COMPOSITE GLASS FIBER MATERIAL COMPRISING A THERMOSETTING POLYMER

Abstract

A composite glass fiber material includes a thermosetting polymer, which is obtained from a curable resin composition that includes (i) an ethylenically unsaturated resin and (ii) a reactive diluent. The reactive diluent is an N-vinyloxazolidinone of formula (I)

##STR00001##

in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently from one another a hydrogen atom or an organic moiety having 1 to 10 carbon atoms. The reactive diluent (ii) is present in an amount of at least 0.5 wt-% relative to the total amount of reactive diluent (ii) and further reactive diluents.

Claims

1: A composite glass fiber material comprising a thermosetting polymer, wherein the thermosetting polymer is obtained from a curable resin composition comprising (i) an ethylenically unsaturated resin; and (ii) a reactive diluent, which is an N-vinyloxazolidinone of formula (I) ##STR00006## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently from one another selected from the group consisting of a hydrogen atom and an organic moiety comprising 1 to 10 carbon atoms; and wherein the reactive diluent (ii) is present in an amount of at least 0.5 wt-% relative to a total amount of reactive diluent (ii) and further reactive diluents.

2: The material according to claim 1, wherein at least two moieties selected from the group consisting of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are a hydrogen atom; or R.sup.1 is a C.sub.1-C.sub.4 alkyl group and R.sup.2, R.sup.3 and R.sup.4 are a hydrogen atom; or R.sup.4 is a C.sub.1-C.sub.4 alkyl group and R.sup.1, R.sup.2 and R.sup.3 are a hydrogen atom; or R.sup.1 and R.sup.2 are a hydrogen atom and R.sup.3 and R.sup.4 are a C.sub.1-C.sub.4 alkyl group.

3: The material according to claim 1, wherein the N-vinyloxazolidinone of formula (I) is 3-vinyloxazolidin-2-one, 4-methyl-3-vinyl-oxazolidin-2-one or 5-methyl-3-vinyl-oxazolidin-2-one.

4: The material according to claim 1, wherein the ethylenically unsaturated resin (i) is selected from the group consisting of an ethylenically unsaturated polyester resin, a vinyl ester resin and a urethane (meth)acrylate resin.

5: The material according to claim 1, wherein a weight ratio of the ethylenically unsaturated resin (i) to the total amount of reactive diluents in the curable resin composition is in a range of 15:85 to 85:15.

6: The material according to claim 1, wherein the ethylenically unsaturated resin (i) has at least one feature selected from the group consisting of: a number average molecular weight, as determined by gel permeation chromatography, in a range of 500 to 10,000 g/mol; an acid value in a range of 5 to 80 mg KOH/g, as determined via titration according to DIN EN ISO 2114; and a hydroxyl value in a range of 5 to 80 mg KOH/g, as determined via titration according to DIN EN ISO 4692-2.

7: The material according to claim 1, wherein the ethylenically unsaturated resin (i) has an ethylene group density in a range of 0.5 to 10 mol/kg, wherein the ethylene group density signifies a molar proportion of ethylene groups per kg of resin, as determined via nuclear magnetic resonance spectroscopy.

8: The material according to claim 1, wherein the curable resin composition comprises the ethylenically unsaturated resin (i) in an amount of 15 to 85 wt. % based on a total weight of the curable resin composition.

9: The material according to claim 1, wherein the curable resin composition comprises one or more further reactive diluents selected from the group consisting of styrene, styrene derivatives, epoxides, vinyl ethers, acrylates and methacrylates.

10: The material according to claim 1, comprising glass fibers having a length-to-diameter ratio in a range of 20 to 100000.

11: The material according to claim 1, comprising the thermosetting polymer in an amount in the range of 10 to 90 wt. %, based on a total weight of the material.

12: A method for producing a composite glass fiber material, the method comprising contacting glass fibers with a curable resin composition comprising (i) an ethylenically unsaturated resin; and (ii) a reactive diluent, which is an N-vinyloxazolidinone of formula (I) ##STR00007## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently from one another selected from the group consisting of a hydrogen atom and an organic moiety comprising 1 to 10 carbon atoms; and wherein the reactive diluent (ii) is present in an amount of at least 0.5 wt-% relative to a total amount of reactive diluent (ii) and further reactive diluents; and curing the curable resin composition to form a thermosetting polymer, thereby obtaining the composite glass fiber material.

13-14: (canceled)

15: A curable resin composition comprising (i) an ethylenically unsaturated resin; and (ii) a reactive diluent, which is an N-vinyloxazolidinone of formula (I) ##STR00008## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently from one another selected from the group consisting of a hydrogen atom and an organic moiety comprising 1 to 10 carbon atoms; and wherein the reactive diluent (ii) is present in an amount of at least 0.5 wt-% relative to a total amount of reactive diluent (ii) and further reactive diluents; and wherein the ethylenically unsaturated resin (i) is selected from the group consisting of an ethylenically unsaturated polyester resin, a vinyl ester resin, and combinations thereof.

16: The curable resin composition of claim 15, wherein the curable resin composition comprises the ethylenically unsaturated resin (i) in an amount of 15 to 85 wt. % based on the total weight of the curable resin composition.

17: The material according to claim 1, wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are a hydrogen atom.

18: The material according to claim 1, wherein the N-vinyloxazolidinone of formula (I) is 5-methyl-3-vinyl-oxazolidin-2-one.

19: The material according to claim 1, wherein the ethylenically unsaturated resin (i) comprises at least one resin selected from the group consisting of: an ethylenically unsaturated polyester resin having an ethylene group density of 2.0 to 9.0 mol/kg; a vinyl ester resin having an ethylene group density of 1.0 to 4.5 mol/kg; and a urethane (meth)acrylate resin having an ethylene group density of 1.0 to 5.0 mol/kg; wherein the ethylene group density signifies a molar proportion of ethylene groups per kg of resin, as determined via nuclear magnetic resonance spectroscopy.

