Abstract: Linear aromatic polymeric species, particularly oligomers and polymers are produced under mild conditions in good yield by reacting an at least binuclear aromatic compound with an alkylidene bisphenol in the presence of a non C-alkylatable hydroxy substituted aromatic compound effective to stabilize a generated carbonium ion intermediate; the alkylidene bisphenol may be formed in situ from a ketone or aldehyde in the presence of a catalytic amount of a hydroxy substituted aromatic compound effective to generate a carbonium ion with the ketone or aldehyde; carrying out the reaction under reduced pressure, particularly high vacuum permits direct production of high polymers; the oligomers are useful in the manufacture of high molecular weight engineering or industrial plastics; the polymers may be used directly as such plastics.

Abstract: Amino resins, e.g., urea-formaldehyde and melamine-formaldehyde thermosetting resins, are cured with a latent catalyst which is a thermally-decomposable adduct of an aromatic sulfonic acid (e.g., p-toluene sulfonic acid) and a bicyclic oxazolidines (e.g., 1-aza-3,7-dioxa-5-ethylbicyclo (3.3.0) octane. The coating compositions can contain other conventional co-reactants, such as polyols, polyacids, alkyd resins, polyester resins, epoxies, acrylics and the like. Coatings containing the amino resin, co-reactant, and latent catalyst have an acceptable viscosity stability, cure rapidly at temperatures lower than some other latent catalysts, and produce films with no wrinkles.

Abstract: Moldings, in particular foams and fibers, based on melamine/formaldehyde condensation products, in which from 0.1 to 70 mol % of the melamine have been replaced by melamine substituted by from 1 to 3 hydroxyoxaalkyl groups of the formula--(CH.sub.2 --CH.sub.2 --O).sub.n --CH.sub.2 --CH.sub.2 --OHn=1-5)have increased elasticity.

Abstract: Spherical, hard mono- or oligodisperse particles of diameter from 0.1 to 100 .mu.m are prepared by condensation of partially etherified melamine-formaldehyde precondensates which form a clear solution in water in every ratio, in an aqueous solution of a water-soluble polymer which has strongly acid groups and a K value of from 100 to 160, at pH 3 to 6 and at 20.degree. to 100.degree. C., and condensation of the resulting cloudy solution is continued until the precondensate has been consumed, resulting in a dispersion of the particles. The dispersion is neutralized. The particles can be used in the form of the aqueous dispersion or after isolation from the dispersion.The particles are spherical, hard and non-swellable and can be used, for example, as sizes for plastics, polishes, delustrants, extruders and/or as pigment.The process makes it possible to produce particles of predetermined size and size distribution.

Abstract: An open chain poly Reissert can be formed by the initial reaction of an aromatic dialdehyde (e.g., terephthaldicaboxaldehyde) and ammonia or a primary amine (e.g., methylamine) to form a reaction product which is then reacted with an aliphatic acid chloride (e.g., adipoyl chloride).

Abstract: According to the present invention, spherical melamine resin particulates having a uniform particle size and crosslinked structure can be prepared by adding an acid catalyst to an aqueous solution containing at least 0.5 to less than 5% by weight of a melamine derivative which is polymerizable in the acid region, to adjust the pH of the aqueous solution to at least 4 to less than 5, and carrying out heat-treatment of the aqueous solution.The spherical melamine resin particulates thus obtained are useful as additives for coating compositions, pigments and other materials.

Abstract: The present invention relates to copolyethers comprising copolymers of 7,oxa-bicyclo(2,2,1)heptane, and its alkyl-derivatives, with one or more single-ring or condensed-rings cycloaliphatic ethers, comprising the characteristic group; ##STR1## wherein R' is hydrogen and R" is H, a halogen, or an alkyl radical containing a small number of carbon atoms, and which may also be halogen-substituted.If the ether contains one ring only, it contains from 5 to 12 atoms in the ring, and if it contains a condensed-ring system, it contains a total number of from 10 to 18 atoms in the rings.Those copolyethers show a anisotropic behaviour in the molten state, and therefore have liquid-crystal properties.

Abstract: A continuous preparation method of an amino resin particulate having a maximum particle size of 40 .mu.m or less and an average particle size of from 5 to 15 .mu.m is described. The method comprises the steps of reacting amino compounds with aldehydes in the presence of an acid catalyst in an aqueous solution to form a solid product and classifying said solid product in the form of a slurry with a combination of at least two grinders and at least two classifiers.

