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In this article, a series of tetra-functional quinoxaline-based benzoxazine/ monofunctional benzoxazine (P-a) blending resins were prepared. Differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TGA) were utilized to study the curing behavior of blends and heat resistance and thermal stability of the corresponding resins. The obtained blends show lower onset and peak exothermic temperatures than that of a phenol/phenylamine-based benzoxazine. Additionally, the cured blends possess much better heat resistance, higher char yields, and better thermal stability than monofunctional benzoxazine resins.

A new series of aniline and aniline-mixed tetrafunctional fluorene-based oxazine monomers were synthesized using 2,7-hydroxy-9,9-bis-(4-hydroxyphenyl) fluorene, paraformaldehyde, and primary amines (including aniline or aniline mixed with n-butylamine or n-octylamine composition). Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy were used to characterize the structure of the monomers. The copolymers were obtained by adding the monomers into a typical monofunctional polybenzoxazine (phenol-aniline-based benzoxazine). Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis were performed to study the thermal properties of the copolymers. The copolymers exhibited high glass transition temperature values (164–201°C). A good thermal stability was also obtained with a 5% weight loss temperature over 355°C and high char yields at 800°C (42–50%).

A series of tetra-functional fluorene-based benzoxazines containing both flexible linear aliphatic chain and rigid aromatic structure in their backbones were synthesized using mixed amines such as aniline and n-octylamine, 2,7-dihydroxy-9,9-bis-(4-hydroxyphenyl)fluorene (THPF) and paraformaldehyde as raw materials via Mannich reaction. The prepared benzoxazine monomers were identified by fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (1H NMR). In addition, the curing behavior, curing kinetics and rheological properties of these monomers as well as the thermal and mechanical properties of their cured resins were studied using a rheometer, differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), and dynamic thermomechanical analyzer (DMA). The newly developed benzoxazines show good processibility, excellent thermal stability and high glass transition temperature (Tg) values ranging from 291 to 307 °C. By varying the proportion of n-octylamine to aniline, the properties of these resins are tuned.

This study deals with the influences of both the length of the aliphatic spacer within the phthalonitrile monomers backbones, and the amount of the silane surface modified zirconia nanoparticles on the mechanical and thermal properties of the so-called second generation phthalonitrile resins. Investigation on the curing behavior under differential scanning calorimeter outlined an important gain in the processability as the aliphatic spacer became longer. Results from the mechanical tests revealed that changing the length of the aliphatic spacer affects the mechanical properties in different ways. For instance, as the aliphatic spacer became longer, the toughness state was enhanced. At the same time, the tensile modulus and stress as well as the microhardness values were slightly reduced. It was also noticed that the introduction of the reinforcing phase caused an increase in all the tested mechanical properties. Furthermore, results from the thermogravimetric analysis and dynamic mechanical analysis revealed that reducing the length of the aliphatic spacer and adding nanofillers caused an increase in the thermal stability, storage modulus, and glass transition temperature. Moreover, a morphological study has been conducted under scanning electron microscope and transmission electron microscope to put in light the mechanisms of enhancements. Finally, this study demonstrated that the excellent properties of the phthalonitrile resins can be tailored by two ways either by monomers design or by inorganic nanoparticles reinforcement.

A new kind of thermally-conductive polymer nanocomposite was produced by reinforcing the typical polybenzoxazine matrix P(BA-a) with silane-treated Si 3 N 4 nanoparticles using a compression molding technique. By adding 0 to 70% nano-Si 3 N 4 , the nanocomposite׳s thermal conductivity was enhanced from 0.18 to 5.78 W/m K. Based on the analyzed morphology, the Si 3 N 4 nanoparticles tend to form continuous conductive chains within the polybenzoxazine matrix, which are responsible for the improved thermal conductivity of the polybenzoxazine resin. Also, these new nanocomposites exhibited improved dielectric, coefficient of thermal expansion, and flexural properties. The thermal stability of these materials significantly improved upon the addition of the nano-Si 3 N 4 fillers. Their unique thermal and dielectric properties make them suitable for microelectronic packaging applications.

