CAS no: 80-43-3
EC/LİST no: 201-279-3
Dicumyl peroxide (systematic name bis(1-methyl-1-phenylethyl) peroxide) is an organic-chemical, aromatic compound from the group of peroxides.
Dicumyl peroxides name is derived from the cumyl residue, which is linked to a second, similar residue via a peroxide bridge.
Dicumyl peroxide is synthesized by reacting 2-phenyl-2-propanol with hydrogen peroxide/urea additive at 35 °C in the presence of a base mineral acid.
In another synthesis, 2-phenyl-2-propanol reacts with cumene hydroperoxide.
Dicumyl peroxide is a white to yellowish powder with a characteristic odor, practically insoluble in water (0.4-2 mg / l), but well soluble in alcohols, esters and aromatic hydrocarbons.
The solid crystallizes in a rhombic crystal lattice.
Thermal decomposition starts above 70 °C.
Peroxide promotes fire and should never come into contact with combustible materials.
Dicumyl peroxide is used as a crosslinking agent for polyolefins and elastomers and for curing unsaturated polyester resins.
Many plastics, such as polyethylene, are post-treated with dicumyl peroxide to improve material properties such as elasticity, oil and acid resistance through further crosslinking of polymer chains.
Physical State :
Soluble in chloroform (25 mg/ml), and most organic solvents.
Insoluble in water.
Store at 4° C
Melting Point :39-41° C (lit.)
Boiling Point :396° C
1.56 g/cm3 at 25° C (lit.)
Refractive Index :n20D 1.54
Usage and production of Dicumyl Perxide:
Electrical and electronic products
Dicumyl peroxide applications:
Compound containing peroxide group (-o-o-), chain structure, containing two oxygen atoms, each bound to the other and a radical or an element.
Hydrogen peroxide is commercially recognized as the starting material for the preparation of organic and inorganic peroxides.
The most valuable feature of hydrogen peroxide is that it breaks down into water and oxygen and therefore does not form persistent toxic residual compounds.
Dicumyl peroxide is used in epoxidation, oxidation, hydroxylation and reduction processes.
Solutions have oxidizing properties.
Vulcanization or curing is transformation of plastics rubber compound into highly elastic product – vulcanizate.
The fundamental of curing is formation of physical and mainly chemical cross-links between rubber chain segments, which leads to the creation of three-dimensional spatial network structure within the rubber matrix.
A lot of curing systems have been developed within history in order to perform efficient vulcanization of rubber compounds, such sulfur based curing systems, organic peroxides, quinones, phenolformaldehyde resins, metal oxides and others .
The type of curing system determines not only the quantity, but mainly the quality of the formed crosslinks, which is subsequently reflected in the final properties of rubber compounds and their thermooxidative stability
Generally, sulfur curing systems are the most widely used for cross-linking of unsaturated diene type rubbers.
Application of sulfur curing systems leads to the formation of sulfur based cross-links with various length between rubber chain segments (monosulfidfic, disulfidic and polysulfidic cross-links).
Sulfur cured vulcanizates usually exhibit very good tensile characteristics, high tensile and tear strength and good elastic and dynamic properties.
Their main drawbacks are poor heat ageing resistance and high propensity to thermo-oxidative ageing.
Although, cross-linking of rubber compounds has been performed for more than 170 years, the chemistry of sulfur vulcanization is very complex and still not fully understood .
Dicumyl peroxide vulcanization of rubber compounds has been known since 1915 when Russian chemist Ostromyslenki first used organic peroxides for cross-linking of elastomers.
But industrial interest in applying of peroxides as cross-linking agents became more obvious with the introduction of plenty of saturated rubbers, mainly ethylene-propylene type rubbers (EPM, EPDM), silicone rubbers (VMQ, FVMQ) or fluoro elastomers (FKM), etc.
This is because not only unsaturated, but also saturated rubbers can be efficiently cured with peroxides.
The application of organic peroxides leads to the formation of carbon-carbon cross-links between rubber chain segments.
