Tensile Properties Of Plastics Research Articles

On the Use of Pad Mechanical Properties as a Proxy for Conditioning Response

A proliferation of pad materials in recent years, coupled with the increasing complexity of process integration and limited resources available for process development, has highlighted the need for a more in depth understanding of conditioning interactions and better predictive tools for process and consumable design. We have previously noted a range of conditioning response as illustrated in Figure 1. As the figure illustrates, on some materials the surface height distribution imparted by the pad conditioner is shifted to the left relative to the exponential signature of the pad native porosity which is used as a reference. Denoted regime 1, these surfaces are characterized by the prevalence of “eyelid” features which obscure the line-of-sight path to the bottoms of the pores. In regime 2, the surface height distribution is more balanced, with a smooth transition between the exponential porosity signature and the conditioning signature. In regime 3, there is an abrupt disconnect between the exponential porosity signature and the conditioner signature. Such surfaces are characterized by deep gouges.We are investigating pad material tensile properties as a proxy to help understand and predict these conditioning responses. Figure 2 illustrates the range of typical tensile behavior for polymers. While Figure 2 invokes temperature as the variable that drives these behaviors, note that strain rate can also drive tensile behavior across this range with high temperature being analogous to low strain rate and vice versa.Figure 3 and Table 1 summarize some results from our testing of IC1000, VP5000, VP6000, IK4250H and IK4350L. We have determined that grooved pad materials at their nominal dimensions are adequate for testing according to ASTM D638: Standard Test Method for Tensile Properties of Plastics. Typical delivered pad thickness is within the specifications for sample thickness, and as long as the grooves are oriented to be substantially parallel with the strain axis (pulling direction) reproducible results can be obtained. A range of properties spanning at least about 2x is observed in these pads.Figure 4 gives one example of how this information can be directly applied. The figure illustrates a manifestation of the threshold behavior that is typically observed when conditioning with a pad conditioner with uniform tip height, where all the cutting points are controlled within a height range of about 10 µm. As opposed to a conventional conditioning platform, where there is a much wider range of tip heights, the uniform height-controlled conditioner exhibits a threshold behavior where no measurable cutting occurs below a limiting condition down-force (cdf). Figure 4 illustrates the disconnect between a high down-force, accelerated cutting test, using 14 lbs cdf and designed to return the “CR” value for a conditioner, and typical process cdf levels, in the range of 5 lbs cdf. Note that CR values are generally about an order of magnitude higher than comparable polishing tool level pad wear rates. Whereas conventional platforms yield a linear response between CR and tool level pad wear rates, the uniform height design exhibits an offset, such that at low CR levels, low pad wear rates are observed. The position of this threshold is a function of pad type. These data suggest that this threshold can be correlated with the mechanical strength of the pad material, as determined by the tensile test results.We have also explored the effect of strain rate on tensile response. Strain rates in a typical CMP process may be as high as 105 s-1, and as shown in Figure 2, strain rate can have a significant effect on material behavior. Figure 5 illustrates typical results, illustrating the extremes of response for this group of pads, and Figure 6 shows the normalized response of offset yield and tensile strength as a function of strain rate. Of these materials, only IK4350L exhibits a divergent response, and as shown in Figure 7, IK4350L typically exhibits the most abrupt transition between the exponential porosity signature and the conditioner cutting signature, indicating a tendency towards the gross over-conditioning behavior characteristic of regime 3.Over the range of strain rates explored here, all of these materials can be characterized as “rubbery”. This rubbery behavior can be understood in the context of reported property measurements of CMP pads, which indicate distinct glass transitions related to the soft and hard phases of the polyurethane from which the pad is made. This analysis suggests that pad behavior is dominated by the “rubbery plateau” of the soft segment of the polymer, with the glass transition of the hard segment occurring above typical polishing temperatures. Figure 1

Characterization of composite material specimens manufactured in 3D printing for the construction of a shoulder Rehabilitation Prototype

The present work seeks to characterize polymer specimens with aluminum and stainless steel reinforcements, using additive manufacturing for their elaboration and thus increase their tensile strength and implement them for industrial, medical and automotive use. The methodology to follow consists of a documentary investigation of related articles and standards such as ASTM D638, where the tensile properties of plastics are specified, continuing with the manufacture of the test tubes in a 3D printer, this according to the corresponding standard., to later carry out stress tests on the universal machine. The contribution of the work developed lies in the increase in the tensile strength of the composite material experienced, resulting for a first test tube an increase of 52.4% in the maximum tensile strength with an aluminum reinforcement, and an increase of 59.1%, this with a steel reinforcement, in the second specimen submitted to tests with aluminum reinforcement an increase of 20.04% was obtained and with the steel reinforcement it was 84.54%.

