WO1998031083A1

WO1998031083A1 - Sealing structure and method

Info

Publication number: WO1998031083A1
Application number: PCT/US1998/000505
Authority: WO
Inventors: David L. Diggs; George W. Mckinney, Iii; Lev Bromberg; Mara Stein; Elmer C. Lupton, Jr.
Original assignee: Medlogic Global Corporation
Priority date: 1997-01-07
Filing date: 1998-01-07
Publication date: 1998-07-16

Abstract

Sealing structure including a mastic combined with a swellable hydrophilic material. In one embodiment, the swellable hydrophilic material is a superabsorbent material such as a cross-linked polymer gel. In another embodiment, the swellable hydrophilic material is a fiber. The swellable hydrophilic material may be applied as a coating on a mastic substrate or combined throughout the mastic material. The sealing structure may be used to wrap groups of wires within a wire bundle to provide a barrier to the passage of liquids. If the liquid is oil-based, a lyogel is used in combination with the mastic.

Description

SEALING STRUCTURE AND METHOD

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of Provisional Application

Serial No. filed January 7, 1997 entitled Superabsorbent Mastic which application is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention This invention relates to a superabsorbent material and more particularly to a superabsorbent mastic material to provide a barrier to liquids.

State of the Art In many different contexts it is desirable to provide a barrier to prevent the passage of liquids such as water, oils and other solvents through an opening through which extend objects such as wire harnesses, pipes, conduits, etc. As a relevant example, there is a need for a barrier to prevent water from traversing along a wire bundle, particularly in a transportation vehicle, between an environmentally open compartment (an engine compartment) and an enclosed compartment (a passenger compartment). Such a need arises in automobiles, airplanes, boats, other transportation vehicles and in stand-alone electronics units. Because of liquids will flow along the bundle. Thus, water may migrate into a passenger compartment.

Many approaches to solving this problem have been attempted in the past. Most prior art approaches utilize a hydrophobic material to physically block the invading water or other liquid. One group of solutions involves melting a thermoplastic inside the bundle and then encasing the bundle within another material such as heat shrinkable tubing which creates a smooth surface and provides a good seal with a grommet which may be provided between compartments. This approach creates a barrier both around and through the wire bundle which retards the passage of liquids. This approach has become problematic as wire bundles have gotten bigger. In the process of melting the thermoplastic material near the center of large wire bundles, the insulation on wires in the outer regions of the bundle are often damaged. This problem is substantially a heat transfer problem.

Another prior art approach involves using a pliable material to seal the wire harness or bundle. A wad or tape is massaged into a bundle and a tight wrap is applied thereafter. This method is craft sensitive, permits little or no quality control for the seal, and often deteriorates over time under flexing and vibration. PCT published Application No. WO94/ 16884 discloses a double reticulate tape including a porous, open cell material flanking a hydrophobic gel. Under compressive stresses, the gel moves through the outer reticulate tape to provide a barrier. The tape is wrapped around groups of wires to create a bundle. U.S. Patent Nos. 4,867,526 and 5,296,650 disclose techniques for preventing water or other liquids from propagating inside the sheath of a communications cable. These patents do not, however, relate to preventing a fluid from wicking along the outside of individual wires in a bundle. _{Λ 1U},„,_M, O 98/31083

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SUMMARY OF THE INVENTION

The sealing structure of the invention comprises a mastic combined with a swellable hydrophilic material. In a preferred embodiment, the swellable hydrophilic material is a superabsorbent material. In this embodiment, a suitable superabsorbent material is a crosslinked polymer gel such as 2-Acrylamido-2-methyl-l-propanesulfonic acid (AMPS) based crosslinked polymer. The AMPS may be copolymerized with acrylamide, acrylic acid or with a vinyl-based monomer. Suitable crosslinkers are polyfunctional monomers such as methylbisacrylamide or diethyleneglycoldiacrylate. In certain embodiments, it is preferred that the gel be neutralized.

The mastic material may be hydrophobic or hydrophilic. Suitable hydrophobic mastics are butyl based or silicon based. The mastic may also be a hydrophilic polymer such as poly vinyl alcohol crosslinked with boric acid.

