Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/34—Heterocyclic compounds having nitrogen in the ring
  • C08K5/35—Heterocyclic compounds having nitrogen in the ring having also oxygen in the ring
  • C08K5/357—Six-membered rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/02—Polyamines
  • C08G73/0233—Polyamines derived from (poly)oxazolines, (poly)oxazines or having pendant acyl groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D265/00—Heterocyclic compounds containing six-membered rings having one nitrogen atom and one oxygen atom as the only ring hetero atoms
  • C07D265/04—1,3-Oxazines; Hydrogenated 1,3-oxazines
  • C07D265/12—1,3-Oxazines; Hydrogenated 1,3-oxazines condensed with carbocyclic rings or ring systems
  • C07D265/14—1,3-Oxazines; Hydrogenated 1,3-oxazines condensed with carbocyclic rings or ring systems condensed with one six-membered ring
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D265/00—Heterocyclic compounds containing six-membered rings having one nitrogen atom and one oxygen atom as the only ring hetero atoms
  • C07D265/04—1,3-Oxazines; Hydrogenated 1,3-oxazines
  • C07D265/12—1,3-Oxazines; Hydrogenated 1,3-oxazines condensed with carbocyclic rings or ring systems
  • C07D265/14—1,3-Oxazines; Hydrogenated 1,3-oxazines condensed with carbocyclic rings or ring systems condensed with one six-membered ring
  • C07D265/16—1,3-Oxazines; Hydrogenated 1,3-oxazines condensed with carbocyclic rings or ring systems condensed with one six-membered ring with only hydrogen or carbon atoms directly attached in positions 2 and 4
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
  • C08K5/37—Thiols
  • C08K5/375—Thiols containing six-membered aromatic rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/61—Polyamines polyimines
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component

Definitions

• benzoxazines offers a number of advantages as compared to other thermosetting resins including relatively long shelf-life, molecular design flexibility, low cost, high glass transition temperature (T g ), high modulus, relatively low viscosities, good flame retardant properties, low moisture absorption, no byproducts released during curing and very low shrinkage upon curing. Furthermore, benzoxazines are capable of being self-cured upon heating; i.e. there is no need for an additional curing agent. This combination of properties means benzoxazines are potentially attractive for use in aerospace applications.
• blends of multifunctional benzoxazines are based on the combination of a difunctional benzoxazine component and a multifunctional benzoxazine component with functionality of greater than 2, particularly, benzoxazines with average functionality from 2.1 to 3.
• Benzoxazine resins are known to be very resistant to water uptake, commonly uptaking ⁇ 2% at saturation. This benefit allows them to have a low differential between their (higher) dry T g and (lower) wet T g , meaning that their usage
• temperature can be higher than, for example, epoxy resins or benzoxazine-epoxy hybrids with comparable dry T g .
• Benzoxazines have been known to have extremely good solvent resistance with reports for MEK uptake at room temperature to be ⁇ 0.2% after a 7-month MEK soak. MEK resistance tests are critical as they are used by most aerospace composite manufacturers as part of their design criteria. Surprisingly, it has been found that, in boiling MEK, the uptake in a neat benzoxazine could be >23% in just 16 hrs. This was not the case for a benzoxazine-epoxy hybrid system, which took up approximately 2.5% after 190 hrs.
• benzoxazine-epoxy hybrid systems have a good balance of properties, they do not possess the extremely high flexural modulus of the neat benzoxazine systems (i.e 100% benzoxazine).
• This discovery offers the potential to utilise neat benzoxazine resin systems in aerospace composites by mitigating a potential resin failing.
• An alternative strategy to address this failing could have been to formulate a more hydrophilic component into the formulation.
• the risk would have been a damaging uptake in water absorption.
• a major benefit of the approach taken is reflected in the fact that there is a very minor effect on water uptake in these neat benzoxazines.
