Patent Publication Number: US-2004053062-A1

Title: Resins for lining surfaces

Description:
FIELD AND BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to a method of utilizing resins for lining substrate surfaces which are damaged or cracked.  
       [0002] Substrates which are exposed to outdoor conditions are utilized in, for example, sidewalks, roads, reservoirs, and the like. These substrates are typically formed from concrete, metals, and polymer composites. In addition to the above, the substrates are employed underground and used in a number of applications relating to the transport of petroleum, natural gas, chemicals, municipal water, and the like. Due to exposure to a number of influences over time such as, for example, temperature fluctuations, ground movements, corrosive fluids, etc., the pipes tend to crack and damage. As a result, the pipes often are unable to successfully transport the above mentioned fluids and thus become unsuitable for their intended use.  
       [0003] Various methods have been proposed to repair the pipes. One approach is presented in U.S. Pat. No. 4,009,063 to Wood, and involves lining the inside of the pipe with a tubular fibrous felt impregnated with a thermosetting resin which contains a catalyst. Wood teaches that the impregnated felt is inserted into the damaged pipe and is inflated using hot air or water. The expansion of the tubular felt molds it into the shape of the pipe. Heat from the hot air or water activates the catalyst causing the resin to cure and form a rigid liner.  
       [0004] Another approach involves utilizing glass fiber which is woven into a tubular shape. The glass fiber is impregnated with a thermosetting resin containing a catalyst, and the resin is then cured. Carbon fiber may be interwoven with the glass fiber such that curing may be accomplished by applying an electrical current to the carbon fibers to generate heat. As a result, the catalyst is activated and the resin cures forming a rigid pipe lining. In this instance, hot air or hot water is not required.  
       [0005] The use of thermally activated catalysts which is described above, however, present disadvantages. Since the catalysts typically require temperatures well above ambient, the viscosity of the impregnated resin decreases while in the pipe. As the viscosity decreases, the resin tends to sag. The resulting pipe lining formed from the resin is non-uniform in appearance and often possesses non-uniform physical properties.  
       [0006] In order to address the above difficulties, agents such as fumed silica have been added to the resins such that they become thixotropic. A thixotropic material is advantageous in that its flow at room temperature is limited in the absence of an applied shear force. Nonetheless, using thixotropic materials is problematic in that their viscosities are excessively high making them difficult to pump. Also, heating thixotropic materials reduces the resin viscosity such that the materials run off and are difficult to contain.  
       [0007] It would be desirable to provide a method of lining damaged surfaces such as those found in pipes or conduits which addresses the problems mentioned above.  
       SUMMARY OF THE INVENTION  
       [0008] It is therefore an object of the present invention to provide a method for lining a surface with a resin which may be transported more easily to the surface and provide more uniform physical properties to the surface.  
       [0009] To this end and others, the invention provides a method of lining a surface. The method comprises providing a reactive mixture which comprises (1) a resin containing active hydrogens; (2) a polycarbodiimide; and (3) an organic diluent; reacting the resin containing active hydrogens and the polycarbodiimide to chemically bind the resin and the polycarbodiimide; applying the chemically bound resin and polycarbodiimide to the surface of the substrate; and curing the chemically bound resin and polycarbodiimide to form a cured resin material which lines the surface of the substrate.  
       [0010] To cure the chemically bound resin, an initiator is employed. Additionally, in another embodiment, a promoter may be used in conjunction with the initiator.  
       [0011] The invention also provides a method of lining a surface which defines a conduit. The method comprises providing a reactive mixture which comprises (1) a resin containing active hydrogens; (2) a polycarbodiimide; and (3) an organic diluent; inserting the reactive mixture into a tube, the tube being defined by an inner membrane and an outer membrane; reacting the resin containing active hydrogens and the polycarbodiimide to chemically bind the resin and the polycarbodiimide; inserting the tube into a conduit having an inner surface; applying pressure to the tube such that the tube comes in contact with the inner surface of the conduit; and curing the chemically bound resin and polycarbodiimide to form a crosslinked resin material which lines the surface of the conduit. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012] In the drawings which form an original portion of the disclosure as filed:  
     [0013]FIG. 1 illustrates a tube filled with a resin according to the invention;  
     [0014]FIG. 2 illustrates a tube filled with a resin according to the invention being present inside a conduit;  
     [0015]FIG. 3 illustrates a tube filled with a resin according to the invention being urged by pressure against an inner surface of a conduit; and  
     [0016]FIG. 4 illustrates a tube filled with a resin according to the invention being urged by pressure against a tube previously inserted and against an inner surface of a conduit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0017] The present invention will now be described more fully hereinafter, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.  
     [0018] In one aspect, the invention relates to a method for lining a surface of a substrate with a resin, typically the surface of a conduit such as a pipe. The method comprises providing a reactive mixture which comprises (1) a resin containing active hydrogens, (2) a polycarbodiimide, and (3) an organic diluent. The polycarbodiimide is preferably dispersed or contained in the organic diluent during the providing step. The reaction mixture preferably contains greater than about 5 percent by weight of polycarbodiimides. The resin containing active hydrogens and the polycarbodiimide then react such that the resin and the polycarbodiimide become chemically bound, namely the resin becomes thickened. This step is preferably carried out at a temperature between about 5° C. and about 60° C. The chemically thickened resin preferably has a viscosity ranging from about 30,000 centipoise to about 50 million centipoise, and more preferably from about 100,000 centipoise to about 20 million centipoise.  
     [0019] The chemically bound resin and polycarbodiimide is then applied to the surface of the substrate. Subsequently, chemically bound resin and polycarbodiimide is cured to form a crosslinked resin material which lines the surface of the substrate. The curing step is preferably carried out at a temperature between about 40° C. and about 150° C., more preferably between about 50° C. and about 100° C. The curing step is performed in the presence of an initiator.  
     [0020] The invention is advantageous in that the glass transition temperature (T g ) of the cured resin material may be enhanced by virtue of the method disclosed herein. Preferably, the T g  of the cured resin material increases from about 5 percent to about 600 percent, and more preferably from about 10 percent to about 300 percent. As a result of this elevation in T g , the physical properties of the cured resin are believed to be enhanced.  
     [0021] As a result of this elevation in T g , it is believed that the physical properties of the cured resin materials are enhanced. Preferably, the cured resin material has a flexural strength ranging from about 3000 psi to about 80,000 psi; a tensile strength ranging from about 1000 psi to about 50,000 psi; and a percent elongation ranging from about 1 to about 1000. In addition to the above, it should be appreciated that various types of resins may have differing preferred ranges of physical property values. For example, cured unsaturated polyester resins preferably have tensile strengths ranging from about 3000 psi to about 50,000 psi and elongations ranging from about 1 to about 10 percent, while cured polyurethanes preferably have tensile strengths ranging from about 800 to about 5000 psi and elongations ranging from about 70 to about 1000.  