In preferred embodiments, the swellable hydrophilic material comprises particles less than 600 μm in size and more preferably less than 300 μm in size. The swellable hydrophilic material may also be in fiber form. In one embodiment, the swellable hydrophilic material comprises approximately 10 wt% of the mastic substrate. One suitable superabsorbent hydrophilic material in fiber form is FiberDri 1161 from Camelot.

Yet another aspect of the invention is a method for sealing the space between at least one object and an opening through which the object extends comprising applying to the object a mastic substrate having a swellable hydrophilic coating thereon or mixed therewith. Suitable materials for use in the present invention will be described in detail below. BRffiF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic illustration of a suitable process for producing the mastic/swellable hydrophilic material combination.

FIG. 2 is a schematic illustration showing a strip of the material of the invention.

FIG. 3 is a schematic illustration showing the material of the invention surrounding groups of wires in a wire bundle.

FIG. 4 is a cross-sectional view of a completed wire harness assembly using the barrier material of the invention.

DETAILED DESCRDTTION OF THE INVENTION

As discussed above, prior art attempts to prevent wicking along a wire bundle involved the use of hydrophobic materials to block physically the invading water or solvents. The present invention is based on the recognition that one can use a material that combines with the invading liquid to prevent its passage. The material absorbs the initial challenges of the liquid and swells or expands to prevent any further liquid from invading a protected area. The swelling property will also provide a mechanism for healing the resulting seal should it become corrupted. If the offending liquid is water or water-based, a suitable hydrophilic material is a superabsorbent material consisting of a crosslinked polymer or gel. The gel is dry upon installation into the wire bundle. When moisture invades the bundle, the crosslinked gel absorbs the water preventing moisture from passing between compartments through which the wire bundle extends. As the gel swells, it will block any breaks which may appear in the seal since the water will migrate to voids in the seal and gel will swell toward the water. Performance will be improved in subsequent water exposures. The inventors herein have observed that, unlike a sponge, a swollen or partially swollen gel provides an effective block to the bulk transport of water.

One preferred type of hydrophilic material is a superabsorbent material in fiber form such as Camelot's FiberDri 1161. The fibers are dry upon installation into a wire bundle and swell upon exposure to water creating an impenetrable barrier. If the offending liquid is an oil or is oil- based, then a hydrophobic gel (lyogel) such as poly ethylhexylacry late is used.

The swellable material, whether it be a superabsorbent hydrophilic material in bead or fiber form, or a hydrophobic lyogel, is combined with a mastic.

A mastic is a pliable material having a putty-like appearance. The term "mastic" is well understood in the adhesives and sealing industry. The superabsorbent material is either coated upon or otherwise combined with the mastic to form the barrier material of the invention. Mastics can be either of a hydrophobic nature such as butyl or silicone-based materials, or hydrophilic in nature.

The mastic/superabsorbent combination is applied to areas where barrier control is needed and the mastic forms the bulk of the seal. The absorbent material which is formed as a coating or contained within the mastic expands when exposed to the offending liquid to form a final tight seal. The swellable absorbent can be in any common form, including granular, fiber or bead. Increased surface to volume ratio provides a rapid intake of the invading liquid and increases the efficiency of the system. In one embodiment, the granules, fibers or beads of the superabsorbent material are placed on the surface of the mastic. If the mastic has a tendency to crack over time, the superabsorbent material is incorporated into the mastic rather than merely coating the surface. „„,„„„, 98/31083

If the offending liquid is not a pure liquid, or if different liquids can challenge the system, a mixture of non-swollen gels to respond to these liquids is provided since not every polymer network will swell in every liquid. By providing a mixture of gels a barrier can be provided to different liquids. Further, if the offending liquids appear in a sequential pattern, a gel swollen with one liquid can form a block to flow of a later- appearing liquid. For example, if water is commonly present, but occasionally a hydrocarbon solvent is also present, then a gel network is chosen which swells in water and the swollen network functions as a flow retardant and/or block both to water and to the hydrocarbon.