Abstract: Amino resin solutions having an electrical conductivity of <100 .mu.S/cm for impregnating paper are obtainable byA) methylolation of melamine with aqueous formaldehyde in a molar ratio of from 1:2 to 1:5 in the presence of a tertiary organic amine at a pH of from 7 to 12,B) etherification with a molar excess, based on the methylol groups, of a C.sub.1 -C.sub.4 -alcohol in the presence of an unsubstituted or substituted dicarboxylic acid and/or polycarboxylic acid at a pH of from 3 to 6,C) neutralization of the reaction mixture with an inorganic base and removal of the volatile components by distillation, except for a water content of <10% by weight, based on the reaction mixture, andD) addition of a C.sub.1 -C.sub.4 -alcohol to give a solids content of from 40 to 90% by weight, based on the amino resin solution, and removal of insoluble components by filtration.

Abstract: A process for producing a condensed resin dispersion, which comprises subjecting an aldehyde and a compound condensable with the aldehyde, or their precondensate, to a condensation reaction in a dispersion medium consisting essentially of water and/or an organic solvent, to precipitate fine condensed resin particles which hardly settle in said dispersion medium, and then replacing the water and/or the organic solvent by an active hydrogen-containing compound having at least two active hydrogen-containing groups reactive with isocyanate groups.

Abstract: Disclosed are cationic aqueous emulsions containing (a) sizing composition comprising the reaction product of melamine formaldehyde compound, long chain saturated alcohol and long chain saturated or unsaturated polyethoxylated alcohol; and (b) cationic surfactant. The emulsions when used to surface size paper impart improved oil, water and polar solvent resistance thereto. The emulsions may be used alone or as substantial replacements for anionic or non-ionic fluorocarbon based emulsions that are typically used to impart oil resistance to paper.

Abstract: A glue composition comprises a heat-hardenable resin, urea and possibly one or several glue additives, and is characterized by the presence of an additional gluing compound is polyol having a functionality of at least equal to three. This glue can be used for mineral fibers in the manufacture of insulation products having improved properties.

Abstract: Moulding compositions comprising(a) a melamine/formaldehyde resin, a melamine/phenol/formaldehyde resin or a mixture of said resins,(b) organic and/or inorganic fillers,(c) a lubricant, and(d) 0.1 to 2% by weight, based on the total composition, of 3-chloro-1,2-propanediol as latent hardener,are suitable for the production of mouldings by injection moulding. The latent hardener employed permits extremely short cycle times coupled with long residence times at the cylinder temperature of the injection moulding machine. The moulding compositions are distinguished at the same time by very good flow properties.

Abstract: A process for the preparation of a urea-formaldehyde resin exhibiting reduced gel time and improved stability, wherein the resin contains not more than 10% melamine, which is added during the first stage of the reaction with the other reactants, and wherein the reaction is conducted at an acidic pH.

Abstract: Electrically conducting polymer complexes, prepared from N-substituted carbazoles, p-acetoxylbenzaldehyde, and protic acids, are soluble in polar organic solvents giving conductive polymer solutions processable to stable conductive films, coatings, and sponges.

Abstract: The continuous preparation of melamine/formaldehyde precondensate solutions is carried out by a process in which melamine, formaldehyde and, if required, modifiers and/or additives are metered into a continuous mixer, and the homogeneous mixture is passed into a single-screw or twin-screw extruder, condensed at elevated temperatures, cooled and extruded.

Abstract: A process for producing oxymethylene copolymers and terpolymers is disclosed which involves the non-linear addition of gaseous formaldehyde to a cyclic ether having at least two adjacent carbon atoms (1) and, in the case of a terpolymer, to a mixture of at least one (1) and one monoethylenically unsaturated aliphatic diol formal having at least four carbon atoms in its main chain (2), or to a mixture of (1) with a (2), in the presence of a polymerization initiator at a rate controlled so as to conform to a rate determined by kinetic equations that describe the rate of decomposition of trioxane to formaldehyde during conventional copolymerization of trioxane with a cyclic ether. The process and kinetic equations of the invention are applicable to batch reactions, single stream continuous reactions and dual stream continuous reactions.

Abstract: The present invention provides an improved adhesive composition for wood gluing, comprising a formaldehyde condensation resin and a minor amount of a surface active agent. This invention further provides a method for manufacture of composite wood products comprising applying an adhesive composition, which includes a formaldehyde condensation resin and a small amount of a surface active agent, to the wood and curing the adhesive.

