The Experts below are selected from a list of 9855 Experts worldwide ranked by ideXlab platform
Hatsuo Ishida - One of the best experts on this subject based on the ideXlab platform.
-
a smart latent catalyst containing o trifluoroacetamide functional benzoxazine precursor for low temperature formation of very high performance polybenzoxazole with low dielectric constant and high thermal stability
Macromolecules, 2017Co-Authors: Kan Zhang, Pablo Froimowicz, Hatsuo IshidaAbstract:A novel difunctional benzoxazine with o-trifluoroacetamide functionality has been synthesized via Mannich condensation. The chemical structure of synthesized monomer has also been confirmed by 1H, 13C, and 19F nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The ring-opening polymerization of the resin and the subsequent conversion of the freshly generated polybenzoxazine into polybenzoxazole are studied by FT-IR and differential scanning calorimetry (DSC). In addition to the advantage of low polymerization temperature as other reported o-amide Benzoxazines, the o-trifluoroacetamide benzoxazine also exhibits an unexpected lower benzoxazole formation temperature. Furthermore, the resulting fluorinated polybenzoxazole derived from the benzoxazine monomer possesses the combined excellent properties of facile synthesis, easy processability, low dielectric constant, high thermal stability, and long shelf life, evidencing its potential applications in microelect...
-
Oxazine Ring-Related Vibrational Modes of Benzoxazine Monomers Using Fully Aromatically Substituted, Deuterated, 15N Isotope Exchanged, and Oxazine-Ring-Substituted Compounds and Theoretical Calculations
2017Co-Authors: Lu Han, Seishi Ohashi, Daniela Iguchi, Phwey Gil, Tyler R. Heyl, Victoria M. Sedwick, Carlos R. Arza, Daniel J. Lacks, Hatsuo IshidaAbstract:Polymerization of benzoxazine resins is indicated by the disappearance of a 960–900 cm–1 band in infrared spectroscopy (IR). Historically, this band was assigned to the C–H out-of-plane bending of the benzene to which the oxazine ring is attached. This study shows that this band is a mixture of the O–C2 stretching of the oxazine ring and the phenolic ring vibrational modes. Vibrational frequencies of 3-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazine (PH-a) and 3-(tert-butyl)-3,4-dihydro-2H-benzo[e][1,3]oxazine (PH-t) are compared with isotope-exchanged and all-substituted compounds. Deuterated benzoxazine monomers, 15N-isotope exchanged benzoxazine monomers, and all-substituted benzoxazine monomers without aromatic C–H groups are synthesized and studied meticulously. The various isotopic-exchanges involved deuteration around the benzene ring of phenol, selective deuteration of each CH2 in the O–CH2–N (2) and N–CH2–Ar (4) positions on the oxazine ring, or simultaneous deuteration of both positions. The chemical structures were confirmed by 1H nuclear magnetic resonance spectroscopy (1H NMR). The IR and Raman spectra of each compound are compared. Further analysis of 15N isotope-exchanged PH-a indicates the influence of the nitrogen isotope on the band position, both experimentally and theoretically. This finding is important for polymerization studies of Benzoxazines that utilize vibrational spectroscopy
-
synthesis and ring opening polymerization of 2 substituted 1 3 benzoxazine the first observation of the polymerization of oxazine ring substituted Benzoxazines
Polymer Chemistry, 2016Co-Authors: Seishi Ohashi, Francis Cassidy, Stephanie Huang, Kevin Chiou, Hatsuo IshidaAbstract:2-Substituted 1,3-Benzoxazines (two benzoxazine monomers used in this paper are abbreviated as PH-a-[2]ba and PH-pda-[2]ba) having a phenyl group as an oxazine ring substituent are synthesized with benzaldehyde through 2-hydroxy-N-phenylbenzylamine structures. The polymerization of these monomers is observed for the first time and confirmed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR). The poly(PH-a-[2]ba) derived from 2-substituted 1,3-Benzoxazines exhibits good thermal properties based on TGA analysis, despite showing slight inferiority to poly(PH-a), an unsubstituted counterpart of PH-a-[2]ba. Additionally, benzylideneaniline is extracted during the polymerization, indicating that this compound is the byproduct of the polymerization mechanism. Structural verification is achieved by synthesizing benzylideneaniline and comparing its 1H-NMR spectrum with the reaction byproduct.