Evaluation of the tensile properties of polished and unpolished 3D SLA- and DLP-Printed specimens used for surgical guides fabrication.

Abstract Introduction: The fundamental mechanical properties of 3D printed surgical guides used in orthodontics represent an important indicator for the accuracy of the insertion of skeletal anchorage devices. The tensile strength of devices printed by stereolithography (SLA) and digital light processing (DLP) methods, respectively, is influenced by factors such as finishing process. Aim of the study: This study illustrates a comparison of the tensile strength in two different types of 3D printed devices (SLA, DLP respectively) undergoing or not a standard process of polishing. Material and methods: Twenty-four specimens obtained according to ASTM D638-14 (Standard Test Method for Tensile Properties of Plastics) were used for the evaluation of tensile strength. Four groups of 6 samples from each category were created: SLA polished, SLA unpolished, DLP polished and DLP unpolished. After removing the support, finishing was performed to obtain smooth surfaces, according to the manufacturer’s recommendation. Type V specimen was used to perform tensile tests in accordance with the standard procedures ASTM D638-14 which recommends at least five specimens to be tested for each sample. One-way analysis of variance (ANOVA) and t-test showed statistically significant results at p < 0.05. SPSSv17 software was used for statistical analysis of the numerical variables, and also descriptive statistics were performed. Results: The measurements included: tensile strength (maximum load), tensile stress at maximum load and tensile strain at maximum load. The maximum load (tensile strength) of the polished specimens was lower, both for the SLA and DLP, with no statistical significance results. Conclusions: The conclusions indicated differences between maximum load and tensile stress at maximum load between polished and unpolished specimens, in both SLA and DLP groups. Althought the polishing process reduces the tensile strenght, the data analysis did not present statistically significant results.

Variables affecting unstable fracture load of cracked pipes under hydrogen environment

This paper presents an analytical equation for the reduction of the unstable fracture load for a cracked pipe due to hydrogen embrittlement. The proposed equation shows that the reduction of the unstable fracture load due to hydrogen embrittlement depends not only on the toughness reduction due to hydrogen embrittlement but also on plastic tensile properties and the degree of plastic yielding at fracture of a pipe without hydrogen embrittlement (quantified using the proximity parameter for plastic collapse). Note that the proximity parameter for plastic collapse is affected by the pipe and crack geometries, loading condition and fracture toughness before hydrogen embrittlement. Two case study results are presented using published material data. The first case considers stainless steel data to demonstrate the effect of the toughness reduction due to hydrogen exposure and the degree of plastic yielding at fracture on the reduction of the unstable fracture load for a cracked pipe under hydrogen embrittlement. The second case uses two sets of API 5L X42 and X70 pipeline steel data to illustrate the effect of plastic tensile properties.

Strength testing of low-cost 3D-printed transtibial prosthetic socket.

Measurement and production of traditional prosthetic sockets are time-consuming, labor-intensive, and highly dependent on the personnel involved. An alternative way to make prostheses is using computer-aided design (CAD) and computer-aided manufacturing (CAM). Fused Filament Fabrication (FFF) may be an alternative to make low-cost prosthetic sockets. This study investigates the tensile properties of potential printing materials suitable for FFF according to ISO527 (Standard Test Method for Tensile Properties of Plastics). To ensure that FFF-printed sockets are safe for patient usage, the structural integrity of the 3D-printed prosthesis will be investigated according to ISO10328 (International Standard Structural Testing of Lower Limb Prostheses). Tough PLA was the most suitable print material according to ISO 527 testing. The Tough PLA printed socket completed 2.27 million cycles and a static test target value of 4025 N. Future research remains necessary to continue testing new potential materials, improve print settings, and improve the socket design for the production of FFF-printed transtibial prosthetic sockets. FFF using Tough PLA can be used to create transtibial prostheses that almost comply with the International Standard for Structural Testing of Lower Limb Prostheses.