Abstract: Urea-formaldehyde resins which may be cured to give products having a low total extractable formaldehyde content are prepared by the following process:(i) an aqueous solution containing more than 50% formaldehyde and urea are mixed in a formaldehyde:urea molar ratio of 2-3:1 at pH 6-11,(ii) this mixture is heated to at least 80.degree. C.,(iii) a mineral or organic acid is added to bring the mixture to pH 0.5-3.5,(iv) the mixture is heated at a temperature between 80.degree. C. and the reflux temperature, preferably for 15 minutes to 1 hour,(v) keeping the temperature at or above 80.degree. C., a base is added to bring the mixture to pH 6.5-9 and(vi) urea is added to the mixture at a temperature up to 45.degree. C. until the formaldehyde:urea molar ratio is within the range 0.8-1.8:1.

Abstract: Urea-formaldehyde resins which may be cured to give products having a low total extractable formaldehyde content are prepared by the following process:(i) aqueous 30-50% formaldehyde and urea are mixed in a formaldehyde:urea molar ratio of 2-3:1 at pH 6-11,(ii) this mixture is heated to at least 50.degree. C., preferably to at least 80.degree. C.,(iii) a mineral or organic acid is added to bring the mixture to pH 0.5-3.5,(iv) the mixture is heated at a temperature between 80.degree. C. and the reflux temperature, preferably for 15 minutes to 1 hour,(v) keeping the temperature at or above 80.degree. C., a base is added to bring the mixture to pH 6.5-9 and(vi) urea is added until the formaldehyde:urea molar ratio is within the range 0.8-8:1.In a modification of the process, solid particulate resins are obtained by reacting the mixture from step (v) with urea at a pH below 7 to increase the viscosity thereof, adding a base until the mixture reaches a pH of 6.5-9 and dehydrating the resulting mixture.

Abstract: A wall board structure is formed of one of pulverized straw, pulverized chaff and pulverized palm material having a maximum dimension of from 1 to 3 mm. The pulverized material is mixed with a substantially equal quantity of clay. A fibrous material is added to the mixture, the fibrous material including one or more of palm material fibers, hemp fibers and shredded straw, the fibrous material having a length of from 3 to 5 cm. The mixture of pulverized material and clay and the added fibrous material is poured into a form and then dried. The form preferably includes means for forming one of recesses and through holes in the poured mixture.

Abstract: Polymers are provided that are useful for making biodegradable sustained release agent dispensers and which contain at least one of the following mer units (I) and (II) ##STR1## wherein X is a quadrivalent organic grouping, A and B are hydrogen or lower alkyl, and R is hydrocarbyl or oxyhydrocarbyl of 1 to 14 carbon atoms and, if oxyhydrocarbyl, containing 1 to 4 oxy groups, and may be either aliphatic or aryl, unsubstituted or substituted with one or more lower alkyl, amino, nitro or halogen moieties. Methods of synthesizing the novel polymers are also provided, as biodegradable beneficial agent dispensers prepared using the novel polymers.

Abstract: Acetal polymer and copolymer are prepared by polymerizing formaldehyde or its cyclic oligomer as a principal monomer, or copolymerizing the principal monomer with a comonomer copolymerizable therewith, using an isopoly acid or an acid salt thereof as a polymerization catalyst.

Abstract: An open chain poly Reissert can be formed by the initial reaction of an aromatic dialdehyde (e.g., terephthaldicaboxaldehyde) and primary amine (e.g., methylamine) to form a reaction product which is then reacted with an aliphatic acid chloride (e.g., adipoyl chloride).

Abstract: Moulding compositions comprising(a) a melamine/formaldehyde resin, a melamine/phenol/formaldehyde resin or a mixture of said resins,(b) organic and/or inorganic fillters,(c) a lubricant, and(d) 0.1 to 2% by weight, based on on the total composition, of 3-chloro-1,2-propanediol as latent hardener,are suitable for the production of mouldings by injection moulding. The latent hardener employed permits extremely short cycle times coupled with long residence times at the cylinder temperature of the injection moulding machine. The moulding compositions are distinguished at the same time by very good flow properties.

