ASTM--D5289-1995

Designation:D5289–95(Reapproved2001)

Standard Test Method for

Rubber Property—Vulcanization Using Rotorless Cure Meters1

This standard is issued under the?xed designation D5289;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.

1.Scope

1.1This test method speci?es a method for the measure-ment of selected vulcanization characteristics of rubber com-pounds using rotorless linear shear,unsealed torsion shear,and sealed torsion shear cure meters.The three types of instruments may not give the same results.

N OTE1—An alternative method for the measurement of vulcanization characteristics is given in Test Method D2084.

1.2The values stated in SI units are to be regarded as the standard.The values given in parentheses are for information only.

1.3This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.

2.Referenced Documents

2.1ASTM Standards:

D1349Practice for Rubber—Standard Temperatures for Testing2

D1556Test Method for Density and Unit Weight of Soil in Place by the Sand-Cone Method3

D2084Test Method for Rubber Property—Vulcanization Using Oscillating Disk Cure Meter2

D4483Practice for Determining Precision for Test Method Standards in the Rubber and Carbon Black Industries2 2.2ISO Standard:4

ISO6502Rubber—Measurement of Vulcanization Charac-teristics with Rotorless Curemeters

3.Terminology

3.1De?nitions of Terms Speci?c to This Standard:

3.1.1rotorless cure meter—a name for a class of cure meters that uses one of the two specimen shaping members or dies to sense the torque or stress during strain application. Rotorless cure meters do not have a third member in the form of a rotor(see de?nitions of cure meter in Test Methods D1556 and D2084).

3.1.2torque—for an oscillating shear cure meter,the value measured by a torque transducer at the peak strain amplitude of the oscillating cycle.

3.1.3The following measurements may be taken from the recorded curve of force or torque as a function of time(see Fig.

1).

3.1.3.1minimum force or torque—measure of the stiffness of the unvulcanized test specimen at the speci?ed vulcanizing temperature,taken at the lowest point in the vulcanization curve.

3.1.3.2maximum,plateau,or highest force or torque—measure of the stiffness or shear modulus of the vulcanized test specimen at the vulcanization temperature,measured within a speci?ed period of time.

3.1.3.3time to incipient cure(scorch time)—measure of the time at which a speci?ed small increase in force or torque has occurred;it indicates the beginning of vulcanization.

3.1.3.4time to a percentage of full cure—measure of cure based on the time to develop some percentage of the difference in force or torque from the minimum to the maximum.

4.Summary of Test Method

4.1A rubber test piece is contained in a die cavity which may be closed or almost closed and maintained at an elevated temperature.The cavity is formed by two dies,one of which is oscillated through a small linear or rotary amplitude.This action produces a sinusoidal alternating linear or torsional strain in the test piece and a sinusoidal shear force or torque which depends on the stiffness(shear modulus)of the rubber compound.The envelope curve,which is de?ned as the amplitude of the oscillating force or torque,is continuously recorded as a function of time(see Fig.2).

4.2The stiffness of the rubber test piece increases as vulcanization proceeds.The test is completed when the re-corded force or torque rises to either an equilibrium or maximum value,or when a predetermined time has elapsed (see Fig.1).The time required to obtain a vulcanization curve is a function of the test temperature and the characteristics of the rubber compound.

1This test method is under the jurisdiction of ASTM Committee D11on Rubber

and is the direct responsibility of Subcommittee D11.12on Processability Tests.

Current edition approved Sept.10,1995.Published November1995.Originally

published as D5289–https://www.wendangku.net/doc/6f13525010.html,st previous edition D5289–93a.

2Annual Book of ASTM Standards,V ol09.01.

3Annual Book of ASTM Standards,V ol04.08.

4Available from American National Standards Institute,25W.43rd St.,4th

Floor,New York,NY10036.

1

Copyright?ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.

5.Signi?cance and Use

5.1This test method is used to determine the vulcanization characteristics of (vulcanizable)rubber compounds.

5.2This test method may be used for quality control in rubber manufacturing processes,for research and development testing of raw-rubber compounded in an evaluation formula-tion,and for evaluating various raw materials used in preparing (vulcanizable)rubber compounds.

5.3The test piece in a rotorless cure meter approaches the test temperature in a shorter time and there is a better temperature distribution in the test piece due to the elimination of the unheated rotor found in oscillating disk cure meters.5.4Several manufacturers produce rotorless cure meters with design differences that may result in different torque responses and curve times for each design.Correlations of test results between cure meters of different designs should be established for each compound tested,and for each set of test conditions.

6.Apparatus

6.1Rotorless cure meters of three types can be used.In each case,an oscillation of small amplitude is applied to one die.6.1.1Linear Strain Rotorless Cure Meter —This type of cure meter measures the force produced by a linear strain of constant amplitude (see Fig.3(a)).