-
intramolecular hydrogen bonding in Benzoxazines when structural design becomes functional
Chemistry: A European Journal, 2016Co-Authors: Pablo Froimowicz, Kan Zhang, Hatsuo IshidaAbstract:The future evolution of Benzoxazines and polyBenzoxazines as advanced molecular, structural, functional, engineering, and newly commercial materials depends to a great extent on a deeper and more fundamental understanding at the molecular level. In this contribution, the field of Benzoxazines is briefly introduced along with a more detailed review of ortho-amide-functional Benzoxazines, which are the main subjects of this article. Provided in this article are the detailed and solid scientific evidences of intramolecular five-membered-ring hydrogen bonding, which is supposed to be responsible for the unique and characteristic features exhibited by this ever-growing family of ortho-functionalized Benzoxazines. One-dimensional (1D) 1H NMR spectroscopy was used to study various concentrations of Benzoxazines in various solvents with different hydrogen-bonding capability and at various temperatures to investigate in detail the nature of hydrogen bonding in both ortho-amide-functionalized benzoxazine and its para counterpart. These materials were further investigated by two-dimensional (2D) 1H–1H nuclear Overhauser effect spectroscopy (NOESY) to verify and support the conclusions derived during the 1D 1H NMR experiments. Only highly purified single-crystal benzoxazine samples have been used for this study to avoid additional interactions caused by any impurities.
-
thermally stable polyBenzoxazines via ortho norbornene functional benzoxazine monomers unique advantages in monomer synthesis processing and polymer properties
Polymer, 2015Co-Authors: Kan Zhang, Hatsuo IshidaAbstract:Abstract Monofunctional and difunctional Benzoxazines with ortho -norbornene functionality have been synthesized via Mannich condensation. The structure of synthesized monomers has been confirmed by 1 H nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR). The ortho -norbornene functional benzoxazine resins show excellent features both in the synthesis of benzoxazine monomers and the properties of the corresponding thermosets. The Benzoxazines containing norbornene groups can polymerize with multiple polymerization mechanisms rather than the single mechanism common to traditional 1,3-benzoxazine resins. The polymerization mechanisms are monitored by in situ FT-IR and differential scanning calorimetry (DSC). Activation energy of polymerization is also studied by DSC. Moreover, the thermoset derived from the difunctional benzoxazine monomer exhibits high thermal stability with the glass transition temperature of 365 °C and a high T d5 of 463 °C.
Yusuf Yagci - One of the best experts on this subject based on the ideXlab platform.
-
Coumarines as masked phenols for amide functional Benzoxazines
Polymer Chemistry, 2019Co-Authors: Gizem Kaya, Baris Kiskan, Yusuf YagciAbstract:Benzoxazines with amide linkages were successfully prepared. Initially, 3,4-dihydrocoumarine (DHC) was used as the reagent to synthesize phenolic amides via a ring-opening reaction using primary amines. The phenolic amides were then reacted with formaldehyde and primary amines to produce amide containing Benzoxazines. Moreover, the polymeric amide functional benzoxazine precursor was prepared with bisamine end-functional poly(propylene oxide) by Mannich type polycondensation. The obtained polymer exhibited good film forming properties and free standing flexible films were easily solvent-cast on glass plates. All of the monomers and polymeric precursors were characterized by 1H NMR and FTIR spectroscopic analysis and their curing behavior and thermal stability were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Additionally, the mechanical properties of both cured and uncured polymeric benzoxazine precursors were studied by tensile test measurements.
-
Benzoxazine resins as smart materials and future perspectives
Thermosets, 2018Co-Authors: Baris Kiskan, Yusuf YagciAbstract:Abstract PolyBenzoxazines are high-performance thermosets having a range of properties and capability to overcome drawbacks of traditional resole- and novolac-type phenolics. They exhibit low water absorption, high T g , high char yield, flame resistance, low shrinkage, and also limited or no release of by-products during curing, and they have comparable mechanical performance with bismaleimide resins. In this chapter, we provide an overview of polyBenzoxazines highlighting in the progress in the synthesis of both benzoxazine monomers and polybenzoxazine prepolymers, their resulting materials, and their composites. Moreover, industrially important Benzoxazines and current advances of benzoxazine applications as smart materials ranging from self-healing materials to electroactive coatings were reviewed.