Description

EXAMPLES

[0159] Ethylenically unsaturated resins were obtained as described below.

[0160] The following table provides an overview of the reactants, stabilizers and initiators used in the working examples.

TABLE-US-00001 Material Manufacturer maleic anhydride Mller Chemie Gmbh & Co. KG fumaric acid ESIM Chemicals phthalic anhydride Thermo Scientific Acros tetrahydrophthalic anhydride Merck KGaA propylene glycol (99.0%) chemiekontor.de GmbH dipropylene glycol ACROS Organics Thermo Scientific Acros diethylene glycol Mller Chemie Gmbh & Co. KG neopentyl glycol BASF 2-methyl-2-propylpropane-1,3-diol TCI Deutschland GmbH hydroquinone (99.5%) ACROS Organics butylstannoic acid (95.0%, Fascat 4100) Thermo Fisher (Kandel) GmbH 3,5-di-tert-butyl-4-hydroxytoluene Sigma-Aldrich Chemie GmbH 4-methoxyphenol Alfa Aesar dibutyltin dilaurate Sigma-Aldrich Chemie GmbH triphenylphosphine Merck Schuchardt OHG benzyldimethylamine Alfa Aesar Lupranat MI BASF SE bisphenol-A-diglycidylether Sigma-Aldrich Chemie GmbH methacrylic acid ACROS Organics t-butyl acrylate Thermo Fisher (Kandel) GmbH 1,4-butanediol acrylate BASF 1,4-butanediol dimethacrylate (1,4-BDDMA) Evonik Performance Materials GmbH triethylene glycol dimethacrylate Evonik Performance Materials GmbH 2-hydroxypropyl methacrylate Evonik Performance Materials GmbH cyclohexyl vinyl ether BASF 4-methylstyrene Sigma-Aldrich Chemie GmbH 4-tert-butylstyrene Thermo Fisher (Kandel) GmbH divinylbenzene Merck KGaA aceto acetoxy ethyl methacrylate (AAEMA) Merck KGaA dimethyl itaconate (DMI) ACROS Organics 5-methyl-3-vinyl-oxazolidin-2-one BASF (>94.0%, VMOX, comprising about 4% of 4-methyl-3- vinyl-oxazolidin-2-one) Tinuvin 765 BASF (mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate) Irganox 819 (bis(2,4,6-trimethylbenzoyl) BASF phenylphosphine oxide) tert-Butyl peroxybenzoate (TBPB) ACROS Organics (98.0%) Thermo Scientific Acros methyl ethyl ketone peroxide (MEKP) United Initiators GmbH BFA-Accelerator Co 1 Bfa Chemicals GmbH & Co. KG Trigonox 21 (tert-butyl peroxy-2-ethylhexanoate) Nouryon Chemicals Holding B.V.

A-1. Production of Ethylenically Unsaturated Polyester Resins

[0161] Ethylenically unsaturated polyester resins were obtained by reacting the compounds specified in the table below in the indicated molar ratios. The ethylenically unsaturated polyester resins were prepared by melt polycondensation.

[0162] A four-neck flask (2L) was provided. In the middle neck, a stirrer with a single blade was mounted. The bearing casing of the stirrer was constantly cooled with water. On the three other necks, a thermocouple, an insulated packed column and a plug were provided. A distillation bridge with a ground-joint thermometer was mounted on the column so as to monitor the head temperature of the system during polycondensation. A graduated cylinder (250 mL) was attached to the distillation bridge to collect and measure the amount of condensed water. The thermocouple was connected to a Julabo laboratory controller (PID) and controlled the reactor temperature via a computer program (JULABO EasyTemp Professional). A heating mantle, which was also controlled by the Julabo laboratory controller, served as the heating source.

[0163] At the beginning of the reaction 500 ppmw of hydroquinone, relative to the total reaction mixture, were added as a free radical scavenger. As esterification catalyst, 400 ppmw of Fascat 4100 (butyltinic acid), relative to the total reaction mixture, were added the beginning of the reaction. The reaction was carried out under nitrogen atmosphere (99.999% nitrogen) in a four-neck flask (2 L) with a stirrer and a thermometer as described above.

[0164] Heating from room temperature to 80 C. was carried out via program control, as fast as possible while avoiding overheating. At 80 C., the ring opening of the maleic anhydride takes place and an exothermic reaction takes place. The heating was switched off in order not to overheat the melt. After completion of the exothermic reaction, the temperature was further increased up to 110 C. Subsequently, the reaction temperature was increased by 10 C. per hour up to 190 C. At 135 to 145 C., the first formation of water was observed. Once the melt of the unsaturated polyester reached 190 C., the reaction was stopped. The polymer was cooled and left in its solid form overnight.

[0165] Subsequently, the polymer was melted again by heating to 190 C. The reaction was carried out until the required acid value was obtained. For the polyesters with phthalic anhydride, the melt was cooled down to 155 C. and stirred for one hour. Subsequently, the unsaturated polyester was poured into a shallow rectangular mold, where it cooled and solidified.

[0166] The acid value (neutralization number) is the mass of potassium hydroxide (KOH) in milligrams required to neutralize one gram of the ethylenically unsaturated resin. The acid value indicates the number of carboxylic acid groups per gram of compound and was determined via titration according to DIN EN ISO 2114.

[0167] The hydroxyl value is the amount of potassium hydroxide (KOH) in milligrams required to neutralize the acetic acid taken up on acetylation of one gram of a chemical substance containing free hydroxyl groups. The hydroxyl value indicates the number of free hydroxyl group per gram of compound and was determined via titration according to DIN EN ISO 4692-2.

