Chain entanglement crosslinked proppants and related uses

A rigid chain entanglement crosslinked polymer made by dispersing at lease one monomer and at least one initiator in an immiscible liquid medium to form a liquid dispersion; and decomposing the initiator in the fluid dispersion to activate polymerization and thereby produce a chain entanglement crosslinked polymer; and the polymer that can be utilized as proppants, as ball bearings, as lubriglide monolayers, and for drilling mud applications

FIELD OF THE INVENTION
 The present invention relates to chain entanglement crosslinked polymers
 manufactured by a method comprising: dispersing at least one monomer and
 at least one initiator in an immiscible liquid medium to form a fluid
 dispersion; and decomposing the initiator in the fluid dispersion to
 activate polymerization and thereby produce chain entanglement crosslinked
 polymers. The chain entanglement crosslinked polymers of the present
 invention can be utilized as proppants, as ball bearings, as lubriglide
 monolayers, and for drilling mud applications.
 BACKGROUND OF THE INVENTION
 The rigidity of polymers can be enhanced by utilizing high levels or
 concentrations of polyfunctional crosslinking agents. Most crosslinked
 polymers can be manufactured by suspension or droplet polymerization where
 a liquid monomer mixture is dispersed or suspended in an immiscible liquid
 medium. Suspension polymerization produces spherical polymer particles
 that can be varied in size by a number of mechanical and chemical
 methodologies. These methodologies for making crosslinked polymers are
 well known and practiced in the art of suspension polymerization.
 All of the crosslinking agents known in the art are chemical crosslinkers.
 There are many polyfunctional crosslinking agents in use, but the most
 prominent crosslinking monomer is divinylbenzene. Divinylbenzene is used
 to make insoluble, rigid polymers from acrylate esters, methacrylate
 esters, vinyl acetate, styrene, vinylnaphthalene, vinyltoluene, allyl
 esters, olefins, vinyl chloride, allyl alcohol, acrylonitrile, acrolein,
 acrylamides, methacrylamides, vinyl fluoride, vinylidene difluoride, etc.
 Almost any molecule carrying a carbon-carbon double bond (C.dbd.C) can be
 crosslinked and made rigid by copolymerization with divinylbenzene. Other
 crosslinking monomers are polyfunctional acrylates, methacrylates,
 acrylamides, methacylamides and polyunsaturated hydrocarbons.
 Another crosslinking methodology known in the art is macroneting. In
 macroneting, a preformed polymer is swelled in a difunctional reactant and
 crosslinked with the assistance of a catalyst. An example of macroneting
 is the crosslinking of polystyrene swelled in a dihalohydrocarbon by the
 action of a Friedel-Crafts catalyst such as aluminum chloride or ferric
 chloride.
 The beads of this invention differ from the prior art in that the polymeric
 beads are made rigid and nonelastic by the physical crosslinking of chain
 entanglement rather than by the chemical crosslinking of polyfunctional
 monomers.
 SUMMARY OF THE INVENTION
 In one embodiment, the present invention relates to a polymer made by a
 method comprising: dispersing at least one monomer and at least one
 initiator in an immiscible liquid medium to form a fluid dispersion; and
 decomposing the initiator in the fluid dispersion to activate
 polymerization and to thereby produce a chain entanglement crosslinked
 polymer. For purposes of this invention, chain entanglement crosslinking
 is defined as an irreversible, physical entanglement of polymer chains in
 which two or more polymer chains are physically intertwined. The term
 "activate" means to initiate or to start polymerization In another
 embodiment, the initiator is first added with the monomer to form a
 mixture and the mixture is dispersed in the liquid medium. In still
 another embodiment, the initiator has a concentration of greater than 1%
 of the monomer weight. In yet another embodiment, the method of
 manufacturing the chain entanglement crosslinked polymer further comprises
 the step of increasing the concentration of the initiator to increase the
 level of chain entanglement crosslinking. In a further embodiment, the
 method further comprises the step of adding at least one chemical
 crosslinking agent.
 In yet another embodiment the level of chain entanglement crosslinking is
 increased by increasing the number of growing radical chains per minute
 (or per second) by an accelerating rate of decomposition of the initiator.
 The accelerating rate of initiator decomposition is accomplished by an
 escalating temperature ramp, by a catalytic decomposition of the
 initiator, and/or by photolysis of the initiator.
 In still another embodiment, the monomers are olefinic monomers and the
 initiator are selected from a group consisting essentially of peroxy
 dicarbonates, diacyl peroxides, peroxyesters, dialkyl peroxides,
 peroxyketals, ketone peroxides, peroxy acids, azo compounds, photo
 initiators and mixtures thereof.
 In still yet another embodiment, the present invention relates to polymers
 manufactured by a method comprising: adding at least one monomer with at
 least one initiator to form a mixture; dispersing the mixture in an
 immiscible liquid medium to form a liquid dispersion; and decomposing the
 initiator in the fluid dispersion to activate polymerization and thereby
 produce chain entanglement crosslinked polymers.
 In a further embodiment, the decomposing of the initiator in the
 manufacturing method is performed by the photolysis of the initiator. For
 purposes of this invention, photolysis is defined as the use of radiant
 energy to produce chemical changes including the decomposition of the
 initiator into radical fragments. In one embodiment, photolysis is
 conducted using electromagnetic radiation and the frequencies of
 electromagnetic radiation that can be used effectively for the ultra
 violet (UV) regions, 10 to 400 nm, in the absence or presence of
 photosensitizor molecules such as benzophenone and its derivatives, and
 the x-ray region 0.1-10 nm. Photosensitizor molecules convert single
 energy states into triplet energy states using the energy transfer to
 produce free radicals from the initiator molecules more effectively. In
 another embodiment, photolysis is conducted by a process consisting
 essentially of UV radiation, gamma radiation, x-ray radiation, electron
 beam radiation, benzophenone activated UV radiation and mixtures thereof.