-
Ring-Opening Polymerization of 1,3-Benzoxazines via Borane Catalyst
MDPI AG, 2018Co-Authors: Mustafa Arslan, Baris Kiskan, Yusuf YagciAbstract:Tris(pentafluorophenyl)borane was used as Lewis acid catalyst to lower the ring opening polymerization temperature (ROP) of 1,3-Benzoxazines. Dynamic scanning calorimeter studies revealed that on-set ROP temperatures were decreased as much as 98 °C for model benzoxazine compounds. Catalytic polymerization was traced by both FTIR and 1H NMR, and revealed that tris(pentafluorophenyl)borane acted rapidly and fast curing achieved. Moreover, thermal properties of resulting polyBenzoxazines were investigated by thermogravimetric analysis (TGA) and found out that the catalyst has high impact on char yield and even 3 mol % catalyst augmented char yields up to 13%
-
post modification of polybutadienes by photoinduced hydrogen abstraction from Benzoxazines and their thermally activated curing
Macromolecules, 2016Co-Authors: Mustafa Arslan, Baris Kiskan, Yusuf YagciAbstract:Side-chain benzoxazine functional polybutadienes was synthesized by photoinduced hydrogen abstraction process. First, photoactive Benzoxazines having both chromophoric carbonyl and hydrogen donating sites were synthesized using vanillin or 4-hydroxybenzophenone by conventional benzoxazine synthesis methodology. Irradiation of neat polybutadiene (PB) in the presence of the corresponding Benzoxazines, namely benzophenone benzoxazine (BPh-ptol) and vanillin benzoxazine (Van-a) under 300–350 nm light, gave PBs with approximately 4–5 benzoxazine units per chain. Successful modification was confirmed by the spectral and thermal investigations. It is demonstrated that PBs attached with Benzoxazines undergo thermally activated curing without any catalyst to form polybutadiene thermoset with high char yield.
-
Post-Modification of Polybutadienes by Photoinduced Hydrogen Abstraction from Benzoxazines and Their Thermally Activated Curing
2016Co-Authors: Mustafa Arslan, Baris Kiskan, Yusuf YagciAbstract:Side-chain benzoxazine functional polybutadienes was synthesized by photoinduced hydrogen abstraction process. First, photoactive Benzoxazines having both chromophoric carbonyl and hydrogen donating sites were synthesized using vanillin or 4-hydroxybenzophenone by conventional benzoxazine synthesis methodology. Irradiation of neat polybutadiene (PB) in the presence of the corresponding Benzoxazines, namely benzophenone benzoxazine (BPh-ptol) and vanillin benzoxazine (Van-a) under 300–350 nm light, gave PBs with approximately 4–5 benzoxazine units per chain. Successful modification was confirmed by the spectral and thermal investigations. It is demonstrated that PBs attached with Benzoxazines undergo thermally activated curing without any catalyst to form polybutadiene thermoset with high char yield
Kan Zhang - One of the best experts on this subject based on the ideXlab platform.
-
a smart latent catalyst containing o trifluoroacetamide functional benzoxazine precursor for low temperature formation of very high performance polybenzoxazole with low dielectric constant and high thermal stability
Macromolecules, 2017Co-Authors: Kan Zhang, Pablo Froimowicz, Hatsuo IshidaAbstract:A novel difunctional benzoxazine with o-trifluoroacetamide functionality has been synthesized via Mannich condensation. The chemical structure of synthesized monomer has also been confirmed by 1H, 13C, and 19F nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The ring-opening polymerization of the resin and the subsequent conversion of the freshly generated polybenzoxazine into polybenzoxazole are studied by FT-IR and differential scanning calorimetry (DSC). In addition to the advantage of low polymerization temperature as other reported o-amide Benzoxazines, the o-trifluoroacetamide benzoxazine also exhibits an unexpected lower benzoxazole formation temperature. Furthermore, the resulting fluorinated polybenzoxazole derived from the benzoxazine monomer possesses the combined excellent properties of facile synthesis, easy processability, low dielectric constant, high thermal stability, and long shelf life, evidencing its potential applications in microelect...