Anisotropic properties of 3-D printed Poly Lactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) plastics

Research was conducted on the mechanical and anisotropic properties of 3-D printed plastics (PLA and ABS), and the prevailing orientation and deposition of additive layers. Samples were tested in accordance with ASTM D638 - Standard Test Method for Tensile Properties of Plastics. Five print orientations were tested, including 0°, 30°, 45°, 60°, and 90°. Six samples were tested in each orientation, with a total of 30 samples being tested in each iteration of the experiment. An initial, “proof of concept” iteration was conducted with PLA plastic, followed by a second iteration which tested both PLA and ABS.Testing was conducted and based on the hypothesis that the material printed in the 0° orientation (parallel to the direction of applied tension) would be stronger, and that the strength of test specimens would be largely dependent on orientation of the material. In contrast, it was believed that the strength of 90° samples (perpendicular to the direction of applied tension) would be largely dependent on the strength of the bonds formed during the layer by layer deposition of heated material, and comparatively weaker. This was largely proven during testing. Samples printed in the 0° orientation exhibited statistically higher properties of both stress and strain. Conversely, plastics printed in the 90° orientation exhibited statistically weaker properties. It was noted that samples printed in the 30°, 45°, and 60° orientations exhibited some measure of improved ductility, although this was not the focus of the study.

3D-printed polypropylene transtibial sockets: Mechanical behavior

This paper defines the tensile properties of a successfully worn 3D-printed transtibial socket. The socket was printed from a proprietary polypropylene filament and FDM 3D-printing process. Fused disposition modeling involves producing successive cross-sectional layers on top of one another and welding them together. Because of this, a notch is formed between the printed layers. As part of this investigation, tensile test specimens were die-cut perpendicular to the material direction and tested according to ASTM D638—Standard Test Method for Tensile Properties of Plastics. From the measured load–elongation data, stress–strain curves and the corresponding material properties were determined, including modulus of elasticity E, Poisson’s ratio ν, yield strength Sy, and ultimate strength Su. The average values for each of these material properties were 955 MPa, 0.35, 11.4 MPa, and 16.3 MPa, respectively. In addition to defining tensile properties, this work demonstrated a viable methodology for characterizing the as-built material behavior of 3D-printed sockets.

Improved Tensile Ductility by Severe Plastic Deformation for Nano-Structured Metallic Glass.

The effect of severe plastic deformation by high-pressure torsion (HPT) on the structure and plastic tensile properties of two Zr-based bulk metallic glasses, Zr55.7Ni10Al7Cu19Co8.3 and Zr64Ni10Al7Cu19, was investigated. The compositions were chosen because, in TEM investigation, Zr55.7Ni10Al7Cu19Co8.3 exhibited nanoscale inhomogeneity, while Zr64Ni10Al7Cu19 appeared homogeneous on that length scale. The nanoscale inhomogeneity was expected to result in an increased plastic strain limit, as compared to the homogeneous material, which may be further increased by severe mechanical work. The as-cast materials exhibited 0.1% tensile plasticity for Zr64Ni10Al7Cu19 and Zr55.7Ni10Al7Cu19Co8.3. Following two rotations of HPT treatment, the tensile plastic strain was increased to 0.5% and 0.9%, respectively. Further testing was performed by X-ray diffraction and by differential scanning calorimetry. Following two rotations of HPT treatment, the initially fully amorphous Zr55.7Ni10Al7Cu19Co8.3 exhibited significantly increased free volume and a small volume fraction of nanocrystallites. A further increase in HPT rotation number did not result in an increase in plastic ductility of both alloys. Possible reasons for the different mechanical behavior of nanoscale heterogeneous Zr55.7Ni10Al7Cu19Co8.3 and homogeneous Zr64Ni10Al7Cu19 are presented.

Seawater effects on static loads and interlayer cracking performance for polyvinyl chloride foam-cored sandwich composites

The diffusion influence of seawater on the static and interlayer cracking properties of a polyvinyl chloride foam sandwich structure is investigated in this study. After soaking specimens in seawater for various durations, various comparison tests are performed to investigate the effects of seawater. Compression tests for H60 and H200 polyvinyl chloride foam specimens are conducted to study strength and modulus degradation, and the results show that immerging time and temperature have significant effects on polyvinyl chloride foam properties. Tensile tests for glass-fibre-reinforced plastic panels, four-point bending tests and double cantilever bending tests for polyvinyl chloride foam sandwich specimens are also performed. The results show that seawater immerging treatment has a noticeable influence on glass-fibre-reinforced plastic tensile properties and interlayer critical energy release rate values, but has almost no effect on bending properties of foam sandwich specimen. Furthermore, a rate-dependent phenomenon is observed in double cantilever bending tests, in which higher loading rate will lead to larger critical energy release values. Numerical simulation is also performed to illustrate the cracking process of double cantilever bending tests and shows a certain accuracy. The simulation also demonstrates that the viscoelasticity of foam material after immerging treatment results in the rate-dependent characterization of double cantilever bending tests.

