This standard specifies the sampling method for raw rubber in packages, blocks and bags, and also specifies the operating procedures for preparing physical and chemical test specimens from the rubber samples. GB/T 15340-1994 Sampling and sample preparation methods for natural and synthetic raw rubber GB/T15340-1994 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Sampling and further preparative procedures for natural and synthetic raw rubberRubber ,raw,natural and syntheticSampling and further preparative proceduresGB/T15340-94wwW.bzxz.Net
ISO1795：1992
This standard is equivalent to the international standard ISO1795：1992 "Sampling and further preparative procedures for natural and synthetic raw rubber". 1 Scope
This standard specifies the sampling method for raw rubber in packages, blocks and bags, and also specifies the operating procedures for preparing physical and chemical test specimens from the rubber samples.
2 Reference standards
GB/T1232 Determination of Mooney viscosity of unvulcanized rubberGB6038 Compounding, mixing and vulcanization equipment and operating procedures for rubber test compoundsGB6378 Sampling procedures and charts for metrological inspection of defective product rateGB/T6737 Determination of volatile matter content of synthetic raw rubberGB/T8087 Determination of volatile matter content of natural raw rubberGB/T 9869 Determination of vulcanization characteristics of rubber compounds (disc oscillation vulcanizer method)3 Terminology
This standard adopts the following terms, among which "package" includes "block" and "bag" (chips, powders and sheets are all packed in bags). 3.1 Batch: All rubber packages with the same grade and batch number. 3.2 Sample: A group of rubber packages selected to represent the batch. 3.3 Laboratory sample: A rubber sample taken from a sample rubber package and representing the rubber package. 3.4 Laboratory mixed sample: A rubber sample representing the sample made by mixing equal amounts of laboratory samples. 3.5 Test material: a rubber sample taken from a laboratory sample or a laboratory mixed sample for testing (including sample preparation). 3.6 Test sample: a rubber sample taken from a test material for a certain test. 4 Sampling method
The more packages of the sample, the more representative the sample is for the batch. However, in most cases, a reasonable limit should be set based on practical considerations. The number of rubber packages randomly selected should be agreed upon by the supplier and the buyer. If feasible, a statistical sampling plan can be selected from GB6378. 5 Selection of laboratory samples
Laboratory samples are selected from the selected rubber packages according to the following recommended method: remove the outer sheath, polyethylene packaging film, rubber package coating or other surface objects from the rubber package; cut through the rubber package with two knives perpendicular to the largest surface of the rubber package without using lubricants, and take out a whole piece of rubber from the middle of the rubber package. Sampling should be carried out in this way for arbitration inspection; laboratory samples can also be selected from any convenient part of the rubber package. According to the items to be tested, the total amount of each laboratory sample is set at 600~1500g. If the rubber is in crumb or powder form, samples of the same weight shall be randomly taken from the rubber bag. Approved by the State Technical Supervision Commission on December 22, 1994 and implemented on September 1, 1995
GB/T 15340--94
If the laboratory sample is not tested immediately, it shall be placed in a moisture-proof container or packaging bag with a volume not exceeding twice the volume of the sample for inspection. Note: The surface layer may be removed if it is contaminated by talcum powder or other isolating agents. 6 Sampling report
The sampling report shall include the following:
All details required to identify the sample, such as batch mark;
Rubber type and grade;
The number and type of rubber packages or bags that make up the batch; the number of rubber packages or bags in the sample;
Differences from this standard.
7 Testing
Each laboratory sample shall be tested separately and reported separately. Note: When doing quality inspection, laboratory mixed samples can be used to determine chemical properties and vulcanization characteristics. 8 Sample preparation
Rubber refining uses an open mill that complies with GB6038. 8.1 Natural rubber
Weigh the laboratory sample to an accuracy of 0.1g, adjust the roller distance of the open mill to 1.3±0.15mm, keep the roller temperature at 70±5℃, and pass the roll 10 times to make the laboratory sample uniform. When passing the roll for the 2nd to 9th time, roll the film and put the film into the roller one end at a time and pass the roll again. All the scattered solids are mixed into the rubber; after the 10th roll, remove the film, put the film into the dryer to cool, and then weigh it again to an accuracy of 0.1g. Note: There is a loss of volatile components during the homogenization process, so the volatile matter can be calculated using the initial and final values ​​of the mass (see GB/T8087 oven method). If the volatile matter is not measured immediately, the homogenized rubber sample shall be placed in a sealed container with a volume not exceeding twice its volume or wrapped tightly with two layers of aluminum box for testing. 8.1.1 Chemical and physical tests
Cut the specimens from the homogenized laboratory samples and distribute the test materials according to the requirements of the specific test items. All tests shall be carried out in accordance with the corresponding national standards, and the volatile matter content shall be determined by the oven method specified in GB/T8087. 8.1.2 Mooney viscosity
Take 30~~40g of homogenized rubber sample and measure the Mooney viscosity according to GB/T1232. 8.1.3 Vulcanization characteristics
Use the homogenized rubber sample to determine the vulcanization characteristics according to the methods specified in GB6038 and Appendix B. 8.2 Synthetic rubber
8.2.1 Chemical and physical tests
Cut 250±5g of test sample from the laboratory sample (if the sample is crumb rubber or powder rubber, randomly take out test sample of the same weight), and measure the volatile content according to the hot roll method specified in GB/T6737. Take the rubber sample after the volatile content is measured for the specified chemical test. Some rubbers will stick to the roller when using the hot roller method. If this happens, use the GB/T6737 oven method instead. Even if the oven method is used to measure the volatile content, the rubber sample still needs to be dried by the hot roller method before the chemical test. If this is not possible, take the test sample directly from the laboratory sample. Note: If the test is performed according to the steps in the note of Chapter 7, the rubber samples after the volatile content is measured are mixed according to the steps specified in 8.2.2.2 to prepare a 250±5g laboratory mixed sample.