     [0022] Preferably, the reactive mixture contains between about 3 to about 50 percent by weight of polycarbodiimide, more preferably between about 3 and about 20 weight percent polycarbodiimide, and most preferably between about 6 and about 12 weight percent polycarbodiimide.  
     [0023] The resin which contains active hydrogens may be selected from a number of resins well known to those skilled in the art. For the purposes of the invention, the term “resin containing active hydrogens” refers to any resin which contains functional groups containing active hydrogens. Functional groups containing active hydrogens can be defined as those which are capable of reacting with polycarbodiimide repeating units (N═C↑N). Suitable functional groups including, for example, hydroxyl, carboxyl, amino, phenol, silanol, —P—OH, —P—H, as well as other appropriate substituents. Resins containing active hydrogens include, but are not limited to, saturated polyester resins (e.g., resins employed in hot melt adhesives and powder coatings), unsaturated polyester resins (e.g., resins used in forming molded articles), aliphatic and aromatic polyethers, vinyl ester resins (e.g., resins used in filament winding and open and closed molding), polyurethanes, and mixtures of any of the above.  
     [0024] For the purposes of the invention, unsaturated polyester resins, saturated polyester resins, and vinyl ester resins are preferably employed. An unsaturated polyester resin may be formed from conventional methods. Typically, the resin is formed from the reaction between a polyfunctional organic acid or anhydride and a polyhydric alcohol under conditions known in the art. The polyfunctional organic acid or anhydride which may be employed are any of the numerous and known compounds. Suitable polyfunctional acids or anhydrides thereof include, but are not limited to, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexane dicarboxylic acid, succinic anhydride, adipic acid, sebacic acid, azealic acid, malonic acid, alkenyl succinic acids such as n-dodecenylsuccinic acid, docecylsuccinic acid, octadecenylsuccinic acid, and anhydrides thereof. Lower alkyl esters of any of the above may also be employed. Mixtures of any of the above are suitable.  
     [0025] Additionally, polybasic acids or anhydrides thereof having not less than three carboxylic acid groups may be employed. Such compounds include 1,2,4-benzenetricarboxylic acid, 1,3,5-benzene tricarboxylic acid, 1,2,4-cyclohexane tricarboxylic acid, 2,5,7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,3,4-butane tricarboxylic acid, 1,2,5-hexane tricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-carboxymethylpropane, tetra(carboxymethyl)methane, 1,2,7,8-octane tetracarboxylic acid, and mixtures thereof.  
     [0026] Suitable polyhydric alcohols which may be used in forming the unsaturated polyester resin include, but are not limited to, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3 hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 1,3-butylene glycol, 1,6-hexanediol, hydrogeneated bisphenol “A”, cyclohexane dimethanol, 1,4-cyclohexanol, ethylene oxide adducts of bisphenols, propylene oxide adducts of bisphenols, sorbitol, 1,2,3,6-hexatetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol; 1,2,5-pentanetriol, glycerol, 2-methyl-propanetriol, 2-methyl-1,2,4-butanetriol, trimethylol ethane, trimethylol propane, and 1,3,5-trihydroxyethyl benzene. Mixtures of the above alcohols may be used.  
     [0027] The vinyl ester resins employed in the invention include the reaction product of an unsaturated monocarboxylic acid or anhydride with an epoxy resin. Exemplary acids and anhydrides include (meth) acrylic acid or anhydride, α-phenylacrylic acid, α-chloroacrylic acid, crotonic acid, mono-methyl and mono-ethyl esters of maleic acid or fumaric acid, vinyl acetic acid, sorbic acid, cinnamic acid, and the like, along with mixtures thereof. Epoxy resins which may be employed are known and include virtually any reaction product of a polyfunctional halohydrin, such as epichlorohydrin, with a phenol or polyhydric phenol. Suitable phenols or polyhydric phenols include, for example, resorcinol, tetraphenol ethane, and various bisphenols such as Bisphenol “A”, 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydrohy byphenyl, 4,4′-dihydroxydiphenyl methane, 2,2′-dihydroxydiphenyloxide, and the like. Novolac epoxy resins may also be used. Mixtures of any of the above may be used. Additionally, the vinyl ester resins may have pendant carboxyl groups formed from the reaction of esters and anhydrides and the hydroxyl groups of the vinyl ester backbone.  
     [0028] The resins containing reactive hydrogens may be used alone or in conjunction with other appropriate materials to help enhance physical properties of the resin. Suitable materials include, for example, fibrous reinforcements, fillers, flame retardants, woven and nonwoven fibrous sheets and mats, and the like. Any conventionally known fibrous reinforcement material may be used including fiberglass, polyester, carbon, metal, graphite, high modulus organic fibers (e.g., aromatic polyamides, polybenzimidazoles, and aromatic polyimides), other organic fibers (e.g., polyethylene, liquid crystals, and nylon), and natural fibers. The fibrous materials may be incorporated into the resin in accordance with techniques which are known in the art. Fillers may include but are not limited to calcium carbonate, aluminum oxide, aluminum hydroxide, silica gel, barite, graphite powder, and the like. Mixtures of the above may also be used.  
     [0029] Saturated polyester resins and polyurethanes which are thickened include, for example, those described in U.S. Pat. Nos. 4,871,811; 3,427,346; and 4,760,111; the disclosures of which are incorporated herein by reference in their entirety. The saturated polyester resins and polyurethanes are particularly useful in hot melt adhesives and pressure sensitive adhesive applications. Appropriate saturated polyester resins include, but are not limited to, crystalline and amorphous resins. The resins may be formed by any suitable technique. For example, the saturated polyester resin may be formed by polycondensating an aromatic or aliphatic di-or polycarboxylic acid and an aliphatic or alicyclic di- or polyol or its prepolymer. Optionally, either the polyols may be added in excess to obtain hydroxyl end groups or the dicarboxylic monomers may be added in excess to form carboxylic end groups. Suitable polyurethane resins may be formed by the reaction of diols or polyols as described in U.S. Pat. No. 4,760,111 along with diisocyanates. The diols are added in an excess to obtain hydroxyl end groups at the chain ends of the polyurethane.  
     [0030] Polycarbodiimides which may be employed in the present invention include those which are known in the art. Exemplary polycarbodiimides are described in U.S. Patent Nos. 5,115,072; 5,081,173; 5,008,363; and 5,047,588; the disclosures of which are incorporated herein by reference in their entirety. The polycarbodiimides can include aliphatic, cycloaliphatic, or aromatic polycarbodiimides.  