Abstract: Urea-aldehyde polycondensates usable as surface coating binders are obtainable by step-wise reaction of(a) urea and/or urea derivatives with acidic CH aldehydes in a molar ratio of urea:aldehyde of 1:2 in the presence of acids and at from 60.degree. to 120.degree. C. with(b) a mixture of 3 moles of formaldehyde per mole or urea and 3 moles of an acidic CH aldehyde per mole of urea at from 60.degree. to 120.degree. C. with subsequent removal of the water of reaction and treatment of the reaction mixture with an alkali metal alcoholate at from 80.degree. to 100.degree. C.

Abstract: Novel anionic polymeric hydrogels based on sulfonated amino aldehyde resins and a process for preparing such hydrogels are described. The hydrogels may include poly(N-vinyl 2-pyrrolidone) and other additives. Such hydrogels may be prepared by a four step process in which melamine and/or urea are reacted with formaldehyde, sulfonated, condensed to form a viscous gel and dried.

Abstract: The invention relates to polycycloacetals of formula I ##STR1## wherein n is an integer from 1 to 500, x and y are each independently of the other 0 or 1, R.sup.1 is a carbon atom or a tetravalent hydrocarbon radical having a molecular weight not greater than 1000 and which can additionally contain ether oxygen atoms or oxygen atoms in hydroxyl, carbonyl or epoxy groups, and R.sup.2 is a tetravalent hydrocarbon radical derived from a dialdehyde or a diketone.The polycycloacetals can be used together with conventional hardeners and/or curing catalysts for epoxy resins for the fabrication of cross-linked (cured) products having good properties, especially having excellent fastness to solvents, light and weathering.

Abstract: Cyclic formals, other than trioxane, form macromers with an olefinically unsaturated alcohol which functions as a propagating species to form a macromer of polyformal having a molecular weight generally less than about 10,000. A cationically ring-openable ether may be used to provide a polyether spacer in the alkenyl alcohol so that the macromer of polyformal formed contains a polyether block. Thus, the polyformal macromer may have a acryloyl, allyl, or styryl head group. Macromers of polyformal block copolymers are formed sequentially by first forming the block of first formal and then without isolating the macromer so formed, sequentially polymerizing a second formal monomer to form the second formal block. A macromer of randon copolymer may be formed with one or more cyclic formals or a cyclic ether. Macromers of random copolymers may also be formed with formaldehyde or trioxane.

Abstract: A new class of polyhydroxypolyamides is disclosed. The polyhydroxypolyamides, useful as fibers, plastics, coatings and adhesives, are characterizied by the repeating structural unit--CO--(CHOH).sub.x --CO--NHCH.sub.2 --(CR.sup.1 H).sub.y --CH.sub.2 NH].sub.nwhere R.sup.1 and R.sup.2 are the same or different and are hydrogen, C.sub.1 -C.sub.50 alkyl, C.sub.2 -C.sub.50 alkenyl or C.sub.7 -C.sub.50 aralkyl; x is an integer of 1 to 6; y and z are the same or different and are 0 or an integer of 1 to about 30; and n is an integer of at least about 10.A process for making these polyhydroxypolyamides is also taught. It includes the steps of reacting an aldaric compound, said compound selected from the group consisting of a diacid, an acid-lactone, a dilactone and mixtures thereof, with an alkanol to form an esterification product and forming the polyhydroxypolyamide by polymerizing the esterification product with a primary amine in a polar solvent.

Abstract: Cationic fixing agents based on the reaction products of(a) a monofunctional or polyfunctional amine having one or more primary and/or secondary and/or tertiary amino groups and(b) cyanamide, dicyandiamide, guanidine or bisguanidinegive improved results when the reaction takes place in the presence of a catalyst (K) selected from metals, metal salts and heterocyclic nitrogen-containing organic bases, particularly zinc chloride.

Abstract: A hydraulic cement composition is effectively dispersed with the use as a dispersion agent of a reaction product obtained by oxidizing and polymerizing a condensate of formaldehyde with a naphthalenesulfonic acid salt and/or an alkylnaphthalenesulfonic acid salt to produce a constitutional unit which is derived by elimination of a methylene group, hydroxyzation and condensation polmerization, or oxidation and ring-opening of the naphthalene ring.

Abstract: Polyurethane dispersions based on reaction products from (A) bismethylolated urethanes having at least 2 urethane groups and (B) polyhydroxyl compounds which contain groups which are capable of ion formation, these groups being present in neutralized form, and a process for the preparation thereof. The use of the dispersions for the surface-coating of metal, plastics, glass, leather and paper.