-
intramolecular hydrogen bonding in Benzoxazines when structural design becomes functional
Chemistry: A European Journal, 2016Co-Authors: Pablo Froimowicz, Kan Zhang, Hatsuo IshidaAbstract:The future evolution of Benzoxazines and polyBenzoxazines as advanced molecular, structural, functional, engineering, and newly commercial materials depends to a great extent on a deeper and more fundamental understanding at the molecular level. In this contribution, the field of Benzoxazines is briefly introduced along with a more detailed review of ortho-amide-functional Benzoxazines, which are the main subjects of this article. Provided in this article are the detailed and solid scientific evidences of intramolecular five-membered-ring hydrogen bonding, which is supposed to be responsible for the unique and characteristic features exhibited by this ever-growing family of ortho-functionalized Benzoxazines. One-dimensional (1D) 1H NMR spectroscopy was used to study various concentrations of Benzoxazines in various solvents with different hydrogen-bonding capability and at various temperatures to investigate in detail the nature of hydrogen bonding in both ortho-amide-functionalized benzoxazine and its para counterpart. These materials were further investigated by two-dimensional (2D) 1H–1H nuclear Overhauser effect spectroscopy (NOESY) to verify and support the conclusions derived during the 1D 1H NMR experiments. Only highly purified single-crystal benzoxazine samples have been used for this study to avoid additional interactions caused by any impurities.
-
thermally stable polyBenzoxazines via ortho norbornene functional benzoxazine monomers unique advantages in monomer synthesis processing and polymer properties
Polymer, 2015Co-Authors: Kan Zhang, Hatsuo IshidaAbstract:Abstract Monofunctional and difunctional Benzoxazines with ortho -norbornene functionality have been synthesized via Mannich condensation. The structure of synthesized monomers has been confirmed by 1 H nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR). The ortho -norbornene functional benzoxazine resins show excellent features both in the synthesis of benzoxazine monomers and the properties of the corresponding thermosets. The Benzoxazines containing norbornene groups can polymerize with multiple polymerization mechanisms rather than the single mechanism common to traditional 1,3-benzoxazine resins. The polymerization mechanisms are monitored by in situ FT-IR and differential scanning calorimetry (DSC). Activation energy of polymerization is also studied by DSC. Moreover, the thermoset derived from the difunctional benzoxazine monomer exhibits high thermal stability with the glass transition temperature of 365 °C and a high T d5 of 463 °C.
-
An anomalous trade-off effect on the properties of smart ortho-functional Benzoxazines
Polymer Chemistry, 2015Co-Authors: Kan Zhang, Hatsuo IshidaAbstract:A series of ortho-difunctional benzoxazine monomers containing amide, imide and amide–imide groups have been synthesized in order to obtain basic design rules toward preparing higher performance polybenzoxazoles based on smart benzoxazine chemistry. The structures of the synthesized monomers have been confirmed by 1H nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). The polymerization behavior of benzoxazine monomers is studied by differential scanning calorimetry (DSC). The trade-off between a symmetric imide and a symmetric amide results in an asymmetric amide–imide functional monomer exhibiting the broadest processing window and the lowest activation energy of the ortho-functional Benzoxazines studied. After polymerization, the thermal stability of each polybenzoxazine is studied by thermogravimetric analysis (TGA). The polymer obtained from ortho-(amide–imide) functional benzoxazine gives the highest thermal stability, which is against the traditionally designed poly(amide-co-imide), possessing the thermal stability between polyamide and polyimide. The activation energy for benzoxazine polymerization and the degradation of polybenzoxazole are also studied by DSC and TGA, respectively. The relationship between the benzoxazine monomer structures and the thermoset properties has been discussed.
Muthukaruppan Alagar - One of the best experts on this subject based on the ideXlab platform.