     [0031] The polycarbodiimides can be prepared by a number of known reaction schemes. Preferably, the polycarbodiimides are synthesized by reacting an isocyanate-containing intermediate and a diisocyante under suitable reaction conditions. The isocyanate containing intermediate is formed by the reaction between a component, typically a monomer, containing active hydrogens and a diisocyanate. Included are also polycarbodiimides prepared by the polymerization of isocyanates to form a polycarbodiimide, which subsequently react with a component containing active hydrogens.  
     [0032] Components containing active hydrogens, which may be employed are well known and numerous, with monomers being typically utilized. Examples of such monomers include, but are not limited to, acrylates, alcohols, amines, esters, polyesters, thiols, phenols, aromatic and aliphatic polyethers, siloxanes, phosphorus-containing materials, olefins, unsaturated aromatic monomers, and mixtures thereof. Alcohols are typically used, with monofunctional alcohols being preferably employed. Monofunctional alcohols which may be used include, for example, ethanol, butanol, propanol, hexanol, octanol, ethylhexyl alcohol, and longer-chain alcohols (i.e., those alcohols containing up to 50 carbon atoms) and their isomers.  
     [0033] Other monomers having active hydrogens which may be used include, for example, acrylic acid, methacrylic acid, acetic acid, phenylacetic acid, phenoxyacetic acid, propionic acid, hydrocynnamic acid, and the like. Hydroxyalkyl acrylates or methacrylates such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and the like may also be employed. Polyols can be additionally be used including, but not limited to, ethylene glycol; 1,2 and 1,3-propylene glycol; 1,4 and 2,3-butylene glycol; 1,5-pentanediol; 1,6-hexanediol; 1,8-octanediol; neopentyl glycol; 1,4-bis-hydroxymethyl cyclohexane; 2-methyl-1,3-propanediol; glycerol; trimethylolpropane; 1,2,6-hexanetriol; trimethylol ethane; pentaerythritol; quinitol; mannitol; sorbitol; diethylene glycol; triethylene glycol; tetraethylene glycol; 1,4-butanediol; polyethylene glycols having a molecular weight of up to 400; dipropylene glycol; ethoxylated and propoxylated bisphenol “A”; polybutylene glycols having a molecular weight of up to 400; methyl glucoside; diethanolamino-N-methyl phosphonic acid esters; castor oil; diethanolamine; N-methyl ethanolamine; and triethanolamine. Mixtures of any of the above may be used. Any of the above compounds may also include any one or a combination of halogens such as chlorine, fluorine, bromine, or iodine; or phosphorus, or silicon groups.  
     [0034] Diisocyanates which are used in the above reactions are well known to the skilled artisan. For the purposes of the invention, diisocyantes include aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic diisocyantes of the type described, for example, by W. Siefken in  Justus Liebigs Annalen der Chemie,  562, pages 75 to 136, (1949) for example, those corresponding to the following formula:  
     OCN—R—NCO  
     [0035] wherein R represents a difunctional aliphatic, cycloaliphatic, aromatic, or araliphatic radical having from about 4 to 25 carbon atoms, preferably 4 to 15 carbon atoms, and free of any group which can react with isocyanate groups. Exemplary diisocyantes include, but are not limited to, toluene diisocyanate; 1,4-tetramethylene diisocyanate; 1,4-hexamethylene diisocyanate; 1,6-hexamethylene diisocyanate; 1,12-dodecane diisocyante; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane; 2,4-hexahydrotolylene diisocyanate; 2,6-hexahydrotolylene diisocyanate; 2,6-hexahydro-1,3-phenylene diisocyanate; 2,6-hexahydro-1,4-phenylene diisocyanate; per-hydro-2,4′-diphenyl methane diisocyanate; per-hydro-4,4′-diphenyl methane diisocyanate; 1,3-phenylene diisocyanate; 1,4-phenylene diisocyanate; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanates; diphenyl methane-2,4′-diisocyanate; diphenyl methane-4,4′-diisocyanate; naphthalene-1,5-diisocyanate; 1,3-xylylene diisocyanate; 1,4-xylylene diisocyanate; 4,4′-methylene-bis(cyclohexyl isocyanate); 4,4′-isopropyl-bis-(cyclohexyl isocyanate); 1,4-cyclohexyl diisocyanate; 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI); 1-methyoxy-2,4-phenylene diisocyanate; 1-chloropyhenyl-2,4-diisocyante; p-(1-isocyanatoethyl)-phenyl isocyanate; m-(3-isocyanatobutyl)-phenyl isocyanate; and 4-(2-isocyanate-cyclohexyl-methyl)-phenyl isocyanate. Mixtures of any of the above may be employed. When deemed appropriate, a diisocyante may be employed which contains other functional groups such as hydroxy or amino functionality.  
     [0036] In the reaction involving the component containing active hydrogens and the diisocyanate, it is preferred to employ a catalyst. A number of catalysts known to the skilled artisan may be used for this purpose. Such catalysts include, but are not limited to, an organo tin catalyst such as dibutyl tin diacetate, dibutyl tin di-2-ethylhexoate, dibutyl tin dilaurate, dibutyl tin oxide, and the like. Tertiary amines, such as triethyl amine, tributylamine, triethylene-diamine tripropylamine, and the like may also be used. Mixtures of the above catalysts may be used. The catalyst may be used in various suitable amounts, preferably between about 0.005 and about 0.50 percent based on the weight of the component containing active hydrogens and the diisocyanate.  
     [0037] The reaction between the component containing reactive hydrogens and the diisocyanate forms a isocyanate-containing intermediate. The isocyanate-containing intermediate is then reacted with any of the diisocyantes described herein to form a poly-carbodiimide. The latter reaction described above is preferably carried out in the presence of a catalyst. Suitable catalysts which may be used include, for example, those described in U.S. Pat. No. 5,008,363; the disclosure of which is incorporated herein by reference in its entirety. Particularly useful classes of carbodiimide-forming catalysts are the phospholene-1-oxides and phospholene-1-sulfides. Representative compounds within these classes are triphenyl phosphine; 3-methyl-1-phenyl-3-phospholine 1-oxide; 1-ethyl-phenyl-3-phospholine 1-oxide; 3-(4-methyl-3-pentynyl)-1-phenyl-3-phospholine 1-oxide; 3-chloro-1-phenyl-3-phospholine 1-oxide; 1,3-diphenyl-3-phospholine 1-oxide; 1-ethyl-3-phospholine 1-sulfide; 1-phenyl-3-phospholine 1-sulfide; and 2-phenyliso-phosphindoline 2-oxide; 1-phenyl-2-phospholene 1-oxide; 3-methyl-phenyl-2-phospholene 1-oxide; 1-phenyl-2-phospholene 1-sulfide; 1-ethyl-2-phospholene 1-oxide; 1-ethyl-3-methyl-2-phospholene 1-oxide; and 1-ethyl-3-methyl-2-phospholene 1-oxide. Other isomeric phospholenes corresponding to all the above-named compounds also can be used. Mixtures of any of the above may be used. The catalyst may be used in various suitable amounts, preferably from about 0.005 to about 10 percent based on the weight of the reactants, more preferably from about 0.02 to about 5 weight percent, and most preferably from about 0.03 to about 2 weight percent.  