C-C cross-link have higher bonding energy when compared to sulfur cross-links, therefore typical feature of peroxide cured vulcanizates are good resistance to thermo-oxidative ageing and high thermal stability.
Low compression set, good electrical properties or simple formulation of rubber compounds are next advantages of peroxide cured elastomers .
However, there are also some disadvantages when compared to sulfur curing systems, as worse elastic and dynamic properties, worse tensile strength and lower abrasion resistance of vulcanizates.
In this work, five different types of elastomers (NR, BR, SBR, NBR and EPDM) were cured with dicumyl peroxide.
The main goal of the work was to investigate the influence of the curing temperature on cross-linking process and physicalmechanical properties of the vulcanizates.
Then, the influence of the amount of dicumyl peroxide on curing characteristics of rubber compounds, cross-link density and physical-mechanical properties of final vulcanizates was evaluated.
In the first part of the research, the influence of the vulcanization temperature was under consideration.
Compound containing the peroxy group (-O-O-), chainlike structure, containing two oxygen atoms, each of which is bonded to the other and to a radical or some element.
Dicumyl peroxide is considered that hydrogen peroxide is the starting material to prepare organic and inorganic peroxides commercially.
Hydrogen Peroxide H2O2, is a powerful oxidizing agent.
The most valuable property of hydrogen peroxide is that it breaks down into water and oxygen and therefore does not form any persistent, toxic residual compounds.
Dicumyl peroxide is used in the processes of epoxidation, oxidation, hydroxylation and reduction.
Dicumyl peroxides oxidizing properties are used in the bleachings and deodorizing for textile, hair and in paper manufacture.
Dicumyl peroxide is also used medicinally as an antiseptic.
Dicumyl peroxides application involves the production of chemicals like perhydrates as well as organic peroxides in which some organic (or inorganic) substituents have replaced one or both hydrogens.
Some metals form peroxides in air sodium, barium or zinc.
Metal peroxide releases oxygen slowly in contact with atmospheric moisture and used to as disinfectants in cosmetics, detergents, toothpaste and pharmaceuticals.
They can be used in the bleachings and deodorizing and a oxygen release source in agricultural application to generate contaminated soils and lakes.
Organic Peroxides are powerful oxidizing agents releasing oxygen.
They are widely used as initiators,catalysts and crosslinking agent for the polymerization process in the plastics manufacturing industry and as chemical intermediates, bleaching agents, drying and cleaning agents.
They are also used as antiseptics, disinfectants and germicides medically for cosmetics, detergents, toothpaste and pharmaceuticals.
Organic peroxides are classified in peroxydicarbonates, peroxyketals, peroxyesters, ketone peroxides, hydroperoxides, dialkyl peroxides, diacyl peroxides by HMIS.
Dicumyl peroxide is a strong free radical source ; used as a polymerization initiator, catalyst and vulcanizing agent.
The half-life temperatures are 61 C (for 10 hours), 80 C (1 for 1 hour) and 120 C (for 1 minute).
DCP decomposes rapidly, causing fire and explosion hazard, on heating and under influence of light.
Dicumyl peroxide reacts violently with incompatible substances or ignition sources (acids, bases, reducing agents, and heavy metals).
Dicumyl peroxide is recommended to store in a dry and refrigerated (< 27C or 39 C max) and to keep away from reducing agents and incompatible substances.
Dicumyl peroxide is used as a high temperature catalyst in the rubber and plastics industries.
Compounds containing Di-Cup® are normally processed at temperatures up to 250°F (121°C) and can be cured at temperatures above 300°F (149°C).
Dicumyl peroxide is available in pure form or as supported grades (40% peroxide on an inorganic substrate or as a rubber Masterbatch).
The molecular weight of dicumyl peroxide is 270; its structural formula is below.
Dicumyl peroxide, a pale yellow to white granular solid, melts at 100°F (38°C).
Dicumyl peroxide 40C and 40KE are free-flowing off-white powders under normal storage conditions.
Tests have shown that these materials do not lump or cake below 100oF (38°C).
