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RUBBER
UBEPOL-VCR
Introduction
UBEPOL-VCR is a new type of synthetic rubber developed by UBE's original technology. UBEPOL-VCR consists of micro-dispersed syndiotactic 1,2-polybutadiene(SPB) with high melting point and crystallinity, and high cis-1,4-polybutadiene rubber matrix. UBEPOL-VCR is improved about the processability and a lot of physical properties of the conventional polybutadiene rubber
Structure of VCR and basic characteristics of SPB
(1)Structure of VCR
| VCR | Matrix ; High cis BR | | Dispersed phase ; Syndiotactic1,2-polybutadiene with high melting temperature |
The dispersion of SPB in BR matrix is as follows (see Figure-1):
Fig.-1 Transmission electron micrograph
(with respect to the dispersion of SPB in BR matrix.)
(2)Morphology of SPB
- Melting point ; about 200°C
- Crystallinity ; 70 - 80%
- Size
Table-1 Size of SPB. | | Basic unit | Aggregation | | SPB | Radius : 20 - 100mµ
Specific surface area: 85 m2/g | Radius : 20 - 100mµ
Length : 12 | | HAF Carbon | Radius : 29mµ
Specific surface area: 100 m2/g | Radius : Less than 1µ |
Schematic aggregative structure
Fig.-2 Schematic aggregative structure of SPB and carbon black.
Effective volume fraction of filler
 -w ; shear
stress
B ; die swell
 * ; effective
volume fraction of filler
0 ; true volume
fraction
Fig.-3 Estimation of effective volume(°C°C) from die swell.
*:
effective volume fraction of filler
0 : true volume
fraction
*By A.I.Medalia ; Colloid & Interface Sci. ,32 115
Characteristics of various VCR
Table-3 Characteristics of various VCR | Grade name | ML1+4 | n-Hexane Insolubles(1)(wt%) | Characteristics | | VCR412 | 45 | 12 | This grade is a standard of
UBEPOL-VCR which has the excellent processabilty and the good physical properties. | | VCR617 | 62 | 17 | This grade contains about 17wt% syndiotactic 1,2-polybutadiene and
emphasizes processability, high hardness and modulus. |
(1) abbreviation :HI
(2) Index of syndiotactic 1,2-polybutadiene content.
Summary of UBEPOL-VCR
1) Compound properties
- High extrusion rate
It means improving the productivity. As a result, it means realizing to reduce the manufacturing cost per tire. - Small die swell (Small shrinkage)
he dimensional stability after extrusion process is very excellent, and the part of the edge is sharp shape. So it mean improving the uniformity of a tire.
It means being suitable for thinning down the various components for a tire because of lightening.- High green strength
Efficiency of work is improved and it shall be possible to realize automation of manufacturing tire. As a result, it means realizing to reduce the manufacturing cost per tire.
2)Vulcanizate properties
- High hardness & High modulus
It is possible to lighten the various components for a tire. It means being suitable for thinning down the various components for a tire because of lightening.
In case of estimating at same hardness, it is possible to reduce carbon black in recipe. So it is suitable for the tire aimed lower rolling resistance. - Excellent cut growth resistance at the practical condition
It is possible to ensure against risks, and prolong the lifetime.
UBEPOL-VCR Grades
Table 1 | | UBEPOL-VCR412 | UBEPOL-VCR617 | UBEPOL-VCR406 | UBEPOL-VCR303 | | Mooney Viscosity(1) (ML1+4, 100°C) | 45 | 62 | 45 | 38 | | n-Hexane insolubles, HI(2) (wt.%) | 12 | 17 | 6 | 3 | | Molecular Chain Linearity of polybutadiene Rubber Matrix | medium | medium | linear | linear |
Note
(1) ASTM D1646
(2) Index of syndistactic 1,2-polybutadiene content
- UBEPOL-VCR412 is a standard type of UBEPOL-VCR which has the excellent processability and the good physical properties.
- UBEPOL-VCR617 contains about 17wt% syndiotactic 1,2-polybutadiene and emphasize processability, high hardness and high modulus.
