ISO 37:2017 pdf free download.Rubber vulcanized or thermoplastic-Determination tensile stress-strain properties.
WARNING 1 — Persons using this document should be familiar with normal laboratory practice. ISO 37 does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in ISO 37 might involve the use or generation of substances, or the generation of waste, that could constitute a local environmental hazard. Reference should be made to appropriate documentation on safe handling and disposal after use.
1 Scope
ISO 37 specifies a method for the determination of the tensile stress-strain properties of vulcanized and thermoplastic rubbers.
The properties which can be determined are tensile strength, elongation at break, stress at a given elongation, elongation at a given stress, stress at yield and elongation at yield. The measurement of stress and strain at yield applies only to some thermoplastic rubbers and certain other compounds.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of ISO 37. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5893, Rubber and plastics test equipment — Tensile, flexural and compression types (constant rate of traverse) — Specification
ISO 23529:2016, Rubber — General procedures for preparing and conditioning test pieces for physical test methods
For non-product tests, the maximum time between vulcanization and testing shall be 4 weeks and, for evaluations intended to be comparable, the tests shall, as far as possible, be carried out after the same time Interval.
For product tests, whenever possible, the time between vulcanization and testing shall not exceed 3 months. In other cases, tests shall be made within 2 months of the date of receipt of the product by the customer.
10.2 Protection of samples and test pieces
Samples and test pieces shall be protected as completely as possible from all external influences likely to cause damage during the interval between vulcanization and testing, e.g. they shall be protected from iight and heat.
10.3 ConditIoning of samples
Condition all samples, other than those from latex, in accordance with lSc3 23529 at a standard laboratory temperature, without humidity control, for not less than 3 h prior to cutting out the test pieces.
Condition all prepared latex samples in accordance with ISO 23529 at a standard laboratory temperature, with humidity control, for not less than 96 h prior to cutting out the test pieces.
10.4 Conditioning of test pieces
Condition all test pieces in accordance with ISO 23529, If the preparation of test pieces Involves buffing. the Interval between buffing and testing shall be not less than 16 hand not greater than 72 h.
For tests at a standard laboratory temperature, test pieces that do not require further preparation may be tested immediately, if cut from conditioned test samples. Where additional preparation is involved, a minimum conditioning period of 3 hat standard laboratory temperature shall be allowed.
For tests at temperatures other than a standard laboratory temperature, condition the test pieces at the temperature at which the test Is to be conducted for a period sufficient to enable the test pieces to attain substantial equilibrium in accordance with ISO 23529 (see also 2.42),
11 Marking of dumb-bell test pieces
Ifusinga non-contact extensometer, mark the dumb-hell test pieces with two reference marks to define the test length as specified in Tabkl using a suitable marker. The test piece shall be unstrained when it is marked.
The lines shall be marked on the narrow part of the test piece, as shown in Figure 2. i.e. equidistant from the centre of the test piece and at right angles to its longitudinal axis.
12 Measurement of test pieces
12.1 Dumb-bells
Measure the thickness at the centre and at each end of the test length with the thickness gauge. Use the median value of the three measurements to calculate the area of the cross-section. In any one dumbbell, none of the three thickness measurements of the narrow portion shall differ by more than 2% from the median thickness. The width of the test piece shall be taken as the distance between the cutting edges of the die in the narrow part, and this distance shall be measured in accordance with ISO 23529 to the nearest 0,05 mm. Test pieces cut from products might have a non-rectangular cross-section. in which case the width shall be measured directly on the test piece.
12.2 Rings
Measure the radial width and axial thickness at six approximately equally spaced positions around the ring. The median value of each set of measurements shall be used in calculating the area of the cross-section. The Internal diameter shall be measured to the nearest 0,1 mm. Calculate the internal circumference and the mean circumference as follows.
Internal circumference = it internal diameter
Mean circumference . it * (internal diameter + radial width)
12.3 Comparison of groups of test pieces
if two groups of test pieces (either dumb-bells or rings) are being compared, the median thickness for each group shall be within 7,5 % of the grand median thickness for the two groups.
13 Procedure
13.1 Dumb-bell test pieces
Insert the test piece into the tensile-testing machine, ensuring that the end tabs are gripped symmetrically so that the tension is distributed uniformly over the cross-section. It is strongly recommended that the load cell be reset to zero before each test. If necessary, apply a prestress of 0,1 MPa so that the test piece Is not bent when the initial test length (see Figure 2) Is measured. If necessary, set up the extensometry device. Start the machine and monitor continuously the change In test length and force throughout the test.
The nominal rate oltraverse of the moving grip shall he 500 mm/mm for type 1. type IA and type 2 test pieces and 200 mm/rn in for type 3 and type 4 test pieces.
Any test piece that breaks outside the narrow portion or yields outside the test length shall be discarded and a repeat test conducted on an additional test piece.
In making visual measurements, care should be taken to avoid inaccuracies due to parallax.
13.2 Ring test pieces
Set the correct Initial distance between the pulleys as follows:
— 3012 mm between the centres olthe standard pulleys for type A rings:
— 35 mm between the centres or the alternative pulleys for type A rings;
— S.5. mm between the centres olthe standard pulleys for type B rings. Set the load to zero before mounting the test piece on the pulleys.
Place the test piece cm the pulleys and start the machine, monitoring continuously the distance between the pulleys and the increase in stress throughout the test.
The nominal rate of traverse or the moving pulley shall be 500 mm/mm for type A test pieces and 100 mm/mm for type B test pieces. The driven pulley shall rotate at the correct speed from the start to the end of the test.