Dicumyl peroxide, at practical use concentrations, is soluble in a variety of organic compounds, as shown in In addition,
Dicumyl peroxide is soluble, or disperses readily, in natural and synthetic rubber compounds, silicone gums, and polyester resins.
Dicumyl peroxide is soluble in vegetable oils and insoluble in water.
Dicumyl peroxide decomposes when heated to form alkoxy radicals that, in turn, abstract hydrogen from the polymer backbone, forming polymer radicals.
A combination of two polymer radicals results in a crosslink.
In general, the cure rate (or rate of crosslinking) is equivalent to the rate of Dicumyl peroxide thermal decomposition.
The rate of Dicumyl peroxide cure, therefore, is dependent primarily on cure temperature and is predictable for each polymer system.
Care should be exercised to differentiate between rate of cure and state of cure.
In a given polymer, rate of cure with Dicumyl peroxide is affected primarily by temperature, while state of cure is influenced by the level of Dicumyl peroxide and other factors.
The major factor affecting the rate of peroxide decomposition and, therefore, cure rate, is temperature.
However, the polymer or medium in which the peroxide decomposes does have some effect on rate of peroxide decomposition.
Dicumyl peroxide is much less sensitive to its environment than many other peroxides but still requires some modification of the cure time and temperature for each polymer system.
Selection of the proper cure time, for a vulcanizate based on Dicumyl peroxide, depends on performance requirements of that vulcanizate.
Figure 1 is a plot of the crosslinking half-life of Dicumyl peroxide in various systems.
In addition to the polymers shown, cis-polybutadiene (BR) has a half-life curve between those of nitrile rubber (NBR) and ethylenepropylene terpolymer (EPDM).
Polyisoprene (IR), natural rubber (NR), and styrene-butadiene rubber (SBR) have approximately the same half-life curves, and this common curve lies between those of NBR and the solution.
Under commercial curing conditions, the stock temperature and peroxide decomposition rate are influenced by mold heat-up time, vulcanizate thickness and shape, and other practical factors.
Therefore, optimum factory cure conditions require experimentation.
This is best accomplished by test-curing the compounds in production equipment for the cure times calculated from the half-lives Resulting vulcanizates then are tested for either physical properties such as modulus and elongation, or unreacted peroxide.
Plotting any of these against cure time will result in a curve from which cure time to reach the desired state can be read.
Cure conditions developed in this manner will assure optimum performance with the peroxide-cured vulcanizate.
A laboratory evaluation will optimize laboratory procedure, but will serve only as a guide to production practice.
The cross-linking of rubber with organic peroxide is ofconsiderable and practical interest.
The peroxides pro-duce vulcanizates with physical properties such ashigh modulus, high hardness, and low compressionset and, of course, their heat aging properties are farsuperior to sulfur cure systems.
On the other hand, theperoxide systems have disadvantages, the vulcani-zates present low tensile and tear strengths, a slowerrate of cure, and lack of delayed action during cure.
These factors have drastically restricted their use indiene rubbers.
Dicumyl peroxide interact with polymers in a variety ofways.
The effect that a peroxide has on the cross-linking reaction depends on the polymer nature, type,and concentration of peroxide, reaction temperature,and reactivity of other components that might bepresent (i.e., antioxidants).
The peroxide reaction con-sists of several competing mechanisms, and the prop-erties of the ﬁnal cure state will depend on the balancebetween these often opposite reactions.
The mechanism of peroxide vulcanization has beenthe subject of important reviews.
The cross-linkingreaction involves the homolytic decomposition of theperoxide molecule to produce two radical fragments.
Next, these radicals remove hydrogen atoms from thepolymer forming a polymer radical in what is calledthe hydrogen abstraction reaction.
The polyaddition of vinyl groups can be activated at low temperature by the addition of a free radical generator as Dicumyl peroxide.
According to the literature , this reaction takes place for a temperature between 50 and 1508C for a polymethylvinylsilazane resin with addition of a peroxide cure initiator.