[0168] The ethylene group density signifies the molar proportion of ethylene groups per kg of resin. The ethylene group density was determined via nuclear magnetic resonance (NMR) spectroscopy.

[0169] The glass-transition temperature T.sub.g of ethylenically unsaturated polyester resins was determined via Differential Scanning calorimetry (DSC). The DSC measurements were carried out using a DSC device Sirius 3500 from Netzsch. Hermetically sealable Tzero aluminium pans were used. For the DSC measurement, about 15 mg of unsaturated polyester resin were added to a Tzero pan. The Tzero lid was then placed on the pan and sealed with the help of a press, the pan was inserted into the DSC and the measurement was started.

[0170] In a first heating cycle, the pans were first cooled to 0 C. and then heated up to 100 C. at 10 K/min. In a second heating cycle, the pans were cooled to 80 C. and then heated up to 100 C. at 10 K/min. The T.sub.g was determined from the second heating cycle.

[0171] The mass-average molecular weight M.sub.w and the number-average molecular weight M.sub.n were determined by gel permeation chromatography, in particular using styrene-divinylbenzene copolymer as a stationary phase and tetrahydrofuran (THF) as an eluent, and calibration using polystyrene of defined molecular weight. Gel permeation chromatography can be carried out using a SECcurity GPC Systems apparatus from PSS Polymer Standard Solution. The polydispersity index Q was calculated as M.sub.w/M.sub.n.

[0172] In particular, an analytical column from PSS Polymer Standard Solution was used as the separation column. The stationary phase consisted of styrene-divinylbenzene copolymer (SDV) with a particle size of 3 m and a nominal pore size of 100 . The eluent was tetrahydrofuran (THF). The separation column was tempered to 35 C. in the column oven. The injected sample volume was 50 L at a sample concentration of 4.94 g/L, which in sample preparation corresponds to 50 mg sample to 9 g eluent. The flow rate of the eluent was 0.5 mL/min. The samples were detected with a refractive index detector and a UV-VIS detector, with the measurement signal being registered every second. Two GPC measurement series were carried out for each polyester. The chromatograms were evaluated using PSS WinGPC UniChrom software. Calibration was carried out with a suitable standard kit of styrene oligomers and polymers.

[0173] The melt viscosity was determined according to the table below at 100 C. or 150 C. via an ICI-Cone-Plate viscosimeter from Epprecht Control & Instrument (FIC). A standard cone C (=19.5 mm, cone angle) 0.5 was used for the measurements. Approximately 0.5 g of the solid unsaturated polyester resins were used for the measurements.

[0174] The following table shows the composition and properties of the unsaturated resins.

TABLE-US-00002 Ethylenically Unsaturated Resin shear (molar ratio AV .sup.1 EGD .sup.2 T.sub.G M.sub.n M.sub.W T.sub.V .sup.4 rate .sup.5 # of reactants) [mg (KOH)] [g/mol] [ C.] [g/mol] [g/mol] Q .sup.3 [ C.] [s.sup.1] [mPa .Math. s] 1-1 maleic anhydride - 45 591.30 9.5 570 1500 2.6 150 2500 2640 phthalic anhydride - propylene glycol (1.0:2.0:3.3) 1-2 maleic anhydride - 35 270.63 11.1 950 2600 2.7 150 2500 2600 phthalic anhydride - propylene glycol (1.0:0.5:1.65) 1-3 maleic anhydride - 25 171.63 1.2 2200 5650 2.6 150 2500 2560 propylene glycol - neopentyl glycol (1.0:0.93:0.20) 1-4 maleic anhydride - 46 315.83 25.7 800 2100 2.6 100 10000 220 tetrahydrophthalic anhydride - diethylene glycol (1.0:0.5:1.59) 1-5 maleic anhydride - 25 225.67 0.0 1721 4932 2.9 100 2500 2053 phthalic anhydride - propylene glycol - dipropylene glycol (1.0:0.2:1.0:0.3) .sup.1 AV = acid value .sup.2 EGD = ethylene group density .sup.3 Q = polydispersity index .sup.4 T.sub.V = temperature at which the viscosity measurement was conducted .sup.5 = viscosity

B. Prediction of the Hansen Solubility Parameters of the Unsaturated Resins

[0175] The Hansen Parameters of the unsaturated resins were predicted on the basis of the corresponding oligomers using the software COSMOquick 2021. First, the molecules were drawn as 12-mer oligomers in the included JChemPaint module. Then, the corresponding SMILES strings were generated. Finally, quantitative structure-activity relationship (QSPR) models were used to obtain the Hansen Solubility Parameters. The QSPR results were fitted to empirical published Hansen values (Hansen Solubility Parameters: A User's Handbook, C. M. Hansen, 2007, 2nd Edition, CRC). The results are shown in the table below.

TABLE-US-00003 Hansen Solubility Parameter [MPa.sup.1/2] # Unsaturated Resin .sub.p .sub.d .sub.h 1-1 maleic anhydride - phthalic anhydride - propylene glycol 5.019 17.527 14.101 (1.0:2.0:3.3) 1-2 maleic anhydride - phthalic anhydride - propylene glycol 4.735 17.381 14.263 (1.0:0.5:1.65) 1-3 maleic anhydride - propylene glycol - neopentyl glycol 4.162 16.345 9.130 (1.0:0.93:0.20) 1-4 maleic anhydride - tetrahydrophthalic anhydride - 6.006 17.908 15.614 diethylene glycol (1.0:0.5:1.59)

C. Curable Resin Compositions

C-1. Production of Curable Resin Compositions

[0176] The solidified ethylenically unsaturated resins obtained according to item A-1 were crushed using a hammer. If the unsaturated resins did not solidify at room temperature, they were cooled with liquid nitrogen and then crushed in cold state. The crushed resins were used to produce the curable resin composition according to the tables below. First, the unsaturated resin particles were weighed into glass bottles. Subsequently, the reactive diluent or reactive diluent mixtures according to the table below were added. Tinuvin 765 (1,000 ppmw) was added to the resins with VMOX as reactive diluent so as to suppress gelation. The bottles were placed on a roller mixer and mixed for several days. The curable resin compositions were considered ready for use when the unsaturated resin particles were completely dissolved in the reactive diluent or reactive diluent mixtures.