 For purposes of this invention, "radiation" is defined as a process of
 emitting radiant energy (such as gamma, electron or x-ray) to activate or
 speed up chemical or physical changes including the initiation of
 polymerization.
 In yet a further embodiment, the decomposing of the initiator in the
 manufacturing method is performed by catalysis of the initiator. For
 purposes of this invention, catalysis is defined as a phenomenon in which
 a relatively small amount of substance augments the rate of a chemical
 reaction without itself being consumed. In another embodiment, catalysis
 is conducted using transition metals, halogens, quarternary ammonium salts
 and lithium halides such as LiCl, LiBr, and LiI. The transition metals are
 the metals with unfilled d and f orbitals and consist essentially of Cu,
 Fe, Co, Cr, Ni, Mn, Ce, Mo, Tc, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, Au and
 mixtures thereof. The transition metals also includes their various
 oxidation states. The halogens consist essentially of Cl.sub.2, Br.sub.2,
 I.sub.2 and mixtures thereof
 In still yet a further embodiment, the decomposing of the initiator in the
 manufacturing method is performed by thermolysis of the initiator. For
 purposes of this invention, thermolysis is defined as the use of heat to
 produce chemical or physical change. In another embodiment, thermolysis is
 conducted by heating the fluid dispersion to the ten-hour half-life
 temperature of the initiator.
 In a firer embodiment, the polymer of the present invention further
 comprises a chemical crosslinking agent.
 In another embodiment, the geometry of the polymer can be beads, spheroids,
 seeds, pellets, granules, and mixtures thereof. In still another
 embodiment, the polymer of the present invention comprises a combination
 of low levels of a chemical crosslinking agent and high levels of chain
 entanglement crosslinking. In a further embodiment, the physical strength
 of the polymer is a result of both the chain entanglement and the chemical
 crosslinking agents.
 In still a further embodiment, the chemical crosslinking agent of the
 polymer comprises from about 1.0% to about 100% by weight of the polymer.
 In one embodiment, the chemical crosslinking agent is divinylbenzene in
 the amount from about 1.0% to about 100% by weight of the polymer.
 In another embodiment, the chemical crosslinking agent of the polymer is
 selected from a group consisting of trimethylolpropane trimethacrylate,
 trimethylolpropane triacrylate, trimethylolpropane dimethacrylate, and
 trinmethylolpropane diacrylate.
 In a further embodiment of the invention, the chemical crosslinking agent
 of the polymer can be selected from a group consisting of pentaerythritol
 tetramethacrylate, pentaerytiritol trimethacrylate, pentaerytliritol
 dimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate
 and pentaerythritol diacrylate.
 In still a further embodiment, the chemical crosslinking agent can be
 selected from a group consisting of ethyleneglycol dimethacrylate,
 ethyleneglycol diacrylate, diethyleneglycol dimethacrylate,
 diethyleneglycol diacrylate, triethyleneglycol dimethacrylate and
 triethyleneglycol diacrylate.
 In another embodiment of the present invention, the chemical crosslinking
 agent is a bis(methacrylamide) having the formula:
 ##STR1##
 In yet another embodiment, the chemical crosslinking agent is a
 bis(acrylamide) having the formula:
 ##STR2##
 In a further embodiment, the chemical crosslinking agent is a polyolefin
 having the formula:
EQU CH.sub.2.dbd.CH--(CH.sub.2).sub.x --CH.dbd.CH.sub.2
 where x=0 to 100
 In still another embodiment, the chemical crosslinking agent is a
 polyethyleneglycol dimethacrylate having the formula:
 ##STR3##
 In another embodiment, the chemical crosslinking agent is
 polyethyleneglycol diacrylate having the formula:
 ##STR4##
 In one embodiment, the chain entanglement of the polymer is produced by a
 rapid rate polymerization procedure. The procedure comprises the step of
 elevating a radical flux by employing large concentrations of an initiator
 within the range from about 1.0% to about 10% weight of the monomers and
 elevating the polymerization temperature to a temperature greater than the
 ten-hour half-life temperature by an increasing temperature ramp.
 In another embodiment, the radical flux is kept constant throughout the
 period of polymer growth by a temperature ramping rate that matches the
 decreasing first order rate of decay of initiator. In a further
 embodiment, the radical flux is a continually increasing value by
 employing both multiple initiators with increasing decomposition
 temperatures and an increasing temperature ramp.
 In a still further embodiment, the temperature ramping rate for
 polymerization is one degree centigrade (Celsius) every three minutes.
 Such a temperature ramp for polymerization can be continuous or can be a
 series of step functions of temperature increases followed by plateaus of
 varying length so that the temperature ramp has the form of increasing
 steps.
 The initiators can be selected from a group consisting of
 peroxydicarbonates, diacyl peroxides, peroxyesters, dialkyl peroxides,
 peroxyketals, ketone peroxides, peroxyacids, azo compounds,
 photoinitiators and mixtures thereof.
