Tensile strength, paper testing

The bursting strength is the hydrostatic pressure required to mpture a specimen when it is tested in a specified instmment under specified conditions. It is the pressure required to produce mpture of a circular area of the paper (30.5-mm dia) when the pressure is apphed at a controlled rate (TAPPI T403). It is related to tensile strength and extensibiUty and is used extensively throughout the industry for packaging and container grades. 

Creep test data when plotted on log-log paper usually form a straight line and tend themselves to extrapolation. Tlie slope of the straight line, which indicates a decreasing modulus, depends on the nature of the material (principally its rigidity and temperature of heat deflection), the temperature of the environment in which the product is used, and the amount of stress in relation to tensile strength. 

Figure 4.5 Relationship between tensile strength of paper (expressed as a breaking length) and the number of fibres which fail during the test.

The test piece is a cylinder of 29 0.5 mm diameter by 12.5 +0.5 mm height. The sample is compressed in a tensile strength machine. The sample must not be allowed to move on the compression anvils (fine emery paper is suggested between the anvil and sample). 

Melt index is close to 3.5, tensile strength about 1,500 psi (6.9 MPa), melting point of 99 to 100C, and needle penetration test at 25C is 1 to 10. Just over 10wt% of LDPE produced in the USA find use in typical wax applications, such as paper coatings and floor polishes. A major use is coated paperboard for milk cartons. 

In the burst test a flat sheet of paper is clamped by a cireumferential ring and a small rubber diaphragm underneath is gradually inflated with fluid, foreing the sheet to bulge until it ruptures. The hydrostatic pressure at the moment of failure is measured. The virtues of the burst test are its simplicity and the speed with which it can be undertaken. The reeorded hydraulic pressure offers a quantitative measure of bonding between fibres. It is linearly related to tensile strength. 

Flexural strength varies primarily with thickness. It also varies with the tensile strength of the paper on the side tested, but the paper used on any one product is reasonably uniform. The correlation coefficients on individual products show slight increases indicating that there may be some correlation with the variations in paper strength, but the changes are hardly significant. 

Grain can also be detected by a Mullen burst test (and tensile strength)—see Paper and board testing below. 

Tensile strength, both wet and dry BS 4415 1992 ISO 1924 (1992). The maximum tensile force per unit width that a paper or board will withstand before breaking. The stretch at break is the measured elongation at the moment of rupture of a test piece, when tested under specific conditions. 

The ideal mechanical test would be one in which the properties related to the use of the paper were tested. Although weak papers have low tensile strength it may be of more interest to measure how they behave when folded. A test that measures the tensile strength after one fold has been proposed. 

The paper is outlined as follows. After a brief description of the specimen preparation and the stress measurement by OFS, crack and spallation patterns on oxidised NiAl specimens are shown, which have been produced by bend and indentation tests at room or oxidation temperature. In the second part of the paper, first attempts to an interpretation of the crack patterns are presented. In particular, the possibility to derive the oxide fracture toughness and tensile strength from the crack patterns is discussed. 

Two factors define the worklife of coated sand and determine the usefullness of a coated sand mixture the ability to flow and be formed into a shape and the ability to be cured into a rigid sand body For the purposes of this paper, coated sand was judged unsuitable if a cured sand body had a tensile strength lower than 0 7MPa, lOOpsi Flow properties of coated sand are less readily defined Since a suitable test has not been accepted by the foundry industry the following test was devised to determine the flowability of a sand formulation ... 

Other characterization tests were performed, such as porosimetry by mercury intrusion, thermal analysis and density by intrusion of helium, but the main characterization was possible from the tests already cited. As part of a more comprehensive characterization still in progress, other tests are being performed, namely durability performance tests such as penetration of chloride ions, electrical resistivity, capillary absorption and oxygen permeability. The results presented in this paper refer only related to the mechanical properties of compressive and tensile strength. 

In this paper, amodified SHPB technique and Brazilian test method is presented to test the dynamic tensile strength of coal, shale and sandstone rock samples. Totally four different kinds ofloading rate were tested to investigate the relationship between tensile strength and dynamic loading. Static test results are also presented for the comparison. 

Paper frame method for testing tensile strength of thin monofilaments at room temperature. A Paper frame with monofilament test sample fixed by an adhesive on the frame. B The paper frame in the holding equipment of the testing machine C The paper frame after cutting just before measurement D The broken filament after measurement. 

Fig. 2. Comparison of destructive tensile strength tests on honeycomb sandwich panels with the predicted strengths using the Fokker bond testa-. A saies of honeycomb constructions is represented, where the foil thicknesses and the cell sizes are both varied ( ), foU thickness 0.007 in. (0.177 mm), ceU size 0.125 in. (3.175 mm) ( ), foil thickness 0.003 in. (0.076 mm), cell size 0.250 in. (6.25 mm) (A), foil thickness 0.002 in. (0.05 mm), cell size 0.1875 in. (4.762 mm) (O), foil thickness 0.001 in. (0.025 mm), ceU size 0.250 in. (6.35 mm). (From R E Clemens, Paper presented at the Amoican Society for Non-destructive Testing Technical Meeting, California, February 1962)...

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