User:Nisal sandeep
peroxide testing method and the uses of dicumyl peroxide.DCP
THE INDUSTRIAL USES OF PEROXIDES. [ IN POLYMER CHEMISTRY]
Organic peroxides find numerous applications often involving similer chemistry,Thus peroxide serve as Accelerators,Activators,Cross-linking agents,Curing and vulcanizing agents( S , DCP ) Hardnesses, Polymerisation, Initiators and Promoters.also drying olis.
Peroxide have a bleaching effect on organic substances.
AS A INDUSTRY WICH USE RUBBER AND POLYMERS FOR PRODUCTS FOR THE PREPARATION OF EVA SHEETS( Ethylene Vinyl Acetate) , THE S.COM (samsons compound) USES DCP( Dicumyl Peroxide) 99% [ industrial named 400-499] AS THE BENIFITS OF ORGANIC PEROXIDE.
[C6H5(CH3)2]2O2 DCP
mollercular weight- 270.37gmol-1. Store temp.2-80c
Definition –The peroxide value is defined as the amount of peroxide oxygen per 1 kilogram of fat or oil ( the DCP sample) Traditonally this was expressed in units of milliequilents.
Method- The peroxide value is determined by measuring the amount of iodine which is formed by the reaction of peroxides (formed in DCP) with iodine ion.
2I- + H20 + ROOH-------- > ROH + 2OH- + I2
NOTE- That the base prodused in this reaction is taken up by the excess of acetic acidpresent.The iodine liberated is titrated with soddium thiosulphate.
2S2O32- +I2 -------- > S4O62- + 2I-
The acetic conditions prevents formation of hypoiodide, which would interfere with the reaction.The indicator used in this reaction is a starch solution where amylose forms a blue to black solution with iodine and is colourless where iodine is titrated. A precaution that should be observed is to add the starch indicator solution only near the end point (the end point is near when fading of the yellowish iodine colour occurs)
THE CHEMICAL ANALYSIS. [ O-O]2- R1-----O--O-----R2 R-----O--O
Organic hydroxide – blue.( peroxo group)
The oxygen-oxygen chemical bond of peroxide is unstable and easily split in to reactive radicals via homolytic cleavage.
Added potassium iodide into iodine,which reacts with starch producing a deep blue-colour.
solutions for testing.
1.Acetic Acid -15 ml 2.Cloroform - 10 ml. 3.Distilled or deionizide water.( Each 30 ml) 4.Saturated Potasium Iodide solution.store in the dark. 5.Sodium Thiosulphate solution,0.1N. commercially available. 6.1% Starch solution.
Determination of peroxide value.
Weigh 3.00 g oil (with precision of 0.001 g) into a 250 ml Erlenmeyer flask. Add 10 ml chloroform and swirl to dissolve oil. Add 15 ml acetic acid, 1.0 ml KI solution, mix and leave for 5 minutes (exactly !) in a dark place.
Colour change-light amber colour.(yellow wish)
Add 30 ml distilled water and 1 ml starch inducator. Solution titrate with sodium thiosulfate until blue colour disappears.
Do a blank determination (10 ml chloroform + 15 ml acetic acid + 1.0 ml KI + 30 ml H2O). Add starch indicator (1 ml) before titrating and titrate dropwise.Titrate until the blue gray colour disappears in the aqueous.(upper layer)
Repeat the titration procedure at least 3 times.
CALCULATION.
PV = (V1 – V0 ) x T x 1000 / m [miliequivalent available oxygen/kgsample ] [meq. / kg]
where: V1 – volume of thiosulfate solution required to titrate the sample [ml]; V0 – volume of thiosulfate solution required to titrate the blank determination [ml]; T - titre of the sodium thiosulfate solution [normality]; m – mass of sample [g]
PV= Peroxide Value.
The following chemicals may form explosive peroxides after an extended period of time. They should be checked before using and discarded if dangerous levels of peroxides are found. • Benzyl alcohol • sec-Butyl alcohol (2-Butanol) • Cyclohexanol • Cyclohexene • Diethyl ether • Isoamyl alcohol (isopentyl alcohol) • Methyl isobutyl ketone • 2-Octanol One or more of the following tests should be done on any suspect chemicals. It must be noted that these tests are valid only for simple chemicals. Some organic compounds may also act as oxidizing agents and create false positive tests. When dealing with peroxidizable materials that may be insoluble in the test solution, it may be necessary to use a co-solvent such as peroxide-free isopropanol to complete the test. ________________________________________ METHOD A Note: This method is the most rapid method of peroxide detection. Add 0.5 to 1.0 mL of the material to be tested to an equal volume of glacial acetic acid to which has been added 0.1 g of sodium iodide or potassium iodide. yellow colour = low peroxide concentration in sample brown colour = high peroxide concentration in sample Always prepare the iodide-acetic acid mixture at the time of the test to avoid false results due to oxidation. ________________________________________ METHOD B (Recommended by the Manufacturing Chemists Association) Note: Colour development in this method may take up to 10 minutes. Add 1 mL of a freshly-prepared 10% aqueous solution of potassium iodide to 10 mL of the compound being tested in a 25 mL glass-stoppered cylinder of colourless glass protected from strong light. Barely discernable yellow colour = 0.001 to 0.005% peroxide as H2O2 Definite yellow colour (*) = 0.01 % Brown colour (*) = ?