Abstract: Compositions comprising an oligomer which (a) comprises the repeating unit (AR - CHR), and where Ar is an aromatic group and R is hydrogen or a hydrocarbyl group of hydrogen, (b) has pendant and/or terminal groups which include inter alia acyloxymethyl, hydroxymethyl and carboxyl, and (c) has a functionality between 0.5 and 10, and processes for the preparation thereof are described. These compositions may be used in dental, electrical and electronic applications.

Abstract: Electroactive organic polymeric materials of poly(heterocycle diyl methylenes) containing alternating heterocyclic conjugated segments of varying sizes and methylene or substituted methylenes in the main chain and random copolymers of such poly(heterocycle diyl methylenes) together with a method of making them are disclosed.

Abstract: A highly reactive aromatic hydrocarbon-formaldehyde resin having a diarlymethane content of not more than 5% by weight, essentially containing reactive groups of any one of CH.sub.2 OH, CH.sub.2 OCH.sub.3 and CH.sub.2 OCH.sub.2 OCH.sub.3 at both molecular terminals and having a xylenol value of at least 15 mol/kg as an index of reactivity with a compound having active hydrogen atoms is prepared by reacting an aromatic hydrocarbon such as xylene, mesitylene or naphthalene with formaldehyde at a molar ratio of the formaldehyde to the aromatic hydrocarbon of 2.0 to 5.0, a sulfuric acid concentration of 15 to 35% by weight in an aqueous layer and a reaction temperature of 80.degree. to 110.degree. C. while controlling a formaldehyde conversion within a range of 50 to 70% by mole over the range 4 to 8 hours.

Abstract: A process for producing an oxymethylene copolymer by copolymerizing trioxane with at least one cyclic comonomer selected from the group consisting of cyclic ethers and cyclic formals, said process comprising(1) polymerizing trioxane alone or with a cyclic comonomer in the presence of a polymerization catalyst until the conversion of trioxane reaches 10 to 95%, and(2) thereafter adding a cyclic comonomer and a polymerization catalyst to the reaction system and continuing the polymerization.

Abstract: Tricarbocyanine polymeric dyes have formulae I and II: ##STR1## where Y can be ##STR2## --S--, --Se-- or --O--, A can be ##STR3## in which R.sup.19 can be alkyl or --Cl, and p can be 0 or 1, R.sup.6 and R.sup.7 independently can be alkyl of (C.sub.1 -C.sub.30), preferably (C.sub.1 -C.sub.18),R.sup.4 and R.sup.5 independently can be --H, C.sub.6 H.sub.5 SO.sub.2 --, or CF.sub.3 SO.sub.2 --,Z can be --SO.sub.2 --, --CH.sub.2).sub.m, or vinylene,W can be I.sup.-, Br.sup.-, Cl.sup.-, ClO.sub.4.sup.-, PECHS.sup.- (polyethylcyclohexylsulfonate), F.sub.3 CSO.sub.3.sup.- (trifluoromethanesulfonate), or other commonly used dye anions,m is an integer of 1 to 20, andn is an integer of 5 to 10,000.

Abstract: Furfuryl alcohol-formaldehyde resins which can be prepared by using a water soluble multivalent metal salt as the catalyst, thereby eliminating the use of an acid catalyst and the necessary attention it requires.

Abstract: Compositions comprising an oligomer which (a) comprises the repeating unit (Ar--CHR), and where Ar is an aromatic group and R is hydrogen or a hydrocarbyl group or hydrogen, (b) has pendant and/or terminal groups which include inter alia acyloxymethyl, hydroxymethyl and carboxyl, and (c) has a functionality between 0.5 and 10, and processes for the preparation thereof are described. These compositions may be used in dental, electrical and electronic applications.

Abstract: A process for modifying a polymer of a conjugated diene, which comprises reacting a polymer of a conjugated diene containing at least one metal selected from alkali metals and alkaline earth metals with a compound having a linkage of the following formula ##STR1## wherein X represents an oxygen or sulfur atom, in the molecule.

Abstract: The object of the present invention are new thermoset resins having quickened curing, a process for their preparation, and their applications. The resins according to the invention consist, at least in part, of the products resulting from the polycondensation of one or more pyridine derivatives containing at least two methyl groups in the 2, 4 or 6 positions, with one or more aromatic dialdehydes, and the addition of one or more additives consisting of phenol compounds. These resins are used to the fabrication of composite materials.

