Mechanical behavior of high impact polystyrene based on SB copolymers as a function of synthesis conditions: Part II

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Ramón Díaz de León ◽  
Graciela Morales ◽  
Pablo Acuña ◽  
Florentino Soriano
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Volume Fraction ◽  
Interparticle Distance ◽  
Tensile Tests ◽  
High Impact ◽  
Synthesis Conditions ◽  
High Impact Polystyrene ◽  
Transmission Electron ◽  
Rubber Phase

AbstractThe mechanical properties of different high impact polystyrene (HIPS) were determined by means of impact and tensile tests. Impact strength (IS), yield stress (σy) and Young’s modulus (E) were evaluated as a function of the rubber phase morphological features such as type and particle size (Dp), volume fraction (Φ) and interparticle distance (IPD). In order to evaluate the changes produced in the rubber phase, the initiator, chain transfer agent (CTA), and type and concentration of SB copolymer were varied during the synthesis of HIPS. Transmission electron microscopy was used to analyze the materials’ morphology and the data obtained reveal that the Dp and Φ increases mainly with an increase in the PB content and/or with the use of CTA and decreases with an increase in initiator concentration. In addition, E and yield stress diminishes when increasing the dimensions of the rubber phase (Dp and Φ), contrary to the IS. The IPD/Dp ratio also indicates the dependency of the mechanical properties with respect to the rubber phase features. An increase in IPD/Dp provokes an increases in E and σy, whereas IS diminishes.

Temperature and Stress State Influence on Mechanical Properties and Damage Evolution of Dual-Phase Steels

2014 ◽  
Vol 783-786 ◽  
pp. 886-891
Author(s):  
Mayerling Martinez ◽  
Jerôme Chottin ◽  
Eric Hug
Keyword(s):  
Mechanical Properties ◽  
Automotive Industry ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Transmission Electron ◽  
Structural Applications ◽  
Microstructure Parameters ◽  
Evolution Of Microstructure

Dual Phase steels are increasingly selected for structural applications including parts in automotive industry because of their interesting mechanical properties and their good formability. This work presents an experimental analysis of the evolution of microstructure of a DP1000 alloy submitted to thermomechanical loadings. Monotonous tensile tests were performed at various plastic strain levels up to fracture for temperatures ranging between 25 °C and 440 °C. A strong degradation of the mechanical properties is observed for temperatures higher than 275 °C. The evolution with plastic strains and temperature of the microstructure was studied by scanning and transmission electron microscopy. Different microstructure parameters such as volume fraction of martensite and carbide precipitation were taken into account in order to understand the mechanical behavior of DP1000 steels tested in this temperature range. The microstructural observations indicate that diminution of carbon in martensite, due to its diffusion to form carbides, could partially explain the drop in mechanical properties at around 275 °C.

Shape Memory Characteristics and Superelasticity of Ti-Ni-Cu Alloy Ribbons with Nano Ti2Ni Particles

2008 ◽  
Vol 8 (2) ◽  
pp. 722-727 ◽  
Author(s):  
Tae-hyun Nam ◽  
Cheol-am Yu ◽  
Jung-min Nam ◽  
Hyun-gon Kim ◽  
Yeon-wook Kim
Keyword(s):  
Melt Spinning ◽  
Volume Fraction ◽  
Deformation Behaviour ◽  
Parent Phase ◽  
Tensile Tests ◽  
Constant Load ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Average Size ◽  
Memory Characteristics

Microstructures and deformation behaviour of Ti-45Ni-5Cu and Ti-46Ni-5Cu alloy ribbons prepared by melt spinning were investigated by transmission electron microscopy, thermal cycling tests under constant load and tensile tests. Spherical Ti2Ni particles coherent with the B2 parent phase were observed in the alloy ribbons when the melt spinning temperature was higher than 1773 K. Average size of Ti2Ni particles in the ribbons obtained at 1873 K was 8 nm, which was smaller than that (10 nm) in the ribbons obtained at 1773 K. Volume fraction of Ti2Ni phase in the ribbons obtained at 1873 K was 40%, which was larger than that (20%) in the ribbons obtained at 1773 K. The stress required at temperatures of Af + 10 K for the stress-induced martensitic transformation increased from 93 MPa to 229 MPa and apparent elastic modulus of the B2 parent phase increased from 56 GPa to 250 GPa with increasing the melt spinning temperature from 1673 K to 1873 K in Ti-45Ni-5Cu alloy ribbons. The critical stress for slip deformation of the ribbons increased by coherent Ti2Ni particles, and thus residual elongation did not occur even at 160 MPa, while considerable plastic deformation occurred at 60 MPa in the ribbons without Ti2Ni particles. Almost perfect superelastic recovery was found in the ribbons with coherent Ti2Ni particles, while only partial superelastic recovery was observed in the ribbons without coherent Ti2Ni particles.

