DELTECH CORPORATION TECHNICAL BULLETIN
DIVINYLBENZENE - STORAGE AND HANDLING
Divinylbenzene (DVB) is an extremely reactive monomer and must be carefully handled to prevent
polymerization. Deltech DVB products, 63% DVB (DVB63) or 80% DVB (DVB80), can rapidly polymerize if
exposed to incorrect conditions. Prevention of preformed polymer is the greatest concern when storing. Deltech
DVB. In addition, oxidation can cause degradation of product quality by color formation or free particle formation
during long-term storage.
DIVINYLBENZENE - PROPERTIES
PROPERTY
TEMP-oC
Molecular Weight
Boiling Point, oC at 760 mm
Density, lb/gal
Viscosity, cps
Solubility-DVB in Water, %
Solubility-Water in DVB, %
Refractive Index, D-Line
Heat Capacity, cal/g oC
Heat of Vaporization, cal/g
Flash Point, oC TCC
Autoignition Temperature, oC
Vapor Density (air=1)
Vapor Pressure, mm Hg
20
25
30
25
25
25
25
25
25
0
25
50
75
100
125
150
175
200
DVB63
DVB80
130.19
197
7.64
7.60
7.57
1.0
0.0052
0.054
1.5585
0.42
96.9
69
505
4.5
0.08
0.6
2.9
11.4
35.0
91.1
207.1
422.3
788.2
130.19
200
7.69
7.65
7.61
1.0
0.0052
0.054
1.5585
0.42
96.9
69
494
4.5
0.08
0.6
2.8
10.7
33.0
86.3
197.7
406.5
764.8
The formation of polymer in stored DVB will generally degrade the product quality and prevent use in most
applications. Practice of proper inventory management is required to ensure the product quality is maintained
until product is used. Deltech DVB can be safely stored for extended periods if the proper conditions are
maintained. Understanding the polymerization characteristics, maintenance of storage equipment and proper
polymerization inhibitor use for DVB combine to support good inventory management.
POLYMERIZATION CHARACTERISTICS OF DIVINYLBENZENE
Heat initiated free radical polymerization can easily occur in DVB. When heated, the monomer molecule
becomes unstable and forms a free radical which is a reactive species. The free radical reacts with another DVB
molecule and starts a polymer chain. The chain grows in length until some type of chain terminating event
occurs or until all molecules are reacted. The polymerization reaction is exothermic (energy is produced by the
reaction) which causes the temperature of the bulk liquid to increase and accelerate the formation of more free
radicals and more polymerization. DVB polymerization is self promoting and auto-accelerating. Once started;
the energy generated by the reaction can rapidly increase the polymerization rate and amount of polymer
formation. DVB polymerization in a bulk storage can proceed at a rate that causes the temperature of the bulk
liquid to increase to a level where vigorous vapor venting can occur which creates a dangerous fire hazard. DVB
polymerization in a closed container such as a metal drum can cause the buildup of extreme pressure leading to
container failure with release of explosive force.
Polymerization inhibitors are added to reactive monomers to prevent undesired polymerization during transport
or storage. An inhibitor reacts with the free radical to prevent reaction with DVB molecules and polymer
formation. Use of inhibitors to control polymer formation in bulk liquid is discussed below.
Storage of reactive monomers in bulk tanks can also result in another type of polymer contamination due to
polymerization of uninhibited monomer on tank surfaces. During storage of bulk liquid DVB, some of the DVB is
vaporized and the vapors condense into droplets on the roof and sides of the storage tank. These monomer
droplets do not contain polymerization inhibitor and may begin to polymerize if allowed to adhere to the roof or
sides of the tank. Once polymer begins to form, additional droplets are trapped and the polymerization can
increase to form sheets of polymer on tank sides or large accumulations from the roof (stalactites). If the
polymer accumulation becomes large enough, the weight causes detachment from the tank sides or roof into
the bulk liquid. The polymer is insoluble in DVB monomer but can cause hard polymer particle contamination in
the product which degrades product quality and prevents use in many applications. Use of a properly designed
storage tank is required to reduce the potential for polymer accumulation on tank surfaces.
STORAGE TANK DESIGN
DVB monomer is a combustible liquid and the accepted equipment design and material handling techniques for
this hazard class must be practiced to prevent conditions that can cause fire or explosion. The storage tank
used should meet all applicable code requirements including adequate grounding connections on tank and
pump. DVB storage tanks should be installed within a suitable diked enclosure to contain any unintended leaks
or spills. Consult the Deltech MSDS for recommendations for recycle or disposal of off-specification DVB.
Additional storage tank design requirements not related to safe handling practices are also necessary to allow
DVB storage without product degradation. A vertical storage tank with self-supporting dome roof is
recommended for DVB storage. The tank should be designed to meet applicable code standards for
atmospheric tanks.