 For all free radical initiators, k.sub.d, the rate constant for initiator
 decomposition at the ten-hour half-life temperature is:
 ##EQU1##
EQU k.sub.d =1.155.times.10.sup.-3 min.sup.-1
 Since initiator decomposition is
 ##EQU2##
 the rate is
 ##EQU3##
 rearranging gives
 ##EQU4##
 integrating between the limits of I.sub.0 and I.sub.1 and t.sub.0 and
 t.sub.1, where I.sub.0 and I.sub.1 are concentrations, gives
EQU -1n(I.sub.0 -I.sub.1)=k.sub.d (t.sub.0 -t.sub.1)
 reorganizing gives
 ##EQU5##
 since k.sub.d t.sub.0 at time zero=0
 ##EQU6##
 and therefore -1n 2=-k.sub.d t.sub.1 or 1n 2=k.sub.d t.sub.1 or
 ##EQU7##
 when t.sub.1/2 =10 hours or 600 minutes
 ##EQU8##
 To obtain the quantity of initiator decomposed in elapsed time t.sub.1,
 rearrange extract exponents and solve.
 ##EQU9##
 where;
 I.sub.0 =initial initiator concentration
 I.sub.1 =initiator or concentration of elapsed time T.sub.1
 X.sub.1 =amount of initiator decomposed during elapsed time T.sub.1
 So that, I.sub.1 =I.sub.0 -X.sub.1.
 Substituting into the rate equation allows the quantity of initiator
 decomposed to be calculated for any elapsed time period.
 I.sub.0 -X.sub.1 =I.sub.0 e.sup.-k,t,
 X.sub.1 =I.sub.0 -I.sub.0 e.sup.-k,t,
 X.sub.1 =I.sub.0 (1-e.sup.-k,t,)
 The rate constant, k.sub.d, can be calculated by the equation
EQU K.sub.d =Ae.sup.-Ea/RT
 if A and E are known where A=preexponential frequency factor in either
 min.sup.-1 or sec.sup.-1
 EA=activation energy for the reaction in Kcal/mole
 R=1.98719.times.10.sup.-3 Kcal/mol-.degree.K.
 T=degrees Kelvin, .degree.K.,
 K=273.15+.degree.C.
 In another embodiment, the above-mentioned polymers of the present
 invention can be used as a proppant, as ball bearings, as a lubriglide
 monolayer, and for oil and gas drilling applications.
 In one embodiment, the present invention also provides a method of
 manufacturing rigid polymers having high levels of chain entanglement
 crosslinking. In another embodiment, the method comprises the step of
 generating chain entanglement by rapid rate polymerization. In yet another
 embodiment, the rapid rate polymerization procedure comprises the step of
 elevating a radical flux by employing large concentrations of an initiator
 within the range from about 1.0% to about 10% weight of monomer weight and
 elevating the polymerization temperature to a temperature greater than the
 ten-hour half-life temperature of the initiator. In another embodiment,
 the radical flux is also elevated by an increasing temperature ramp. In
 still yet another embodiment, the radical flux can also be kept constant
 throughout the period of polymer growth by a temperature ramping rate that
 matches the decreasing first order rate of decay of initiator. In a
 further embodiment, the radical flux can be a continually increasing value
 by employing both multiple initiators with increasing decomposition
 temperatures and an increasing temperature ramp. In yet a further
 embodiment, a preferred temperature ramping rate is one degree centigrade
 (Celsius) every three minutes. The temperature ramp of the radical flux
 can also be a series of step functions of temperature increases followed
 by plateaus of varying lengths so that the temperature ramp has the form
 of increasing steps. In another embodiment, the method further comprises
 the step of adding low levels of chemical crosslinkers from about 1% to
 about 100% of the polymer weight and preferably from about 1% to about 20%
 of the polymer weight.
 In one embodiment, the present invention relates to a method of
 manufacturing chain entanglement crosslinked polymers comprising:
 dispersing at least one monomer and at least one initiator in an
 immiscible liquid medium to form a fluid dispersion; and decomposing the
 initiator in the fluid dispersion to activate polymerization to thereby
 produce a polymer containing chain entanglement crosslinking polymers.
 In another embodiment, the method further comprises the step of increasing
 the concentration of the initiator to increase the level of chain
 entanglement crosslinking. In still another embodiment, the method further
 comprises the step of adding a chemical crosslinking agent. In a further
 embodiment, the initiator is first added with the monomer to form a
 mixture and the mixture is dispersed in the liquid medium.
 In yet another embodiment, the decomposition step is performed by the
 photolysis of the initiator and the photolysis is conducted by in process
 consisting essentially of UV radiation, gamma radiation, x-ray radiation,
 electron beam radiation, benzophenone activated UV radiation and mixtures
 thereof. In a further embodiment, the decomposition step is performed by
 the catalytic splitting of the initiator into free radicals and the
 catalysis is conducted by using transition metals, halogens, quarternary
 ammonium halide salts and lithium halides (such as LiBr, LiCl, LiI). In
 yet further embodiment, the decomposition step is performed by the
 thermolysis of the initiator and the thermolysis is conducted by heating
 the dispersion to the ten-hour half-life temperature of the initiator.
 In one embodiment, the present invention relates to a proppant comprising
 chain entanglement crosslinked polymers, the polymer is made by a method
 comprising: dispersing at least one monomer and at least one initiator in
 an immiscible liquid medium to form a fluid dispersion;
 and decomposing the initiator in the fluid dispersion to activate
 polymerization to produce a chain entanglement crosslinked polymer. In
 another embodiment, the method further comprises the step of increasing
 the concentration of the initiator to increase the level of chain
 entanglement crosslinking. In still another embodiment, the method further
 comprises adding a chemical crosslinking agent. In a further embodiment,
 the initiator is first added with the monomer to form a mixture and the
 mixture is dispersed in the liquid medium.