-
Polypyrrole inter-layered low temperature curing benzoxazine matrices with enhanced thermal and dielectric properties
Journal of Polymer Research, 2020Co-Authors: P. Prabunathan, Aravind Hariharan, Archana Vasanthakumar, Manuja Manoj, Muthukaruppan AlagarAbstract:In the present work, curing reaction of benzoxazine was studied with the incorporation of different weight percentage of polypyrrole (PPy). Conventional benzoxazine derived from Bisphenol-F, aniline (BF-a) and bio-based benzoxazine derived from cardanol, furfurylamine (C-f) were synthesized and studied. Significant change in curing temperature (Tp) was observed with the addition of PPy to both C-f and BF-a monomers. With the incorporation of 5 wt% PPy, the Tp of C-f significantly reduced from 245 °C to 185 °C and similarly for BF-a monomer from 226 °C to 165 °C. The plausible mechanism of the benzoxazine ring opening reaction in presence of PPy is also discussed. Further, scanning electron microscopy (SEM) and X-ray diffraction studies suggest that the incorporation of PPy leads to the formation of fractal morphology. Consequently, the PPy inter-layered poly(C-f) and poly(BF-a) matrices contribute to the achievement of low value of dielectric constant (K = 3.39 and 3.83). In addition, PPy interlayer provokes enhanced thermal stability and higher LOI value. Thus, the present work demonstrates the catalytic role of PPy towards the curing reaction of Benzoxazines and its contribution towards thermal and dielectric behaviour the of resulted matrices.
-
Exploration of high corrosion resistance property of less hazardous pyrazolidine-based Benzoxazines in comparison with bisphenol-F derivatives
Journal of Coatings Technology and Research, 2020Co-Authors: Manuja Manoj, P. Prabunathan, R. Mangalam, Aravind Hariharan, Arthi Kumaravel, Muthukaruppan AlagarAbstract:The present work describes the design of nontoxic pyrazolidine bisphenol (PYBP)-based hydrophobic benzoxazine (PBz) matrices, in comparison with that of bisphenol-F-based Benzoxazines, and investigates their efficiency toward corrosion protection on mild steel surfaces. The preliminary in vitro toxicity assay studies infer the nontoxic nature of PYBP. Data obtained from thermal and surface studies indicate that the PYBP-based PBzs possess higher thermal stability than those of bisphenol-F Benzoxazines. Observations from SEM images suggest that the inherent hydrophobic nature was due to the formation of rough surfaces. The corrosion studies of the specimens were carried out using open-circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization. Among the mild steel specimens, coated with different Benzoxazines, the poly(PYBP-oda)-coated specimen was found to be less aggressive toward corrosion showing 90% efficiency and charge transfer resistance ( R _ct) of 381 kΩ cm^2. Thus, data obtained from different studies suggest that the PYBP-based Benzoxazines can be used as a better coating material for steel and steel products against corrosion.
-
Blends of Chalcone Benzoxazine and Bio-Benzoxazines Coated Cotton Fabrics for Oil–Water Separation and Bio-silica Reinforced Nanocomposites for Low-k Applications
Journal of Polymers and the Environment, 2019Co-Authors: A. Hariharan, P. Prabunathan, S. S. Subramanian, M. Kumaravel, Muthukaruppan AlagarAbstract:In the present work, chalcone benzoxazine (Chal-Bz) was co-polymerized with two bio-based Benzoxazines namely cardanol (CrAb) and eugenol (EuAb) benzoxazine and coated over cotton fabric. The Chal-Bz/CrAb and Chal-Bz/EuAb blends coated cotton fabrics show water contact angle values of 163° and 156° respectively and their oil–water separation efficiency were observed found to be 97 and 96% respectively. In addition, the glycidoxypropyltrimethoxysilane (GPTMS) functionalized bio-silica in varying weight percentages (1, 3, 5, 7 and 10 wt%) was also reinforced with two co-polymerized blended matrices to obtain respective composites. The developed composites were studied for their dielectric, thermal and morphological behaviours. The values of dielectric constant of 10 wt% bio-silica reinforced Chal-Bz/CrAb and Chal-Bz/EuAb composites were found to be 2.1 and 2.3, respectively. Similarly the values of contact angle of 10 wt% bio-silica reinforced chal-Bz/CrAb and Chal-Bz/EuAb composites were 137° and 116°, respectively. Data obtained from different studies suggest that these bio-silica reinforced benzoxazine composites can be used in the form of coatings, adhesives, sealants and encapsulants for high performance micro-electronics insulation applications under adverse environmental conditions. Thermal assisted polymerization of chalcone based benzoxazine (Chal-Bz) with bio based Benzoxazines cardanol-aniline based benzoxazine (CrAb) and eugenol-aniline based benzoxazine (EuAb)) for low k and oil–water separation application.