Starch-Based Biodegradable Packaging Materials of Antimicrobial

With the gradual increase of the global environmental awareness and environmentally friendly voice rising, the deal with the problem of plastic waste has become the focus of public opinion around the world has also become a hot topic of scientific research. This paper can be made of polystyrene as main raw material, adding starch and antibacterial agents containing silver nanoscale titanium dioxide, and by the synthesis of biodegradable packaging materials performance. The results showed that: 0.25mm sheet of polystyrene made of the thickness of the main raw material by injection molding process, and factors affecting the performance of the sheet, the better the performance of the film material process parameters. According to the definition of the GB/T1040-92 national standards of the People's Republic of China "plastic tensile properties of test methods and GB/T20197-2006 degradable plastics, classification, marking, and degradation of the performance requirements" and GB4789.3-94 "State Microbiological examination of coli form bacteria in the standard of food hygiene as determined by experimental methods for testing. The orthogonal experiment results show that the expandable polystyrene Dosage: 80%; starch dosage: 2%; toluene, acetone and put ratio: 3:2 .The mechanics of materials, degradation, and antimicrobial properties.

Cellulose-Based Biodegradable Packaging Materials of Antimicrobial

In recent years, with the requirements of environmental protection of packaging materials improve, biodegradable antibacterial materials more and more attention to. This paper to can hair sex polystyrene as main raw materials, and by the synthesis of biodegradable bacteriostasis of study on the properties of packaging materials. The results shows that can hair sex polystyrene as the main raw material made by injection molding process thickness of 0.25 mm plate, and influence factors of sheet material performance, get the film material performance is the ideal process parameters. According to People's Republic of China national standard GB/T1040-92"plastic tensile properties test method" and GB/T20197-2006"degradable plastics the definition, classification, signs and degrade the performance requirements," as determined by the experimental method for testing. The orthogonal experiment results show that can hair sex polystyrene usage: 6 g; Microcrystalline cellulose usage: 0.2g; The antibacterial agent type: silver nanotio2 in the system performance and degrade the performance of the material mechanics and antibacterial good performance.

Dynamic Tensile Properties of Plastics over a Wide Range of Strain Rates

Dynamic tensile properties of a variety of plastics, were studied over a wide range of strain rates from 10-2 s-1 to 103 s-1 by using the Sensing Block Type High Speed Material Testing System (SBTS). The plastics were composed of seven kinds of polycarbonate, eight kinds of polyamide, one kind of polypropylene and acrylic-butadiene-styrene (ABS). It was observed for all the tested plastics, that the flow stress at each plastic strain increased monotonically with the logarithmic strain rate, and also increased linearly over the strain rates from 0.01s-1 to 32 s-1. It was observed that the strain rate sensitivity of the flow stress of these plastics decreased monotonously with the enhanced quasi-static flow stress. These phenomena are similar to those observed frequently for many metallic materials. The plastics were classified tentatively into three groups based on the rate sensitive characteristics. The possibility of expressing these dynamic properties for each group by using Tanimura-Mimura model was discussed.

Poliuretana derivada de óleos vegetais exposta ao intemperismo artificial

Foram obtidas as propriedades mecânicas e viscoelásticas da poliuretana derivada do óleo de mamona após sua exposição ao intemperismo artificial, a fim de avaliar a aplicabilidade deste material como revestimento polimérico para substratos de concreto na Construção Civil. Os procedimentos experimentais foram realizados em conformidade com a ASTM G 53 for "Operating Light and Water Exposure Apparatus (Fluorescent UV - Condensation Type) for Exposure of Nonmetallic Materials"[1]. O ensaio para a caracterização mecânica dos corpos-de-prova após exposição ao intemperismo artificial foi realizado conforme a norma ASTM D 638M-96 "Standard Test Method for Tensile Properties of Plastics (Metric)"[2]. Foi empregado o método de análise dinâmico-mecânica para a obtenção das propriedades viscoelásticas da poliuretana vegetal. Os resultados mostraram que a exposição ao intemperismo artificial não ocasionou mudanças significativas nas propriedades do revestimento polimérico para o tempo de exposição estudado.