C-2. Solubility

[0177] The bottles obtained according to item C-1 were placed on a roller mixer and mixed for several days. The bottles obtained according to item C-1 wherein the curable resin compositions comprised cyclohexyl vinyl ether were subsequently placed in an oven at 60 C. for 3 h. The solubility of the ethylenically unsaturated resin particles in the reactive diluent was visually checked at regular intervals.

[0178] The results of the solubility tests are shown in the table below.

TABLE-US-00004 Unsaturated Reactive Observations on Resin Diluent Solubility 1-1 VMOX (50 wt.-%) clear solution VMOX (60 wt.-%) clear solution VMOX (70 wt.-%) clear solution tert-butyl acrylate (60 wt.-%) turbid solution 1,4-butanediol diacrylate (60 wt.-%) clear solution cyclohexyl vinyl ether (70 wt.-%) clear solution 4-methylstyrene (50 wt.-%) clear solution 4-methylstyrene (70 wt.-%) turbid solution 4-tert-butylstyrene (50 wt.-%) insoluble 4-tert-butylstyrene (70 wt.-%) insoluble divinylbenzene (50 wt.-%) clear solution divinylbenzene (70 wt.-%) turbid solution 1-2 VMOX (50 wt.-%) clear solution VMOX (60 wt.-%) clear solution VMOX (70 wt.-%) clear solution tert-butyl acrylate (60 wt.-%) clear solution 1,4-butanediol diacrylate (60 wt.-%) clear solution cyclohexyl vinyl ether (70 wt.-%) initially turbid solution, almost clear at 60 C. 4-methylstyrene (50 wt.-%) turbid solution 4-methylstyrene (70 wt.-%) turbid solution 4-tert-butylstyrene (50 wt.-%) insoluble 4-tert-butylstyrene (70 wt.-%) insoluble divinylbenzene (50 wt.-%) turbid solution divinylbenzene (70 wt.-%) turbid solution, two phases 1-3 VMOX (50 wt.-%) clear solution VMOX (60 wt.-%) clear solution VMOX (70 wt.-%) clear solution tert-butyl acrylate (60 wt.-%) initially clear solution, turbid after two weeks 1,4-butanediol diacrylate (60 wt.-%) clear solution cyclohexyl vinyl ether (70 wt.-%) initially turbid solution, two phases at 60 C. 4-methylstyrene (50 wt.-%) turbid solution 4-methylstyrene (70 wt.-%) turbid solution 4-tert-butylstyrene (50 wt.-%) insoluble 4-tert-butylstyrene (70 wt.-%) insoluble divinylbenzene (50 wt.-%) turbid solution divinylbenzene (70 wt.-%) turbid solution, two phases 1-4 VMOX (50 wt.-%) clear solution VMOX (60 wt.-%) clear solution VMOX (70 wt.-%) clear solution tert-butyl acrylate (60 wt.-%) clear solution cyclohexyl vinyl ether (70 wt.-%) initially turbid solution, two phases at 60 C. 4-methylstyrene (50 wt.-%) turbid solution 4-methylstyrene (70 wt.-%) turbid solution, two phases 4-tert-butylstyrene (50 wt.-%) insoluble 4-tert-butylstyrene (70 wt.-%) insoluble divinylbenzene (50 wt.-%) turbid solution divinylbenzene (70 wt.-%) turbid solution, two phases

[0179] Turbid solutions indicate that dissolution is not fully achieved. It is evident that VMOX allows for full solubility of the examined unsaturated resins.

C-3. Surface Tackiness and Curing Properties

[0180] The surface of unsaturated polyester thermosets made from resins with acrylates as reactive diluents may be tacky after curing under air. The tackiness of the thermoset surface is induced by oxygen inhibition during the radical curing process. The tackiness of thermosetting polymers obtained from curable resin compositions comprising tert-butyl acrylate or VMOX, respectively, was compared.

[0181] Unsaturated polyester resin 1-2 was dissolved in 60 wt.-% of tert-butyl acrylate or VMOX, as indicated in the table below, to obtain curable resin compositions. 1 wt.-% of Trigonox 21 was added to each of the curable resin compositions. The curable resin compositions were cured using the following curing profile: 2 h at 60 C., then 2 h at 80 C., then 2 h at 100 C. The results are shown in the table below.

TABLE-US-00005 Unsaturated Reactive Diluent Resin (60 wt.-%) Observations 1-2 tert-butyl acrylate slightly tacky surface after curing 1-2 VMOX* no tackiness of surface after curing *1000 ppmw of Tinuvin 765 (relative to the total amount of the curable resin composition) were added with VMOX to improve storage stability.

[0182] Both curable resin compositions can be cured to yield thermosetting polymers having smooth surfaces, wherein the thermosetting polymer obtained from the curable resin composition comprising VMOX displays no surface tackiness. It is noted that this effect is achieved in the resin composition comprising VMOX despite the presence of Tinuvin 765, which may act as an inhibitor in the curing process.

[0183] Further, the curing properties of unsaturated resins 1-1 to 1-4 in 1,4-butanediol diacrylate were examined. The respective unsaturated resin was dissolved in 60 wt.-% of 1,4-butanediol diacrylate to obtain curable resin compositions. 1 wt.-% of Trigonox 21 was added to each of the curable resin compositions. The curable resin compositions were cured using the following curing profile: 2 h at 60 C., then 2 h at 80 C., then 2 h at 100 C. to obtain thermosetting polymers.