Phase Stability and Mechanical Properties of Ti(Ni, Ru) Alloys

2002 ◽  
Vol 753 ◽  
Author(s):  
Masahiro Tsuji ◽  
Hideki Hosoda ◽  
Kenji Wakashima ◽  
Yoko Yamabe-Mitarai
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Phase Stability ◽  
Hot Forging ◽  
Tensile Tests ◽  
Lattice Parameter ◽  
Solid Solution Hardening ◽  
Scanning Calorimetry ◽  
Arc Melting ◽  
Transmission Electron

ABSTRACTEffects of ruthenium (Ru) substitution on constituent phases, phase transformation temperatures and mechanical properties were investigated for Ti-Ni shape memory alloys. Ti50Ni50-XRuX alloys with Ru contents (X) from 0mol% (binary TiNi) to 50mol% (binary TiRu) were systematically prepared by Ar arc-melting followed by hot-forging at temperatures from 1173K to 1673K depending on chemical composition. Phase stability was assessed by DSC (differential scanning calorimetry), XRD (X-ray diffractometry) and TEM (transmission electron microscopy). Mechanical properties were investigated using hardness and tensile tests at room temperature. With increasing Ru content, it was found that the lattice parameter of B2 phase increases, the martensitic transformation temperature slightly decreases, and the melting temperature increases monotonously. Besides, R-phase appears for Ti-Ni alloys containing 3mol% and 20mol%Ru but no diffusionless phase transformation is seen in Ti-Ni alloy containing 5mol%Ru. Vickers hardness shows the maximum at an intermediate composition (HV1030 at 30mol%Ru); this suggests that large solid solution hardening is caused by Ru substitution for the Ni-sites in TiNi.

Cellulose Whiskers Micro-Fibers Effect in the Mechanical Proprieties of PP and PLA Composites Fibers Obtained by Spinning Process

2011 ◽  
Vol 146 ◽  
pp. 12-26 ◽  
Author(s):  
A. Gherissi ◽  
R.Ben Cheikh ◽  
E. Dévaux ◽  
Fethi Abbassi
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Volume Fraction ◽  
Young's Modulus ◽  
Tensile Tests ◽  
Advanced Materials ◽  
Uniaxial Tensile ◽  
Failure Resistance ◽  
Cellulose Whiskers ◽  
Limit Strength

In this study, we present the manufacturing process of two new composites materials in the form of long fibers of polylactic-acid (PLA) or polypropylene (PP), reinforced by cellulose whiskers micro-fibers loads. In order to evaluate the mechanical properties of these advanced materials, a several uniaxial tensile tests were carried out. The PP and the PLA have initially been spinning without the addition of cellulose whiskers micro-fibers. In order to study the effects of cellulose whiskers micro-fibers reinforcements in the Mechanical behavior of the PLA and PP filaments, we determinate the proprieties of these advanced material from the tensile results. For the PP composite filaments material case, the whiskers reinforcement increases Young's modulus and failure resistance, but it reduces the limit strength failure. For the PLA composites the addition of 1% wt of cellulose whiskers from the total volume fraction of the material, increase the Young’s modulus more than 50% and a decrease of the failure resistance and the limit strength of composite. The obtained composites fibers are very rigid and brittle. What follows, that the addition of cellulose whiskers micro fibers in PP matrix, provides mechanical properties more convenient compared to the PLA matrix.

Study on Non-Halogen Flame-Retarded HIPS with High Strength HIPS

2008 ◽  
Vol 47-50 ◽  
pp. 1245-1249
Author(s):  
Zhong Wei Wu ◽  
Qing Jie Jiao ◽  
Chong Guang Zang ◽  
Hui Lan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
High Strength ◽  
High Impact ◽  
High Impact Polystyrene ◽  
Flame Retarded ◽  
Notch Impact Strength

PPO was a better intensifier and charred material for High-impact polystyrene (HIPS), it could make HIPS achieve UL94V-0 with APP, MC, RDP. Especially, RDP not only improved the flame-retarded property but also controlled the hole producing, and had the best consistent with matrix which could improve the mechanical properties. SBS and SEBS were better consistent with matrix, especially SEBS was tiny granule, which could be dispersed in matrix easily. The properties of SEBS toughened the non-halogen flame-retarded HIPS was followed: tensile strength: 18.83MPa; izod notch impact strength: 15.7kJ/m2; UL94V-0.