8.2.2 Mooney viscosity
8.2.2.1 Direct method (preferred)
Cut a sample of appropriate thickness from the laboratory sample and determine the Mooney viscosity according to GB/T1232. The sample should be as free of air as possible to prevent the entrained air from attaching to the rotor and cavity surface. The crumb or granular rubber should be evenly distributed above and below the rotor. 8.2.2.2 Roller method
GB/T15340-94
Sometimes, it is necessary to compact the rubber with an open mill before testing (see note 8.2.2.2). For a specific rubber, the corresponding evaluation method will specify whether the roller method is used. The roller method should be carried out according to the following steps: Take about 250±5g of the test sample from the laboratory sample, adjust the roller distance of the open mill to 1.4±0.1mm, keep the roller surface temperature at 50±5℃, and roll the sample 10 times (note that special provisions are made for cis-butyl rubber, EPDM, chloroprene rubber and some butyl rubber below). When rolling for the 2nd to 9th time, fold the film in half, and after the 10th time, put it directly on the roll without folding, and then measure the Mooney viscosity according to GB/T1232. Cis-butyl rubber (BR), EPDM: The roller surface temperature is 35±5℃. Chloroprene rubber (CR): roller surface temperature is 20 ± 5 ° C, roller distance is 0.4 ± 0.05 mm, and rollers are passed twice. Some nitrile rubber (NBR): roller distance is 1.0 ± 0.1 mm, roller surface temperature is 50 ± 5 ° C. Note: The "roller method" should be used in the following cases: a. The rubber is porous or extremely uneven, b. The rubber viscosity is too high; c. Semi-finished rubber powder; d. Carbon black masterbatch. The Mooney viscosity value measured by the roller method may be different from that measured by the direct method. In addition, the reproducibility of the measurement results of the roller method is poor. 8.2.3 Vulcanization characteristics Cut the test sample from the laboratory sample (if it is a crumb or powdered rubber, take the material randomly), and measure the vulcanization characteristics according to the evaluation method corresponding to the rubber being tested.
If the steps in the note to Chapter 7 are followed, sufficient rubber samples are taken from each laboratory sample, and the appropriate amount of mixed laboratory samples is prepared by the initial operation steps of the mixing procedure.
A1 Scope
GB/T 15340--94
Appendix A
Natural Rubber Identification Procedure
(Supplement)
This appendix specifies the physical and chemical test methods for raw rubber and the standard push materials, standard test formulas, equipment and processing methods used to evaluate the vulcanization characteristics of natural rubber (NR).
A2 Reference standards
Determination of tensile properties of vulcanized rubber and thermoplastic rubber GB/T 528
GB2941 Standard temperature, humidity and time for environmental conditioning and testing of rubber specimens GB/T 3510 Determination of plasticity of raw rubber and mixed rubber Rapid plastometer method Rubber testing Equipment and operating procedures for compounding, mixing and vulcanization of rubber compounds GB 6038
Determination of ash content of natural raw rubber
GB/T 8085
Determination of volatile matter content of natural raw rubber
GB/T 8086
A3 Sampling and sample preparation methods
A3.1 Laboratory samples with a mass of about 1500g should be prepared using the method described in this standard. A3.2 Sample preparation should comply with the provisions of this standard. A4 Physical and chemical tests on raw rubber
A4.1 Mooney viscosity
The Mooney viscosity of the sample prepared according to A3.2 is determined in accordance with the provisions of GB/T1232. Record the result of ML (1+4) 100℃.
