SBS和ABS/GF环状试样的疲劳性能

采用ABS/SBS和ABS/GF材料成型了圆环状试样,使用了自行设计的试验装置对环状试样进行疲劳试验,分析比较在环状下不同填料对ABS的疲劳性能的影响。从而获得ABS/SBS和ABS/GF环状试样在不同应力下的疲劳曲线和疲劳变化趋势。     

Evaluation of low strain rate constitutive equation of 7075 aluminium alloy at high temperature

Abstract

The 7075 aluminium alloy is one of the most important engineering alloys utilised extensively in aircraft and transportation industries due to its high specific strength. In the present research, the flow behaviour of this alloy has been investigated using hot compression test at strain rates of 0·001, 0·01, 0·1 and 1 s^?1 and temperatures of 350, 400 and 450°C. The results reveal that dynamic softening occurred in these temperatures and strain rates. The activation energy, strain rate sensitivity and two constitutive equations (hyperbolic sine law and the power law) are derived from the results. It is shown that the hyperbolic sine law has a better agreement with the experimental results.     

Microstructure evolution of ZK40 magnesium alloy during high strain rate compression deformation at elevated temperatures

Abstract

Microstructure evolution of the homogenised ZK40 magnesium alloy was investigated during compression in the temperature range of 250–400°C and at the strain rate range of 0·01–50 s^?1. At a higher strain rate (?10 s^?1), dynamic recrystallisation developed extensively at grain boundaries and twins, resulting in a more homogeneous microstructure than the other conditions. The hot deformation characteristics of ZK40 exhibited an abnormal relationship with the strain rate, i.e., the hot workability increased with increasing the strain rate. However, the dynamic recrystallisation grain size was almost the same with increasing the temperature at the strain rate of 10 s^?1, while it increased obviously at the strain rates of 20 and 50 s^?1. Therefore, hot deformation at the strain rate of 10 s^?1 and temperature range of 250–400°C was desirable and feasible for the ZK40 alloy.     

Establishment and comparison of four constitutive relationships of PC/ABS from low to high uniaxial strain rates

The objective of this paper is to accurately predict the rate/temperature-dependent deformation of a polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blend at low, moderate, and high strain rates for various temperatures. Four constitutive models have been employed to predict stress–strain responses of PC/ABS under these conditions, including the DSGZ model, the original Mulliken–Boyce (M–B) model, the modified M–B model, and an adiabatic model named the Wang model. To more accurately capture the large deformation of PC/ABS under the high strain rate loading, the original M–B model is modified by allowing for the evolution of the internal shear strength. All of the four constitutive models above have been implemented in the finite element software ABAQUS/Explicit. A comparison of prediction accuracies of the four constitutive models over a wide range of strain rates and temperatures has been presented. The modified M–B model is observed to be more accurate in predicting the deformation of PC/ABS at high strain rates for various temperatures than the original M–B model, and the Wang model is demonstrated to be the most accurate in simulating the deformation of PC/ABS at low, moderate, and high strain rates for various temperatures.