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1、BRITISH STANDARD BS 5738:1980 Methods of test for Evaluation of vulcanization characteristics for raw natural rubbers UDC 678.4:678.032:678.01:678.028 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:59:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5738:1980 This British Standard, having
2、 been prepared under the direction of the Rubber Standards Committee, was published under the authority of the Executive Board and comes into effect on 31 March 1980 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference RUC/27 Draft for comment 77/54983 DC
3、 ISBN 0 580 10804 X Cooperating organizations The Rubber Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: British Association of Synthetic Rubber Manufactu
4、rers British Rubber Manufacturers Association* Department of Industry (Chemicals and Textiles) Medical Sterile Products Association Ministry of Defence Rubber and Plastics Research Association of Great Britain Rubber Growers Association* Society of Motor Manufacturers and Traders Limited The Malaysi
5、an Rubber Producers Research Association* The organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Tyre Manufacturers Conference (Service Committee) Amendments issued
6、since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:59:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5738:1980 BSI 09-1999i Contents Page Cooperating organizationsInside front cover Forewordii 1Scope1 2References1 3Principle1 4Apparatus1 5Pure
7、 gum-stock formulation and preparation of the test mix1 6Evaluation of vulcanization characteristics of pure gum-stock mix2 7Carbon black reinforced formulation and preparation of the test mix3 8Evaluation of vulcanization characteristics of carbon black reinforced mix4 9Report4 Table 1 Values of ad
8、justments to relaxed tensile stress for Mooney viscosity3 Publication referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:59:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5738:1980 ii BSI 09-1999 Foreword This British Standard has been published under the direct
9、ion of the Rubber Standards Committee. It supersedes BS 1673 “Methods of testing raw rubber and unvulcanized compounded rubber” Part 4 “Evaluation of vulcanizing characteristics”, first issued in 1953, which is now withdrawn. The principal changes introduced in this new standard are as follows: a) t
10、he deletion of scorch tests using the Williams plastimeter or Mooney viscometer; b) the deletion of the test involving swelling in benzene; c) the exclusion of the relaxed tensile stress (relaxed modulus) test method which will be issued as BS 903-A41; d) the inclusion of oscillating disc curemeter
11、tests; e) the inclusion of tests on a carbon black reinforced vulcanizate, thus bringing the standard into closer alignment with ISO 1658. This British Standard differs from ISO 1658 in the following important respects: 1) the restriction of the stress-strain tests on the pure gum-stock vulcanizate
12、to the relaxed tension stress test since this is believed to give the best information on curing characteristics, e.g. rate of cure; 2) the inclusion of the oscillating disc curemeter test which is not yet dealt with in ISO 1658. This method does not detail precautions necessary to meet the requirem
13、ents of statutory regulations, such as the Health and Safety at Work etc. Act, 1974. Attention should be paid to any necessary safety precautions, and the method should only be operated by trained personnel. A British Standard does not purport to include all the necessary provisions of a contract. U
14、sers of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, an inside back cover and
15、 a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:59:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5738:198
16、0 BSI 09-19991 1 Scope This British Standard specifies standard ingredients, apparatus and test methods for evaluating the vulcanization characteristics of raw natural rubbers. Two standard test formulations are specified: a) pure gum-stock: a very cure-sensitive formulation for applications involvi
17、ng non-black-filled mixes, b) carbon black reinforced: a formulation more appropriate for applications involving black-filled mixes. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Principle The vulcanization characteristics of raw natu
18、ral rubber, such as rate of cure and maximum state of cure which can be developed, depend upon the level and type of naturally occurring non-rubber substances present. The contribution of these depends critically upon the formulation used. Furnace blacks and amine or amine-based accelerators tend to