     [0038] A vinyl monomer may also be included as a diluent with the polycarbodiimide and the unsaturated and saturated resins. Suitable monomers may include those such as, for example, styrene and styrene derivatives such as alpha-methyl styrene, p-methyl styrene, divinyl benzene, divinyl toluene, ethyl styrene, vinyl toluene, tert-butyl styrene, monochloro styrene, dichloro styrene, vinyl benzyl chloride, fluorostyrene, and alkoxystyrenes (e.g., paramethoxy styrene). Also, toluene, xylene, chlorobenzene, chloroform, tetrahydrofuran, ethyl acetate, isopropyl acetate, butyl acetate, butyl phthalate, acetone, methyl cellosolve acetate, cellosolve acetate, butyl cellosolve, methyl ethyl ketone, diethyl ketone, and cyclohexanone may be used. Other monomers which may be used include, for example, diallyl phthalate, hexyl acrylate, octyl acrylate, octyl methacrylate, diallyl itaconate, diallyl maleate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and mixtures thereof.  
     [0039] Any suitable polyfunctional acrylate may be used in the resin composition, including those described, for example, in U.S. Pat. No. 4,916,023 to Kawabata et al., the disclosure of which is incorporated by reference herein in its entirety. Such compounds include ethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane triacrylate, trimethylolmethane tetramethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, ethoxylated polyhydric phenol diacrylates and dimethacrylates containing from 1 to 30 ethylene oxide units per OH group in the phenol, propoxylated polyhyric phenol diacrylates and dimethacrylates containing from 1 to 30 propylene oxide groups per OH groups in the phenol. Examples of some useful di-and polyhydric phenols include catechol; resorcinol; hydroquinone; 4,4′-biphenol; 4,4′-ispropylidenebis(o-cresol); 4,4′-isopropylidenebis(2-phenyl phenol); alkylidenediphenols such as bisphenol “A”; pyrogallol; phloroglucinol; naphthalene diols; phenol; formaldehyde resins; resorcinol/formaldehyde resins; and phenol/resorcinol formaldehyde resins. Mixtures of the above di-and polyacrylates may also be employed.  
     [0040] The vinyl monomers and polyfunctional acrylates may be used in varying amounts, preferably from about 20 to 50 based on the weight of the components which may be dissolved therein, and more preferably from about 30 to 45 weight percent.  
     [0041] The method of thickening a resin may be carried out using known equipment. Typically, for example, a resin containing active hydrogens is placed in a vessel, mixing tank, or other reactor along with a catalyst that will be mixed for a period lasting from about 5 to about 20 minutes. Subsequently, a polycarbodiimide which is present (typically dissolved) in an organic diluent is added to the above resin and is allowed to mix therein for a period lasting typically from about 3 to about 15 minutes. In general, the reactive mixture of resin containing active hydrogens and polycarbodiimide is applied to a surface of a substrate and the resin containing active hydrogens and the polycarbodiimide become chemically bound. An alternative way of mixing the resin containing active hydrogens and the polycarbodiimide may be accomplished by using a self balancing internal mix chopper system made commercially available from Magnum Industries from Clearwater, Fla.  
     [0042] The reactive mixture includes an initiator to facilitate curing of the chemically bound resin and polycarbodiimide. The initiator is typically added to the reactive mixture prior to the thickening of the resin. An example of an initiator is an organic peroxide compound. Exemplary organic peroxides that may be used include, for example, cumene hydroperoxide; methyl ethyl ketone peroxide; benzoyl peroxide; acetyl peroxide; 2,5-dimethylhexane-2,5-dihydroperoxide; tert-butyl peroxybenzoate; di-tert-butyl perphthalate; dicumyl peroxide; 2,5-dimethyl-2,5-bix(tert-butylperoxide)hexane; 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne; bix(tert-butylperoxyisopropyl)benzene; ditert-butyl peroxide; 1,1-di(tert-amylperoxy)-cyclohexane; 1,1-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane; 1,1-di-(tert-butylperoxy)-cyclohexane; 2,2-di-(tert-butylperoxy)butane; n-butyl-4,4-di(tert-butylperoxy butylperoxy)valerate; ethyl-3,3-di-(tert-amylperoxy)butyrate; ethyl-3,3-di(tert-butylperoxy)-butyrate; t-butyl peroxy-neodecanoate; di-(4-5-butyl-cyclohexyl)-peroxydicarbonate; lauryl peroxyde; 2,5-dimethyl-2,5-bis(2-ethyl-hexanoyl peroxy) hexane; t-amyl peroxy-2-ethylhexanoate; 2,2′-azobis(2-methylpropionitrile); 2,2′-azobis(2,4-methlbutanenitrile); and the like. Mixtures of any of the above may be used. The initiator is preferably employed in an amount from about 1 to 2.5 percent based on the weight of the thickened resin, more preferably from about 1 to 1.5 percent by weight, and most preferably from about 1 to 1.25 percent by weight.  
     [0043] Suitable initiators used in curing the thickened resin may also encompass photoinitiators which may be activated upon exposure to a source of energy such as infrared, visible, or ultraviolet radiation. Examples of suitable photoinitiators include, but are not limited to, an aliphatic or aromatic diketone and a reducing agent (e.g., benzil and dimethyl benzyl amine); vicinal polyketaldonyl compounds (e.g., diacetyl benzil and benzil ketal); a-carbonyl alcohols (e.g., benzoin); acyloin ethers (e.g., benzoin methyl ether); polynuclear quinones (e.g., 9,10-antraquinone), and benzophenone. Preferably, the amount of photoinitiator ranges from about 0.005 to 5 percent based on the weight of the thickened resin. Suitable commercial photoinitiators include those available from Ciba-Geigy Corporation sold under the tradenames Irgacure 500, Irgacure 369, Irgacure 1700, Darocur 4265, and Irgacure 819. It should be appreciated that other commercial photoinitiators may be used for the purposes of the invention.  