-
Low Temperature Cure Siloxane Based Hybrid Renewable Cardanol Benzoxazine Composites for Coating Applications
Journal of Polymers and the Environment, 2019Co-Authors: Vaithilingam Selvaraj, T. R. Raghavarshini, Muthukaruppan AlagarAbstract:The siloxane based flexible cardanol benzoxazine was synthesised using cardanol, 1,3-bis(aminopropyl) tetramethyldisiloxane and p -formaldehyde through solvent free method and was characterised by different analytical techniques. A new fangled nanocomposites of amine functionalised rice husk ash silica reinforced siloxane based flexible cardanol benzoxazine were developed and their molecular structure, molecular weight, morphology, cure behaviour, thermal stability, dielectric character and corrosion resistant behaviour were carried out by appropriate test methods. Data obtained from differential calorimetric analysis and experimental cure process infer that the siloxane based cardanol benzoxazine cures at 110 °C, which is significantly lower temperature when compared to that of conventional Benzoxazines cure between 220 and 280 °C. Results from dielectric and corrosion resistant studies indicate that these renewable hybrid composite materials can be conveniently used in the form of adhesives, encapsulants, sealants and potting compounds for high performance, low k materials in microelectronics and as coatings to protect steel surfaces from corrosion and microbial deterioration.
-
Synthesis and characterization of a novel class of low temperature cure Benzoxazines
Journal of Polymer Research, 2017Co-Authors: Aravind Hariharan, C. Murthy, K Srinivasan, Muthukaruppan AlagarAbstract:A series of a novel class of low cure Benzoxazines (BZ-1 to BZ-12) based on phenol, bisphenol-A, bisphenol-F mixture and 4, 4 isomers of bisphenol-F were synthesized using aniline, N, N-dimethyl amino propyl amine (DMAPA) and caprolactam (CPL) modified DMAPA. The molecular structure of benzoxazine monomers was characterized by 1H NMR, FT-IR, and LC mass spectrometry analysis. DSC and TGA analysis were carried out to study the polymerization process and stability of Benzoxazines respectively. Among the benzoxazine systems studied, PBZ-5 is found to possess the reasonably lower cure temperature with good char yield, Tmax and Tg values. The catalytic effect on curing behavior of BZ-5 with different types of catalysts such as mono hydroxy (C1-C6), polyhydroxy (C7-C9) and acidic catalysts (C10 to C13) was studied and discussed in detail. Among the catalysts used, 4,4-thiobisphenol (C7) was found to be the most effective catalyst towards the ring opening polymerization and in turn lowers the cure temperature (amount, acidity, basicity and structural compatibility of the catalysts) than that of other catalysts (C2-C13). In addition, the catalytic behavior of starting materials (bisphenol-A and bisphenol-F) towards Benzoxazines BZ-5, BZ-6, BZ-8 and BZ-9 were also studied and it can be found that bisphenol-A/F also acts as an effective catalyst which can bring down the cure exotherm to a significant extent.
Tarek Agag - One of the best experts on this subject based on the ideXlab platform.
-
polymerization behavior of methylol functional benzoxazine monomer
Reactive & Functional Polymers, 2013Co-Authors: Mohamed Baqar, Hatsuo Ishida, Tarek Agag, Syed QutubuddinAbstract:Abstract This study focuses on methylol functional Benzoxazines as precursors to build a network structure utilizing both benzoxazine and resole chemistry. The first part is a review of systems that contain methylol groups which play a role on their crosslinking formation. The polymerization mechanism and properties of resoles will be highlighted as the most abundant polymers that are characterized by polymerization through condensation reaction of methylol group. In the second part, the effect of incorporating methylol group into benzoxazine monomers is studied. Differential scanning calorimetry (DSC) is used to study the effect of methylol group on the rate of polymerization. Kissinger and Ozawa methods using non-isothermal DSC at different heating rates show that methylol monomer exhibits lower average activation energy compared to the un-functionalized monomer. The effect of adding catalysts into the monomers is also studied. p -Toluene sulfonic acid (PTSA) is found to be more efficient than 1-methyl-imidazole (IMD) and lithium iodide (LiI) in the case of methylol monomer due to its ability of accelerating both the methylol condensation and ring-opening polymerization. Additionally, thermal behavior of the monomers is studied using thermogravimetric analysis (TGA).