[0184] It was found that each of the resins with 1,4-butanediol diacrylate as reactive diluent foamed during thermal curing under air. The surface of the obtained thermosetting polymers was uneven and rough, and its quality was not sufficient for further investigations.

C-4. Glass-Transition Temperature T.SUB.g

[0185] The glass-transition temperatures of thermosetting polymers obtained from curable resin compositions comprising different reactive diluents according to the table below was compared. The curable resin compositions each comprised 1 wt.-% of tert-butyl peroxybenzoate. The curable resin compositions were cured using the following curing profiles to obtain thermosetting polymers: A) 2 h at 60 C., then 2 h at 80 C., then 2 h at 100 C.; or B) 1 h at 80 C., then 1 h at 160 C. The results are shown in the table below.

TABLE-US-00006 T.sub.g of Thermosetting Curable Resin Composition Polymer Resin 1-3 in 50 wt.-% of VMOX 209 C. (Curing Profile A) Resin 1-3 in 50 wt.-% of 1,4-butanediol dimethaycrylate 166 C. (Curing Profile A) Resin 1-3 in 50 wt.-% of triethylene glycol 165 C. dimethacrylate (Curing Profile A) Resin 1-1 in 50 wt.-% of VMOX 106 C. (Curing Profile B) Resin 1-1 in 70 wt.-% of VMOX 144 C. (Curing Profile B) Resin 1-1 in 50 wt.-% of 4-methylstyrene 113 C. (Curing Profile B) Resin 1-1 in 50 wt.-% of divinylbenzene 94 C. (Curing Profile B)

[0186] It is evident that VMOX as reactive diluent induces at least 40 C. higher glass transition temperatures of the thermosetting polymer obtained with resin 1-3 than the use of 1,4-butanediol dimethacrylate or triethylene glycol dimethacrylate as reactive diluent. It is moreover evident that VMOX as reactive diluent at high concentrations induces high glass transition temperatures, which are not obtainable with 4-methylstyrene or divinylbenzene due to solubility issues at comparably high concentrations of these reactive diluents.

C-5. Cold Curing

[0187] The properties of thermosetting polymers obtained by cold curing of curable resin compositions according to the table below with VMOX or 1,4-butanediol dimethacrylate (1,4-BDDMA) as reactive diluent were compared. Aceto acetoxy ethyl methacrylate (AAEMA) and dimethyl itaconate (DMI) were used as further reactive diluents. Before curing, 1.5 wt.-% of cobalt accelerator (BUFAR-Accelerator Co 1) was added to the curable resin composition and the composition was homogenized in a roller mixer for 1 h. Subsequently, 1.5 wt.-% of methyl ethyl ketone peroxide (MEKP) was added and mixed with the curable resin composition using a wooden spatula. The curable resin composition processed immediately after addition of MEKP.

[0188] Approximately 10 g of the resin were placed on a metal mold (dimensions: 10 cm10 cm). The resin was evenly distributed, and a layer of biaxial fiberglass fabric (831 g/m.sup.2, 0/9 0, item number S14EB490-00831-01300-474000 from Saertex, dimensions: 10 cm10 cm) was placed in the resin. Once all air bubbles had been removed using a wooden spatula, the second layer of resin was added. A second fiberglass fabric layer was placed at an angle of 90 to the first layer and also wetted with resin. This process was repeated once again so that the metal dish contained three layers of glass fiber at 90 to each other and about 30 g of resin composition.

[0189] Cold curing was performed at a temperature of approximately 25 C. The tackiness of the obtained samples was haptically controlled in regular intervals of about 6 h during the daytime. The results are shown in the table below.

TABLE-US-00007 Unsaturated Time until Surface Resin VMOX 1,4-BDDMA AAEMA DMI of Samples was [40 wt.-%] [wt.-%] [wt.-%] [wt.-%] [wt.-%] Non-Tacky 1-1 60 5 days 58 2 4 days 56 4 7 days 53 * 2 4 days 43 * 2 10 2 days 1-2 60 4 days 58 2 3 days 56 4 1 day 56 4 7 days 1-3 60 2 days 58 2 1 day 56 4 7 days * carried out with 45 wt.-% of unsaturated resin

[0190] It is evident that cold curing of resins containing VMOX as reactive diluent proceeds faster than that of resins containing 1,4-BDDMA as reactive diluent.

C-6. Curable Resin Compositions with Further Reactive Diluents

[0191] An ethylenically unsaturated polyester resin obtained from fumaric acid and 2-methyl-2-propylpropane-1,3-diol (molar ratio 1.0:1.02, .sub.p=5.702 MPa.sup.1/2) was provided in accordance with item A-1. The unsaturated resin was cooled with liquid nitrogen and then crushed in cold state. The crushed unsaturated resin was used to produce a curable resin composition. First, the unsaturated resin particles were weighed into glass bottles. Subsequently, a mixture of styrene and VMOX as well as stabilizer were added according to the tables below.

[0192] The bottles were placed on a roller mixer. The solubility or the progress of the dissolution process of the unsaturated polyester particles in the reactive diluent was visually checked at regular intervals. The resin compositions were considered ready for use as soon as everything was dissolved.

[0193] The results of the solubility tests are shown in the tables below. In order to determine the Hansen solubility parameters of the mixture of styrene and VMOX the mass fractions were converted into volume fractions by using the following formula:

[00003]${}_1=\frac{\left(\frac{{}_1}{{}_1}\right)}{\left(\frac{{}_1}{{}_1}\right)+\left(\frac{{}_2}{{}_2}\right)}$

wherein .sub.1 is the volume fraction of component 1, .sub.1 is the mass fraction of component 1, .sub.2 is the mass fraction of component 2, .sub.1 is the density of component 1 and .sub.2 is the density of component 2. The density of styrene is 0.909 kg/m.sup.3. The density of VMOX is 1.098 kg/m.sup.3.