TANK ARRANGEMENT
A simplified storage tank arrangement is shown below
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The tank should be equipped with:
Roof mounted vacuum-pressure relief device (Protectoseal No. 830)
Roof mounted manhole/emergency relief device (Protectoseal No. 51300)
Roof mounted gauging/sampling hatch (Protectoseal No. 4980)
Side mounted 20" manhole for inspection/cleaning entry
Internal sump with drain valve
Temperature indicator
TANK LINING
Tank roof and sides must be smooth to prevent polymer accumulation. Carbon steel tank construction with the
proper tank lining material will provide the desired smooth surface. Use of the dome roof without internal
supports permits simple lining installation and allows monomer vapors that condense on the roof surface to
quickly drain back to the liquid.
Condensed monomer vapors do not contain polymerization inhibitor. Uninhibited monomer can form polymer
deposits if allowed to collect. Non-porous, non-wettable smooth tank linings prevent retention and attachment of
uninhibited monomer droplets. As a result monomer drains quickly back into the bulk of the inhibited liquid
monomer before polymerization can occur. Baked phenolic, modified epoxy and catalyzed epoxy linings all
perform well to prevent entrainment and polymer accumulation above the liquid level. Tank linings must be
applied according to manufacturer's direction.
Recommended tank linings
Interzinc 22
International Paint Inc.
6001 Antoine Drive
Houston, Texas 77091
713 682-1711
(800) 589-1267
CAUTION: Inorganic zinc coatings are not electrically conductive. The bottom 30 centimeters of the tank should
be coated with an inorganic silicate lining to provide adequate electrical grounding.
TANK INSULATION
Maintaining DVB product storage temperature below 65 oF is important to maximize product quality for extended
storage periods. If atmospheric conditions require, the tank should be insulated with suitable insulation to
prevent direct sunlight impingement on the tank. Use of a package refrigeration system is recommended to
control storage temperature within the desired range.
PUMP REQUIREMENTS
Self-priming centrifugal pumps with a suitable mechanical seal should be used for DVB service. Continual flow
through the pump must be verified when the pump operates to prevent deadheading the pump which can cause
heat generation within the pump. Heating the DVB can cause thermally induced free radical polymerization as
described above.
POLYMERIZATION INHIBITOR
DVB monomer is treated with tertiary Butyl Catechol (TBC) as an inhibitor to prevent premature free radical
polymerization. Products are shipped with a minimum of 1000 parts per million (ppm) of TBC and may contain
up to 1200 ppm TBC upon customer request. TBC acts a proton donor to stabilize a free radical and prevent
reaction of the free radical with a monomer molecule to start a polymer chain. The chemistry of free radical
inhibition can be found below.
An inhibitor level of 1000 ppm is normally effective in preventing polymerization for 60 days at maximum
temperatures of 65 oF. TBC is an effective inhibitor only in the presence of oxygen. DVB products shipped by
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Deltech are saturated with oxygen allowing full utilization of the TBC inhibitor. Use of nitrogen or inert gas
blanketing on DVB storage tanks is not recommended.
INHIBITOR DEPLETION
The most significant cause of TBC depletion is related to DVB monomer storage temperature. Temperature of
stored monomer should be maintained at less than 65 oF to avoid excessive depletion of TBC. The TBC
concentration will deplete over time under ideal storage conditions which will leave the monomer unprotected
against free radical polymerization.
Due to the solubility of TBC in water, the presence of free water in the DVB storage can cause the TBC content
of the monomer to be rapidly depleted. DVB storage tanks should be routinely checked to ensure that water is
not present.
INHIBITOR MAINTENANCE
The TBC concentration in DVB monomer is determined using ASTM Test Method D4590. Deltech will provide
assistance in specifying the equipment required for TBC analysis at the storage location. Deltech will also
perform this analysis as a service for DVB customers. Contact Deltech for sample shipping instructions and the
laboratory contact for sample receipt.
If TBC concentration in DVB monomer is depleted below 900 ppm, additional TBC should be added to the
storage to increase the concentration to the desired range. Contact Deltech for assistance in obtaining the TBC
solution suitable for addition to DVB monomer.
MAINTAINING OXYGEN CONTENT
A minimum oxygen concentration of 15 ppm in DVB monomer is required to ensure the TBC inhibiting capability
is effective. Deltech ships DVB monomer saturated with oxygen (30-40 ppm). Saturation ensures that minimum
oxygen concentration is maintained. Storage conditions and TBC depletion in storage can cause oxygen
concentration to decrease over time. In a bulk storage which is vented to atmosphere, intermittent or continuous
agitation of the monomer usually assures that minimum oxygen concentration will be maintained. Circulating the
tank using the transfer pump is a convenient method of tank agitation.