• the level of uptake is increased on addition of 30% multifunctional benzoxazine but still remains below 1 .6% at equilibrium.
• the resin composition contains a blend of (A) a di-functional benzoxazine component and (B) a multifunctional benzoxazine component with an average functionality of > 2, particularly, benzoxazines with an average functionality of about 2.1 up to about 3.
• the retardation in solvent uptake e.g. MEK
• the multifunctional benzoxazine component may be present in an amount of up to 30% by weight based on the total weight of the benzoxazine blend.
• the weight ratio of multifunctional benzoxazine component (B) to difunctional benzoxazine component (A) may be in the range of 1 :99 to 30:70.
• the multifunctional benzoxazines refer to polymerizable benzoxazine compounds with at least two oxazine moieties in the compound, enabling the formation of crosslinks. More specifically, difunctional benzoxazine contains two oxazine moieties, and tri-functional benzoxazine contains three oxazine moieties. Blends of benzoxazines with non-integer average
• the multifunctional benzoxazine compounds in the blends include multifunctional monomers and oligomers that can be polymerized by curing to form a thermoset resin.
• the multifunctional benzoxazine compounds Upon curing, the multifunctional benzoxazine compounds readily polymerize via ring opening polymerization. Such polymerization is usually initiated cationically (using cationic initiators) or thermally.
• MEK methyl ethyl ketone
• the solvent in the context of solvent uptake includes organic solvents such as MEK. This effect would be expected to be observed to a greater or lesser extent in benzoxazine hybrid systems (e.g. benzoxazine-epoxy systems). Neat or pure (100%) benzoxazine system in this context refers to a benzoxazine-based
• composition which is void of any other curable/thermosettable resin such as epoxy, cyanate ester, BMI and phenolic / phenol-formaldehyde resins but may include catalysts/initiators, toughening agents or functional additives.
• functional additives include, but are not limited to, fillers, color pigments, rheology control agents, tackifiers, conductive additives, flame retardants, ultraviolet (UV) protectors, and the like.
• These additives may take the form of various geometries including, but are not limited to, particles, flakes, rods, and the like.
• the multifunctional benzoxazine component discussed above includes one or more multifunctional benzoxazines having functionality of >2, including tri-functional benzoxazines represented by the following generic structure I:
• Ri , F3 ⁇ 4 and R3 are independently selected from alkyl (preferably Ci-s alkyl), cycloalkyi (preferably C 5- 7 cycloalkyi, particularly Ce cycloalkyi), and aryl, wherein the cycloalkyi and aryl groups are optionally substituted, for instance by Ci -8 alkyl, halogen and amine groups, and preferably by Ci-s alkyl, and where substituted, one or more substituent groups (preferably one substituent group) may be present on each cycloalkyi and aryl group;
• R 4 is selected from hydrogen, halogen, alkyl and alkenyl.
• the tri-functional benzoxazine is represented by the following structure II:
• Ri , R2 and R3 are independently selected from alkyl (preferably Ci-s alkyl).
• the multifunctional benzoxazine component with functionality >2 may be a reaction product of a trihydric phenol (or tris-phenol), an aromatic amine, and formaldehyde.
• a particularly suitable tris-phenol is 1 ,1 ,1 -tris (4- hydroxyphenyl)ethane.
• the multifunctional benzoxazine component is a reaction product of 1 ,1 ,1 -tris (4-hydroxyphenyl)ethane, p-toluidine, and p-formaldehyde.
• benzoxazines with functionality >2 would be a blend of the above tri-functional structure I, II or III and a similar structure with only two completely closed oxazine moieties, the final phenol being either unreacted, partially reacted with formaldehyde or ring opened.