 In yet another embodiment, the decomposition step is performed by the
 photolysis of the initiator and the photolysis is conducted by a process
 consisting essentially of UV radiation, gamma radiation, x-ray radiation,
 electron beam radiation, benzophenone activated UV radiation and mixtures
 thereof. In a further embodiment, the decomposition step is performed by
 the catalysis of the initiator and the catalysis is conducted using
 transition metals, halogens, quarternary ammonium, halide salts and
 lithium halides. In yet a further embodiment, the decomposition step is
 performed by the thermolysis of the initiator and the thermolysis is
 conducted by heating the dispersion to the ten-hour half-life temperature
 of the initiator.
 In another embodiment, the present invention relates to a drilling mud
 application comprising a chain entanglement crosslinked polymer, the
 polymer being made by a method comprising: dispersing at least one monomer
 and at least one initiator in an immiscible liquid medium to form a fluid
 dispersion; and decomposing the initiator in the fluid dispersion to
 activate polymerization to produce a chain entanglement crosslinked
 polymer.
 In another embodiment, the method further comprises the step of increasing
 the concentration of the initiator to increase the level of chain
 entanglement crosslinking. Instill another embodiment, the method further
 comprises the step of adding a chemical crosslinking agent. In a further
 embodiment, the initiator is first added with the monomer to form a
 mixture and the mixture is dispersed in the immiscible liquid medium.
 In still another embodiment, the present invention relates to a lubricant
 containing a chain entanglement crosslinked polymer, the polymer being
 manufactured by a method comprising: dispersing at least one monomer and
 at least one initiator in an immiscible liquid medium to form a fluid
 dispersion; and decomposing the initiator in the fluid dispersion to
 activate polymerization to produce a chain entanglement crosslinked
 polymer.
 In another embodiment, the method further comprises the step of increasing
 the concentration of the initiator to increase the level of chain
 entanglement crosslinking. In still another embodiment, the method further
 comprises the step of adding a chemical crosslinking agent. In a further
 embodiment, the initiator is first added with the monomer to form a
 mixture and the mixture is dispersed in the immiscible liquid medium.
 In still a further embodiment, the present inventions relates to ball
 bearings comprising a chain entanglement crosslinked polymer, the polymer
 being manufactured by a method comprising: dispersing at least one monomer
 and at least one initiator in an immiscible liquid medium to form a fluid
 dispersion; and decomposing the initiator in the fluid dispersion to
 activate polymerization to produce a chain entanglement crosslinked
 polymer.
 In another embodiment, the method farther comprises the step of increasing
 the concentration of the initiator to increase the level of chain
 entanglement crosslinking. In still another embodiment, the method further
 comprises the step of adding a chemical crosslinking agent. In a further
 embodiment, the initiator is first added with the monomer to form a
 mixture and the mixture is dispersed in the liquid medium.
 In yet a farther embodiment, the present invention relates to a lubriglide
 monolayer comprising a chain entanglement crosslinked polymer, the polymer
 being made by a method comprising: dispersing at least one monomer and at
 least one initiator in an immiscible liquid medium to form a fluid
 dispersion; and decomposing the initiator in the fluid dispersion to
 activate polymerization to produce a chain entanglement crosslinked
 polymer.
 In another embodiment, the method further comprises the step of increasing
 the concentration of the initiator to increase the level of chain
 entanglement crosslinking. In still another embodiment, the method further
 comprises the step of adding a chemical crosslinking agent. In a further
 embodiment, the initiator is first added with the monomer to form a
 mixture and the mixture is dispersed in the liquid medium.

DETAILED DESCRIPTION OF THE INVENTION:
 The polymer of the present invention is generally spherical beads of a
 non-porous gelular structure having a skeletal density of between 1.040
 and 1. 1 50 g/ml. With a skeletal density in this range, the polymeric
 beads are readily mixed with water and aqueous salt solutions to give
 stable slurries. By control over the method of synthesis, the spherical
 particles can be varied in size from 0.1 to 5.0 millimeters in diameter,
 and the size distribution can be made to be Gaussian or monosized (all
 beads of one diameter). Monosized beads can be prepared by jetting, and a
 Gaussian distribution arises from a stirred reactor system.
 The following examples which describe the method of polymer synthesis to
 enhance chain entanglement crosslinking during polymer formation are
 illustrative of the invention of this patent and are not to be construed
 in any way as limitations to the methods of introducing greater levels of
 chain entanglement crosslinking. The bead polymers of the present
 invention are prepared by suspension polymerization with the assistance of
 the polymeric dispersants. Some of the polymeric dispersants in present
 use are sodium polyacrylates of moderate molecular size (60,000 to 250,000
 daltons) such as Acumer 1510.TM. (Rohm and Haas Co.), Sokalan PA 80S.TM.,
 and Sokalan PA 110S.TM. (BASF Corp.); cellulosic polymers such as Culminal
 CMC-2000.TM. (Aqualon), hydroxethylcellulose such as the Natrosol.TM.'s
 (Aqualon), and hydroxyproplycellulose such as the Klucel.TM.'s (Aqualon);
 and poly (N,N-diallyl-N,N-dimethylammonium chloride) Cat-Floc B.TM.