In bulk storage, use of nitrogen or inert gas padding or blanketing is not recommended. If inert gas blanketing is
necessary due to regulatory requirements, a rigorous program of oxygen addition must be enforced to maintain
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the minimum oxygen concentration in DVB monomer. The monomer should be sparged with clean dry air on a
scheduled basis that will add the required oxygen content to the monomer. An oxygen monitor should be used
to test the monomer to verify oxygen content is adequate and determine the proper air sparging schedule.
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POLYMER TESTING
The presence of preformed polymer in DVB monomer can be determined using the simple test method ASTM
D2121. Performing the test is required because DVB polymer is soluble in the monomer and can be present in
quantities that degrade product quality although not visually apparent.
1.Obtain a representative sample of DVB monomer from storage.
2. Add 5 milliliters (ml) of sample to a clean, clear test tube.
3. Add 25 ml of dry reagent grade methanol to the test tube.
4. Mix thoroughly.
Solution will remain clear if no polymer is present.
Solution will be hazy at low (less than 20 ppm) polymer concentration.
Solution will be cloudy/milky at higher (greater than 20 ppm) polymer concentration.
If quality of DVB monomer is not known, product should be tested for polymer concentration before use.
INVENTORY MANAGEMENT AND TESTING
Deltech recommends that DVB stored in bulk for periods exceeding 30 days be routinely monitored to ensure
product quality is maintained. Storage temperature should be checked daily and product analysis performed as
shown below:
Test
Frequency
Test Method
TBC
Polymer
Once per week
Once per week
ASTM D4590
ASTN D2121
EXPECTED STORAGE LIFE
Typical storage life for DVB products (no observable degradation of quality due to polymerization or oxidation
products) in bulk storage is about 30 days if recommended storage conditions are not followed. This storage life
can be extended if the tank configuration and lining meet the recommended requirements, inhibitor
concentration is maintained, monomer is saturated with oxygen and bulk liquid storage temperature is
maintained below 65 oF. Proper precautions must also be observed to assure that localized heat sources do not
increase the surface temperature of the tank or associated piping.
Storage temperature is the single most critical factor in the storage life of DVB products. Use of an insulated
tank and refrigeration through a close loop circulation system are recommended when the temperature of the
stored product may exceed 65 oF without refrigeration. For longest term DVB storage, a temperature of 65 oF is
recommended.
DVB DRUM STORAGE
DVB monomer is often supplied in 55 gallon steel drums for customers with lower requirements. Storage in
drums is acceptable if proper precautions are observed:
Storage Condition: DVB in drums must be stored in a location that is shaded from direct sunlight. Storage in a
covered warehouse type facility with adequate ventilation to avoid excessive temperature increase is
recommended. DVB drums should not be stored where temperature reaches 85 oF for extended periods. DVB
drums must not be stored in locations where external heat sources such as hot pipes can contact the drum and
increase DVB temperature. Temperature of stored DVB drums should be monitored on a routine basis to ensure
drums are not overheating.
Storage Period: DVB in drums should be used within 30 days if stored in an area where temperatures are
greater than 80 oF for sustained periods. Storing at lower temperatures will extend the product life. For extended
storage, DVB drums should be stored at controlled temperature of less than 65 oF.
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Oxygen Content: DVB drums stored for longer than 30 days should be aerated with clean dry air to ensure the
monomer contains adequate oxygen for TBC inhibitor to be active.
Inhibitor Concentration: DVB drums stored for longer than 30 days should be tested for TBC concentration to
ensure adequate inhibitor is available.
CAUTION: DVB drums exposed to direct sunlight or other external heat sources can begin to polymerize.
Polymerization will cause the drum temperature to increase and could cause an uncontrollable polymerization
which will result in pressure buildup and explosive drum failure. DVB drums that show indication of
polymerization should be immediately cooled with water to reduce temperature.
TECHNICAL ASSISTANCE
Deltech technical product representatives are available to answer questions concerning DVB storage and
handling. Recommendations may be case specific depending upon use and storage conditions. Deltech also
offers assistance in analysis for TBC and polymer content, setting up customer testing capability and recovering
downgraded product (depending upon DVB condition).
For assistance contact:
Gene Fluharty
Telephone:
Email
225 358-3170
efluharty@deltechcorp.com
Deltech Corporation
11911 Scenic Highway
Baton Rouge, LA 70807
This information is provided as a service to Deltech customers. No warranty, express or implied, is given nor is freedom from any patent to
be inferred. Inasmuch as any assistance furnished by Deltech with reference to the proper use and disposal of Deltech products is provided
without charge, Deltech Corporation assumes no obligation or liability thereof.
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