Microsample tensile testing of LIGA nickel for MEMS applications

Electro-deposited LIGA Ni components are being considered for use in a number of microelectromechanical systems (MEMS) and applications. The metrology of these components and their non-equilibrium microstructures play an important role in determining the mechanical response of these structures. Microsample testing has proven to be a reliable way of measuring the elastic and plastic tensile properties of these 100–200 μm thick films. Measured values of the in-plane Young's modulus (180±24 GPa) are significantly lower than the modulus for bulk coarse grained Ni (207 GPa), but can be explained and modeled in terms of the crystallographic texture in the as-deposited films. Variations in strength associated with post-processing heat treatments are highlighted and explained in terms of microstructural coarsening. The effect that coarsening and the related drop in strength have on the performance of LIGA Ni spring-like structures is discussed, and the need for further high temperature testing is highlighted.

Yield and fracture of lamellar [formula omitted] TiAl alloys

Lamellar TiAl is formed from α 2 grains by Shockley dislocations sweeping alternate basal planes, thereby transforming the structure into the tetragonal γ phase which exhibits close-packed planes and directions aligned with the hexagonal substrate. Mismatches at the lamellar interfaces, of the order of 1%, give rise to internal stresses and interfacial dislocations. Both the flat plate geometry of the grains and the structure of the interfaces contribute to an extreme plastic anisotropy. The main trends evident in the plastic tensile properties are as follows: both the yield and fracture stresses are low when deformation occurs in the plane of the lamellae (soft mode) and are high when deformation occurs across the lamellae (hard mode); the ductility is high when the tensile axis lies close to the lamellar plane and is low when the tensile axis is nearly normal to the lamellar plane. The trends in the yield and fracture stresses and in the ductility may be understood by considering dislocations piled up at either lamellar (in hard mode) or domain (in soft mode) boundaries. Depending on the strength of the interface, which in turn depends on the type of interface and on the orientation of the adjacent grain, the stress field of the pile up may either cause dislocations to cross into the next grain (ductile, Hall-Petch behavior) or to nucleate cracks (semibrittle, Stroh behavior). The anisotropies of the yield and fracture stresses are explained principally by the effects of Schmid factors and anisotropies in the Hall-Petch (or Stroh) stresses resulting from the lamellar shapes.

Internal Strains and Relaxations in Lamellar TiAl

ABSTRACTIn the lamellar form of the ordered intermetallic TiAl, mismatches at the lamellar interfaces, of order 1%, give rise to internal stresses and lo interracial dislocations. The geometry of the microstructure ensures extreme plastic anisotropy. Three main trends are evident in the plastic tensile properties: Both the yield and fracture stresses are low when deformation occurs in the plane of the lamellae and they are high when deformation occurs across the lamellae, the ductility is high when the tensile axis lies close to the lamellar plane and low when the tensile axis is nearly normal to the lamellar plane. The variations of the yield stress and the fracture stress are explained principally by the effects of Schmid factors and anisotropies in the Hall-Petch (or Stroh) stresses resulting from the lamellar shapes. The variation in ductility may be understood in terms of a competition between the ductile propagation of dislocations across interfaces and the creation of Stroh cracks at the heads of dislocation pile-ups.

The effect of hydrostatic pressure on the tensile properties of plastics

AbstractThe effect of hydrostatic pressure, up to 112,000 lb/in.2, on the tensile properties of four polymers is reported. The pressure soaking of polystyrene in castor oil had no significant effect on the material's residual properties when tested under ambient conditions. When tested under pressure polystyrene necked, like a metal, and exhibited a brittle ductile transition at 40,000 lb/in2. Between 40,000 to 112,000 lb/in.2 the tensile strength increased by about 30%. Young's modulus and yield strength were only slightly affected by pressure. Similar results were obtained for specimens sheathed to prevent possible plasticization of the polystyrene. Polymethylmethacrylate tested at 112,000 lb/in.2 failed just short of its instability point and with only a slight increase in Young's modulus. These amorphous polymers thus behaved under pressure in a generally similar manner to metals.Pressure had a marked effect on the stress‐strain curves of two crystalline polymers polyethylene and nylon. Young's modulus and tensile strength were considerably increased and elongation decreased. Pressure inhibited ‘drawing’ of the materials. Deformation was restricted to a small necked region.