A suitable hydrophobic mastic is the butyl variety which is preferred in the automotive industry to silicone-based materials. Butyl mastic is a sticky gum that usually comes in a sheet or tape form. A preferred example of a superabsorbent gel is a 2-Acrylamido-2-methyl-l- propanesulfonic acid (AMPS) based crosslinked polymer. This material can be co-polymerized with acrylamide, acrylic acid or a vinyl-based monomer. It is crosslinked with polyfunctionalized monomers, such as methylbisacrylamide or diethyleneglycoldiacrylate. If the acid variety is used, it functions better if the gel is neutralized. The speed of hydration and thermal stability is greatly increased when neutralized. The gel is synthesized, dried and ground to a fine particulate (less than 600 μm). This dried particulate will stick to the butyl-based mastic. The tape is then wound between the wires in a typical harness bundle as will be described in more detail below. The application may be performed at room temperature. In one embodiment, heat shrinkable tubing (HST) or a tight wrap with tape is then applied to provide a smooth surface to the seal. If HST is used, only the outside of the bundle needs to be heated to apply the tubing. This technique eliminates the heat transfer problems pointed out above. Tests have shown that the material of the invention will prevent water with a 2" head from penetrating the seal along a longitudinal axis. The superabsorbent component improves drastically the performance of the mastic alone. Detailed examples are presented later in this specification.

The capability to withstand elevated temperatures is an important capability for this class of seal. Under elevated temperature conditions, the hydrated gel will dry out. However, it will quickly rehydrate upon subsequent exposure to water and reform the barrier. The seal or barrier of the invention has been shown to last for at least two weeks at 125 °C, both in a dry and in a hydrated state. The seal has also been shown to be resistant to typical fluids found in an automobile environment such as motor oil, brake fluid, antifreeze, carwashing fluid and salt solutions (tap, 1 % and 10% by weight). The seal remains intact down to temperatures of at least -15 °C and will survive physical shocks. The components of the material of the invention have a pre-installation shelf life of 6 months at 50 °C. The fiber embodiment using 1161 FiberDri or FiberDri 1161 showed no decrease in performance after being placed in a 100% relative humidity environment for 24 hours.

In yet another embodiment of the invention, the hydrophobic butyl mastic is replaced with a hydrophilic polymer mastic, which increases the available material to absorb water. A suitable hydrophilic mastic is polyvinyl alcohol crosslinked with boric acid. It functions best when combined and coated with a non-ionic superabsorbent such as polyacrylamide. The advantage of a polyvinyl alcohol-based material crosslinked with boric acid is that it will flow in elevated temperatures.

The cross-links are not thermally stable and will break down at elevated temperatures which lowers the viscosity of the mastic and allows it to flow between wires and form a more homogeneous seal. The mastic will carry the superabsorbent with it as it flows. When the temperature drops, the cross-links reform and hold the gel block in place. The heating may be accomplished during the process of heating a heat shrinkable tubing. During such heating, the viscosity of the polyvinyl alcohol decreases and the force provided by the heat shrinkable tubing distributes the polyvinyl alcohol throughout the bundle. A gel coating, by absorbing some of the water in the polyvinyl alcohol, will prevent the polyvinyl alcohol from "creeping" under use conditions.

Gel synthesis will now be described. Original synthesis was done on a 35 ml total volume. Each gel was made in a 40 ml vial with a rubber septa. Water was first added to the vial and then the cross-linker was dissolved. Once the cross-linker was dissolved in the solvent, the monomers were then added. The vial was sealed with a septa and then was degassed for fifteen minutes. Once degassed, the initiator was added with a 250 μl syringe and the resulting gel was placed in a 70 °C (158°F) oven overnight. The gel was occasionally poked with a needle to release any pressure build up and to keep the septa from blowing off. After sitting in the oven overnight, the gel was removed and placed on an aluminum pan.

The pan with the gel was placed back into the 70 °C oven and dried overnight. If the gel was to be neutralized, it was first swelled in a sodium hydroxide solution. (The molarity of the sodium hydroxide solution was determined by a 1: 1 molar ratio of sodium hydroxide to the ionic monomer, i.e. , acrylic acid or AMPS.) Once dry, the gel was ground and separated by size using sieves at 300 μm and 600 μm. See below for the amounts needed:

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Abbreviation Chemical Name

BIS N , N ' -Methy lenebisacry lamide

AAc Acrylic Acid

AAm Acrylamide

AMPS 2- Acrylamido-2-methyl- 1 -propanesulfonic acid

VP 1 - Vinyl-2-pyrrolidinone

MAPTAC [3-(Methacryloylamino)propyl]trimethylammonium chloride

[MAPTAC was a 50 wt% solution in water from

Aldrich.]