 (Calgon Corp.) A protective colloid such as gelatin is used to provide
 droplet stability or increased lifetime. An aqueous phase free radical
 inhibitor such as sodium nitrite is used to quench emulsion polymerization
 in the aqueous medium, and a sodium borate buffer at pH of 9-11 is
 utilized to keep the nitrite anion in anionic salt form throughout the
 polymer formation.
 The polymerizations can either be carried out under an atmosphere of
 nitrogen to inactivate the phenolic free radical inhibitors in the
 monomers or the phenolic inhibitors (t-butylcatechol in the DVB and
 monomethyl ether of hydroquinone (MEHQ) in the styrene) can first be
 extracted by sodium hydroxide prior to using such monomers.
 Crosslinked bead polymers are presently prepared via suspension
 polymerization by initiation with a molecule that forms free radicals
 either thermally, photochemically, or by induced radical formation. The
 most prominent initiators used today are those that develop free radicals
 by thermal decomposition. The free radical flux used most frequently is
 that which develops at the ten-hour half life temperature with an
 initiator concentration of from about 0.2 to about 1.0 wt. % of the total
 monomer weight when the polymerization is conducted isothermally. The
 elasticity or rigidity is controlled by the chemical crosslinker level.
 It has been discovered that rigid, non-elastic particles are able to be
 made at moderately low levels of a chemical crosslinker (20% DVB or less)
 by enhancing chain entanglement. Chain entanglement has been discovered to
 increase greatly during polymer formation by conducting the polymerization
 as rapidly as possible. It has been discovered that the faster the rate of
 the propagation step (more polymer chains growing per minute), the greater
 is the degree or the level of crosslinking by chain entanglement. And
 although chain entanglement crosslinking is not equivalent to chemical
 crosslinking in regulation of volume changes on solvent swelling, it does
 impart an increased rigidity to the polymer particles such that it can be
 substituted for chemical crosslinkers.
 The propagation rate of polymer growth is greatly enhanced by conducting
 the polymerization at temperatures above the ten-hour half-life
 temperature of the specific initiator and by increasing the initiator
 concentration above the normally employed concentration range (which is
 from about 0.2% to about 1.0 wt. % of monomer weight). Since the rate of
 polymer growth (propagation rate) is related to the square root of the
 radical concentration, doubling the initiator concentration increases the
 polymer growth rate only by the factor of 1.41 or by about 41% (41.42%).
 Consequently, the polymer growth quantity and, concomitantly, the rate of
 chain entanglement crosslinking are increased more effectively by
 increasing the temperature. In order not to reduce the efficiency of the
 initiating radical by cage product, a very effective program for speeding
 up the radical flux and the polymer growth rate is by a temperature ramp.
 The temperature ramp rate can be designed so that the radical flux remains
 constant throughout the polymerization process up to about 90% conversion
 of the monomer to a polymer at which point polymer growth becomes
 diffusion controlled. Also, dual initiators or higher multiples of
 initiators can be used so that as the temperature progresses up the ramp,
 a second initiator (and/or a third initiator, etc.) with a higher
 temperature of decomposition can be activated to supply the initiating
 radicals. In utilizing such a technique, the radical flux can be
 increased, held constant or decreased slightly as the temperature of the
 polymerization process is ramped to higher values. The only limiting
 element in high radical-fluxed, ramped-temperature polymerizations is the
 rate or the control over the removal of the heat of polymerization. For
 suspension (droplet) polymerization the control over the heat of polymer
 growth, which is an exothermic reaction for most monomers, is exercised by
 varying the monomer slurry concentration. The immiscible, slurring medium
 acts as a heat sink, and the larger the concentration of the inert medium,
 the greater the heat sink.
 The specific examples below will enable the invention to be better
 understood. However, they are given merely by way of guidance and do not
 imply any limitation.
 EXAMPLE 1
 The first polymer synthesis is an isothermal polymerization carried out at
 80.degree. C., a temperature far above the ten hour half-life temperature
 of the two initiators being used to generate the free radicals for
 initiating the polymerization. This temperature differential of 28.degree.
 C. and 16.degree. C. above the ten hour half-life temperature of the
 respective initiators generates a large radical flux. The dual initiator
 system was 2,2-azobis(2-cyano-4-methylpentane), Vazo 52 (ten hour
 half-life of 52.degree. C.) from duPont, and 2,2-azobis(2-cyanopropane),
 Vazo 64 (ten hour half-life of 64.degree. C.) from duPont. At 80.degree.
 C., the half-life for thermal decomposition of Vazo 52 is 13.33 minutes
 and for Vazo 64 is 73.91 minutes. The concentration of the combined
 initiators was 4.279 wt % of the monomer charge. Such a system has a
 radical flux 68 times that of a standard polymerization initiated with 1.0
 wt % benzoyl peroxide (BPO) during the first minute at 80.degree. C. and
 has an average radical flux over the first ten minutes 57 times that of
 the standard BPO initiated polymerization. These high radical fluxes
 develop the increased crosslinking by chain entanglement.
 Table 1 illustrates the components of the aqueous phase composition for the
 suspension polymerization.
