Product Name
Rubber, natural
Synonyms
RUBBER LATEX;RUBBERFUME
Description
Isoprene, stabilized appears as a clear colorless liquid with a petroleum-like odor. Density 5.7 lb / gal. Flash point -65°F. Boiling point 93°F. May polymerize exothermically if heated or contaminated. If polymerization takes place inside a closed container, the container may rupture violently. Less dense than water and insoluble in water. Vapors heavier than air.;Liquid; OtherSolid;OtherSolid;VERY VOLATILE COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR.
IUPAC Name
2-methylbuta-1,3-diene
Molecular Weight
68.12g/mol
Molecular Formula
C5H8;CH2=C(CH3)CH=CH2;C5H8
Canonical SMILES
CC(=C)C=C
InChI
InChI=1S/C5H8/c1-4-5(2)3/h4H,1-2H2,3H3
InChI Key
RRHGJUQNOFWUDK-UHFFFAOYSA-N
Boiling Point
93 °F at 760 mm Hg (NTP, 1992);34.0 °C;34.067 °C;34 °C
Melting Point
-184 °F (NTP, 1992);-145.9 °C;-145.95 °C;The generally accepted crystal melting temperature of natural rubber is 30 °C.;-146 °C
Flash Point
-65 °F (NTP, 1992);-65 °F (-54 °C) (Closed cup)
Density
0.681 at 68 °F (USCG, 1999);0.679 g/cu cm at 20 °C;0.906-0.916 g/cu cm @ 20 °C;Relative density (water = 1): 0.7
Solubility
less than 1 mg/mL at 70.7° F (NTP, 1992);0.01 M;In water, 642 mg/L at 25 °C;Practically insoluble in water;Miscible with ethanol, ethyl ether, acetone, benzene;Soluble in alcohol, ether, hydrocarbon solvents;Natural rubber is soluble in most aliphatic, aromatic, and chlorinated solvents, but its high molecular weight makes it difficult to dissolve.;Practically insol in water, alcohol, dil acids, or alkali; sol in abs ether, chloroform, most fixed or volatile oils, petroleum ether, carbon disulfide, oil of turpentine.;Raw rubber dissolves (or at least swells very strongly) in many organic liquids such as benzene, petroleum ether, crude petroleum, and carbon tetrachloride. In contrast, vulcanized rubber can only swell because the chemical cross-liking prevents dissolution.;Solubility in water, mg/l at 25 °C: 642 (very poor)
Color/Form
Colorless volatile liquid;Colorless, watery liquid;Nearly colorless and transparent in thin layers.;Amorphous when unstretched, but has oriented crystalline structure on stretching /Cured (unvulcanized)/
Covalently-Bonded Unit Count
1
EC Number
201-143-3;232-689-0;614-502-8;618-362-9;618-550-0
Heat of Vaporization
26.39 kJ/mol at 25 °C; 25.87 kJ/mol at 34 °C
Log P
2.42 (LogP);log Kow = 2.42;2.30
MeSH Entry Terms
2-methyl-1,3-butadiene;isoprene
Monoisotopic Mass
68.0626g/mol
Odor
Petroleum-lke;Odorless
Other Experimental
1 mg/L equivalent to 358 ppm and 1 ppm equivalent to 2.79 mg/cu m at 25 °C, 760 mm Hg;Heat of fusion: 4.88 kJ/mol at -145.95 °C;Forms binary azeotropes with methanol, methylamine, acetonitrile, methyl formate, bromoethane, ethyl alcohol, methyl sulfide, acetone, propylene oxide, ethyl formate, isopropyl nitrate, methylal, ethyl ether, and n-pentane.;VP: 400 mm Hg at 15.4 °C;Henry's Law constant = 7.7X10-2 atm-cu m/mol at 25 °C (est);Hydroxyl radical reaction rate constant = 1.01X10-10 cu-cm/molc sec at 25 °C;Ozone reaction rate constant = 1.43X10-17 cu cm/molecule-sec at 25 °C;Thermoplastic until mixed with sulfur and vulcanized; supports combustion;The chain-like molecules are quite separate and only when they have been cross-linked by the process of vulcanization are the physical properties of rubber fully realized.;The properties of elasticity and resilience which first attracted man stem from the unusual molecular structure of rubber. This comprises a particular type of long chain-like molecule consisting of a large number of small molecular units joined together end to end.;Durometer hardness (or shore)= 20-100; ultimate elongation= 750-850 % at 23 °C /From table/;Natural rubber crystallizes below 20 °C because of its stereoregular molecular structure. The rate of crystallization varies with temperature and the type of rubber.;The best grades of raw rubber (pale crepe or smoked sheet) contain about 95% rubber hydrocarbon. The rest consists of proteins (2-3%), acetone-sol resins and fatty acids (2%), small amounts of sugar and a little mineral matter. Vulcanization, which consists of heating rubber with 1-3% of sulfur, introduces cross links between chains to produce a 3-dimensional lattice of improved elasticity, strength, temp sensitivity. Accelerators such as zinc dimethyldithiocarbamate greatly decrease the time or lower the temp required for vulcanization.;Natural rubber comprises a range of polymers with varying molecular weight estimated as <100,000 to 4 X 10 + 6.;Properties: Chemically unsaturated, not stable to temperature changes (thermoplastic), readily oxidizable by mastication; soluble in acetone, carbon tetrachloride, and most organic solvents; refraction index 1.52; dielectric constant 2.5. Processed by calaendars and extruders; can be injection-molded with low sulfur and high accelerator. Cured by hot-molding or in open steam, at temperatures from 120-150 /degree/ C after addition of 3% sulfur, 1% organic accelerator, 3% zinc oxide, plus fillers or reinforcing agents. The only factors of significance in vulcanization are the time of exposure to heat and the temperature used. /Crude (unvulcanized) natural rubber/;Properties: High tensile strength; relatively low permanent set; insensitive to temperature changes. Attacked by heat, atmospheric oxygen, ozone, hydrocarbons, and unsaturated fats and oils. Insoluble in acetone. Permeable to gases; supports combustion; abrasion resistance poor unless compounded with carbon black; dissipates vibration shock; high electrical resistivity. /Cured (vulcanized, i.e. sulfur cross-linkages)/;Specific heat: 1.905 kJ kg-1 K-1;Viscosity stablizing agent: hydroxylamine-neutral sulfate
Refractive Index
Index of refraction: 1.42160 at 20 °C/D;Index of refraction: 1.5195 at 20 °C /Ribbed smoked sheets/;Index of refraction: 1.5218 at 20 °C /Pale crepe/;Index of refraction: 1.52 /Cured (unvulcanized)/
Stability
Stable under recommended storage conditions. Contains the following stabilizer(s): 4-tert-Butylpyrocatechol (>/= 100 to = 150 ppm);Latex can be defined as a stable aqueous dispersion containing discrete polymer particles about 0.05 to 5 um in diameter.
UN Number
1218;1218;1218;1218
Vapor Density
2.35 (NTP, 1992) (Relative to Air);2.35 (Air = 1);(Air= 1);Relative vapor density (air = 1): 2.4
Vapor Pressure
400 mm Hg at 59.7 °F ; 493 mm Hg at 68° F (NTP, 1992);550.05 mmHg;550 mm Hg at 25 °C;Vapor pressure, kPa at 20 °C: 53.2
Viscosity
The viscosity of natural rubber can be stabilized with the addition of small amounts of hydroxylamine hydrochloride or semicarbazide hydrochloride.;0.3 mm2/s at 20-25 °C