[0194] The Hansen solubility parameters of the mixture of styrene and VMOX in comparison to the Hansen solubility parameters of the unsaturated polyester resins were used to determine the R.sub.a value according to the following formula:

[00004]$Ra=\sqrt{4.Math.{\left({}_{D1}-{}_{D2}\right)}^2+{\left({}_{P1}-{}_{P2}\right)}^2+{\left({}_{H1}-{}_{H2}\right)}^2}$

TABLE-US-00008 Mixture of Hansen Solubility Reactive Diluents Parameter of Mixture of Solubility in Styrene VMOX Reactive Diluents [MPa.sup.1/2] R.sub.a for Mixture of Mixture of [wt. %] [wt. %] .sub.d .sub.p .sub.h Reactive Diluents Reactive Diluents 70 0 18.600 1.000 4.100 12.779 Turbid solution 69 1 18.592 1.095 4.121 12.721 Clear solution 68 2 18.583 1.190 4.143 12.663 Clear solution 67 3 18.575 1.286 4.164 12.605 Clear solution 66 4 18.567 1.382 4.186 12.548 Clear solution 65 5 18.558 1.479 4.208 12.491 Clear solution 60 10 18.515 1.970 4.318 12.209 Clear solution 50 20 18.426 2.990 4.548 11.675 Clear solution 40 30 18.332 4.064 4.789 11.193 Clear solution

TABLE-US-00009 Hansen Solubility Reactive Diluents Parameter of Mixture of Solubility in Styrene VMOX Reactive Diluents [MPa.sup.1/2] R.sub.a for Mixture of Mixture of [wt. %] [wt. %] .sub.d .sub.p .sub.h Reactive Diluents Reactive Diluents 60 0 18.600 1.000 4.100 12.779 Turbid solution 59 1 18.590 1.111 4.125 12.711 Turbid solution 58 2 18.581 1.222 4.150 12.644 Clear solution 57 3 18.571 1.334 4.175 12.577 Clear solution 56 4 18.561 1.447 4.200 12.510 Clear solution 55 5 18.551 1.560 4.226 12.443 Clear solution 50 10 18.501 2.136 4.356 12.117 Clear solution 40 20 18.395 3.342 4.627 11.507 Clear solution 30 30 18.283 4.623 4.915 10.978 Clear solution

[0195] It is evident that the presence of even small amounts of VMOX improves the solubility of the examined polyester resin in comparison to pure styrene.

C-7. Tensile Testing

[0196] Curable resin compositions prepared according to C-1 were used to prepare samples for the tensile testing. Before the samples preparation, 0.3 wt.-% of Irganox 819 and 1 wt.-% tert-butyl peroxybenzoate (TBPB) were added to the curable resin compositions. The samples for the tensile test were prepared by vacuum infusion method.

[0197] For this purpose, sealing tape was applied to a glass plate (2817 cm) and provided with two parallel opposing spiral hoses at the lengths. The spiral hoses were pressed firmly to the sealing tape to avoid possible leaks. A vacuum hose was inserted into each spiral hose at about 3 cm depth. The vacuum hose was covered and sealed by small pieces of sealing tape. This construction represented the framework for the vacuum infusion.

[0198] Subsequently, six layers of fiberglass fabric (2413 cm, 831 g/m.sup.2, 0/9 0, item number S14EB490-00831-01300-474000 from Saertex) were placed on the glass plate. The layers were alternately aligned at a 45 angle. A release film (Peel ply 64 g/m.sup.2 (plain weave) 150 cm, item no. 190181-150-5) and a resin bleed layer (INFUPLEX with ISONET, width 145 cm, item no. 3903426), having the same size as the fabric layers, were applied. The release film provides a smooth surface of the test specimen. The resin bleed layer consisted of a two-layered system: perforated flow and flow aid. This system is permeable to resins and allows a uniform and complete wetting of the laminate through the fine commercial structure. Finally, the mold was firmly sealed with a vacuum foil.

[0199] The curable resin compositions were deaerated by a vacuum pump before the infusion process. For the infusion, a shorter vacuum hose was placed in the resin and a longer one was connected to the vacuum circuit. The set up consists of a vacuum pump, a desiccator and an interposed cold trap. The desiccator comprised a collecting vessel for surplus flowing resin. The plates should be produce in the dark place to avoid possible premature curing. As soon as the plate was finally laminated, the vacuum hoses were compressed by means of clamps and then cut off. Next, the plate was photochemically cured in a Xenon tester (Original Hanau, serial number 7011, overall dimensions 700470350 mm, power supply: 220 V/50 Hz/1500 W) for 20 min. The laminate was carefully removed from the glass plate and post-cured in a convection oven at 80 C. for 1 hour and at 160 C. for 1 hour to obtain thermosets. The specimens were cut on a CNC machine into four equal-sized test specimens of 200 mm length and 25 mm width.

[0200] To evaluate the mechanical properties, tensile tests were performed on a Zwick Z200 in accordance with DIN EN ISO 527-4. For each test, four equally sized test specimens were used. The width and thickness of all specimens were measured with a calliper and documented for the respective test. Each thermoset obtained from the curable resin compositions was tested at room temperature (about 20 C.), at 100 C. and at 120 C. For the measurements at 100 C. and at 120 C., a climate chamber was connected to the Zwick Z200 and preheated for at least one hour. The samples were heated and clamped into the Zwick Z200 for 10 minutes before the measurement start. It is important to ensure that no shearing forces act when clamping the test specimen. This means that the specimen must be mounted vertically in the clamping jaws. The drafts generated by the oven fan are must be switched off for the duration of the measurement. The Zwick Z200 loads the sample until it finally breaks. The tensile modulus of elasticity (E.sub.t), the tensile strength (.sub.m) and the elongation at maximum tensile stress (.sub.m) were recorded.

