Tensile tester

A method for measuring the uniaxial extensional viscosity of polymer soHds and melts uses a tensile tester in a Hquid oil bath to remove effects of gravity and provide temperature control cylindrical rods are used as specimens (218,219). The rod extmder may be part of the apparatus and may be combined with a device for clamping the extmded material (220). However, most of the mote recent versions use prepared rods, which are placed in the apparatus and heated to soften or melt the polymer (103,111,221—223). A constant stress or a constant strain rate is appHed, and the resultant extensional strain rate or stress, respectively, is measured. Similar techniques are used to study biaxial extension (101). 

Tensile Testing. The most widely used instmment for measuring the viscoelastic properties of soHds is the tensile tester or stress—strain instmment, which extends a sample at constant rate and records the stress. Creep and stress—relaxation can also be measured. Numerous commercial instmments of various sizes and capacities are available. They vary greatiy in terms of automation, from manually operated to completely computer controlled. Some have temperature chambers, which allow measurements over a range of temperatures. Manufacturers include Instron, MTS, Tinius Olsen, Apphed Test Systems, Thwing-Albert, Shimadzu, GRC Instmments, SATEC Systems, Inc., and Monsanto. 

A typical stress—strain curve generated by a tensile tester is shown in Eigure 41. Creep and stress—relaxation results are essentially the same as those described above. Regarding stress—strain diagrams and from the standpoint of measuring viscoelastic properties, the early part of the curve, ie, the region... 

We examined the role of vector percolation in the fracture of model nets at constant strain and subjected to random bond scission, as shown in Fig. 11 [1,2]. In this experiment, a metal net of modulus Eo containing No = 10" bonds was stressed and held at constant strain (ca. 2%) on a tensile tester. A computer randomly selected a bond, which was manually cut, and the relaxation of the net modulus was measured. The initial relaxation process as a function of the number of bonds cut N, could be well described by the effective medium theory (EMT) via... 

A loop tack (Fig. 2c) test consists of allowing a tear-shaped loop of conditioned tape to drape into contact with a test surface of specified area (usually 25.4 x 25.4 mm), with the force of contact limited to the weight of the tape itself (ASTM Ref. D-6195). The ends of the loop are held in a tensile tester. After a momentary contact time the tester is engaged and the tape is removed at a specified speed. The maximum in the removal force is ordinarily observed just at the point where the two peel fronts Join. The value is reported in a force per area of tape width, or lb in. -. While this tack test has some popularity, it is perhaps more of a very short dwell time peel test, and it has variables more associated with that test, especially backing effects, since heavier backings lead to higher tack values. 

Tensile tests were carried out on recombinant resilin in PBS buffer on an Instron Tensile Tester (model 4500) at a rate of 5 mm/min and a temperature of 21°C. The swollen strip samples (7 X 1 mm) had a gauge length of 5 mm and were cycled initially up to a strain of about 200%. The... 

The mechanical properties of the cured compounds were determined using a tensile tester according to ISO-37. 

An Automated Analysis System for a Tensile Tester," Tyson T. Gill, in Computer Applications in the Polvmer Laboratory. ACS Symposium Series 313, 1986. 

Mechanical Properties. The mechanical properties of thin, solvent-cast polymer films were measured on an Instron Tensile Tester according to ASTM standard D882-83. In all cases, tensile values were calculated from the average of at least four measurements obtained from four separate specimens per polymer sample. 

An Instron Tensile Tester Model TM was Interfaced to a micro-computer for data collection and transmission to a minicomputer. A FORTRAN program was developed to allow data analysis by the minicomputer. The program generates stress-strain curves from the raw data, calculates physical parameters, and produces reports and plots. 

GILL AND KOEHLER Automated Analysis for a Tensile Tester... 

All tensile and stress-relaxation measurements were done using an Instron Tensile tester. The samples were cut into the dumbbell shape corresponding to the ASTM D412 type C model (total length 4.5 in. straight part 1.5 in. width 0.25 in.). 

Purpose To measure the breaking strength of various household polymer samples using a homemade tensile tester. 

Note A homemade tensile tester (see Figure 15.41) is used in this experiment. The device can be constructed as follows ... 

The adhesion was measured by fastening a lead anchor of known area (2,84 cm ) to the coating with a cyanoacrylate adhesive (Loctite 414) and after curing, pulling it off normal to the surface with a Dillon tensile tester. The force to remove the coating was divided by the area of attachment to convert it to a normalized tensile adhesion value. 

Tensile properties were determined according to ASTM D638 using an Instron tensile tester equipped with a 500 kg load cell. 

The tensile strength, modulus, and elongation at break were measured on an Instron Tensile Tester at a crosshead speed of 20 in./min (ASTM D-412) and the hardness by means of a Shore A Durometer (ASTM D-2240). 

Stress-strain measurements were carried out on molded films ( 1 mm thickness) at room temperature by the use of microdumbell-shaped samples and an Instron tensile tester (model No. 1130, crosshead speed of 5 cm/min). The samples were premolded between Mylar sheets for 10 min at 162 °C at about 5000 psi, then remolded at 165 °C and 7000 psi for 20 min, and slowly cooled ( 1 °C/min) to 50 °C. Select samples were solvent extracted by MEK using a Soxhlet extractor before molding. 

A special split tensile specimen mold was made to measure tensile properties of propellant during cure. A miniature casting is made in a dumbbell-shaped mold. The gage section of the mold is split axially so that it can be removed to expose the partially cured propellant. The mold is placed in a tensile tester, and the specimen is pulled with the end parts in place. Figure 17 shows that during the early stages of cure... 

Mechanical properties - Samples were cured in a Wickert laboratory press (WLP 1600/5 4/3) at a pressure of 100 bar (10 MPa) for the duration of lcured sheet dimensions were 90 x 90 mm2 and 2 mm thick. The stress-strain properties of the cured samples were measured on a Zwick Z020 tensile tester according to ISO-37 type 2. 

The TS of the compacted samples was determined by transverse compression with a custom-built tensile tester. Tensile failure was observed for all the rectangular compacts when compressed between flat-faced platens at a speed ranging between 0.006 and 0.016 mm/sec. Platen speed was adjusted between materials to maintain a time constant of 15 2 seconds to account for viscoelastic differences the constant is the time between the sample break point and when the measured force equals Fbreak/e in the force versus time profile, where the denominator is the mathematical e. Specially modified punch and die sets permitted the formation of square compacts with a centrally located hole (0.11 cm diameter) that acted as a stress concentrator during tensile testing. This capability permitted the determination of a compromised compact TS and thus facilitated an assessment of the defect sensitivity of each compacted material. At least two replicate determinations were performed for each mechanical testing procedure and mean values are reported. 

Tensile properties (tensile strength, elongation, modulus) were measured on an Instron tensile tester (ASTM D882-61T Method A). The tensile modulus was the slope of the initial straight portion of the stress-strain diagram. The heat-distortion... 

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