- A percentage of 0.01% or more is not safe.
________________________________________ METHOD C Prepare a sodium ferrothiocyanate reagent by dissolving 9 g of FeSO4•7H2O in 50 mL of 18% HCl. Add 0.5 to 1.0 g of granulated zinc followed by 5 g of sodium thiocyanate. When the transient red colour fades, add 12 g of sodium thiocyanate and decant the liquid from the unused zinc into a clean stoppered bottle. Add 1 drop of this solution to 1 drop of the compound to be tested in a clear glass vial. Barely discernable pink colour = 0.001% peroxide as H2O2 Pink to cherry red = 0.002% Red (*) = 0.008% Deep red (*) = 0.04 %
- A percentage of 0.01% or more is not safe.
Specifications Dicumyl Peroxide Formula: [C6H5C(CH3)2O]2 CAS:80-43-3 M. W.: 270.36 Purity:DCP not less than 99% Dicumyl Peroxide (DCP) Formula: [C6H5C(CH3)2O]2 CAS:80-43-3 M. W.: 270.36 Purity:DCP not less than 99%
Properties: White crystal, insoluble in water, dissolving in alcohol, ether, benzene, and other organic solvents. Sublimable in high vacuum. Uses: can be used widely in architectural decoration materials, wire and cable, plastic foams and other products of plastic and rubber. Dicumyl Peroxide (DCP) mainly provides as cross-linking agent for various polymers and copolymers, such as PE, EVA, CPE, EPDM, EPR, Silicon rubber, Polyurethane rubber, as well as the polymerization initiator for PS. It is also the curing agent for unsaturated polyester. After crossing linking of DCP, the physical properties of polymer can be improved, for example, cross-linked PE improves its resistance to heat, chemical, pressure and cracking, and increase mechanical strength as well. Storage :Due to the relatively unstable nature of organic peroxides a loss of quality can be detected over a period of time. For this item Max. storage temperature.=30oC Packing in 20kg/carton box
Item Standard DCP content 99% Min Total Volatile 0.10% Max Melting point 39.5oC Active Oxygen 5.9% Min Appearance White Crystal
Relative density:1.082
Specificication White crystals. . Room temperature stability, see the light gradually become yellowish. Insoluble in water, soluble in ethanol, ethyl ether, acetic acid, benzene, and petroleum ether. Active oxygen content of 5.92% (purity 100%), 5.62% (purity 95%). Soluble in benzene. Half-life: 171 oC 1min;117 oC,10h;101oC 100h. It's a strong oxidant. \
Uses
Is mainly used for natural rubber, synthetic rubber curing agent, polymerization initiator are also used for polyethylene resin cross-linking agent. Cross-linked polyethylene for cable insulation material, not only has excellent insulation and processing performance, but also increase their heat resistance, 100 copies were made of polyethylene using the curing agent DCP2.4. Curing agent DCP allows ethylene - vinyl acetate copolymer (EVA) foam material to form a uniform fine bubble holes, while improving product heat resistance and weatherability. In addition, do not drink and polyester for curing cross-linking agent. Packing and Storage (1) Raw isopropyl benzene hydro peroxide is a strong oxidant . Product is an organic oxide, Exposing in the light or heat can cause an explosion. (2) Storage by steel drum lined with polyethylene plastic bag, and marked with signs of dangerous goods. 30oC under dark storage.
KI + CH3COOH --> HI + CH3COO-K+ ROOH + 2HI --> ROH + H2O + I2
TITRATION WITH SODIUM THIOSULPHATE TO DERIVE THE PEROXIDE VALUE
2NA2S2O3 + I2 (PURPLE) --> NA2S4O6 + NaI (COLOURLESS)
Plus the fermented clo will not rapidly increase it's peroxide value when exposed to air as it has not been extracted with heat/industrial processing methods.
The most recent test on the fermented clo peroxide value came in at .4. This is a typical reading.
The Peroxide value of an oil is used as a measurement of the extent to which rancidity reactions have occurred during storage/processing. Other methods are available but peroxide value is the most widely used.
A great oil is under 1 peroxide value, a good oil is under 10 peroxide value and I would question oils above 10 or 15 peroxide value.
To give an example on how low the fclo .4 value is in relation to the industry i will reference a brand of highly processed clo that touts it's product based on low peroxide value. They guarantee below 1 peroxide value and on their web site they show a sample cert that indicates a .76 peroxide value. What they do not discuss is the amount if heavy processing required to achieve this low number nor do they discuss the extent that a highly processed oil deteriorates (increases in peroxide value) once opened/exposed to air.
created by nisal sandeep( sri lanka)