• the difunctional benzoxazine component may be include one or more benzoxazines represented by the following structure IV:
• Z 1 is selected from a direct bond, -C(R 3 )(R 4 )-, -C(R 3 )(aryl)-, -C(O)-, -S-, -O-, -
• R 1 and R 2 are independently selected from alkyi (preferably Ci -8 alkyi), cycloalkyl (preferably C 5- 7 cycloalkyl, preferably Ce cycloalkyl) and aryl, wherein the cycloalkyl and aryl groups are optionally substituted, for instance by Ci-s alkyi, halogen and amine groups, and preferably by Ci-s alkyi, and where substituted, one or more substituent groups (preferably one substituent group) may be present on each cycloalkyl and aryl group;
• Z 1 is selected from a direct bond, -C(R 3 )(R 4 )-, -C(R 3 )(aryl)-, -C(O)-, -S-, -O-, a divalent heterocycle and -[C(R 3 )(R 4 )] x -arylene-[C(R 5 )(R 6 )] y -, or the two benzyl rings of the benzoxazine moieties may be fused;
• R 3 , R 4 , R 5 and R 6 are independently selected from H, Ci-s alkyi (preferably Ci -4 alkyi, and preferably methyl), and halogenated alkyi (wherein the halogen is typically chlorine or fluorine (preferably fluorine) and wherein the halogenated alkyi is preferably CF 3 ); and
• x and y are independently 0 or 1 ;
• Z 1 is selected from a divalent heterocycle, it is preferably 3, 3- isobenzofuran-1 (3h)-one, i.e. wherein the compound of formula (III) is derived from phenolphthalein; where Z 1 is selected from -[C(R 3 )(R 4 )] x -arylene-[C(R 5 )(R 6 )] y -, then the chain linking the two benzoxazine groups may further comprise one or more arylene group(s) and/or one or more -C(R 7 )(R 8 )- group(s) where R 7 and R 8 are independently selected from the groups defined hereinabove for R 3 .
• the arylene group is phenylene.
• the groups attached to the phenylene group may be configured in para- or meta-positions relative to each other.
• the aryl group is phenyl.
• the group Zi may be linear or non-linear, and is typically linear.
• the group Zi is preferably bound to the benzyl group of each of the benzoxazine moieties at the para-position relative to the oxygen atom of the benzoxazine moieties, as shown in formula (I), and this is the preferred isomeric configuration.
• the group Zi may also be attached at either of the meta-positions or the ortho-position, in one or both of the benzyl group(s) in the bis-benzoxazine compound.
• the group Zi may be attached to the benzyl rings in a para/para; para/meta; para/ortho, meta/meta or ortho/meta configuration.
• the difunctional benzoxazine resin component comprises a mixture of isomers, preferably wherein the major portion of the mixture is the para/para isomer shown in structure IV, and preferably this is present in at least 75 mol%, preferably at least 90 mol%, and preferably at least 99 mol%, of the total isomeric mixture.
• the difunctional benzoxazine is selected from compounds wherein Z 1 is selected from -C(CH 3 ) 2 -, -CH 2 - and 3,3-isobenzofuran- 1 (3H)-one, i.e. benzoxazine derivatives of bisphenol A, bisphenol F and
• the difunctional benzoxazine is selected from compounds wherein R 1 and R 2 are independently selected from aryl, preferably phenyl.
• the aryl group may be substituted, preferably wherein the substituent(s) are selected from d -8 alkyl, and preferably wherein there is a single substituent present on at least one aryl group.
• Ci-s alkyl includes linear and branched alkyl chains.
• R 1 and R 2 are independently selected from unsubstituted aryl, preferably unsubstituted phenyl.
• each benzoxazine group of the di-functional benzoxazine compounds defined herein may be independently substituted at any of the three available positions of each ring, and typically any optional substituent is present at the position ortho to the position of attachment of the Z 1 group. Preferably, however, the benzyl ring remains unsubstituted.