 TABLE 1
 Aqueous Phase Composition, 1600.00 gm:
 Water, 98.75 wt %; 1580.00 gm
 Dispersant Polymer, 0.3 wt %; 4.80 gm
 Sodium Nitrate, NaNO.sub.2 ; 0.3 wt % 4.80 gm
 Sodium Metaborate, NaBO.sub.2 ; 0.3 wt % 4.80 gm
 Sodium Hydroxide, NaOH pellets, 0.05 wt %; 0.80 gm
 Gelatin, 0.3 wt %; 4.80 gm
 Total Weight in Grams; 1600.00 gm
 The aqueous phase is prepared externally in a beaker, first by heating the
 water to 55.degree. C. to 60.degree. C. and then slowly mixing in the
 dispersant polymer with sufficient agitation to dissolve the solid
 polymeric dispersant. The dispersant polymer, if added too fast, will form
 large clumps. These large clumps are very difficult to dissolve. After the
 dispersant solution is prepared, the gelatin (dry powder) is slowly
 introduced to avoid the formation of the large clumps. The aqueous liquid
 at this point should be homogeneous and should contain no undissolved
 material. The sodium nitrite, sodium metaborate and sodium hydroxide are
 then rapidly added to the aqueous solution.
 The aqueous liquor is then poured into a round-bottomed flask. The stirring
 rate is set within the range of 105 to 125 rmp--the upper stirring rate
 for smaller particles of 300-400 micron diameter and the lower stirring
 rate for larger particles of 600 to 700 micron diameter. All openings to
 the flask are closed except for a gas inlet and a gas outlet and the air
 in the vapor space of the flask is displaced with nitrogen.
 Table 2 illustrate the components of the organic phase composition.
 In this polymerization, 10.0 wt % of Polymer was Divinylbenzene (DVB), so
 that 72.56 g of monomer charge was pure DVB provided by impure 55%
 commercial divinylbenzene. This lot of Dow DVB was 56.3% DVB, 42.0%
 ethylvinylbenzene (EVB) and 98.3% polymerizable monomers.

DVB, commercial 55% Dow DVB 128.88 gm
 54.13 gm EVB, 7.46%, 2.19 gm inert material,
 10.0% pure DVB, 72.56 gm;
 Styrene, 82.54%; 598.91 gm
 Vazo 52; 2,2'-azobis(2-cyano-4methylpentane),
 2.2964 gm/100 gm of monomer; 16.663 gm
 Vazo 64; 2,2'-azobis(2-cyanopropane),
 1.9826 gm/100 gm of monomer; 14.386 gm
 Total Weight in Grams . . . 758.839 gm
 The organic phase is prepared in a beaker by dissolving the two Vazo
 initiators into the monomer liquid of sytrene, ethylvinylbenzene, and
 divinylbenzene at 20.degree. C. or less. The temperature is kept at
 20.degree. C. or less during the dissolution of the initiators to prevent
 the thermal decomposition of the initiators. This procedure will yield a
 homogeneous liquor. The monomer liquor is then dispersed into the aqueous
 phase by gradual addition dropwise over ten (10) to fifteen (15) minutes
 with stirring. Droplets of monomer liquor form instantaneously within the
 continuous aqueous liquid phase with the droplet size being set by the
 rate of stirring and the temperature. During the addition of monomer
 liquid to the aqueous liquid, the temperature was maintained between
 35.degree. C. to 40.degree. C.
 After the monomer addition is completed, the droplet slurry is then stirred
 for about fifteen minutes to set the droplet size. The temperature is kept
 within 35.degree. C. to 40.degree. C. during the setting of the droplet
 size. At the completion of the droplet size setting stage, the slurry of
 monomer droplets are heated starting at 35.degree. C.-40.degree. C. The
 heat is then increased from about 40 to about 80.degree. C. over a period
 of 30 minutes; the temperature is held at 80.degree. C..+-.2.degree. C.
 over a period of ten hours to transfer liquid monomer droplets into solid
 gel polymeric beads and to decompose all of the initiator. The temperature
 is then allowed to drop to ambient.
 The beads of the polymer are separated from the aqueous mother liquor,
 collected on an 80 mesh sieve, washed four times with tap water, and air
 dried as a thin layer (0.5 inch thick) in an aluminum metal tray. In some
 instances, oven drying at 70.degree. C. was necessary to reach a
 free-flowing state. When the beads became free flowing, the beads were
 screened through a set of sieves of varying sieve openings to give the
 particle size distribution, and the yield of polymeric beads within the 16
 to 60 mesh cut, a particle diameter range of 250 to 1190 microns. The
 yield of beads ranges from about 96% to 98% of theory. Elemental analysis
 show the polymeric beads to be essentially carbon (91.2%) and hydrogen
 (8.1%).
 EXAMPLE 2
 The polymer synthesis in Example 2 is very similar to that of Example I
 except for the level of the two initiators, the time-temperature profile,
 and the stirring rate which is reduced to 88.5 rpm to manufacture large
 beads. The time-temperature profile is a continuous ramp from about
 60.degree. C. to about 87.degree. C. over a 62 minute period for a
 temperature ramping rate of 0.436.degree. C. per minute followed by a high
 temperature plateau at 93.degree. C. for 60 minutes to complete the
 destruction of any remaining initiator.
 Table 3 illustrates the components of the aqueous and monomer phases of
 EXAMPLE 2.
 TABLE 3
 Aqueous Phase, 1600.0 gm:
 Composition is identical to that of Example 1.
 Monomer Phase, 725 6 gm Monomers:
 DVB, Commercial 55% Dow DVB 128.88 gm
 DVB = 72.56 gm, 10.0%
 EVB = 54.13 gm; 7.46%
 Inerts = 2.19 gm
 Polymerizable Monomers = 126.69 gm
 Styrene, 82.5% 598.91 gm
 Vazo 52, 1.8674% of monomer charge: 3.55 gm
 Vazo 64, 1.2348% of monomer charge 8.96 gm
 Table 4 illustrates the procedural steps of EXAMPLE 2 in relation to time
 and temperature.