     [0044] Suitable curing accelerators or promoters may also be used and include, for example, cobalt naphthanate, cobalt octoate, N,N-dimethyl aniline, N,N-dimethyl acetamide, and N,Ndimethyl p-toluidine. Mixtures of the above may be used. The curing accelerators or promoters are preferably employed in amounts from about 0.05 to about 1.0 percent by weight, more preferably from about 0.1 to 0.5 percent by weight, and most preferably from about 0.1 to 0.3 percent by weight of the thickened resin.  
     [0045] Additional additives known by the skilled artisan may be employed in the thickened resin composition of the present invention including, for example, paraffins, fatty acids, fatty acid derivatives, lubricants, and shrink-reducing additives. Various percentages of these additives can be used in the resin composition.  
     [0046] As recited herein, the invention relates to a method of lining the surfaces of substrates. For the purposes of the invention, the term “surfaces” is to be broadly construed and includes, but is not limited to, those which are typically exposed to conditions which may cause damage such as temperature fluctuations, earth movement, and the like. The substrates may be formed from a number of materials such as, but not limited to, concrete, metals, polymeric composites, and mixtures thereof. Flat and contoured surfaces may be encompassed within the scope of the invention. In one embodiment, the invention relates to lining a surface which forms a conduit. The term “conduit” is to be broadly interpreted and includes, for example, pipes. One example involves the lining of a surface which forms a conduit as described in U.S. Pat. No. 4,009,063 to Wood, the disclosure of which is incorporated herein by reference in its entirety.  
     [0047] In general, the resin may be applied to the conduit surface using any of the known and accepted techniques. For the purposes of the invention, the term “lining” substrate surfaces should be construed broadly, and includes employing the resin alone or in conjunction with other materials. For example, as illustrated in FIG. 1, the resin may be inserted into a tube denoted by  10 . The tube depicted in this instance is defined by an outer membrane  30  and an inner membrane  40  which may contain conventional fibrous reinforcement materials such as, but not limited to, fiberglass, polyester, carbon, metal, high modulus organic fibers (e.g., aromatic polyamides, polybenzimidazoles, and aromatic polyimides), other organic fibers (e.g., polyethylene, liquid crystals, and nylon), and natural fibers. The tube  10  may be constructed out of any of a number of appropriate materials known to one skilled in the art including suitable polymeric materials, and is fabricated by conventional methods. As discussed below, since the tube  10  is made to conform to the shape and size of the conduit  20  as illustrated in FIG. 2, it is desirable that the outer membrane  30  be formed from materials which possess a certain degree of elasticity. Examples of suitable materials include, but are not limited to, polyethylene, polyvinylchloride, rubber, cellophane nitrate, neoprene, and polyester film. The dimensions of the tube may be configured in a manner such that the tube fits within a variety of conduits.  
     [0048] The reactive mixture may be inserted into the tube  10  using known procedures, typically involving the impregnation of membrane  40 . The insertion of the reactive mixture typically taking place prior to placing the tube  10  in conduit  20 . For example, the reactive mixture may be pumped or injected into tube  10  through one end or at puncture ports located at several intervals along the tube  10 . Additional materials may be present along with the reactive mixture in tube  10 . Specifically, tube  10  may include those materials which are typically used in conjunction with resins such as, for example, fibrous reinforcement material, woven and nonwoven fibrous sheets or mats, fillers, fire retardants, colorants, and the like. The selection of these materials is known to one who is skilled in the art.  
     [0049] At this point, the reactive mixture is a viscous material in tube  10 , and it is allowed to thicken for 1 to 24 hours or longer to become a gel-like substance which remains flexible. Preferably, the process occurs between about 5° C. and about 60° C., and more preferably between about 10° C. and about 35° C. Tube  10  remains flexible and can allow for good control for its insertion into conduit  20 .  
     [0050] The insertion of tube  10  into conduit  20  may be carried out using various techniques. For example, as shown in FIG. 2, the tube  10  may be drawn into the conduit  20  and expanded or inflated by air pressure such that it fills conduit channel  50  and conforms to the shape of conduit  20 . In another embodiment, illustrated in FIG. 3, the tube  10  may be inverted during insertion into the conduit  20  using, for example, water pressure. As a result, the inner membrane  40  may contact the inner surface of conduit  20 . Moreover, the tube  10  may be inserted by employing an approach which combines both of the above methods. As shown in FIG. 4, a tube  10  is drawn into the conduit  20 . Next, a second tube  10 ′ which contains a thin inner membrane  40  is inverted into the first tube  10  which is drawn into conduit  20  as described herein above.  
     [0051] The curing of the thickened resin which is present in tube  10  contained in conduit  20  may occur using known techniques. For example, hot air, hot water, or other means such as electricity, radiation, and the like may be employed. The temperature under Which the curing takes place preferably ranges from about 40° C. to about 150° C. The cured crosslinked resin material serves to line the conduit  20 . In addition to the tube described above, it should be noted that other tubes, membranes, and the like may be utilized in conjunction with tube  10  to form a multi-layer composite liner structure within conduit  20 .  
     [0052] The following examples are provided to illustrate the present invention, and should not be construed as limiting thereof.  
     EXAMPLES 1-20  
     Polycarbodiimide Preparation Using a Neat Preparation  
     [0053] Examples 1-20 represent polycarbodiimides prepared by using a neat preparation which is described herein below. Table 1 lists the compositions for the polycarbodiimides.  
     [0054] Toluene diisocyanate is placed in a reactor and n-butanol is added at a rate to maintain the reaction temperature below 120° C. The temperature is then increased to 120° C. and maintained for thirty minutes to complete the first step of the reaction. Next, a carbodiimide forming catalyst, 3-methyl-1-phenyl-2-phospholene-1-oxide, is added and the reaction is continued at 140° C. to complete the second step of the reaction. Once a small amount of unreacted isocyanate groups remain, as detected by infrared spectroscopy, a second charge of n-butanol is added to the reaction mixture. After 15 to 60 minutes, when no unreacted isocyanate groups are detected, the temperature is decreased to 100° C. Styrene containing an inhibitor is then added. The reaction is cooled continuously until room temperature is reached, thus completing the reaction.  
     [0055] Table 2 describes the resulting molecular weights (Mn and Mw) and polydispersity (D) for these examples as measured by gel permeation chromatography. Also listed are the viscosities determined by a Brookfield viscometer (LVF #3 spindle at 30 rpm) and percent solids.  