[0201] The results of the measurements are shown in the table below.

TABLE-US-00010 measurement elasticity tensile elongation curable resin temperature E.sub.t strength .sub.m .sub.m composition [ C.] [MPa] [MPa] [%] 50 wt.-% resin 1-3, 20 14,300 (1,980) 84.6 (0.75) 1.8 (0.34) 40 wt.-% VMOX, 10 wt.-% DMI 50 wt.-% resin 1-3, 20 10,800 (439) 58.8 (3.18) 1.6 (0.28) 50 wt.-% VMOX 50 wt.-% resin 1-3, 100 10,200 (799) 65.6 (3.86) 2.7 (0.35) 40 wt.-% VMOX, 10 wt.-% DMI 50 wt.-% resin 1-3, 100 7,120 (302) 44.2 (2.10) 2.1 (0.22) 50 wt.-% VMOX 50 wt.-% resin 1-3, 120 7,020 (642) 55.3 (2.31) 3.7 (0.30) 40 wt.-% VMOX, 10 wt.-% DMI 50 wt.-% resin 1-3, 120 6,660 (349) 41.7 (1.22) 2.0 (0.27) 50 wt.-% VMOX

[0202] All thermosets obtained from the curable resin compositions showed sufficient mechanical properties. Notably, the use of dimethyl itaconate (DMI) as a further reactive diluent was found to improve the mechanical properties as compared to VMOX itself. Without wishing to be bound by theory, DMI, in addition to the unsaturated polyester resin 1-3, may act as a copolymerization partner for VMOX. Therefore, radical copolymerization may occur between the unsaturated polyester resin and VMOX, as well as between DMI and VMOX. The copolymerization between VMOX and DMI increases the possibility of formation of reactive diluent bridges between chains of the unsaturated polyester resin, thus increasing the crosslink density and homogeneity of the network.

D. Composite Glass Fiber Materials

D-1. Dynamic Mechanical Analysis

[0203] Glass fiber reinforced test specimens were fabricated using the resin compositions of item C-1, comprising 70 wt.-% of VMOX. As a first step, tert-butyl peroxybenzoate (Acros Organics, 98%) was added to the resin in an amount of 1 wt.-%. Then, approximately 10 g of the resin were placed in a metal dish (diameter: 10 cm; depth: 1 cm). The resin was evenly distributed, and a layer of biaxial fiberglass fabric (831 g/m.sup.2, 0/9 0, item number S14EB490-00831-01300-474000 from Saertex) of the same diameter was placed in the resin. Once all air bubbles had been removed using a wooden spatula, the second layer of resin was added. A second fiberglass fabric layer was placed at an angle of 90 to the first layer and also wetted with resin. This process was repeated once again so that the metal dish contained three layers of glass fiber at 90 to each other and about 30 g of resin composition.

[0204] The obtained specimen was weighted down with a weight (about 500 grams) wrapped in aluminum foil so as to squeeze excess resin composition out of the mold and so as to obtain a smooth specimen surface. Finally, the specimen and weight were wrapped in aluminum foil. The specimen was thermally cured for 1 h at 100 C. and for 1 h at 160 C. in a laboratory oven under air. After cooling, the obtained composite glass fiber material was broken out of its mold and cut into samples of 1050 mm using a table saw.

[0205] Subsequently, the samples were subjected to Dynamic Mechanical Analysis (DMA) using a DMA 242 C from Netzsch. A three-point bending specimen holder was used. The samples were measured according to the method specified in the table below, under a nitrogen flow of 83 mL/min. The dependencies of storage modulus, loss modulus and loss factor (tan ) of the cured ethylenically unsaturated polyester resin compositions on temperature were determined. The maximum value of the tan curve (T) was considered to constitute the glass transition temperature T.sub.g.

TABLE-US-00011 temperature program Start temperature 30 C. frequency 5.00 Hz Dynamic Load temperature 250 C. heating rate 2.0 K/min frequency 10.00 Hz mechanical parameters proportionality 1.1 maximum amplitude 30.00 m maximum dynamic force 7.2N on the sample

[0206] The glass transition temperatures T.sub.g of the composite glass fiber materials are shown in the following table.

TABLE-US-00012 Unsaturated Polyester Resin # (molar ratio of reactants) T.sub.g 1-1 maleic anhydride - phthalic anhydride - propylene glycol 144 C. (1.0:2.0:3.3) 1-2 maleic anhydride - phthalic anhydride - propylene glycol 166 C. (1.0:0.5:1.65) 1-3 maleic anhydride - propylene glycol - neopentyl glycol 195 C. (1.0:0.93:0.20) 1-4 maleic anhydride - tetrahydrophthalic anhydride - 142 C. diethylene glycol (1.0:0.5:1.59)

D-2. Impact Test

[0207] Composite material test specimens were fabricated using resin compositions derived from unsaturated resin 1-3 in accordance with item C-1, comprising 60 wt.-% of either VMOX or styrene. Tinuvin 765 (1,000 ppmw) was added as stabilizer so as to suppress gelation. Chopped glass fibers (HP-GS3, HP-Textiles) having a fiber length of 3 mm and a diameter of 13 m (length-to-diameter ratio: 231) or talc (finely powdered Mg.sub.3 [(OH).sub.2|Si.sub.4O.sub.10] from Merck, 30-0050) were used. The density of both materials was approximately the same, namely 2.4 to 2.8 g/cm.sup.3.