Biomimetic composites inspired by venous leaf

2017 ◽  
Vol 52 (3) ◽  
pp. 361-372 ◽  
Author(s):  
Gongdai Liu ◽  
R Ghosh ◽  
A Vaziri ◽  
A Hossieni ◽  
D Mousanezhad ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Poisson’S Ratio ◽  
Composite Structures ◽  
Volume Fraction ◽  
Matrix Material ◽  
Poisson's Ratio ◽  
Fiber Volume ◽  
Young’S Moduli

A typical plant leaf can be idealized as a composite having three principal fibers: the central mid-fiber corresponding to the mid-rib, straight parallel secondary fibers attached to the mid-fiber representing the secondary veins, and then another set of parallel fibers emanating from the secondary fibers mimicking the tertiary fibers embedded in a matrix material. This paper introduces a biomimetic composite design inspired by the morphology of venous leafs and investigates the effects of venation morphologies on the in-plane mechanical properties of the biomimetic composites using finite element method. The mechanical properties such as Young’s moduli, Poisson’s ratio, and yield stress under uniaxial loading of the resultant composite structures was studied and the effect of different fiber architectures on these properties was investigated. To this end, two broad types of architectures were used both having similar central main fiber but differing in either having only secondary fibers or additional tertiary fibers. The fiber and matrix volume fractions were kept constant and a comparative parametric study was carried out by varying the inclination of the secondary fibers. The results show that the elastic modulus of composite in the direction of main fiber increases linearly with increasing the angle of the secondary fibers. Furthermore, the elastic modulus is enhanced if the secondary fibers are closed, which mimics composites with closed cellular fibers. In contrast, the elastic modulus of composites normal to the main fiber ( x direction) exponentially decreases with the increase of the angle of the secondary fibers and it is little affected by having secondary fibers closed. Similar results were obtained for the yield stress of the composites. The results also indicate that Poisson’s ratio linearly increases with the secondary fiber angle. The results also show that for a constant fiber volume fraction, addition of various tertiary fibers may not significantly enhance the mechanical properties of the composites. The mechanical properties of the composites are mainly dominated by the secondary fibers. Finally, a simple model was proposed to predict these behaviors.

Rheology of Block Copolymers

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Block Copolymers ◽  
Small Angle ◽  
Volume Fraction ◽  
Synthesis Methods ◽  
Chemical Structures ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Molecular Weight Form

Block copolymer consists of two or more long blocks with dissimilar chemical structures which are chemically connected. There are different architectures of block copolymers, namely, AB-type diblock, ABA-type triblock, ABC-type triblock, and AmBn radial or star-shaped block copolymers, as shown schematically in Figure 8.1. The majority of block copolymers has long been synthesized by sequential anionic polymerization, which gives rise to narrow molecular weight distribution, although other synthesis methods (e.g., cationic polymerization, atom transfer radical polymerization) have also been developed in the more recent past. Owing to immiscibility between the constituent blocks, block copolymers above a certain threshold molecular weight form microdomains (10–50 nm in size), the structure of which depends primarily on block composition (or block length ratio). The presence of microdomains confers unique mechanical properties to block copolymers. There are many papers that have dealt with the synthesis and physical/mechanical properties of block copolymers, too many to cite them all here. There are monographs describing the synthesis and physical properties of block copolymers (Aggarwal 1970; Burke and Weiss 1973; Hamley 1998; Holden et al. 1996; Hsieh and Quirk 1996; Noshay and McGrath 1977). Figure 8.2 shows schematically four types of equilibrium microdomain structures observed in block copolymers. Referring to Figure 8.2, it is well established (Helfand and Wasserman 1982; Leibler 1980) that in microphase-separated block copolymers, spherical microdomains are observed when the volume fraction f of one of the blocks is less than approximately 0.15, hexagonally packed cylindrical microdomains are observed when the value of f is between approximately 0.15 and 0.44, and lamellar microdomains are observed when the value of f is between approximately 0.44 and 0.50. Some investigators have observed ordered bicontinuous double-diamonds (OBDD) (Thomas et al. 1986; Hasegawa et al. 1987) or bicontinuous gyroids (Hajduk et al. 1994) at a very narrow range of f (say, between approximately 0.35 and 0.40) for certain block copolymers. Figure 8.2 shows only one half of the symmetricity about f = 0.5. Transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) have long been used to investigate the types of microdomain structures in block copolymers.

scholarly journals Nondestructive Evaluation of Thermal Aging in Al6061 Alloy by Measuring Acoustic Nonlinearity of Laser-Generated Surface Acoustic Waves