     EXAMPLES 21 THROUGH 27  
     Polycarbodiimide Preparation in the Presence of Styrene  
     [0056] Examples 21-27 are polycarbodiimides which are prepared in the presence of styrene. Specifically, toluene diisocyanate, styrene, and p-benzoquinone are placed in a reactor, and n-butanol is added at a rate to maintain a reaction temperature below 120° C. The temperature is then increased to 120° C. and maintained for thirty minutes to complete the first step of the reaction. Next, a carbodiimide forming catalyst, 3-methyl-1-phenyl-2-phospholene-1-oxide, is added and the reaction is continued at 140° C. to complete the second step of the reaction. Once a small amount of unreacted isocyanate groups remain, as detected by infrared spectroscopy, a second charge of n-butanol is added to the reaction. After 15 to 60 minutes, when no more unreacted isocyanate groups are detected, the temperature is decreased to 100° C. and additional styrene is added to the reaction. The reaction is cooled continuously until room temperature is reached, and thus completing the reaction.  
     [0057] Table 3 describes the resulting molecular weights (Mn and Mw) and polydispersity (D) as measured by gel permeation chromatography. Also listed are the viscosities determined by a Brookfield viscometer (LVF #3 spindle at 30 rpm) and percent solids.  
     [0058] Resins Thickened Using Polycarbodiimides  
     [0059] Described below are resins which have been thickened using the polycarbodiimides referred to above. All resins are available from Reichhold Chemicals, Inc., Durham, N.C.  
     [0060] The resins are as follows. DION® 6694 is a corrosion resistant modified bisphenol fumarate. Polylite® 31612 types are unsaturated polyesters containing propylene glycol and maleic anhydride. Polylite® 31013-00 contains 2-methyl-1,3-propanediol, ethylene glycol, terephthalic acid, and maleic anhydride. Polylite® 31830-00 is an unsaturated polyester containing diethylene glycol, adipic acid, isophthalic acid and maleic anhydride. Polylite® 31506-00 is an unsaturated polyester containing propylene glycol, isophthalic acid, terephthalic acid, and maleic anhydride.  
     [0061] The following catalysts are used in the curing process. Superox® 46744 is a pourable, pumpable BPO dispersion available from Reichhold Chemicals, Inc., Durham, N.C. Trigonox® 21 is a t-butyl peroxy-2-ethylhexanoate catalyst available from Akzo Chemicals, Inc., Chicago, Ill.  
     [0062] The procedure for thickening a resin begins by placing an unsaturated polyester in a container and mixing a catalyst with the resin for five to ten minutes. The polycarbodiimide is then added and mixed for one minute. The percentage of polycarbodiimide used can be varied to achieve the desired viscosity at the required time interval. Viscosities in the following tables are measured with a Brookfield viscometer RVF#4 at 10 rpm if the reported viscosity is below 20,000 cps and with a Brookfield viscometer HBT TC spindle at 1 rpm for viscosities exceeding 20,000 cps.  
     [0063] Description of Data  
     [0064] Table 4 illustrates the chemical thickening profile of DION® 6694 using the polycarbodiimide described in Example 18. A general procedure to line a pipe is described below. FIGS. 1 and 3 illustrate the lining of the pipe. In one embodiment, unsaturated polyester resin Don® 6694 is mixed with Superox® 46744 for about 10 minutes and then the polycarbodiimide described in Example 18 is added in the amount described in Table 4. The reactive mixture is pumped into tube  10  through one end or at several puncture ports located along tube  10 . The reactive mixture is allowed to thicken for 24 hours at room temperature to become a gel-like substance that remains flexible to allow for good control during insertion into conduit  20 . As shown in FIG. 3, tube  10  is inverted during insertion into conduit  20  by using water pressure. As a result, inner membrane  40  is forced inside-out and contacts the inner surface of conduit  20 . After inversion of tube  10 , one of the ends is sealed so that water remains in the inner portion of the tube. The temperature of the water is then gradually increased to about 90° C. for about 1 to about 4 hours. At the end of this period, the impregnated tube  10  becomes a hardened material lining conduit 20.  
     [0065] Table 5 illustrates the chemical thickening profiles of Polylite® 31612 types using two different polycarbodiimide concentrations: (1) 8 weight percent of Example 10 and (2) 10 weight percent of Example 26. Table 6 illustrates the chemical thickening profiles of Polylite® 31013-000 at two different polycarbodiimide concentrations: (1) 8 weight percent of Example 3 and (2) 10 weight percent of Example 9. Table 7 illustrates the chemical thickening profiles for Polylite® 31013-00 and Polylite® 31830-00 blend, 75/25 weight percent respectively, using 8 weight percent of polycarbodiimides prepared in (1) Example 10 and (2) Example 18.  
     [0066] Table 8 illustrates two hour chemical thickening profiles using Polylite® 31506-00 with polycarbodiimides described in Examples 3, 4, 6, and 7. Table 9 illustrates chemical thickening profiles using Polylite® 31506-00 with polycarbodiimides described in Examples 3, 4, 5, 8, 9, 16, 17, 19, and 20. Table 10 illustrates chemical thickening profiles for Polylite® 31506-00 containing styrene-prepared polycarbodiimides described in Examples 21 and 25. Table 11 illustrates the effect of polycarbodiimide concentration on the chemical thickening profile using Polylite® 31506-00 with the polycarbodiimide prepared in Example 9. Table 12 illustrates batch-to-batch variation with polycarbodiimides prepared in Examples 7 and 18 and two batches of Polylite® 31506-00: A and B. Table 13 details the effect of temperature on the chemical thickening profile of Polylite® 31506-00 and the polycarbodiiumide prepared in Example 8.  
     [0067] Comparison of Chemical Thickening Processes  
     [0068] Table 14 compares four different chemical thickening systems. The polycarbodiimide system according to the invention was prepared by mixing 2 g of Superox® 46744 with 180 g of Polylite® 31612-10 for two minutes. The polycarbodiimide prepared in Example 18 was then added in the amount of 20 g and mixed for one minute.  
     [0069] A magnesium oxide system was prepared by mixing 2 g of Superox® 46744 with 200 g Polylite® 31612-10 for two minutes. Maglite D® (C. P. Hall Company, Chicago, Ill.) in the amount of 8 g was then added and mixed for one minute.  
     [0070] A combination magnesium oxide and polycarbodiimide system was prepared by mixing 2 g of Superox® 46744 with 190 g of Polylite® 31612-10 for two minutes. Maglite D® was then added in the amount of 6 g as well as 10 g of Example 18. The material was mixed for one minute.  
     [0071] A Rubinate M® (ICI, Sterling Heights, Mich.) system was made by mixing 2 g of Superox® 46744 with 200 g of Polylite® 31612-10 for two minutes. Rubinate M® in the amount of 10 g and 1 g of dibutyl tin dilaurate were added and mixed for one minute.  