 TABLE 4
 Time-Temperature Profile
 Time in
 Minutes Temp .degree. C. Operation
 0 40 Begin introduction of monomer liquid into
 aqueous phase at stirring rpm of 88.6
 20 40 Monomer introduction completed
 45 41 Begin temperature ramp to 60.degree. C.
 over 15 minutes
 55 54 Stirring rpm = 88.5
 58 60 Begin temperature ramp to 87.degree. C. over 62
 minutes
 120 87 Begin temperature ramp to 93.degree. C. over 10
 minutes
 130 92 Begin Temp. hold for 60 minutes
 190 93 Time-Temperature profile completed; Cool to
 ambient
 Upon completion of the above procedural steps, a milky white bead slurry is
 produced, then cooled to 40.degree. C. and filtered through an 80 mesh
 sieve to collect the beads. The beads are then washed with a water spray
 followed by one slurry washing with tap water. The beads are drained free
 of water by pouring the slurry onto the 80 mesh sieve, placed in an
 aluminum pan and dried overnight in a convection oven at 67.8.degree. C.
 (154.degree. F). The free flowing, dried beads are screened through a
 stack of sieves on a Roto-Tap shaker. The screen analysis is as tabulated
 in Table 5 below, and the yield of polymer from monomer was 96.58% of
 theory (700.8 gm polymer from 725.6 gm monomer).
 TABLE 5
 SCREEN ANALYSIS
 Sieve Gross Tare Wt. Wt. On Cumulative
 Opening Weight of Sieve Sieve % on Wt on % on
 Microns Sieve No. gm gm gm Sieve Sieve Sieve
 1190 16 441.8 391.5 50.3 21.63 50.3 21.63
 840 20 526.1 404.3 121.8 52.36 172.1 73.99
 590 30 425.2 377.2 48.0 20.64 220.1 94.63
 500 35 373.7 366.5 7.2 3.095 227.3 97.72
 420 40 365.2 362.1 3.1 1.33 230.4 99.05
 297 50 330.6 328.9 1.7 0.73 232.1 99.785
 250 60 339.9 339.6 0.3 0.13 232.4 99.914
 -250 -60 339.6 339.4 0.2 0.086 232.6 100.000
 Total: 232.6 gm
 EXAMPLE 3
 The polymer synthesis in Example 3 is similar to that of the first two
 examples with the exception for the level of DVB (5 wt % versus 10 wt %),
 the initiator type and level (benzoyl peroxide) at 23 wt %, and the
 temperature-time profile. DVB level is 5.0 wt % of monomer charge supplied
 by a commercial DVB with 98.0 wt % polymerizable monomers made up of 63.0%
 DVB and 35% ethylvinylbenzene.
 The monomer composition of the polymer in this example is as follows: DVB
 =5.0 wt % EVB=2.78 wt % Styrene 92.22 wt %.
 The initiator is benzoyl peroxide at a level of 1.23 wt % of polymerizable
 monomers. The stirring rate is 103.6 rpm.
 Table 6 illustrates the procedural steps of Example 3 in relation to time
 and temperature.
 TABLE 6
 Time Temperature Profile
 Elapsed Time Temperature
 in Minutes .degree. C. Operation
 0 63 Begin droplet formation by pouring monomer phase
 into
 aqueous phase.
 2 62 All monomer introduced; begin droplet setting
 stage.
 23 63 Begin ramping temperature to 75.degree. C. over
 ten minutes.
 33 74 Begin ramping temperature to 85.degree. C. over
 next 130
 minutes.
 143 81 Temp-time reading.
 163 83 Begin 83-85.degree. C. temperature plateau over
 next 50
 minutes.
 213 85 Ramp temperature over next 10 minutes to
 93.degree. C.
 225 93 Hold temperature at 93.degree. C. for next 60
 minutes.
 285 93 Remove heat and begin cooling slurry to ambient
 temperature.
 Upon completion of the above procedural steps, the slurry is cooled, and
 clear, transparent beads are collected on an 80 mesh sieve. The beads are
 then washed four times by slurrying in fresh tap water, and drained free
 of excess water on the 80 mesh sieve. The beads are air-dried over three
 days as a thin layer spread over the 80 mesh sieve. After three days, the
 beads are free flowing and are then screened through a stack of sieves on
 a Roto-Tap shaker to give the particle size distribution tabulated below
 in Table 7. The yield of transparent beads from the monomer charged is
 95.58% of theory.
 TABLE 7
 Screen Analysis
 Cumulative
 Sieve Gross Tare % %
 Opening Wt Wt Wt. On Sieve on on Sieve
 in Microns Sieve No in gm in gm in gm Sieve Wt on Sieve
 1190 16 440.50 423.29 17.21 5.499 17.21
 5.499
 840 20 589.24 403.51 185.95 59.415 203.16
 64.914
 710 25 470.40 400.51 69.89 22.331 273.05
 87.245
 590 30 406.00 385.99 20.01 6.394 293.06
 93.638
 500 35 378.55 369.30 9.25 2.956 302.31
 96.594
 420 40 379.78 374.70 5.08 1.623 307.39
 98.217
 350 45 354.59 352.11 2.48 0.792 309.87
 99.009
 297 50 349.59 349.02 0.57 0.182 310.44
 99.192
 none pan 510.08 507.55 2.53 0.808 312.97 100.00
 Total . . . 312.97 gm
 The polymers labeled with the suffix RRP, which stands for rapid rate
 polymerization, in Table 9 were all prepared at a very rapid rate of
 polymer growth at varying levels of chemical crosslinking from about ten
 (10 wt %) to about twenty weight percent (20 wt %) divinylbenzene. The
 polymers labeled with the suffix ITP, which stands for isothermal
 polymerization, in Table 8, were all prepared by the standard isothermal
 polymerization process at 75.degree. C. with initiation by two wt %
 t-butyl peroctoate whose ten-hour half-life temperature is 77.degree. C.