A4.2 Volatile matter
The volatile matter content of the sample prepared according to A3.2 is determined by the oven method in accordance with the provisions of GB/T8086. A5 Preparation of test rubber
Three formulations are recommended:
a. Two non-carbon black filled pure rubber formulations for the comparative test of natural rubber vulcanization characteristics. b. Carbon black filled rubber formulation for the comparative test of natural rubber vulcanization characteristics. Note: It can also be used for the comparative test of isoprene rubber (IR). A5.1 Standard test formulation
The standard test formulation is listed in Table A1.
The raw materials should be the NIST standard reference materials shown in Table A1 or other equivalent national standard reference materials. T2
Raw materials
Natural rubber
Zinc oxide
Stearic acid
Hydraulic furnace black (HAF)1)
TBRSa)
GB/T 15340—94
Standard test formula
NIST standard
Reference material
Formula 1
Mass fraction
Formula 2
Note: 1) NBS378 can be used instead of the current industrial reference carbon black, but the results may be slightly different. 2) 2-Mercaptobenzothiazole.
Formula 3
Filled carbon black
3) N-butyl-2-benzothiazolesulfenamide. This accelerator should be in powder form and the initial aldehyde or ethanol insoluble content should not exceed 0.3%. This material should be stored in a closed container at room temperature and the content of ether or ethanol insolubles should be checked every 6 months. If the insoluble content is found to exceed 0.75%, the material should be discarded or recrystallized. A5.2 Procedure
A5.2.1 Equipment and procedures
The equipment and operating procedures for batching, mixing and vulcanization should comply with the provisions of GB6038. The surface temperature of the rolls of the open mill should always be maintained at 70±5℃ during mixing. The raw rubber should be homogenized in accordance with the provisions of this standard. A5.2.2 Mixing procedure for formulations 1 and 2 (pure rubber compound) A5.2.2.1 The raw rubber is passed twice between rolls with a roll gap of 0.2mm without wrapping the rolls. A5.2.2.2 Adjust the roll gap to 1.4mm so that the raw rubber wraps the rolls. After the roll-wrapped rubber is smooth, adjust the roll gap to 1.8mm. Duration 4min. A5.2.2.3 Add zinc oxide, stearic acid, sulfur and MBT or TBBS. Duration 4min. A5.2.2.4 Perform 3/4 cuts 3 times on each side of the open mill. Duration 3min. A5.2.2.5 Remove the rubber from the open mill. Adjust the roller distance to 0.8mm and allow the rolled rubber to pass through the mill from one end 6 times. Duration 2min.
Total time 13min.
6 Check the quality of the rubber (see GB6038). If the difference between the batch quality and the theoretical value exceeds 0.5%, discard the batch and re-mix.
A5.2.2.6
A5.2.2.7 Cut enough rubber from the batch for vulcanizer test. If necessary, determine the Mooney viscosity of the unvulcanized rubber in accordance with the provisions of GB/T1232. The rubber compound is pressed into a film of about 2.2 mm thickness for the preparation of test films, or pressed into a film of appropriate thickness for the preparation of GB/T528 ring specimens.
A5.2.2.8 The mixed rubber compound should be conditioned for 2~~4 hours before vulcanization, if possible, at the standard temperature and humidity specified in GB2941.
A5.2.3 Mixing procedure for masterbatch mixing formulas 1 and 2 (pure rubber compounds) Accelerators, sulfur or fillers can be mixed into the rubber to make a masterbatch. In addition to being easy to operate, this process can also improve the accuracy of mixing the compounding ingredients.
The procedure for preparing masterbatch and pure rubber test compounds is shown in Appendix B. 533
GB/T 15340—-94
A5.2.4 Mixing procedure for formula 3 (carbon black filled rubber) A5.2.4.1 Add the raw rubber to the open mill with a roll gap of 0.5 mm and plasticize until a smooth roll-wrapped rubber and rolling accumulation are obtained. After plasticizing, the rapid plasticity value is determined in accordance with the provisions of GB/T3510. The rapid plasticity value shall not exceed 45, which is approximately equivalent to 70 Mooney viscosity values ​​determined in accordance with the provisions of GB/T1232. The mixing process is as follows: Adjust the roll gap of the open mill to 1.4 mm so that the plasticized rubber wraps the roll. Duration 1 min. a.
Add stearic acid and perform a 3/4 cut on each side of the open mill. Duration 1 min. b.
Add zinc oxide and sulfur and perform a 3/4 cut on each side of the open mill. Duration 2 min. d. Add carbon black evenly over the entire roll. After about half of the carbon black has been mixed in, adjust the roll gap to 1.9 mm, make a 3/4 cut on each side of the mill, and then add the rest of the carbon black. After all the carbon black has been added, make a 3/4 cut on each side of the mill. Make sure that the carbon black that falls into the drop tray is added to the rubber. Duration 10 minutes. Add TBBS and make three 3/4 cuts on each side of the mill. Duration 3 minutes. e.
f. Remove the rubber from the mill. Adjust the gap to 0.8 mm and pass the rolled rubber through the roll horizontally 6 times. Duration 3 minutes. The total time for the above is 20 minutes.