               TABLE 1                          General Polycarbodiimide Production                             Total Charge Weight Percent                             Raw Material   Neat Preparation   Sytrene Preparation                                 Toluene diisocyanate   48.78   48.78       Styrene   0   20.00       p-benzoquinone   0.0112-0.0300   0.0300       n-butanol   13.835   13.835       Phospholene oxide*   0.03-0.05   0.03-0.05       Sytrene   37.31-37.34   17.31-17.33                          
 
     [0072]               TBALE 2                          Polycarbodiimide Production       Neat Preparation                                     Physical               Molecular   Properties   n-Butanol Charge                                         Weight Data   Viscosi-   Percent   Percent   Percent                                             Example   Mn   Mw   D   ty cps   Solids   1 st  Add   2 nd  Add                                                      1   1570   23600   15   260   58.1   86.7   13.3        2   1650   30300   18   310   57.6   86.7   13.3        3   1460   14400   10   364   57.1   86.7   13.3        4   1440   13100   9   324   57.5   86.7   13.3        5   1430   10500   7.4   204   56.2   86.7   13.3        6   1370   11500   8.4   420   57.4   95   5        7   1210   7240   6.0   224   57.2   97.5   2.5        8   1110   4280   3.8   180   58.6   98.5   1.5        9   1210   5780   4.8   228   59.2   97.5   2.5       10   1500   9200   6.1   320   59.2   97.5   2.5       11   1270   6310   5   328   59.6   97.5   2.5       12   1290   5960   4.6   284   59.5   97.5   2.5       13   1210   5070   4.2   260   59.8   97.5   2.5       14   1210   5040   4.2   280   59.2   97.5   2.5       15   1170   4370   3.7   240   59.5   97.5   2.5        16*   1190   5040   4.2   380   59.4   97.5   2.5       17   1420   9420   6.6   480   59.4   97.5   2.5       18   1440   9230   6.4   560   59.2   97.5   2.5       19   1200   4680   3.9   344   58.5   97.5   2.5       20   1200   5800   4.8   440   58.6   97.5   2.5                            
     [0073]               TABLE 3                          Polycarbodiimide Production       Styrene Preparation                                     Physical               Molecular   Properties   n-Butanol Charge                                         Weight Data   Viscosi-   Percent   Percent   Percent                                             Example   Mn   Mw   D   ty cps   Solids   1 st  Add   2 nd  Add                                                     21   1170   4630   3.9   268   60.2   90   10       22   1350   10400   7.7   344   61.6   90   10       23   1470   14500   9.9   400   61.4   90   10       24   1530   15600   10   432   60.4   90   10       25   1230   5490   4.5   392   60.9   100   0       26   1100   5620   5.1   336   59.8   98.5   1.5       27   1140   5640   5   480   61.3   98   2                    
     [0074]               TABLE 4                       Chemical Thickening Profile       DION ® 6694                                                Blend Component   Weight Percent                       6694   92           Example 18   8           Superox ® 46744   1 g/100 g mix                           Viscosity           Time from Mixing Minutes   cps                       0   1000           15   1660           30   3120           45   6640           60   14400           90   1.44 × 10 6             120   2.08 × 10 6             24 hours   3.86 × 10 6                               Gel Time Data                                     Gel time at 90° C.   29.5 min           Peak exotherm   205.7° C.           Total time to peak   47.4 min                        
     [0075]               TABLE 5                       Chemical Thickening Profiles       Polylite ® 31612 Types                                                Blend Component   Weight Percent                       31612-10   92           Example 10   8           Trigonox ® 21   1 g/100 g mix                           Viscosity           Time from Mixing Minutes   cps                       0   1200           15   2150           30   3300           45   4600           60   5700           90   7700           120   9100           150   10400           180   10800           24 hours   13140                             Gel Time Data                                     Gel time at 90° C.   6.8 min           Peak exotherm   221.0° C.           Total time to peak   9.0 min                       Blend Component   Weight Percent                       31612-25   90           Example 26   10                           Viscosity           Time from Mixing Minutes   cps                       0   3600           2   4480           4   5240           6   6310           8   7770           10   9620           15   19400           20   30000           25   70000           45   6.44 × 10 6             120   6.72 × 10 6                          
     [0076]               TABLE 6                       Chemical Thickening Profiles       Polylite ® 31013-00                                                Blend Component   Weight Percent                       31013-00   69           Styrene   23           Example 3   8                           Viscosity           Time from Mixing Minutes   cps                       0   500           2   540           4   600           6   660           8   720           10   800           15   1000           20   1200           25   1440           30   1640           45   2420           60   3280           70   3880           80   4500           90   5280           100   5940           110   6500           120   6920           270   12320           360   15660                       Blend Component   Weight Percent                       31013-00   67.5           Styrene   22.5           Example 9   10                           Viscosity           Time from Mixing Minutes   cps                       0   740           15   1200           30   2000           45   2880           60   4560           90   8040           120   14300           20 hours   1.96 × 10 6                          
     [0077]               TABLE 7                       Chemical Thickening Profiles       Polylite ® 31013-00 and Polylite ® 31830-00 Blend                                                Blend Component   Weight Percent                       31013-00   69           31830-00   23           Example 10   8           Trigonox ® 21   1 g/100 g mix                           Viscosity           Time from Mixing Minutes   cps                       0   760           15   1100           30   1500           45   1960           60   2480           90   3340           120   4160           24 hours   8540                             Gel Time Data                                     Gel Time at 90° C.   6.3 min           Peak exotherm   236.7° C.           Total time to peak   15.7 min                       Blend Component   Weight Percent                       31013-00   69           31830-00   23           Example 18   8                           Viscosity           Time from Mixing Minutes   cps                       0   980           15   1540           30   2260           45   3280           60   4060           90   5580           120   6860           24 hours   13200                        