A new type of composite based on phthalonitrile resin reinforced with silicon carbide (SiC) microparticles was prepared. For various weight ratios ranging between 0% and 20%, the effect of the micro-SiC particles on the mechanical and thermal properties has been studied. Results from thermal analysis revealed that the starting decomposition temperature and the residual weight were significantly improved upon adding the reinforcing phase. At the maximum micro-SiC loading, dynamic mechanical analysis (DMA) showed an important enhancement in both the storage modulus and glass transition temperature ( T g ), reaching 3.1 GPa and 338 °C, respectively. The flexural strength and modulus as well as the microhardness were significantly enhanced by adding the microfillers. Tensile test revealed enhancements in the composites toughness upon adding the microparticles. Polarization optical microscope (POM) and scanning electron microscope (SEM) analysis confirmed that mechanical and thermal properties improvements are essentially attributed to the good dispersion and adhesion between the particles and the resin.

A series of fluorene-based benzoxazine copolymers were synthesized from the mixture of 9,9-bis(4-hydroxyphenyl)fluorene and bisphenol A, and 4,4′-diaminodiphenyloxide and paraformaldehyde. And the cured polybenzoxazine films derived from these copolymers were also obtained. Fourier transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonances confirmed the structure of these benzoxazines. Their molecular weight was estimated by gel permeation chromatography. The curing behavior of the precursors was monitored by FTIR and differential scanning calorimetry. Dynamic mechanical analysis and thermogravimetric analysis were performed to study the thermal properties of the cured polymers. The cured polybenzoxazines exhibit excellent heat resistance with glass transition temperatures (Tg) of 286–317°C, good thermal stability along with the values of 5% weight loss temperatures (T5) over 340°C, and high char yield over 50% at 800°C. The mechanical properties of the cured polymers were also measured by bending tests. Copyright © 2015 John Wiley & Sons, Ltd.

A novel tetraphenol fluorene, 2,7-dihydroxy-9,9-bis-(4-hydroxyphenyl)fluorene (THPF), was synthesized via the condensation reaction of 2,7-dihydroxy-9-fluorenone and phenol in the presence of a strong acidic cation exchange resin and 3-mercaptopropionic acid. Thus, a novel tetrafunctional oxazine monomer containing benzoxazine and fluorene-oxazine (t-BF-b) was prepared for the first time using a Mannich condensation reaction of THPF with paraformaldehyde and n-butylamine. The chemical structures of THPF and t-BF-b were characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, 1H and 13C nuclear magnetic resonance (NMR). The viscosity–temperature properties and the polymerization behavior of t-BF-b as well as the thermal and mechanical properties of its cured polymer (poly(t-BF-b)) were studied by rheometry, FTIR, 1H NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). The results show that poly(t-BF-b) displays a lower melting point and wider processing window. The oxazine rings of fluorene-oxazine possess higher reactivity and lower polymerization temperature than those of benzoxazine. Also, its cured poly(t-BF-b) exhibits a higher glass transition temperature than its corresponding bifunctional polybenzoxazines without sacrificing any thermal properties in spite of the introduction of more flexible aliphatic groups into polymer chains.

A series of fluorene-based benzoxazine-endcapped copoly(ether ketone ketone)s (co-PEKKs) were successfully synthesized, in which the co-PEKKs were prepared with different molar ratios of 2,7-dihydroxy-9-fluorenone to bisphenol-A. The obtained phenol-ended co-PEKKs reacted with formaldehyde and n-butylamine to yield the benzoxazine-endcapped co-PEKKs (B-PEKKs). The structure of these oligomers was studied by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy, and the molecular mass of these phenol-ended co-PEKKs was detected by gel permeation chromatography. The thermal behaviors of these B-PEKKs were determined by differential scanning calorimetry. In addition, the thermal and dynamic mechanical properties of the polymer films were investigated by thermogravimetric analysis and dynamic mechanical analysis. The results indicate that the incorporation of co-PEKKs within the benzoxazine backbone considerably improves the toughness of the fluorene-containing polybenzoxazines without much sacrifice of their thermal properties. Furthermore, as the content of 2,7-dihydroxy-9-fluorenone increases, the T5 values decrease, while the Tg values and char yields of the prepared polymers increase to reach their highest values at 256 °C and 64 %, respectively.