A5.2.4.2 Check the quality of the rubber. If the difference between the rubber quality and the theoretical value exceeds 0.5%, discard the batch and re-mix. A5.2.4.3 Cut enough rubber from the rubber to carry out the vulcanizer test. If necessary, measure the Mooney viscosity of the unvulcanized rubber in accordance with the provisions of GB/T1232. Press the rubber into a film of about 2.2 mm thickness for the preparation of test films, or press it into a film of appropriate thickness for the preparation of ring specimens.
A5.2.4.4 The mixed rubber should be conditioned for 2 to 24 hours before vulcanization. If possible, it should be conditioned at the standard temperature and humidity specified in GB2941.
A6 Evaluation of vulcanization characteristics with vulcanizer
According to the provisions of GB/T9869, the following test parameters were measured: ML, MHR, ta, tc50), tc(90). The test conditions used were as follows:
Oscillation rate 1.7Hz (1001/min)
Oscillation arc 1°
The range should be selected to reach at least 75% of the full range at MHR. Cavity temperature 160±0.3℃
Preheating time None
A7 Evaluation of tensile properties of vulcanized rubber
Vulcanize the rubber sheets at 140℃ for 20, 30, 40 and 60min respectively. Adjust the vulcanized rubber sheets at the standard temperature and humidity specified in GB2941 for 16 to 96h. Measure the tensile properties of the vulcanized rubber according to the provisions of GB/T528. A8 Test report
The test report shall include the following:
Indication of the reference to this standard.
All details necessary for identification of the sample.
Standard test formula used.
Reference material used.
Method used for determination of volatile matter content.
Time to reach M in A6.
Rubber test used in A6 (GB9869). Abnormal conditions encountered during the determination.
GB/T15340-94
Operation steps not included in this standard or the referenced standards and optional operation steps, such as whether a masterbatch was used. Test results and the units used to express the results. Test date.
Appendix B
Procedure for preparation of pure rubber compounds using masterbatch (supplement)
B1 Masterbatch formulation
The quality of the raw rubber used to prepare the masterbatch should be similar to that of the raw rubber tested. The weight proportions of the compounding materials used are shown in Table B1. Table B1
Masterbatch
Raw materials
Natural rubber
Zinc oxide
Stearic acid
Accelerator M
Accelerator NS
Test compound formulation
The composition of the test compound is shown in Table B2.
Test raw rubber
Accelerator M Masterbatch
Accelerator NS Masterbatch
Sulfur Masterbatch
Accelerator M
Masterbatch preparation using open mill mixing procedure Table B2
Mass fractions
During the mixing process, tap water was used to keep the open mill rolls cool. The mixing process was as follows:
The roll gap was adjusted to 0.6mm, make the raw rubber roll and plasticize. Operation time 1 min. Accelerator NS Accelerator NS Add zinc oxide, stearic acid and accelerator M or NS or sulfur. Gradually increase the roll distance to keep rolling and accumulating rubber. When about 80% of the raw materials are added (roller distance is about 1.0mm), cut the rubber 3/4 from each side of the roll. Operation time 2min. c. Mix the remaining raw materials. When all the powder is eaten up, cut the rubber 3/4 from each side of the roll until the dispersion is completely uniform. Operation time 5min. Total operation time of the above is 8 min. GB/T 15340-94 d. Cut the masterbatch from the open mill and check the total mass. Cool the roll to 27±5℃ with tap water at ambient temperature. e. Adjust the roller distance to the smallest possible gap, and roll the masterbatch through the rollers for 3 times, rolling the rubber into a triangular package each time the rollers are passed. Adjust the roller distance to 1.4mm and roll the masterbatch off. Store the masterbatch in a sealed container at a temperature of 23±2℃. The storage period shall not exceed 3 months. Preparation of B4 Test Rubber
During mixing, the surface temperature of the roll of the mixing mill shall be maintained at 70±5℃. The mixing process is as follows: Adjust the roller distance to 0.8mm to roll the raw rubber. Perform 3/4 tapping twice from each side. Operation time 0.75min. a.
Add accelerator M or NS and sulfur masterbatch. Perform 3/4 tapping 6 times from each side. Operation time 2.00min. b.
Cut all the rubber from the mixing mill and pass the rolled rubber vertically through the rollers twice. Operation time 0.25min. c.
The total operation time is 3.00min.
Adjust the roller distance to 1.4mm and place the rubber compound under the temperature and humidity specified in GB2941 for 2 to 24 hours after mixing and before vulcanization. Additional remarks:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee on Rubber and Rubber Products Standardization. This standard was drafted by the Beijing Rubber Industry Research and Design Institute of the Ministry of Chemical Industry. The main drafters of this standard are Yi Youyuan and Zhang Tao. 536
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