     [0078]               TABLE 8                       Chemical Thickening Profiles       Polylite ® 31506-00                                                        Weight   Weight   Weight   Weight       Blend Component   Percent   Percent   Percent   Percent               31506-00   92   92   92   92       Polycarbodiimide   8   8   8   8       Polycarbodiimide   Example 3   Example 4   Example 6   Example 7               Time from Mixing   Viscosity   Viscosity   Viscosity   Viscosity       Minutes   cps   cps   cps   cps               0   900   850   700   700       2   980   920   800   800       4   1080   1020   850   800       6   1160   1060   900   800       8   1260   1200   1000   825       10   1360   1300   1000   850       15   1700   1600   1150   1100       20   2240   2120   1350   1200       25   3080   2600   1600   1400       30   4280   3450   18000   1600       40   7020   6300   —   —       45   —   —   300   2400       50   240000   50000   —   —       60   1.12 × 10 6     1.44 × 10 6     5150   3650       70   1.96 × 10 6     2.16 × 10 6     7400   4800       80   2.48 × 10 6     2.60 × 10 6     10950   7200       90   3.08 × 10 6     2.92 × 10 6     &gt;100000   8600       120   4.40 × 10 6     4.12 × 10 6     —   —                    
     [0079]               TABLE 9                          Chemical Thickening Profiles       Polylite ® 31506-00                                         Weight   Weight   Weight   Weight   Weight       Blend Component   Percent   Percent   Percent   Percent   Percent               31506-00   92   92   92   92   92       Polycarbodiimide   8   8   8   8   8       Polycarbodiimide   Example 3   Example 4   Example 5   Example 8   Example 9       Time from Mixing   Viscosity   Viscosity   Viscosity   Viscosity   Viscosity       Minutes   cps   cps   cps   cps   cps       0   —   —   —   700   700       15   1640   1686   1608   1080   1060       30   10   3390   2780   1760   1640       45   —   —   —   2560   2620       60   100000   1.34 × 10 6     42400   3660   4020       75   —   —   —   5940   5800       90   2.40 × 10 6     4.00 × 10 6     2.40 × 10 6     8720   11560       120   —   —   —   40000   120000       150   4.00 × 10 6     5.20 × 10 6     4.08 × 10 6     1.28 × 10 6     1.80 × 10 6         24 Hours   6.70 × 10 6     6.20 × 10 6     8.60 × 10 6     4.84 × 10 6     5.52 × 10 6                                               Weight   Weight   Weight   Weight       Blend Component   Percent   Percent   Percent   Percent               31506-00   92   92   92   92       Polycarbodiimide   8   8   8   8       Polycarbodiimide   Example 16   Example 17   Example 19   Example 20       Time from Mixing   Viscosity   Viscosity   Viscosity   Viscosity       Minutes   cps   cps   cps   cps       0   780   720   750   700       15   1000   1040   1000   1000       30   1260   1460   1400   1500       45   1740   1940   1900   2000       60   2200   2600   2450   2800       90   3280   4320   4200   4100       120   4600   6300   5500   4800       150   —   10780   —   —       24 Hours   1.00 × 10 6     1.48 × 10 6     2.40 × 10 6     2.88 × 10 6                      
     [0080]               TABLE 10                       Chemical Thickening Profiles: Styrene Preparations       Polylite ® 31506-00                                            Blend Component   Weight Percent   Weight Percent               31506-0   92   92       Polycarbodiimide   8   8       Polycarbodiimide   Example 21   Example 25               Time from Mixing Minutes   Viscosity cps   Viscosity cps               0   760   860       2   840   900       4   880   940       6   920   980       8   1000   1020       10   1060   1060       15   1300   1200       20   1600   1380       25   1860   1520       30   2500   1720       45   4780   2460       60   12800   3240       70   0.48 × 10 6     4740       80   2.84 × 10 6     5620       90   4.16 × 10 6     7540       120   —   16000       240   6.64 × 10 6     —       24 Hours   —   3.76 × 10 6                      
     [0081]               TABLE 11                       Chemical Thickening Profiles: Effect of       Polycarbodiimide Concentration                                                        Weight   Weight   Weight   Weight       Blend Component   Percent   Percent   Percent   Percent               31506-00   96   95   94   93       Example 9   4   5   6   7               Time from Mixing   Viscosity   Viscosity   Viscosity   Viscosity       Minutes   cps   cps   cps   cps               0   700   640   660   700       15   900   940   1120   1300       30   1200   1440   2100   3000       45   1600   2420   4360   120000       60   1900   3440   —   880000       90   2800   8260   1.12 × 10 6     1.52 × 10 6         120   3800   80000   1.24 × 10 6     1.84 × 10 6                      
     [0082]               TABLE 12                       Chemical Thickening Profiles       Batch to Batch Variation                                                        Weight   Weight   Weight   Weight       Blend Component   Percent   Percent   Percent   Percent               31506-00   92   92   92   92       Polycarbodiimide   8   8   8   8                             Example 7   Example 18                                 31506-00 Batch   A   B   A   B               Times from Mixing   Viscosity   Viscosity   Viscosity   Viscosity       Minutes   cps   cps   cps   cps               0   800   1400   700   1560       15   1100   2150   1000   2880       30   1640   3550   1300   5460       45   2460   5600   1900   10240       60   4120   9600   2500   20000       90   8020   80000   3900   2.04 × 10 6         120   120000   2.04 × 10 6     5800   3.28 × 10 6         150   1.24 × 10 6     —   8200   —       24 hours   4.96 × 10 6     3.00 × 10 6     3.44 × 10 6     3.60 × 10 6                      
     [0083]               TABLE 13                       Chemical Thickening Profiles - Effect of Temperature                                                    Weight   Weight   Weight       Blend Component   Percent   Percent   Percent               31506-00   92   92   92       Example 8   8   8   8                   Viscosity   Viscosity   Viscosity           cps   cps   cps       Time from Mixing minutes   50° F.   77° F.   90° F.               0   600   600   600       15   1300   900   920       30   1700   1300   1400       45   2100   1900   2000       60   2600   2600   3700       90   3100   4000   6200       120   3800   5800   13600       150   4900   8600   80000       24 hours   1.16 × 10 6     1.14 × 10 6     0.68 × 10 6                      
     [0084]               TABLE 14                          Comparison of Chemical Thickening Processes                                     Weight   Weight   Weight   Weight       Blend Component   Percent   Percent   Percent   Percent                                         31612-10   90   100   95   100       Example 18   10   —   5   —       Maglite D   —   4 g/100 g   3 g/100 g   —               resin   mix       Rubinate M   —   —   —     5 g/100 g                       resin       Dibutyl tin   —   —   —   0.5 g/100 g       dilaurate               resin       Superox ® 46744   1 g/100 g   1 g/100 g   1 g/100 g     1 g/100 g           mix   resin   mix       Time from Mixing   Viscosity   Viscosity   Viscosity   Viscosity       Minutes   Cps   Cps   Cps   Cps       0   800   1140   900   620       15   1200   1140   1800   740       30   2400   1200   2500   980       45   4600   1200   3100   1300       60   5700   1460   41000   1920       60   5700   1460   4000   1920       90   7700   2480   6300   3720       120   9100   5200   10400   8380       24 hours   4.22 × 10 6     3.84 × 10 6     3.20 × 10 6     7.60 × 10 6                   Gel Time Data                                 Gel time at 90° C.   18.1 min   14.6 min   13.2 min   15.0 min       Peak exotherm   215.9° C.   238.5° C.   226.4° C.   200.8° C.       Total time to   27.8 min   19.5 min   18.0 min   22.0 min       peak                    
     [0085] The invention has been described in detail with reference to its preferred embodiments and its examples. However, it will be apparent that numerous variations and modifications can be made without departure from the spirit and scope of the invention as described in the foregoing specification and claims.