6.1.2Unsealed Torsion Strain Rotorless Cure Meter —This type of cure meter measures the torque produced by an angular strain of constant amplitude in a cavity that is not completely closed (see Fig.3(c)).

6.1.3Sealed Torsion Strain Rotorless Cure Meter —This type of cure meter measures the torque produced by an angular

strain of constant amplitude in a cavity that is completely closed and sealed (see Fig.4(a)).

6.2Die Cavity —The die cavity is formed by two dies.In the measuring position,the two dies are ?xed a speci?ed distance apart so that the cavity is almost closed (see Fig.3(b)and 3(d)),or closed and sealed (see Fig.4(a)).

6.2.1The dimensions for typical linear shear curemeter dies include a diameter of 30mm (1.18in.),and a total depth of 4mm (0.16in.).The dimensions for typical torsional shear curemeters include biconical-shaped dies having a diameter of 4062mm (1.5760.08in.),and an angle of separation ranging from 7to 18°,depending on the manufacturer’s design.In the center of the dies,a separation equal to 0.5mm (0.02in.)plus the die gap should be maintained (see Fig.3(b),Fig.3(d),or Fig.4(b)).Manufacturer’s guidelines should be followed to determine if the dies have been excessively worn and should be replaced.

6.2.2Die Gap —The gap between the edges of the dies in the closed position shall be between 0.05and 0.20mm (0.002to 0.008in.),preferably 0.1mm (0.004in.)for unsealed cavities.For sealed cavities,no gap should exist at the edges of the dies.

6.2.3Die Closing Mechanism —A pneumatic cylinder or other device shall close the dies and hold them closed during the test with a force of not less than 8.0kN (1820lbf).

6.3Die Oscillating System —The die oscillating system consists of a rigid eccentric drive,which imparts a linear or torsional oscillating movement to one of the dies,in the plane of the cavity.

6.3.1The amplitude of the oscillation should be either 60.01to 60.1mm,preferably 60.05mm (60.0004to 60.0039in.,preferably 60.0020in.)for linear shear;or 60.1°to 63.0°,preferably 60.5°of arc for torsional shear cure meters.

6.3.2The frequency of oscillation should be between 0.5and 2Hz,preferably 1.760.1Hz.

6.4Force or Torque Measuring System —A force or torque measuring system shall measure the resultant shear force or torque.

6.4.1The force or torque measuring device shall be rigidly coupled to one of the dies and any deformation shall be negligibly small and shall generate a signal which is propor-tional to the force or torque.The total error resulting from zero point error,sensitivity error,linearity,and reproducibility errors shall not exceed 1%of the measuring range selected.

N OTE 2—The elastic deformation of the oscillating and measuring system should not be more than 1%of the oscillating amplitude;otherwise,the curemeter curves must be corrected.

6.4.2The force or torque recorder device shall be used to record the signal from the force or torque measuring device.It shall record the envelope (see Fig.2)and shall have a response time for full-scale de?ection on the force or torque scale of 1s or less.The force or torque shall be recorded with an accuracy of 60.5%of the range.Torque recording devices may include analog chart recorders,printers,plotters,or computers.

6.5Torque or force calibration equipment is required to measure the linear or angular strain amplitude and to calibrate the force or torque measuring device.Examples of

calibration

FIG.1Types of Vulcanization

Curves

FIG.2Envelope Vulcanization

Curve

equipment are shown in Fig.5,Fig.6,and Fig.7.The amplitude of oscillation of the device shall be checked with no test piece in it.A displacement transducer shall be used to measure the amplitude and torque measurements shall be

checked against standard masses using a device as shown in Fig.5or Fig.6.An alternate technique shall use a torque

standard.

FIG.3(a)and (b)—Typical Linear Shear Rotorless Curemeter;(c)and (d)—Typical Unsealed Torsion Shear Rotorless

Curemeter

6.5.1For calibrating linear strain curemeters,a displace-ment transducer shall be coupled by contact to one of the dies or blocks directly attached to it (see Fig.5).The amplitude shall be checked with no test sample present.The force measuring system shall be checked by loading a wire,attached to the die or block by a pulley,with masses corresponding to

the full-scale force to be measured.

6.5.2For calibrating torsion shear curemeters,either a displacement transducer and wire-mass calibration or a torque standard shall be used.

6.5.2.1A displacement transducer for checking angular displacement shall be coupled by a knife-edge bearing in contact with a rod ?xed to one of the dies (see Fig.6).