The initiator used was 2,2'-azobis (2-amidinopropane) dihydrochloride (also known as V-50, supplied by Wako Chemicals USA,

Inc.). First a solution of V-50 was made using 0.6% V-50 to the total monomer weight in 5 ml of water. 100 μl of the V-50 solution would be added for every 10 ml of total solution. For example, 350 μl of V-50 solution would be added to a gel with a total volume of 35 ml. The original set of gels were not neutralized. See below for the neutralized data:

There were two different steps to synthesizing Smart Mastic™ in the lab. The first was to completely coat the mastic with the hydrophilic material. The mastic was dipped into the hydrophilic material and the excess material was brushed away. With the Camelot FiberDri 1161 (1/4") fibers the weight percent of fibers added was 2 % . The weight percent of the ground hydrophilic material depended upon the size of the particle used. The < 300 μm ground hydrophilic gel was 4.8% by weight while the 300-600 μm ground hydrophilic gel was 18.4% by weight. When fabricating larger samples (three foot (91.4 cm) samples instead of a three to five inch (7.6 to 12.7 cm) sample), an inch (2.54 cm) was measured on each end of the strip to determine the approximate weight percent of fibers added. This sampling was done as a quality control measure.

The second approach was the "racing stripe" of hydrophilic material down the middle of the mastic. The mastic worked with had a width of 25 mm. To create the stripe of gel down the middle of the mastic, a piece of paper with a width of 7 mm was placed on either side of the stripe. This paper was pushed lightly down into the mastic to keep the gel from leaking underneath it. The hydrophilic material was then poured on top of the mastic and lightly pushed into the gel. The excess material was brushed away. The paper was carefully pulled off and the gel was flipped onto the other side. (When flipping the mastic over, be careful not to touch the middle stripe of gel so as not to smudge it.) Place the side that has the stripe on another piece of paper so that this stripe is not smudged when creating the stripe on the other side. (The paper used was the paper that the roll of mastic was originally wrapped in. It was used because the mastic did not stick to it.) Repeat the procedure of laying the 7 mm strips of paper down on the outer edges of the mastic and apply the hydrophilic material to the middle, open strip. Once the hydrophilic material/mastic combination was complete, the Smart Mastic™ was formed into a roll and sealed in a plastic baggy. The Smart Mastic™ should be kept in a somewhat air-tight container so as not to pick up too much water. The average amount of Camelot FiberDri 1161 fibers added with the "racing stripe" approach was 1.3% by weight. Again the weight percent of the ground hydrophilic material depended upon the size of the particles. The < 300 μm ground hydrophilic gel was 2.8% by weight while the 300-600 μm ground hydrophilic gel was 8.6% by weight.

The manufacture of the material of the invention will now be described in conjunction with FIG. 1. Mastic is produced by conventionally known techniques in the mastic production element 10. The produced mastic 12 in sheet form passes beneath a gel-filled hopper 14 which contains superabsorbent gels or fibers as described herein. Gel in the form of powder or fibers falls onto the mastic 12 and adheres to the naturally tacky mastic 12. The mastic 12 passes between rollers 16 which gently push the gel into the mastic 12. The mastic 12 passes beneath a second gel-filled hopper 18 which applies powder or fiber to the other side of the mastic 12 and additional roller 20 gently push the powder or fibers into the mastic 12. Thereafter, the now coated mastic 12 passes into the post-processing splitting and rolling apparatus 22.

FIG. 2 shows a strip of the mastic 12 coated with the superabsorbent materials of the invention in the form of a tape which may have a width of approximately 25 mm. The material 12 is known as "Smart Mastic™" .

FIG. 3 illustrates groups of wires 30 being wrapped with the Smart

Mastic material 12. In this embodiment, groups including six individual wires are wrapped with the material of the invention.

FIG. 4 shows the completed structure. The following eamples are offered to illustrate this invention and are not to be construed in any way as limiting the scope of this invention. Unless otherwise stated, all temperatures are in degrees Celsius.