- UBEPOL-VCR406 is designed to contain about 6 wt% syndiotactic 1,2-polybutadiene in high cis-1,4-polybutadiene rubber matrix which has a high molecular weight and a high linearity of molecular chain, in order to well-balance between processability and physical properties.
- UBEPOL-VCR303 contains about 3 wt% syndiotactic 1,2-polybutadiene in high cis-1,4-polybutadiene rubber matrix to be designed to have a high linearity of molecular chain. In consequence of his characteristics, UBEPOL-VCR303 has the good extrudability with having good properties of high cis-1,4-polybutadiene rubber.
Basic Characteristics of Syndiotactic 1,2-Polybutadiene (SPB)
- Melting point; 201°C
- Crystallinity: 70~80%
- Dispersion of SPB: Fig. 1
SPB has high enough melting point that SPB don't melt in practical use, for example, in mixing process.
Fig.1 shows that SPB is micro-dispersed in polybutadiene rubber matrix.
Fig.1 Dispersion of SPB in Polybutadiene Rubber Matrix.
Table 2 | | UBEPOL-VCR412 | UBEPOL-VCR617 | UBEPOL-VCR406 | UBEPOL-VCR303 | UBEPOL-VCR150(2) | | Compound Mooney Viscosity (3) (ML1+4, 100°C) | 68 | 90 | 68 | 63 | 60 | | Mill Shrinkage (4) (%) | 14 | 12 | 18 | 19 | 25 | | Extrudability (5) | Extrusion Rate (lb/min) | 0.280 | 0.313 | 0.298 | 0.296 | 0.271 | | Length of Extrudate (in/min) | 74.4 | 85.4 | 70.5 | 59.8 | 46.5 | | Die Swell | 1.20 | 1.16 | 1.35 | 1.57 | 1.86 | | Rating(6) | Contour | 4.0 | 4.0 | 4.0 | 4.0 | 3.0 | | Edge | 4.0 | 4.0 | 4.0 | 3.5 | 3.5 | | Surface | 4.0 | 4.0 | 4.0 | 4.0 | 4.0 | | Corner | 4.0 | 4.0 | 4.0 | 4.0 | 3.5 | | Total | 16.0 | 16.0 | 16.0 | 15.5 | 14.0 |
Note
(1) Compound recipe and procedure according to ASTM D3189
(2) UBEPOL-BR150 is UBE's standard high cis-1,4 polybutadiene rubber grade
(3) ASTM D1646
(4) ASTM D1917
(5) ASTM D2230 Grarvey-die at 100°C, screw diameter; 40mm°C, screwL/D;8, screw rotational speed; 20rpm
Table 2 shows that UBEPOL-VCR has excellent extrudability compared with high cis-1,4 polybutadiene rubber in spite of high compound mooney viscosity. Also, UBEPOL-VCR has excellent open roll mill behavior, especially at high temperature condition.