After addition of 1wt% of DCPO, vinyl polyaddition is promoted with regard to dehydrogenation.
This inversion in the reaction order should reduce the mass loss at 2008C.
According to TGA results (continuous grey line in Fig. 5), mass loss is reduced by more than 60% at 2008C after addition of 1wt% of Dicumyl peroxide, confirming literature results.
A sharp exothermic peak is obtained around 1508C.
Shows the dynamic DSC scans at 2 of the different tested solutions.
Dicumyl peroxide concentration (represented by the variable x) ranges from 0.1 wt% to 20 wt%.
Two effects are immediately observed with the increase of Dicumyl peroxide concentration: a gradual decrease of the peak temperature (from 1558C for 0.1 wt% to 1218C for 20 wt%), and the occurrence of a second exothermal phenomenon for a concentration higher than 3 wt%.
7 are plotted the DSC scans at 2 K!min21 of the compounds with x values of 1, 5, 10 and 20 wt%, superimposed with the DSC scan of Dicumyl peroxide at 2 K!min21 multiplied by the corresponding x value.
A strong correlation is observed between the second peak of the compound and the principal peak of Dicumyl peroxide decomposition (almost the same amplitude), whose kinetics turns out to be slightly faster in the compound.
Owing to these results, the second peak arising in the compounds for high Dicumyl peroxide concentrations will be attributed to Dicumyl peroxide decomposition in the forthcoming interpretations.
The first exothermal peak observed for the compound is therefore related to PSZ20 crosslinking.
ATG-DSC results plotted in show that this peak is not correlated to a significant mass loss.
Reactions with gaseous products as dehydrogenation and transamination may thus be limited in the presence of Dicumyl peroxide.
Moreover, the radical reactions of methyl and vinyl groups are expected to occur at higher temperature, between 200 and 3008C, according to .
Hydrosilylation and polyaddition of vinyl groups (promoted by DCPO) might be the principal reactions occurring in the crosslinking mechanism in the temperature range investigated.
According to this interpretation the overall heat of reaction (DHtot), which represents the time integral of the curves plotted in Fig. 6, can be additively decomposed into two components, related on the one hand to the contribution of PSZ20
crossli king (initiated by DCPO) and on the other hand to Dicumyl peroxide decomposition.
Both components depend on the variable x, i.e. the mass fraction of Dicumyl peroxide.
The evolution of the overall heat of reaction is presented in Fig. 8 as a function of Dicumyl peroxide concentration and can be well fitted using a bilinear model (Fig.8), with coefficients of determination of 0.999 and 0.997 respectively.
According to the previous discussion regarding the initiation of vinyl group polyaddition by addition of Dicumyl peroxide, it is important to notice that above a certain value of DCPO concentration, the initiator will simply degrade without interacting with PSZ20, forming radicals that will not combine with vinyl groups.
Both terms of the overall heat of reaction are thus proportional to the concentration in the concerned reagent, respectively PSZ20 and DCPO, leading to a linear change of the heat of reaction with x. For low DCPO concentrations (below 1.52wt%), the overall heat of reaction is lower than expected from this linear law.
This is interpreted as a lack of Dicumyl peroxide to interact with all the vinyl groups available in the PSZ20 to complete the crosslinking mechanism related to vinyl groups polyaddition.
In any case, to attain a complete degree of polymerization, it will be necessary to heat the system at 200–3008C, where transamination and dehydrogenation reactions will take place, involving Si-H and N-H groups.
Above 1.52 wt% of DCPO, DHtot can thus be expressed as a linear law, Eq. 2, by introducing the specific enthalpy of polymerization, DHp, and the specific enthalpy of decomposition, DHd.
DHtot5DHp ! ð Þ 12x 1DHd ! x if x # 1:52 wt% (2) By fitting the experimental data with Eq. 2, it is possible to assess the value of both specific heats of reaction. For x50, the intercept of Eq. 2 gives the specific heat of polymerization, Eq. 3, and the specific heat of DCPO decomposition in the compound is obtained for x51, Eq. 4.