EXAMPLES

In the examples below, the following abbreviations have the following meanings. If an abbreviation is not defined, it has its generally accepted meaning.

AUL = adsorption under load cm = centimeter g = gram hr. = hours in. = inch (2.54 cm) min. = minutes mg = milligram ml = milliliter mm = millimeter mM = millimolar μl = microliter μm = micrometer

Example 1 - Pipette Tests

Cut the top off of a ten ml plastic pipette (Fisherbrand Standard

Disposable Polystyrene Serological Pipettes, cat. #13-678-llE). With a funnel on the top of the open end of the pipette, add enough gel to fill the pipette tip to the nine ml mark. If the gel will not stay in the pipette tip as you add it, wet your finger and place it on the bottom of the tip and then add the gel. Occasionally tap the pipette lightly on the counter so that the gel is well-packed. Mark the top of the gel on the pipette with a marker. Fill the majority of the pipette with solvent (i.e. , water, car detergent solution, antifreeze, brake fluid, motor oil, or a salt solution). (When using water, coloring it with a dye would be preferable. Blue dye has the best effect.) When adding the solvent, try to pour down the side of the pipette and not directly on the gel, so as not to break up the firmly packed gel. Begin timing as soon as the solvent hits the gel. At the fifteen second and the sixty second mark, take two readings: one on the height of the gel and one on the penetration of the gel. These measurements should be taken with a ruler and should be in mm.

Example 2 - Wire Bundles Seal a bundle of either twenty wires (twelve gauge) or thirty wires (twenty-two gauge) with the mastic/fibers. On the outside of the insulation use either heat shrinkable tubing or electrical tape to complete the seal.

Take a long glass tube (25 cm) with a diameter of 2 cm that is open at both ends. To one open end, place the sealed bundle as far in as it will go. Seal the area between the end of the glass tube and the sealed bundle with electrical tape so that water will not leak through. Suspend this glass tube so that the exposed wire bundle is on the bottom. Under the tube place a

100 ml graduated cylinder with a large funnel. This will be used to catch the water that drips from the sealed bundle. Add enough water so that there is a two in. (5.08 cm) head of water. As the water level drops, continue to add water. Begin timing as soon as the water is added. At the thirty second, one minute and five minute mark take a reading of how much water dripped into the graduated cylinder. Beware of a false reading if water begins to leak through the seal between the glass tube and the wire bundle.

Example 3 - Free Swell / AUL (Adsorption Under Load)

Free Swell: Use a small plastic container with one open end and one end that is covered by a very small pore size mesh. Weigh and record the weight of the empty vessel. Add about 0.16 g of the gel to be tested, record the weight of the gel and the vessel and place the vessel plus gel into a recrystallizing dish and add the solvent to be tested, making sure to cover the vessel about half way. Cover the top of the recrystallizing dish with parafilm so as to stop evaporation of the solvent. After one hour, remove the free swell testers from the dish, place on paper towels and reweigh the vessel plus gel. Pat the vessel before weighing until no free liquid comes out. Record the one hour weight. Place the vessels plus gel back into the recrystallizing dish after weighing, seal the dish with parafilm and let sit overnight. The next day remove the vessels from the recrystallizing dish, place on a paper towel and pat dry. Once no more free liquid is seen, reweigh the vessels plus gel and record the overnight weight. Take the one hour weight, subtract from the original gel plus vessel weight. This will be the difference of swollen gel to dry gel. Take the difference and divide it by the original dry weight of the gel. Repeat this calculation with the overnight weight.