Abstract: Method of making environmentally stable conductive organic polymers synthesized from carbazole or N-substituted carbazoles and benzaldehyde or substituted benzaldehydes doped with charge transfer acceptors is disclosed.

Abstract: Thermoplastic or thermosettable products are prepared by reacting a heterocyclic compound containing at least one nitrogen atom and at least two pendant groups containing a reactive hydrogen atom attached to a carbon atom which is attached to the aromatic heterocyclic ring such as 2,4,6-trimethylpyridine or 2,3,5,6-tetramethylpyrazine with an aldehyde having a hydrogen atom attached to a carbon atom adjacent to the carbonyl group such as phenylacetaldehyde. Also, heat resistant thermoplastic or thermosettable products are prepared by reacting the above product with either a hydroxy aromatic monoaldehyde such as 4-hydroxybenzaldehyde, aromatic dialdehyde such as terephthaldicarboxaldehyde or mixture thereof. Many of these products exhibit bulk conductive properties when doped with a dopant (doping agent) such as antimony pentafluoride.

Abstract: A moulding composition which forms stable, durable mouldings which are color stable, have good water resistance and can be glass clear and fire-resistant, comprises a melamine-formaldehyde resole of mole ratio melamine:formaldehyde in the range 1:1.1 to 1:5.0, and from 20 to 80% by weight, based on the resole, of a glycol or glycol derivative. The composition may also contain one or more of water, polyvinyl alcohol, aluminium hydroxide and reinforcing fillers. The melamine in the resole may be partially replaced with urea. Cure of the resin composition, after shaping, takes place at a pH of at least 6.0, and is accelerated by boron oxide and also by microwave heating. Foamed products are especially useful.

Abstract: A polymerizable composition comprises a polymerizable olefinically unsaturated aromatic/aldehyde oligomer, a polymeric binder and a photoinitiator system. Such compositions may be used to prepare permanent dry film resists.

Abstract: The polymer or a copolymer of trioxane copolymer is manufactured by adding 0.001 to 2.0 wt. % of a stereo-hindering phenol to the monomer mixture in advance to the polymerization step and polymerizing trioxane and an optional co-monomer in the presence of a cationic, active catalyst and said phenol.

Abstract: An aqueous flocculant solution containing a tannin based polymer compound is produced which is stable and has a shelf life of at least 3-6 months before gelling. The solution is made by reacting at a temperature of from 150.degree.-200.degree. F. a tannin, an amino compound, and an aldehyde under slightly acidic conditions where the pH is less than 7 and where the molar ratio of the primary amine from the amino compound to the tannin repeating unit is from about 1.5:1 to 3.0:1. The intermediate viscosity of the reaction mixture is monitored until the reaction mixture has an intermediate viscosity within the range of the system key intermediate viscosity range. This system key intermediate viscosity range is previously determined for each reactant system to be employed. It is a narrow intermediate viscosity range that is experimentally determined which permits the resulting product to have a long shelf life.

Abstract: A trioxane copolymer is manufactured by adding to trioxane and a co-monomer, 0.0001 to 2.0 percent by weight, based on the total weight of the monomers, of one or more sterically hindered phenols, then co-polymerizing the resultant mixture in the presence of a cation-active catalyst, and then treating the resultant copolymer by heating it at a temperature which is higher than the melting point of the copolymer to melt the copolymer and decompose and remove unstable parts of the copolymer.

Abstract: The present invention relates to polystyrylpyridine-type resins having increased toughness, and composite materials containing these resins.The resin of the invention contains a polycondensation product of at least two reactive methylated substituents, the said resin having the following general formula (I): U.sub.x V.sub.y W.sub.z in which: ##STR1## U denotes the grouping ##STR2## V denotes the grouping ##STR3## W denotes the grouping in which:R, R.sub.1 are identical or different and denote a chain segment consisting of hydrocarbon radicals and able to contain hetero atoms,A, A.sub.1 are identical or different and denote an atom or group forming a bridge between the segment R and an aromatic nucleus of the styrylpyridine chain, containing stereomobile bonds,R.sub.2 denotes hydrogen, or a methyl or ethyl radical, x, y, z denote integers that may be equal to 0, the sum y+z being at least equal to 1.Advantageously, A, A.sub.1 denotes an oxygen atom.