• Z 1 is selected from a direct bond, -C(R 3 )(R 4 )-, -C(R 3 )(aryl)-, -C(O)-, -S-, -O-, -
• R 1 and R 2 are independently selected from hydrogen, alkyl (preferably Ci-s alkyl), cycloalkyl (preferably C 5- 7 cycloalkyl, preferably Ce cycloalkyl) and aryl, wherein the cycloalkyl and aryl groups are optionally substituted, for instance by Ci-s alkyl, halogen and amine groups, and preferably by Ci -8 alkyl, and where substituted, one or more substituent groups (preferably one substituent group) may be present on each cycloalkyl and aryl group;
• Z 1 is selected from a direct bond, -C(R 3 )(R 4 )-, -C(R 3 )(aryl)-, -C(O)-, -S-, -O-, a divalent heterocycle and -[C(R 3 )(R 4 )] x -arylene-[C(R 5 )(R 6 )] y -, or the two benzyl rings may be fused;
• R 3 , R 4 , R 5 and R 6 are independently selected from H, Ci-s alkyl (preferably Ci -4 alkyl, and preferably methyl), and halogenated alkyl (wherein the halogen is typically chlorine or fluorine (preferably fluorine) and wherein the halogenated alkyl is preferably CF 3 ); and x and y are independently 0 or 1 ;
• Z 1 is selected from a divalent heterocycle, it is preferably 3, 3- isobenzofuran-1 (3h)-one, i.e. wherein the compound of formula (VII) is derived from phenolphthalein;
• the chain linking the two benzoxazine groups may further comprise one or more arylene group(s) and/or one or more -C(R 7 )(R 8 )- group(s) where R 7 and R 8 are independently selected from the groups defined hereinabove for R 3 , provided that the or each substituted or unsubstituted methylene group is not adjacent to another substituted or unsubstituted methylene group.
• the arylene group is phenylene.
• the groups attached to the phenylene group may be configured in para- or meta-positions relative to each other.
• the aryl group is phenyl.
• the group Zi may be linear or non-linear, and is typically linear.
• the group Zi may be attached at the meta-positions, the para-positions or the ortho-position, in one or both of the benzyl group(s) in the bis-benzoxazine compound.
• the group Zi may be attached to the benzyl rings in a para/para; para/meta; para/ortho, meta/meta or ortho/meta configuration.
• thermoset benzoxazine resin component (A) comprises a mixture of isomers, preferably wherein the major portion of the mixture is the para/para isomer shown in structure IV, and preferably this is present in at least 75 mol%, preferably at least 90 mol%, and preferably at least 99 mol%, of the total isomeric mixture.
• the di-functional benzoxazine is selected from compounds wherein Z 1 is selected from -C(CH 3 ) 2 -, -CH 2 - and 3,3-isobenzofuran- 1 (3H)-one
• the difunctional benzoxazine is selected from compounds wherein R 1 and R 2 are independently selected from aryl, preferably phenyl.
• the aryl group may be substituted, preferably wherein the substituent(s) are selected from d -8 alkyl, and preferably wherein there is a single substituent present on at least one aryl group.
• Ci-s alkyl includes linear and branched alkyl chains.
• R 1 and R 2 are independently selected from unsubstituted aryl, preferably unsubstituted phenyl.
• the benzyl ring in the di-functional benzoxazine compounds defined herein may be independently substituted at any of the three available positions of each ring, and typically any optional substituent is present at the position ortho to the position of attachment of the Z 1 group. Preferably, however, the benzyl ring remains
• the benzoxazine blend discussed above may be combined with additional components such as catalysts and toughening agents to form a curable composition suitable for the manufacture of resinous films (e.g. adhesive films, surfacing films) or fiber-reinforced composites (e.g. prepregs).
• the curable composition is a pure or 100% benzoxazine system which is void of any other curable/thermosettable resin(s) such as epoxy, cyanate ester, BMI and phenolic / phenol-formaldehyde resins. It is preferred that the total amount of all polymerizable benzoxazine compounds in the curable composition is greater than 80%, preferably 85%, by weight based on the total weight of the curable composition.