AUL: The AUL procedure is in essence the same as the free swell procedure, however a 100 g weight and a small disk to separate the gel from the weight are also used. Use a small plastic container with one open end and one end that is covered by a very small pore size mesh and a small disk that fits inside the vessel. This small disk should just fit within the vessel. It will be used to separate the 100 g weight from the gel. Therefore the disk needs to fit relatively well so that the gel does not ooze out around the edges of the disk. Weigh and record the weight of the empty vessel plus disk. Add about 0.16 g of the gel to be tested, record the weight of the gel, the vessel and the disk. Place the vessel, disk and gel into a recrystallizing dish. Place the 100 g weight into the vessel so that it is on top of the disk. Add the solvent to be tested, making sure to cover the vessel about halfway. Cover the top of the recrystallizing disk with parafilm so as to stop evaporation of the solvent. After one hour remove the AUL testers from the dish, place on paper towels and carefully remove the 100 g weight. As the 100 g weight is removed, be sure not to pull the disk up with it. Pat the vessel (without the weight) before weighing until no free liquid comes out. Reweigh the vessel, disk and gel. Record the one hour weight. Add the 100 g weight and place the vessels back into the recrystallizing dish after weighing. Seal the dish with parafilm and let sit overnight. . The next day remove the vessels from the recrystallizing dish, place on a paper towel, remove the 100 g weight and pat dry. Once no more free liquid is seen, reweigh the vessels and record the overnight weight. Take the one hour weight, subtract it from the original vessel/disk/gel weight. This will be the difference of swollen gel to dry gel. Take the difference and divide it by the original dry weight of the gel. Repeat this calculation with the overnight weight.

Example 4 - Pipette Tests (solvents) FiberDri 1161 (1/4 in. - 0.635 cm) Each hydrophilic component that will be added to mastic is tested with the pipette tests. A battery of solvents is run on each to find out how well they will swell and how much penetration into the gel is caused with a particular solvent. The FiberDri 1161 superabsorbent fibers need to be packed into the pipette with a long thick wire. The fiber should be as well packed as possible.

Pipette Test - FiberDri 1161

Example 5 - Solvent Tests The same solvents that were used in the pipette tests were also used in the solvent test (i.e., DI water, car detergent, antifreeze, brake fluid, motor oil and a 10 wt% sodium chloride solution, plus tap water). Seven wire bundles were sealed with Smart Mastic™ and each was then placed in a beaker filled with the solvent. The beaker was covered with parafilm to stop any evaporation of the solvent and the bundle sat overnight in the solvent. The following day the sealed bundle was any excess solvent was removed. The bundles were tested with the two in. (5.08 cm) head of water. Both the Smart Mastic™ with the ground hydrophilic material and the Smart Mastic™ with the Camelot FiberDri (1/4 in. - 0.635 cm) 1161 fibers passed each of the tests. The tests were also run with an original water test of each bundle before placing them in the solvents overnight. In addition to passing the solvent test without the original water test, the

Smart Mastic™ passed the test with the original water test.

Example 6 - Pipette Tests (water) Different Monomer Combinations This section is all encompassing of the first round of tests run on the different gel combination. The gels were made with different ratios, dried, ground and separated by size. Two sizing groups were then tested. These initial tests were only run with water, so as to see which would perform the best. The gels that performed the best were then retested with the other solvents. The ideal gel has a slight swell (raise) and shows no penetration. The results should also be consistent between the two size ranges.

Abbreviation Chemical Name

AMPS 2-Acrylamido-2-methyl-l-propanesulfonic acid

AAc Acrylic Acid

AAm Acrylamide

VP l-Vinyl-2-pyrrolidinone

MAPTAC [3-(Methacryloylamino)propyl]trimethylammor chloride

[MAPTAC is a 50 wt% solution in water from Aldrich.] Pipette Test - Different Monomer Combinations

Example 7 - Wire Bundles (compare to controls) For each wire bundle made with the mastic/hydrophilic material, there was a control of only mastic used. The control was used as a comparison to see what effect the hydrophilic material had on the overall sealing of the wire bundle. The majority of bundles tested contained thirty wires and were wound every three, four, five, six, seven or eight wires. Depending on the number of wires that are separated with the tape, the improvement is more or less significant. The example below used wires with gauges between 16 and 18. The dry gel was a 3:1 copolymer of AMPS (1575 mM) and acrylamide (525 mM), ground to a particle size of < 300μm and occupied about ten weight percent of the applied mastic material. The fibers used were 1/4" FiberDri 1161 superabsorbent fibers.