The

FIG.4Typical Sealed Torsion Shear Rotorless

Curemeter

FIG.5Calibration Equipment for Linear Shear

Curemeter

FIG.6Displacement Transducer and Wire-Mass Calibration

Equipment for Torsion Shear

Curemeters

FIG.7Typical Torque Standard Calibration Device for Torsion

Shear

Curemeters

force measuring system shall be checked by loading a wire, attached to the die or block by a pulley,with masses corre-sponding to the full-scale force being measured.The torque shall be calculated in this case from the product of the applied force and the radius of the die block where the wire is attached.

6.5.2.2Torque standard calibration checks the torque mea-surement at the selected angular displacement by clamping a reference steel torsion rod to the oscillating die and the torque measuring die of the torsion shear cure meter(see Fig.7).The reference values for angular displacement and corresponding torque have been established by the manufacturer for each torque standard.

6.6Temperature Controlling System—The method of tem-perature control shall maintain the following process param-eters:heating up time,curing temperature,temperature distri-bution,and reference temperature,which are necessary for reproducible measurement of the vulcanization curve.The temperature control system shall permit the reference tempera-ture to be varied between110°C and200°C with an accuracy of60.3°C or better.

6.6.1Die shall heat up in1.5min or less from closure of the die cavity.

6.6.2Once heating up time hs been completed,die tempera-ture shall not vary by more than60.3°C for the rest of the test.

6.6.3The temperature distribution within the test piece shall be as uniform as possible.Within the deformation zone,a tolerance of61°C of the average test piece temperature shall not be exceeded.

6.6.4The reference temperature is determined by a tempera-ture sensor used for control.The difference between the reference temperature and the average test piece temperature shall not be more than2°C.

6.6.5Temperature measurement accuracy shall be

60.3°C for the reference temperature sensor.

6.7Reference Test Temperature—The standard reference test temperature shall be160°C(320°F).Tests may be carried out at other temperatures if required.Temperatures should be selected in accordance with Practice D1349.

7.Sampling

7.1The sample shall be taken from a vulcanizable rubber compound as required by the mixing method or other sampling instructions.

7.2The sample shall be homogeneous,at room temperature, and as free of trapped air as possible.

8.Test Specimens

8.1The recommended test specimen volume is between3 and5cm3,depending on the model of instrument being used. The size of the test specimen should exceed the test chamber volume by a small amount,to be determined by preliminary tests.Typically,specimen volume should be130to190%of the test chamber volume.Once a target weight is established, the weight of specimens should be controlled to within60.5g for best repeatability.

8.2The test specimen taken from the sample should be circular,with a diameter smaller than the test chamber of the instrument to be used.9.Procedure

9.1Preparation for Test—Bring the temperature of both dies to the reference temperature with the cavity closed.Adjust the zero of the force or torque measuring device,if necessary.

9.2Loading the Curemeter:

9.2.1Open the dies,unload the previous sample(if neces-sary),place the test piece in the cavity,and close the dies within20s.

9.2.2The test time shall be counted from the instant that the dies are closed.Oscillation of the movable die shall be started at zero time or before.

10.Report

10.1Report the following information:

10.1.1A full description of the sample,its origin and compound details,

10.1.2Test method and test details,

10.1.2.1Reference to this test method,

10.1.2.2Type and model curemeter used(linear or torsion shear,manufacturer,die options,if any),

10.1.2.3Amplitude of the die oscillation,in millimetres or degrees,

10.1.2.4Frequency of oscillation,

10.1.2.5Force or torque range selected,in Newtons(N)or deci Newton metres(dN·m).(The equation for conversion from dN·m to lbf·in.is1.13(dN·m)=1.00(lbf·in.)),

10.1.2.6Time scale of the recording device,

10.1.2.7Curing temperature in degrees Celsius,and

10.1.2.8Date of the test.

10.2Test results reported are normally chosen from the following parameters(refer to Fig.1for guidance):

10.2.1FL or ML—Minimum force or torque,in N or dN·m (lbf·in.).

10.2.2Maximum Force or Torque—All in N or dN·m (lbf·in.).

10.2.2.1FHF or MHF—Maximum torque where curve plateaus.

10.2.2.2FHR or MHR—Maximum torque of reverting curve.

10.2.2.3FH or MH—Highest torque attained during a speci?ed period of time when no plateau or maximum torque is obtained.

10.2.3tsx—Scorch time,in minutes(time to an increase of x units of force or torque from FL or ML).The preferred scorch time for tests at an oscillation amplitude of60.5°is tsl. 10.2.4Cure Time,in minutes.

10.2.4.1t8x—equal to the time to x%of torque increase or t8x=minutes to ML+x(MH?ML)/100torque.