19、 override the influence of these non-rubber substances. Based upon these considerations, two formulations are specified. 3.1 Pure gum-stock formulation. This formulation is highly discriminatory and one in which the influence of non-rubber materials is maximized. Vulcanization characteristics are be
20、st assessed by the tensile modulus developed after a given cure cycle or by stiffness developed in a curemeter. Other properties, especially tensile strength, are not recommended for assessment of vulcanization as they lack similar discrimination. 3.2 Carbon black reinforced formulation. This formul
21、ation is far less sensitive to the presence of non-rubber materials, and provides data relevant to a wide range of black-filled mixes. In this case, a wider range of vulcanizate properties can be used for assessment. 4 Apparatus 4.1 Mixing mill complying with the requirements of BS 1674. The surface
22、 temperature of the rolls shall be maintained at 70 5 C throughout mixing. NOTEAll guide openings should be adjusted to maintain a good rolling bank at the nip of the rolls during mixing. 5 Pure gum-stock formulation and preparation of the test mix 5.1 Standard test formulation. The test ingredients
23、 to be used shall be in the proportions specified as follows: The compounding ingredients, except for MBT, shall comply with the requirements of BS 4398. Although a standard for MBT has not yet been published, a high grade material in powdered form shall be used. In preparing the mix from this formu
24、lation it is strongly recommended that, to improve accuracy, use is made of masterbatches A and B below. The raw natural rubber for the masterbatches shall be preferably of similar quality to that being tested or alternatively grade 5L complying with the requirements of BS 4396. The standard test fo
25、rmulation then becomes: Masterbatches shall be stored in a dry atmosphere, preferably at a temperature of 23 2 C, but at least at ambient temperature. The storage period shall not exceed three months and should preferably not exceed one month. The standard laboratory mill mix mass, in grams, shall b
26、e four times the test formulation mass. IngredientParts by mass Raw natural rubber under test100.0 Zinc oxide6.00 Sulphur3.50 Stearic acid0.500 2-mercaptobenzothiazole (MBT)0.500 110.50 IngredientParts by mass AB Raw natural rubber100.0100.0 Zinc oxide120.0120.0 Sulphur140.0 Stearic acid10.0010.00 2
27、-mercaptobenzothiazole (MBT)20.00 370.0250.0 IngredientParts by mass Raw natural rubber under test95.0 Masterbatch A9.25 Masterbatch B6.25 110.50 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:59:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5738:1980 2 BSI 09-1999 NOTESmaller batch si
28、zes may be used by reducing the distance between the guides without adjustment of the mixing cycle or nip openings. 5.2 Procedure for mixing the formulations 5.2.1 General. The procedure is to mix on day one, test on the curemeter and vulcanize on day two and measure vulcanizate properties on day th
29、ree. The sequence is designed to allow 16 h to 24 h between mixing and vulcanizing. 5.2.2 Mill mixing procedure using masterbatched ingredients. Sample and homogenize the raw natural rubber under test in accordance with the method specified in BS 1673-1. Weigh 380 g of the homogenized test rubber an
30、d mix in accordance with the following schedule: 5.2.3 Mill mixing procedure using powdered ingredients. Sample and homogenize the raw natural rubber under test in accordance with the method specified in BS 1673-1. Weigh 400 g of the homogenized test rubber and mix in accordance with the following s
31、chedule: 6 Evaluation of vulcanization characteristics of pure gum-stock mixes 6.1 Viscosity. Determine the Mooney viscosity, ML1 + 4 (100 C), of the unvulcanized test mix in accordance with the method specified in BS 1673-3. 6.2 Relaxed tensile stress property. Vulcanize test sheets at 140 C for 40
32、 min in accordance with the method specified in BS 1674. Condition the test sheets at 23 2 C for at least 16 h and not more than 24 h prior to testing. Measure the relaxed tensile stress (relaxed modulus) at 100 % elongation, MR100, in accordance with the method specified in BS 903-A411). Apply a co
33、rrection to the observed stress to allow for the deviation of the Mooney viscosity of the unvulcanized mix from 40 Mooney units in accordance with the values specified in Table 1. Duration (minutes) a) Load the homogenized rubber on to the mill and masticate with the nip set at 0.6 mm1 b) Open the n
34、ip to 0.8 mm, add masterbatch A and make one # cut from each side1 c) Add masterbatch B and make two # cuts from each side2 d) Cut the mix from the mill and roll. Immediately pass the rolled mix endwise through the nip. Repeat twice0.5 e) Sheet the test mix to approximately 6 mm thickness for Mooney