Five Minute Test Two In. (5.08 cm) of Water

Example 8 - Wire Bundles (stripe) Concern was raised that covering the mastic completely in a hydrophilic material, though augmenting the overall performance of the mastic, would actually diminish the advantages of using mastic - namely that the stickiness to the individual wires would be lost. To compensate for 108

- 21 this loss, samples were made that either had a stripe of hydrophilic material down the middle of the mastic or two stripes on either edge of the mastic. These samples would then be compared to both the mastic only control and the standard completely covered mastic. Each sample contains a thirty wire bundle that is wound every six wires with the mastic or mastic/hydrophilic material. The wires are sixteen and eighteen gauges and the test is run for five minutes with a two in. head of water. The hydrophilic material used in these tests were the 1/4 in. (0.635 cm) FiberDri 1161 fibers. The results are as follows:

Example 9 - Wire Bundles (more/less gel)

In order to optimize the sealing capability of the hydrophilic material/mastic combination, different quantities of hydrophilic material were added to the mastic. The hydrophilic material was either caked on to have more than the average amount or it was a racing stripe of gel down the middle of the mastic to show the reduction of hydrophilic material.

This test was done using the Camelot FiberDri 1161 (1/4 in. ~ 0.635 cm) superabsorbent fibers. The average amount of fibers added to mastic when it is completely covered is 1.9% by weight. The amount was either increased to 2.4% by weight or decreased with the "racing stripe" to 1.3% by weight. All three samples blocked a two in. head of water for five minutes.

Example 10 - Thermal Aging There were two separate thermal aging studies. One was the study of a sealed wire bundle with the hydrophilic material/mastic and the other was a study of the thermal stability of individual hydrophilic materials at certain temperatures.

There were numerous testing measures taken with the sealed wire bundle. The first test was sealing a wire bundle with the hydrophilic material/mastic combination and testing the bundle immediately. This bundle was then placed in the 250 °F oven overnight and retested. In the original wire bundle test there was no water leakage after five minutes and this seal remained overnight. To test that the original analysis with water before placing the sealed bundle in the oven was not affecting the thermal study results, a bundle was sealed with the hydrophilic material/mastic combination and placed in the 250°F without an original water test. After sitting in the oven overnight, it was tested with the two in. water head and the bundle held its seal. The bundle was placed back into the oven and tested every couple of days for a week. The seal held with the two in. head of water test.

The other thermal aging test was to take vials of each hydrophilic material that would be used in the Smart Mastic™ combination and place them in different temperature ovens (122°F, 221 °F, 250°F, 300°F) and watch to see what physical changes took place. The first observation was that the gels needed to be neutralized otherwise they would degrade over time. (There was no actual test on whether the gel was degrading or not. The degradation was based strictly on the change of appearance in the gel, usually from white to a yellow or brown color.) The gels that were placed into the oven were AMPS, AMPS/AAc and AMPS/AAm. The AMPS gel was made at 2100 mM, 1 % BIS and neutralized. The two copolymers were a one-to-one ratio (1050mM per monomer), 1 % BIS and neutralized. The gels were ground and the 300-600 μm sized particles were used. These neutralized gels did not change color in the four ovens over a week's time. Example 11 - Thermal Cycling For thermal cycling, a wire bundle was sealed with Smart Mastic™ and tested. This bundle was then placed in a freezer at 5°F (-15 °C) overnight, thawed for an hour and retested. The same bundle was run through this cycle three times and passed each time.

Example 12 - Shock To perform the shock test, a bundle sealed with Smart Mastic™ was placed in the freezer at 5°F (-15 °C) overnight. This bundle was first either soaked in water overnight or thrown in without the presoak. The next day, the sealed bundle would be removed from the freezer, placed on the floor and hit with a hammer. The bundle would then be tested with the two in. head of water test. Both the bundle presoaked in water and the bundle not presoaked passed.

Example 13 - AUL/FS The gels used in this test are AMPS 2100 mM, 1 % BIS; AMPS/AAm 1575 mM/525 mM, 1 % BIS; and the Camelot FiberDri 1161 (1/4 in. - 0.635 cm) fibers. The results are as follows:

Free Swell (FS)

t

Absorption Under Load (AUL)

When calculating the results, the difference was the difference between the one hour weight and the weight of the vessel plus gel. To find the "swell x times" , one would take the difference and divide it by the weight of the dry gel. To find the overnight results, the same calculations are done except the overnight numbers are replaced for the one hour numbers.