N OTE3—This method of determining the cure times is considered the standard method.The most commonly used values of x are50and90.A cure time of t810is sometimes used as a measure of scorch time. 10.2.4.2tx—equal to the time to x%of maximum torque,or tx=minutes to(x·MH)/100torque.

N OTE4—This is an alternate method for cure time determination. 10.2.5Cure Rate Index—equal to100/(cure time?scorch time).

10.2.6“t10%Rise”is the time for the force or torque to rise to110%of the minimum value.This may be used to

measure

scorch in some cases.

11.Precision and Bias

11.1This precision and bias section has been prepared in accordance with Practice D 4483.Refer to Practice D 4483for terminology and other statistical calculation details.

11.2Precision —The precision data presented in Table 1were obtained using a sealed torsion type rotorless curemeter,5with standard dies as illustrated in Fig.5,at 175°C and 60.5°arc.

11.2.1The precision results in this precision and bias section give an estimate of the precision of this test method with the materials (rubbers,etc.)used in the particular inter-laboratory program as described below.The precision param-eters should not be used for acceptance or rejection testing of any group of materials without documentation that they are

applicable to those particular materials and the speci?c testing protocols that include this test method.

11.2.2Type I precision results are given in Table 1.This is a short term precision study,covering a period of 1month or less.In this study,three compounds based on SBR and SBR/NR polymers with sulfenamide cure systems and carbon black reinforcement were carefully mixed and prepared for testing.Precut specimens were sent to 11laboratories along with instructions to test duplicate samples of each compound in one day,and repeat the testing,after checking calibration,one week later.Each determination yielded a test result (four per compound).

11.2.3The precision of this test method may be expressed in the format of the following statements that use what is called an appropriate value of r,R ,(r ),or (R ),that is,that value obtained from Table 1,to be used in decisions about results obtained with the test method.

11.2.4Repeatability —The repeatability,r ,of this test method has been established as the appropriate value for any parameter as tabulated in Table 1.Two single test results,obtained under normal test method procedures,that differ by more than this tabulated r must be considered as derived from different or nonidentical sample populations.

11.2.5Reproducibility —The reproducibility,R ,of this test method has been established as the appropriate value for any parameter as tabulated in Table 1.Two single test results obtained in two different laboratories,under normal test method procedures,that differ by more than the tabulated R must be considered to have come from different or nonidentical sample populations.

11.2.6Repeatability and reproducibility expressed as a per-centage of the mean level,(r )and (R ),have equivalent application statements as 11.2.4and 11.2.5for r and R .For the (r )and (R )statements,the difference in the two single test results is expressed as a percentage of the arithmetic mean of the two test results.

11.3Bias —In test method terminology,bias is the differ-ence between an average test value and the reference (or true)test property value.Reference values do not exist for this test method since the value (of the test property)is exclusively de?ned by the test method.Bias,therefore,cannot be deter-mined.

N OTE 5—Another precision study is to be performed using a greater number of materials differing from each other as much as possible.

12.Keywords

12.1compounds;rheometer;rotorless cure meter;vulca-nization characteristics

5

The Monsanto MDR-2000,available from Monsanto Co.,2689Wingate Ave.,Akron,OH 44314,was used to obtain precision data for this test method.

TABLE 1Precision A

N OTE 1—SR =within laboratory standard deviation,r =repeatability (in measurement units),(r)=repeatability (in percent),

SR =between laboratory standard deviation,R =reproducibility (in measurement units),and (R)=reproducibility (in percent).

Test Parameter

Mean Value Within Laboratory

Between Laboratory

Sr r (r )SR R (R )Compound A:M L (dN·m) 1.350.0070.02 1.40.0710.2014.8M N (dN·m)13.600.0250.070.50.608 1.7212.7t s 1(min) 1.550.0090.02 1.60.0650.1811.8t 850(min) 3.100.0070.030.80.0610.17 5.6t 890(min) 4.930.0150.040.90.1470.428.5Compound B:M L (dN·m) 1.000.0080.02 2.20.0480.1413.6M N (dN·m)10.170.0240.070.70.478 1.3513.3t s 1(min) 2.220.0080.02 1.00.0760.219.6t 850(min) 3.550.0070.020.60.0980.287.8t 890(min) 5.740.0230.06 1.10.1560.447.7Compound C:M L (dN·m) 1.500.0110.03 2.10.0760.2214.3M N (dN·m)12.300.0450.13 1.00.571 1.6213.1t s 1(min) 1.800.0110.03 1.70.0630.189.9t 850(min) 3.340.0090.030.80.0980.288.3t 890(min)

5.73

0.018

0.05

0.9

0.156

0.44

7.7

A

These values are Type I precision values,obtained from fully prepared test specimens (compounds mixed in one laboratory)which were circulated to all participating

laboratories.

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