Renewable highly biobased polybenzoxazine thermosets for composite applications
Inventors
Palmese, Giuseppe R. • Yadav, Santosh K. • LaScala, John J.
Assignees
Drexel University • United States Department of the Army
Publication Number
US-11643406-B2
Publication Date
2023-05-09
Expiration Date
2038-08-21
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Abstract
Benzoxazine compounds, methods of making them, polymers made therefrom and methods of polymerizing the benzoxazines. These renewable benzoxazine monomers and polymers that utilize the variety of building blocks found in renewable plant biomass, demonstrate excellent processability and large temperature windows for processing of resin systems.
Core Innovation
The invention provides novel highly bio-derived benzoxazine monomers and polymers derived from renewable plant biomass. These benzoxazine compounds utilize the various building blocks found in renewable plant biomass and demonstrate excellent processability and large temperature windows for processing of resin systems. The invention also includes methods of preparing the benzoxazine compounds and forming polymers by ring opening polymerization of these benzoxazines.
Benzoxazine monomers are precursors to polybenzoxazine polymers which offer unique advantages such as low melt viscosity, catalyst-free curing, nonvolatile release, and near-zero volumetric change during curing. However, current polybenzoxazines face challenges in supply and cost due to reliance on petroleum. Petroleum-derived monomers also have limited chemical structures and functionalities. To overcome these issues, the invention addresses the development of renewable benzoxazine monomers and polymers inspired by natural plant biomass components, enabling tunable-property polymers with improved processability and properties suitable for various applications.
Claims Coverage
The patent comprises multiple independent claims covering novel benzoxazine compounds, methods to prepare them, and polymers derived therefrom. The claims detail the chemical structures, preparation methods, and polymer compositions involving bio-based benzoxazines and their incorporation into composite materials.
Renewable benzoxazine compounds of novel chemical structures
The invention provides benzoxazine compounds of Formula (I) and Formula (III), wherein various substituents R1, R2, R3, R4, R5, R7, R8, and R9 are independently selected from defined groups including alkyl, alkenyl, alkoxy, aryl, cycloalkyl, and heterocyclic groups with optional substitutions. The compounds include symmetrical embodiments and specific bonding positions on the benzoxazine ring, incorporating furan-containing moieties derived from renewable biomass.
Method for preparing benzoxazine compounds using renewable feedstocks
A method for forming the benzoxazine compounds involves reacting a furfurylamine compound (including difuran diamine or tetrafuran tetraamine), a formaldehyde compound (such as paraformaldehyde or formaldehyde), and a phenol compound selected from phenol, bisphenol A, bisguaiacol, vanillin, carvacrol, or eugenol. The reaction is conducted optionally in an inert organic solvent at temperatures from 60 to 85 °C.
Formation of polymers by ring opening polymerization and epoxy reaction
Polymers are formed by ring opening polymerization of the benzoxazine compounds of Formula (I) or (III), optionally combined with an epoxidation reaction using diepoxide compounds such as bisphenol-A diglycidyl ether (DGEBA) or other specific epoxide resins. The polymers include at least one repeating unit defined by Formula (VII), (VIII), (IX), or (X) with specified substituents.
Polymer compositions incorporating benzoxazine polymers and additives
Polymer compositions include the described benzoxazine-based polymers further combined with one or more fibers, clays, silicates, fillers, pigments, corrosion inhibitors (e.g., zinc phosphate), flame retardants, stabilizers, plasticizers, and other additives suitable for composite applications. The polymers demonstrate glass transition temperatures from 100 °C to 300 °C, flexural moduli from 2 GPa to 4 GPa, flexural strength above 20 MPa at room temperature, and UL-94 flammability ratings of V-0 or V-1.
Overall, the claims cover novel bio-based benzoxazine monomers with specified substitution patterns, methods for their synthesis from renewable starting materials, formation of corresponding polymers including epoxy combinations, and polymer compositions suitable for high-performance composite applications with advantageous thermal and mechanical properties.
Stated Advantages
The benzoxazine monomers demonstrate excellent processability with large temperature windows for processing resin systems, allowing tunable properties.
The polymers show high glass transition temperatures, low water absorption, high char yield, and excellent thermal and electrical properties.
The bio-derived benzoxazine polymers serve as renewable, sustainable alternatives to petroleum-based high-performance phenolic resins.
The biobased polymers achieve flexural modulus and strength suitable for composite applications with UL-94 flammability ratings of V-0 or V-1.
Documented Applications
Use of the renewable benzoxazine polymers in composite materials, particularly in polymer compositions containing fibers such as glass fibers for mechanical reinforcement.
Preparation of benzoxazine-containing molding compositions that can be molded by transfer press for applications including coatings of electronic devices such as semiconductors and circuit boards.
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