• curable composition refers to a composition prior to curing and a "cured matrix resin” refers to a cured resin produced from curing the curable composition.
• catalysts are optional, but the use of such may increase the cure rate and/or reduce the cure temperatures.
• benzoxazine-based composition include, but are not limited to, Lewis acids, such as phenols and derivatives thereof, strong acids, such as alkylenic acids, methyl tosylate, cyanate esters, p-toluenesulfonic acid, 2-ethyl-4-methylimidazole (EMI), 2,4-di-tert-butylphenol, BF 3 O(Et) 2 , adipic acid, organic acids, phosphorous pentachloride (PCI 5 ).
• Lewis acids such as phenols and derivatives thereof
• strong acids such as alkylenic acids, methyl tosylate, cyanate esters, p-toluenesulfonic acid, 2-ethyl-4-methylimidazole (EMI), 2,4-di-tert-butylphenol, BF 3 O(Et) 2 , adipic acid, organic acids, phosphorous pentachloride (PCI 5 ).
• PCI 5 phosphorous
• Toughening agents may be added to produce a toughened matrix resin suitable for high-strength composites, such as those used in aerospace application.
• Suitable toughening agents include, but are not limited to, thermoplastic toughening agents such as polyethersulphone (PES), co-polymer of PES and polyetherethersulphone (PEES), elastomers, including liquid rubbers having reactive groups, particulate toughening agents such as thermoplastic particles, glass beads, rubber particles, and core-shell rubber particles.
• Functional additives may also be included in the curable composition to influence one or more of mechanical, rheological, electrical, optical, chemical, flame resistance and/or thermal properties of the cured or uncured resin composition.
• functional additives include, but are not limited to, fillers, color pigments, rheology control agents, tackifiers, conductive additives, flame retardants, ultraviolet (UV) protectors, and the like.
• UV ultraviolet
• additives may take the form of various geometries including, but are not limited to, particles, flakes, rods, and the like.
• toughener(s) and functional additive(s) is up to 15% by weight based on the total weight of the composition.
• the curable composition as discussed above may be combined with reinforcement fibers to form a composite material or structure.
• Reinforcing fibers may take the form of whiskers, short fibers, continuous fibers, filaments, tows, bundles, sheets, plies, and combinations thereof.
• Continuous fibers may further adopt any of unidirectional, multi-directional, non-woven, woven, knitted, stitched, wound, and braided configurations, as well as swirl mat, felt mat, and chopped-fiber mat structures.
• the composition of the fibers may be varied to achieve the required properties for the final composite structure.
• Exemplary fiber materials may include, but are not limited to, glass, carbon, graphite, aramid, quartz, polyethylene, polyester, poly-p-phenylene-benzobisoxazole (PBO), boron, polyamide, graphite, silicon carbide, silicon nitride, and combinations thereof.
• PBO poly-p-phenylene-benzobisoxazole
• the reinforcing fibers are impregnated or infused with the curable composition using conventional processing techniques such as, but not limited to prepregging and resin infusion.
• curing may be carried out at elevated temperature up to 230°C, preferably in the range of 160°C to 230°C, more preferably at about 170°C -230°C, and with the use of elevated pressure to restrain deforming effects of escaping gases, or to restrain void formation, suitably at pressure of up to 10 bar, preferably in the range of 3 to 7 bar absolute.
• the cure temperature may be attained by heating at up to 5°C/min, for example 2°C to 3°C/min and is maintained for the required period of up to 9 hours, preferably up to 6 hours, for example 3 to 4 hours. Pressure is released throughout and temperature reduced by cooling at up to 5°C/min. for example up to 3°C/min. Post-curing at temperatures in the range of 190°C to 230°C may be performed, at atmospheric pressure, employing suitable heating rates to improve the glass transition temperature (T g ) of the product.