35、 viscosity determination. NOTEThe Mooney viscosity, ML1 + 4 (100 C), of the test mix should lie in the range 35 to 45; for raw natural rubber of high viscosity it may be necessary to pass the test mix through a tight nip several times before the final rolling and upending in order to ensure that the
36、 test mix viscosity is less than 45 Mooney units. f) Return the test mix to the mill and sheet to the appropriate thickness for preparing vulcanized test sheets. g) Condition the test mix in a closed container at 23 2 C for a period of 16 h to 24 h. In the event of any sulphur bloom appearing during
37、 this period the mix shall be rejected. Duration (minutes) a) Pass the homogenized rubber twice between the rolls without banding with the nip set at 0.20 mm b) Band the rubber with the nip set at 1.4 mm. When a smooth band has been obtained, adjust the nip to 1.9 mm4 c) Add the zinc oxide, the stea
38、ric acid, the sulphur and the MBT4 d) Make three # cuts from each side3 e) Cut the mix from the mill and roll. Set the nip to 0.8 mm and pass the rolled mix endwise through the nip. Repeat five times2 f) Sheet and condition the test mix as described in e), f) and g) of 5.2.2. 1) In course of prepara
39、tion; circulated as draft for public comment 78/55295 DC. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:59:14 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5738:1980 BSI 09-19993 Table 1 Values of adjustments to relaxed tensile stress for Mooney viscosity 6.3 Oscillating disc curemeter t
40、est. Measure the following standard test parameters, ML, MHR, ts1, (50), and (90) or (95) in accordance with the methods specified in BS 1673-10, using the following test conditions: NOTE 1The curemeter range should be selected to give a near full scale deflection at optimum torque. NOTE 2The amplit
41、ude of 1 is preferred but 3 may be used if high recorder sensitivity is not available. 7 Carbon black reinforced formulation and preparation of the test mix 7.1 Standard test formulation. The test ingredients to be used shall be in the proportions specified as follows: The compounding ingredients ex
42、cept the HAF black shall comply with the requirements of BS 4398. The TBBS shall be supplied in powder form having an initial ether or ethanol insoluble content of less than 0.3 %. The material shall be stored in a closed container and the ether or ethanol insoluble content shall be checked every si
43、x months. If it is found to exceed 0.75 %, the material shall be discarded or recrystallized and the initial value determined. The results will depend upon the source of HAF black used. For referee testing, a current industry reference black (IRB) shall be used or another agreed common source. The b
44、lack shall be dried and stored in accordance with the conditions specified in BS 1674. The standard laboratory mill mix mass, in grams, shall be based on four times the formulation mass. 7.2 Procedure for mixing the formulation 7.2.1 General. The procedure is to mix on day one, test on the curemeter
45、 and vulcanize on day two and measure vulcanizate properties on day three. The sequence is designed to allow 16 h to 24 h between mixing and vulcanizing. 7.2.2 Mastication. Sample and homogenize the raw natural rubber under test in accordance with the method specified in BS 1673-1. With the nip set
46、at 0.5 mm, load 500 g of the homogenized sample of the rubber under test on to the rolls and masticate until a smooth band and rolling bank is obtained. Continue mastication until the rapid plasticity number, measured in accordance with the method specified in BS 1673-3, using the 10 mm diameter pla
47、ten, does not exceed 45, which is approximately equivalent to a Mooney viscosity of 70 ML1 + 4 (100 C) determined in accordance with the method specified in BS 1673-3. 7.2.3 Mixing. Weigh 400 g of the masticated rubber and mix in accordance with the following schedule: Mooney viscosityAdjustment MPa
48、 44 40 36 32 28 0.07 0.00 + 0.08 + 0.18 + 0.29 oscillation frequency: 1.7 Hz amplitude of oscillation: 1 die temperature: 140 C IngredientParts by mass Raw natural rubber under test100.0 Zinc oxide5.00 Sulphur2.25 Stearic acid2.00 Oil furnace black: HAF: N 33035.00 N-tert-butylbenzothiazole- 2-sulph
49、enamide (TBBS) 0.700 144.95 tc tc tc Duration (minutes) a) Band the homogenized rubber on to the rolls with the nip set at 1.4 mm1 b) Add the stearic acid. Make one # cut from each side1 c) Add the zinc oxide and the sulphur. Make one # cut from each side2 d) Add the carbon black evenly across the rubber at a uniform rate. When about half the black has been incorporated, open the nip to 1.9 mm and make one # cut from each side. Add the remainder of the carbon black. When all the black has been incorporated, make one # cut from each sid
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