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 38 ◽  
Author(s):  
Jihyun Jun ◽  
Hogeon Seo ◽  
Kyung-Young Jhang
Keyword(s):  
Mechanical Properties ◽  
Nondestructive Evaluation ◽  
Thermal Aging ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Tensile Tests ◽  
Acoustic Nonlinearity ◽  
Transmission Electron ◽  
Heat Treated ◽  
Elongation To Failure

The structures in high-temperature environments are prone to undergo hardening and embrittlement as a result of thermal aging; this can cause variations in their mechanical properties. Because these changes occur at the microstructural level, it is difficult to evaluate them through linear ultrasonic techniques. In this work, a surface acoustic wave (SAW) was used to measure and compare the acoustic nonlinearity and mechanical properties of Al6061 alloys heat-treated at 220 °C for different durations (0 min, 20 min, 40 min, 1 h, 2 h, 10 h, 100 h, 1000 h). The SAW was generated by a pulsed laser and then received by an interferometer. Moreover, the yield strength, ultimate strength, and elongation to failure were measured by tensile tests. The results demonstrate that the critical variations in the mechanical properties can be detected by monitoring the variation features in the acoustic nonlinearity. Transmission electron microscopy images were captured to observe the microstructural changes, which shows that the acoustic nonlinearity varied according to the change in the precipitation phase. This supports the acoustic nonlinearity measurement using the laser-generated SAW being an effective technique for the fully noncontact nondestructive evaluation of material degradations as well as changes in mechanical properties.

scholarly journals IMCs Microstructure Evolution Dependence of Mechanical Properties for Ni/Sn/Ni Micro Solder-Joints

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 252 ◽  
Author(s):  
Ning Ren ◽  
Heng Fang ◽  
Dong Wang ◽  
Chenyi Hou ◽  
Yatao Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Brittle Fracture ◽  
Ductile Fracture ◽  
Solder Joints ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Scale Down ◽  
Long Rod

The current miniaturization trend of microelectronic devices drives the size of solder joints to continually scale down. The miniaturized joints considerably increase intermetallic compounds (IMCs) volume fraction to trigger mechanical reliability issues. This study investigated precise relationships between varying IMC volumes and mechanical properties of Ni/Sn(20μm)/Ni micro-joints. A designed method that followed the IMC volume as the only variable was used to prepare micro-joint samples with different IMC volumes. The continuously thickened Ni3Sn4 IMCs exhibited a noticeable morphology evolution from rod-like to chunky shape. The subsequent tensile tests showed unexpected tensile strength responses as increasing Ni3Sn4 volume, which was strongly associated with the Ni3Sn4 morphological evolutions. Fractographic analysis displayed that the ductile fracture dominates the 20%–40% IMC micro-joints, whereas the brittle fracture governs the 40%–80% IMC micro-joints. For the ductile fracture-dominated joints, an abnormal reduction in strength occurred as increasing IMCs volume from 20% to 40%. This is primarily due to severe stress concentrations caused by the transformed long rod-typed morphology of the Ni3Sn4. For the brittle fracture-dominated joints, the strength appeared a monotonous increase as the Ni3Sn4 volume increased. This may be attributed to the increased crack resistance resulting from continuous coarsening of the chunky Ni3Sn4 without any voids. Moreover, the finite element analysis was provided to further understand the joint failure mechanisms.

Microstructure and Mechanical Properties in QT-Treated 9Ni Steel

2012 ◽  
Vol 562-564 ◽  
pp. 39-42
Author(s):  
Hang Su ◽  
Xi Qing Zhao ◽  
Tao Pan ◽  
Xiao Rong Lei ◽  
Qing Feng Wang
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Optical Microscope ◽  
Reversed Austenite ◽  
Tempered Martensite ◽  
Tempering Temperature ◽  
Scavenging Effect ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron ◽  
9Ni Steel

Microstructure and mechanical properties in QT-Treated 9Ni steel were investigated. The detail microstructures were observed by optical microscope (OM) and transmission electron microscope (TEM). The volume fraction of austenite was estimated by XRD. Tensile test at room temperature and Charpy-V-Notch (CVN) impact test at -196°C were carried out. The results showed that the microstructure of QT-treated 9%Ni steel was composed of tempered martensite and reversed austenite. The brittle cementite was absorbed gradually by the increasing reversed austenite as the tempering temperature increased. The optimum tempering temperature range was 560°C~580°C. The reversed austenite could improve the cryogenic toughness of 9Ni steel through the combination of the scavenging effect and the TRIP effect.

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