-
methacryloyl functional benzoxazine photopolymerization and thermally activated polymerization
Macromolecules, 2011Co-Authors: Tarek Agag, Yusuf Yagci, Hatsuo IshidaAbstract:A novel class of photopolymerizable Benzoxazines has been developed. This class has been coined as methacryloyl-functional Benzoxazines. It has been synthesized by the reaction of the new benzoxazine monomers: (3-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-yl)methanol and methacryloyl chloride. The structure of the monomer has been confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR). Its photopolymerization has been successfully carried out with and without photoinitiator, while the thermally activated polymerization is compromised by low temperature degradation.
-
primary amine functional benzoxazine monomers and their use for amide containing monomeric Benzoxazines
Macromolecules, 2010Co-Authors: Tarek Agag, Carlos Rodriguez Arza, Frans H J Maurer, Hatsuo IshidaAbstract:Amino-functional benzoxazine monomers have been successfully prepared. Several routes have been applied to incorporate amino group into benzoxazine structure. These approaches include reduction of the corresponding nitro-functional Benzoxazines and deprotection of protected amino-functional benzoxazine monomers. Various approaches that allow primary amine groups to be prepared without damaging the existing benzoxazine groups have been evaluated. Tetrachlorophthalimide and trifluoroacetyl are found to be suitable protecting groups. In addition, a model compound of amide-functional Benzoxazines is prepared from primary amine-functional benzoxazine. Fourier transform infrared spectroscopy (FTIR) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) are used to characterize the structure of the monomers. The polymerization behavior of amino-functional monomers and model compound are studied by differential scanning calorimetry (DSC).
-
bis benzoxazine maleimide s as a novel class of high performance resin synthesis and properties
European Polymer Journal, 2010Co-Authors: Lin Jin, Tarek Agag, Hatsuo IshidaAbstract:Abstract A new class of benzoxazine-containing monomers, namely bis(benzoxazine-maleimide)s, has been prepared from hydroxyphenylmaleimide, paraformaldehyde and various diamines. This series of difunctional maleimide Benzoxazines has been difficult to synthesize using previously reported benzoxazine synthesis conditions. The structures of the monomers are confirmed by Fourier transform infrared spectroscopy (FTIR), 1 H and 13 C nuclear magnetic resonance spectroscopy (NMR) and elemental analysis. Polymerization behavior of the monomers is studied by differential scanning calorimetry (DSC), showing two exotherms at different temperature ranges. The 1st exotherm is due to the combination of benzoxazine ring-opening polymerization and addition-polymerization of bismaleimide. FTIR is also used to investigate the polymerization process. The dynamic mechanical analyses (DMA) of the obtained polymers reveal the glass-transition temperatures as high as 289–307 °C. Thermogravimetric analyses (TGA) show the 5% weight loss temperatures ranging from 374 to 383 °C with char yield ranging from 55% to 62% at 800 °C in N 2 atmosphere.
-
novel benzoxazine monomer containing diacetylene linkage an approach to benzoxazine thermosets with low polymerization temperature without added initiators or catalysts
Polymer, 2009Co-Authors: Andrey Chernykh, Tarek Agag, Hatsuo IshidaAbstract:Abstract A novel benzoxazine monomer containing diacetylene linkage has been synthesized by applying an oxidative coupling approach. The structure is confirmed by 1 H and 13 C nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) is used to study crosslinking behavior of synthesized material. The benzoxazine monomer exhibits unexpectedly low exothermic peak with the onset around 140 °C, which is significantly lower than conventional Benzoxazines or Benzoxazines containing additional crosslinking sites. Benzoxazine polymerization at this low temperature is also confirmed by FTIR. The initial model studies are made in order to understand this phenomenon and preliminary explanation is given. High thermal stability of the crosslinked thermoset was confirmed by thermogravimetric analysis (TGA).