 Comparison of the resistance to deformation as assessed by the
 conductivity values in Tables 8 and 9, and plotted in the corresponding
 FIGS. 1 and 2, clearly shows that physical crosslinking by chain
 entanglement can be substituted for chemical crosslinking. All three RRP
 polymers have identical resistance to deformation under pressure, even
 though the chemical crosslinking varied by a factor of two--from 10 to 20
 wt. % DVB. Thus, it appears that the chain entanglement crosslinking is
 controlling in the resistance to deformation under pressure. Plotting the
 conductivity values of the RRP polymers with the ITP polymers on FIG. 1
 places the RRP polymers to be equivalent in deformation resistance to that
 ITP polymer with 50 wt % chemical crosslinking by divinylbenzene. It is
 very clearly seen that chain entanglement crosslinking can be substituted
 for chemical crosslinking by divinylbenzene, thereby allowing the use of
 greatly reduced levels of divinylbenzene or any other polyfunctional
 monomer with concomitantly reduced costs in manufacturing of hard plastic
 beads.
 The following procedure was used to determine the conductivity and liquid
 permeability of the bead polymers of the present invention.
 EXAMPLE 4
 Conductivity and Liquid Permeability
 API cells are loaded with the polymer sample to be tested and the polymer
 beads are leveled with a blade device.
 The polymer samples are placed between Ohio Sandstone and are made a part
 of a cell stack.
 The cells are stacked to within 0.005 inch from top to bottom and
 positioned between the plattens of the Drake Press. Pressure is increased
 to 300 psi, and the system is evacuated and saturated with deoxygenated
 aqueous 2% potassium chloride solution at 72.degree. F.
 Once saturated, the enclosure pressure is increased to 500 psi at a rate of
 100 psi/min. The system is allowed to equilibrate at each pressure for 30
 minutes, after which five measurements are taken. Readings are taken at
 pressure increments of 1000 psi.
 The flow rate and pressure differential are measured at each pressure in
 order to calculate conductivity. Five measurements are taken and averaged
 to arrive at each conductivity value. Flow rate is measured with a Mettler
 balance to 0.01 ml/min. Darcy's Law is used for the calculations to
 determine the conductivity.
 With this equipment, Darcy's Law has the following form:
 K.sub.wf =26.78.mu.Q/.DELTA.P
 Where
 K.sub.wf =Conductivity in millidarcies/ft (md/ft)
 26.78=constant to account for 1.5.times.5 inch flow area and the pressure
 in psi
 .mu.=Viscosity of flowing liquid which is a 2 wt % aqueous solution of
 potassium chloride at ambient temperature
 Q=Flowrate in ml/min
 .DELTA.P=Pressure differential across five (5) inch flow path.
 Table 8 illustrates the liquid conductivity of the bead polymers made by
 the rapid rate polymerization (RRP) process.
 TABLE 8
 Liquid Conductivity Around Spherical Gel Polymers as
 a Function of Enclosure Pressure: Polymers with High Levels
 of Chain Entanglement Crosslinking at Varying Levels of
 Crosslinking by Divinylbenzene
 Conductivity, millidarcie ft. at 0.8 lb.ft.sup.2
 Sample.fwdarw. 10% DVB RRP 15% DVB RRP 20% DVB RRP
 Label.fwdarw. RRP - 126 RRP - 132 RRP - 127
 Enclosure Pressure
 PSI
 1000 4500 5000 5500
 2000 3500 3500 3500
 3000 2300 2300 2300
 4000 1600 1600 1600
 5000 900 900 900
 6000 650 650 650
 7000 400 400 400
 8000 190 275 275
 Table 9 illustrates the liquid conductivity of isothermal polymerization
 (ITP) polymers.
 TABLE 9
 Liquid Conductivity Around Spherical Gel Polymers as a Function
 of Enclosure Pressure: Polymers with Low Levels of Chain Entanglement
 Crosslinking at Varying Levels of Crosslinking by Divinylbenzene (8,
 20, 50, 80 wt. % DVB)
 Conductivity, millidarcie ft. at 0.78 lb.ft.sup.2
 Sample.fwdarw. 8% DVB ITP 20% DVB ITP 50% DVB ITP 80% DVB ITP
 Label.fwdarw. Comm Copolymer ITP - 106 ITP - 105 ITP - 101
 Enclosure
 Pressure PSI
 1000 6074 4173 4363 4652
 2000 3118 2234 3599 3599
 3000 1931 1428 1807 2673
 4000 984 642 1259 2077
 5000 671 374 867 1413
 6000 368 257 696 1199
 7000 200 110 444 871
 8000 112 74 367 637
 Table 8 and 9 depict the improved rigidity and improved conductivity and
 liquid permeability of the polymers of the present invention.
 Obviously, numerous modifications and variations of the present invention
 are possible in light of the above teachings. It is therefore to be
 understood that within the scope of the attendant claims appended hereto,
 the invention may be practiced otherwise than as specifically disclosed
 herein.