• T g glass transition temperature
• the powder was then washed in water (600 cm 3 ) for 30 minutes, filtered and ground, then re-washed in cold IPA. A NaOH wash followed (250 cm 3 , 0.10 mol dm "3 ) at 70 °C for 20 minutes. The solid was then macerated with a Silverson L5M in warm water (3.5 dm 3 ) for 40 minutes and filter- dried. This maceration was repeated three times. The final product was dried in vacuo at 40 °C. The yield was around 120 g (0.17 mol), 88%.
• benzoxazine functionality of -2.5 (functionality being defined as the average number of benzoxazine rings per molecule).
• Bis-A benzoxazine (84g) was added to multifunctional benzoxazine (36g) then placed in an oil bath at 140°C.
• the benzoxazines were stirred via an overhead air stirrer. Once melted, the resin was stirred for 30 minutes.
• 10 - 12 g of material was placed in a 60 mm diameter aluminium dish and/or 85 - 90 g was placed in a 6" x 4" steel mould (to make plaques for mechanical and flexural modulus tests). Degassing took place in a Thermo-Scientific vacuum oven for approximately 3 hours at 120°C, depending on the viscosity of the system and vacuum strength.
• FIG. 1 shows the MEK uptake in refluxing MEK of the multifunctional benzoxazine blends and Bis-A benzoxazine. Unless stated otherwise, all solvent uptake and density data are from blends utilising multifunctional benzoxazine were made via method A.
• BOX in the Tables and figures disclosed herein is an abbreviation for benzoxazine.
• Resin specimens for the MEK uptake testing were -40 mm long, 4 mm deep and 1 .6 mm thick. The specimens were refluxed during the day in MEK solvent, cooled to ambient temperature and left at ambient temperature overnight and at weekends. The specimens were removed, air dried and weighed each morning, then placed back into the MEK and refluxed for the rest of the day.
• the graph in FIG. 1 shows the square root of the amount of time at reflux on the X-axis versus the MEK uptake (%) on the Y-axis. Note that in FIG. 1 the rate of uptake in the multifunctional benzoxazine-containing blends is significantly decreased.
• the trace for Bis-A benzoxazine shows a fast MEK pickup compared to the other samples but then shows a weight loss of the specimen after -36 h, this is due to sample degradation and cracking and the flaking off of material.
• FIG. 2 clearly shows that there is reduction in the rate of MEK uptake at even 1 % multifunctional benzoxazine and that as the amount of multifunctional
• benzoxazine in the blend is increased the MEK uptake is slowed even further.
• FIG. 3 A comparison of a blend of 80:20 ratio Bis-A-benzoxazine:multifunctional- benzoxazine with the multifunctional benzoxazine synthesized via either route A or route B is shown in FIG. 3. It can be seen from FIG. 3 that the multifunctional benzoxazine with average functionality of 3 is even more effective in retarding the rate of MEK uptake than multifunctional benzoxazine with average functionality of 2.
• Density measurements of the multifunctional benzoxazine:Bis-A benzoxazine blends using a displacement technique are shown in FIG. 4. As can be seen, the greater the level of multifunctional benzoxazine, the less dense the material.
• Table 3 shows the results of positron annihilation spectroscopy on samples of the benzoxazine blends. Ratios shown are weight ratios. Samples sandwiched a weak 22 Na positron source sealed in thin Kapton sheets that stop 5-10% of the positrons. Gamma detectors of the spectrometer detected annihilation events, this measured the lifetime of the positronium and the intensity of the positronium annihilation. This allowed calculation of the total free volume, hole size free volume and the average hole diameter. This gives a measure of density and molecular packing.
• Table 4 shows the T g measured by peak Tan delta. Note that T g is increased by up to 1 1 °C at 30% multifunctional benzoxazine.

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  • 2014-12-02 WO PCT/US2014/068068 patent/WO2015094635A1/en not_active Ceased
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  • 2014-12-19 TW TW103144636A patent/TWI616441B/zh not_active IP Right Cessation

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