Example 14 - Water Vapor In order to compare the ability to retard water vapor transport, six systems were prepared. In each system, water and desiccant were placed at opposite ends of a glass tube of 6.5 in. (16.5 cm) length and 5/32 in. (0.4 cm) internal diameter, with the blocking material in the middle of the tube. Approximately, ^λh in. of water was placed at one end of each tube and several (3-5) grains of dried desiccant (Drierite, #8 mesh size, W.A. Hammond Drierite Co.) were inserted at the other end. The color of the desiccant changes from blue (dry) through pink to white when exposed to water vapor. The blocking material was placed in the middle, physically separated from both the water and the desiccant. The tube was sealed with a rubber stopper at each end.

A comparison was carried out between superabsorbent hydrophilic gel fibers (Camelot FiberDri 1161 1/4 in. (0.635 cm) fibers), fiber glass (thermal insulation material) and no barrier. Specifically, the tubes contained:

#1 Packed gel fiber plug in contact with water on one side #2 No barrier (reference) #3 Packed glass fiber plug (20.2 mg weight, approximately 1.6cm in length)

#4: Loose glass fiber plug (7.5 mg weight, approximately 1.8 cm in length)

#5: Packed gel fiber plug (66.5 mg weight, approximately 1.6 cm in length) #6: Loose gel fiber plug (25.3 mg weight, approximately 1.9cm in length)

All six systems were kept at room temperature and their images recorded every 2 hours for several days. The results are given in hours in which the desiccant turned from blue to the edges turning pink to all dark pink to all light pink to all white. The results are as follows:

DESICCANT

As seen from the results, the Camelot FiberDri 1161 1/4" fibers blocked some water vapor as compared to both the reference and the glass fibers. As the amount of gel was increased, the water vapor block was also increased.

Claims

WHAT IS CLAIMED IS:

1. A sealing composition comprising: a mastic; and a swellable hydrophilic material.

2. The composition of Claim 1, wherein the swellable hydrophilic material is a superabsorbent material.

3. The composition of Claim 2, wherein the superabsorbent material is crosslinked polymer gel.

4. The composition of Claim 3, wherein the gel is 2-Acrylamido-2- methyl-1-propanesulfonic acid (AMPS) base crosslinked polymer.

5. The composition of Claim 4, wherein the AMPS is co- polymerized with acrylamide.

6. The composition of Claim 4, wherein the AMPS is co- polymerized with acrylic acid.

7. The composition of Claim 4, wherein the AMPS is co- polymerized with vinyl-based monomer.

8. The composition of Claims 4, 5, 6, or 7, wherein the AMPS is crosslinked with polyfunctional monomers.

9. The composition of Claim 8, wherein the polyfunctional monomer is methylbisacrylamide.

10. The composition of Claim 8, wherein the polyfunctional monomer is diethyleneglycoldiacrylate.

11. The composition of Claim 6, wherein the gel is neutralized.

12. The composition of Claims 1-11, wherein the mastic is hydrophobic.

13. The composition of Claim 12, wherein the mastic is butyl- based.

14. The composition of Claim 12, wherein the mastic is silicone- based.

15. The composition of Claims 1-11, wherein the mastic is a hydrophilic polymer.

16. The composition of Claim 15, wherein the hydrophilic polymer is polyvinyl alcohol crosslinked with boric acid.

17. The composition of Claim 1 , wherein the swellable hydrophilic material comprises particles less than 600 ╬╝m in size.

18. The composition of Claim 17, wherein the particles are less than 300 ╬╝m in size.

19. The composition of Claim 1, wherein the swellable hydrophilic material comprises approximately 10 wt% of the mastic.

20. The composition of Claim 1 or 2, wherein the swellable hydrophilic material is a fiber.

21. The composition of Claim 20, wherein the fiber is FiberDriΓäó

1161.

22. The composition of Claim 1, wherein the swellable hydrophilic material is a coating on a mastic substrate.

23. A method for sealing space between at least one object and an opening through which the object extends comprising applying to the object a composition comprising a mastic having a swellable hydrophilic material combined therewith.

24. A method for sealing a wire bundle including a plurality of wires comprising disposing a composition comprising a mastic having a swellable hydrophilic coating combined therewith into intimate contact with the bundle.