Fig. 2 is open roll mill behavior of UBEPOL-VCR412 compared with UBEPOL-BR150. | Surface Temp. of Roll | UBEPOL-VCR412 | UBEPOL-BR150 | | 60°C |  |  | | 100°C |  |  |
Fig. 2 Open mill Roll Behavior
- Compound recipe and procedure according ASTM D3189
- Compound is aged for a day after compounding
- Open mill roll condition;
| Roll size | : 6"°C x 12"L | | Roll speed | : Front 24.0rpm, Rear 30.0rpm | | Roll nip clearance | : 1mm |
Table 3 | | Cure Minutes at 145°C | Unit | UBEPOL-VCR412 | UBEPOL-VCR617 | UBEPOL-VCR406 | UBEPOL-VCR303 | UBEPOL-VCR150 | Test Method | | Tensila Strength | 35' | MPa | 18.0 | 18.1 | 18.6 | 18.2 | 18.1 | ASTM D412 | | 50' | MPa | 17.7 | 17.9 | 18.4 | 18.0 | 18.0 | | Elongation | 35' | % | 350 | 290 | 460 | 500 | 510 | ASTM D412 | | 50' | % | 340 | 290 | 460 | 470 | 480 | | 100% Modulus | 35' | MPa | 4.4 | 6.2 | 2.9 | 2.4 | 2.0 | ASTM D412 | | 50' | MPa | 4.5 | 6.4 | 2.9 | 2.5 | 2.2 | | 200% Modulus | 35' | MPa | 10.0 | 12.9 | 7.1 | 5.8 | 5.2 | ASTM D412 | | 50' | MPa | 10.3 | 13.3 | 7.4 | 6.2 | 5.4 | | 300% Modulus | 35' | MPa | 15.4 | - | 12.1 | 10.3 | 9.3 | ASTM D412 | | 50' | MPa | 16.1 | - | 12.7 | 11.1 | 10.0 | Hardness
Type A Durometer | 35' | - | 72 | 77 | 67 | 64 | 61 | ASTM D412 | | 50' | - | 73 | 78 | 67 | 65 | 62 | Tear resistance
Die C | 35' | kN/m | 54 | 59 | 52 | 42 | 42 | ASTM D2240 | | 50' | kN/m | 58 | 62 | 54 | 48 | 47 | ASTM D624 | | Rebound | 50' | % | 49 | 46 | 53 | 55 | 58 | BS.903,PART22 | Compression Set
Method B, 70°C, 72hrs | 50' | % | 17 | 18 | 16 | 16 | 16 | ASTM D395 | Goodrich Flex
0.175" Stroke, 55lb, 100°C | ^T | 50' | °C | 40 | 44 | 35 | 34 | 32 | ASTM D623 | | P.S. | 50' | % | 17 | 19 | 12 | 11 | 8 | | Pico Abrasion Index | 50' | - | 290 | 330 | 268 | 250 | 209 | ASTM D2228 | Lombourn Abrasion Index(2)
Iwamoto Seisakusyo, Japan | 50' | - | 72 | 62 | 100 | 103 | 100 | UBE Method | Cut Growth (2mm-->15mm)
De Mattia Flexing machine | 50' | times | 29,000 | >105 | 10,000 | 5,000 | 2,700 | ASTM D313 | Cut Generation
De Mattia Flexing Machine | 50' | 104 times | >30 | >30 | >30 | >30 | >30 | ASTM D430 | Wet Skid Resistance on safty-Walk
British Portable Skid Resistance Tester | 50' | - | 22 | 23 | 20 | 20 | 18 | UBE Method |
Note
(1) Recipe and procedure according to ASTM C3189
(2) Index against UBEPOL-BR150, higher means better abrasion resistance
UBEPOL-VCR has the advantages of high hardness, high modulus, good tear resistance, Pico abrasion resistance and cut growth.
Table 3 is the results of UBEPOL-VCR evaluation in the case of same compound recipe. In rubber industries, it is occasionally important that the valcanizates are evaluated in the case of same hardness or same modulus.
Fig. 4~ Fig. 8 shows the typical properties of the valcanizates(1) controlled to be same hardness by carbon black loading.
Fig. 4 Tensile Strength
Fig. 5 Goodrich Flex.
Fig. 6 Goodrich Flex.
Fig. 7 Rebound
Fig. 8 Fatigue Life(2)
Fig. 9 cut Growth
Note (1) Compound recipe | UBEPOL-VCR | 50 | - | (parts by mass) | | UBEPOL-BR150 | - | 50 | | | NR | 50 | 50 | | | HAF Carbon black | Variable | 50 | | | High aromatic oil | 10 | 10 | | | Zinc oxide | 3 | 3 | | | Stearic acide | 2 | 2 | | | Antioxidant 810nA | 2 | 2 | | | Accelerator NOBS | 0.8 | 0.8 | | | Sulfur | 1.5 | 1.5 | | | | | | | | Note (2) 300cpm, maximum strain 50% | | |
Fig 5,6 and 7 indicate that the physical properties, Goodrich Flex.
*T, PS and Rebound are superior to high cis-1,4 polybutadiene rubber, if the hardness of UBEPOL-VCR were equalized with hardness of high cis-1,4 polybutadiene by controlling carbon black loading.
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