[0208] A cobalt accelerator (BUFAR-Accelerator Co 1, Bfa Chemicals) was added to 400 g of each curable resin composition using a round wheel stirrer at a speed of approximately 750 rpm. Subsequently, methyl ethyl ketone peroxide (MEKP, United Initiators) was added and mixed with the curable resin composition using a wooden spatula. For curable resin compositions comprising styrene, 1.25 wt.-% of each of the cobalt accelerator and MEKP were used. For curable resin compositions comprising VMOX, 0.5 wt.-% of each of the cobalt accelerator and MEKP were used.

[0209] Finally, 10 wt.-% of chopped glass fibers or talc as described above were added and mixed into the curable resin compositions for 120 s at 750 rpm. After mixing, each curable resin composition was divided into three metal dishes (diameter: 100 cm) so that the resin was evenly distributed each dish was filled to a height of 10 to 12 mm. Using a desiccator at a pressure of 10 mbar, air bubbles were removed from the compositions during cold curing at room temperature. After cold curing of the compositions was finished (approximately 1 h), the specimens were thermally cured for 8 h at 80 C.

[0210] The cured composite material test specimens were taken out of the metal dishes and cut to size on a CNC cutting machine. Test rods having a width of approximately 8 mm, a height of approximately 4 mm and a length of approximately 80 mm were obtained for each composite material.

[0211] Impact tests were carried out with an impact testing device from Zwick. The impact pendulum had an energy of 0.5 joules. Before the impact test, the width and height of each test rod was determined using a caliper gauge. The test specimens were placed in the impact tester so that the impact pendulum centrally struck one of the narrow sides, i.e., one of the face sides with an area which may be defined as lengthheight.

[0212] The impact strength was determined using the following formula:

[00005]$a_{C}U=\frac{W_C}{h*b}*{10}^3$ [0213] wherein acU is the impact strength in KJ/m.sup.2, W.sub.C is the impact energy in J, h is the height of the specimen, and b is the width of the specimen. The results are shown in the following tables.

TABLE-US-00013 TABLE D-2-1 Composite Material Specimens Derived from VMOX and Talc. Impact Impact Work W.sub.c Height h Width b Strength a.sub.cU Specimen [J] [mm] [mm] [kJ/m.sup.2] 1 0.055 3.92 7.26 1.93 2 0.050 3.80 7.84 1.68 3 0.080 3.74 7.92 2.70 4 0.085 4.08 7.95 2.62 5 0.050 3.86 7.73 1.68 6 0.055 3.95 7.46 1.87 7 0.055 3.90 7.78 1.81 8 0.065 3.78 7.40 2.32 9 0.065 3.87 8.02 2.09 10 0.070 3.95 7.33 2.42 11 0.065 3.96 7.44 2.21 12 0.090 4.03 7.55 2.96 13 0.085 4.05 7.90 2.66 14 0.065 4.04 7.84 2.05 15 0.100 3.92 7.86 3.25 16 0.090 3.87 8.11 2.87 17 0.060 3.97 7.35 2.06 18 0.060 4.05 8.06 1.84 Average 2.28 Standard 0.46 Deviation

TABLE-US-00014 TABLE D-2-2 Composite Material Specimens Derived from VMOX and Glass Fibers. Impact Impact Work W.sub.c Height h Width b Strength a.sub.cU Specimen [J] [mm] [mm] [kJ/m.sup.2] 1 0.110 4.07 8.42 3.21 2 0.090 3.89 8.49 2.73 3 0.135 3.79 8.70 4.09 4 0.080 3.98 8.68 2.32 5 0.105 3.87 8.71 3.12 6 0.135 3.82 7.93 4.46 7 0.105 4.06 8.60 3.01 8 0.135 3.90 8.68 3.99 9 0.125 4.04 8.53 3.63 10 0.140 4.02 7.92 4.40 11 0.140 3.98 8.07 4.32 12 0.090 3.93 8.66 2.64 13 0.095 4.03 7.93 2.97 14 0.100 4.04 7.88 3.14 15 0.125 4.01 8.49 3.67 16 0.130 4.06 8.72 3.67 Average 3.46 Standard 0.64 Deviation

TABLE-US-00015 TABLE D-2-3 Composite Material Specimens Derived from Styrene and Glass Fibers. Impact Impact Work W.sub.c Height h Width b Strength a.sub.cU Specimen [J] [mm] [mm] [kJ/m.sup.2] 1 0.080 4.14 7.61 2.54 2 0.160 4.15 8.73 4.42 3 0.080 4.22 7.69 2.47 4 0.070 4.04 8.39 2.07 5 0.110 4.17 8.00 3.30 6 0.095 4.15 8.02 2.85 7 0.080 4.31 7.60 2.44 8 0.055 4.31 8.54 1.49 9 0.055 4.00 8.50 1.62 10 0.080 4.25 8.49 2.22 11 0.085 4.07 8.38 2.49 12 0.080 4.09 8.11 2.41 13 0.080 4.23 8.02 2.36 14 0.145 4.01 8.20 4.41 15 0.080 4.10 8.29 2.35 16 0.090 3.89 8.22 2.81 17 0.065 4.17 8.38 1.86 Average 2.59 Standard 0.79 Deviation

TABLE-US-00016 TABLE D-2-4 Summary of the Impact Strength Tests Average Impact Strength a.sub.cU Standard [kJ/m.sup.2] Deviation VMOX and Talc 2.28 0.46 VMOX and Glass Fibers 3.46 0.64 Styrene and Glass Fiber 2.59 0.79

[0214] It is evident that composite materials derived from glass fibers have higher impact strength than talc-based composite materials. Moreover, it is evident that composite glass fiber material derived from N-vinyloxazolidinones of formula (I) have higher impact strength than styrene-based composite glass fiber materials. Furthermore, N-vinyloxazolidinones of formula (I) require less initiator for cold curing than styrene.