Silicon nitride (SN) nanoparticle-reinforced polybenzoxazine nanocomposites were produced with good processability at various fractions of nano-SN ranging between 0 and 30 wt% via a compression molding technique. At the maximum nano-SN loading, the DMA of the nanocomposites showed an increase of 2 GPa and 47 °C in stiffness and glass transition temperature (Tg), respectively. In addition, increasing the nano-SN fraction to 30 wt% significantly enhanced both the tensile strength and the micro-hardness of the nanocomposites. The TGA results revealed that the thermal stability of these nanocomposites was highly improved upon the addition of the reinforcing phase. The enhancements in the thermal and mechanical properties of these nanocomposites are attributed to the uniform nanoparticle dispersion and to the strong matrix–particle interactions based on the SEM and TEM results. Therefore, these nanocomposites are more suitable for high performance coating applications.

The recent development of high-molecular weight benzoxazine precursors is discussed in this chapter. Also, the studies of fluorene-based benzoxazine monomers and main chain, side chain, and telechelic high molecular weight benzoxazine oligomers and co-oligomers containing fluorene groups are reviewed in detail. Compared with fluorene-based benzoxazine and fluorene-oxazine monomers, the fluorene-containing high-molecular weight benzoxazine precursors exhibit better thermal properties. Then these benzoxazine precursors are incorporated into traditional monofunctional benzoxazine, P-a. The curing behavior of the obtained blends are studied by differential scanning calorimeter (DSC). The thermal and mechanical properties of the cured blends are evaluated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). These produced blend resins could be good candidates for high performance thermosets.

With the increasing environmental awareness and the fast depletion of petroleum resources, bio-based polymers synthesized from renewably derived chemicals have entered our awareness gradually. Among all renewable resources, furan-containing compounds such as furfuryl alcohol and furfurylamine, which is derived from a variety of agricultural by-products such as corncobs and wheat bran, have been widely used as the precursors of polymers with high-performance. In this chapter, the structure, polymerization, thermal, and thermomechanical properties of various furan-containing, bio-based benzoxazines are briefly introduced. The synthesis, characterization, polymerization behavior, thermal, and thermomechanical properties of a series of novel furan-containing, tetrafunctional fluorene-based oxazine monomers and their polymers that simultaneously contain benzoxazine and fluorene-oxazine are mainly described. By means of the introduction of furan rings and more oxazine rings, these cured polymers and copolymers with typical monofunctional polybenzoxazine (P-a) display an extremely higher Tg value (442°C) and a much better thermal stability than those of traditional difunctional and multifunctional polybenzoxazines due to much more cross-linked sites.

For various molecular ratios ranging between 0% and 30%, the effect of Crab Shell Particles (CSP) on the thermal and thermomechanical properties of polybenzoxazine has been studied. The high contents of CaCO3 particles in CSP clearly improve both the thermomechanical and thermal properties of the polybenzoxazine corresponding to a gain in storage modulus and glass transition temperature of 137% and 25%, respectively, at 30% CSP loading. Thermal analysis reveals that the polybenzoxazine matrix filled with CSP also increases the initial decomposition temperatures and the char yield of composites which reaches 49% at maximum CSP content.

This study investigates the effects of chitosan particles (CTS) on the curing behavior, thermal and thermomechanical properties of polybenzoxazine matrix. The morphological, thermomechanical, and thermal properties of the blends are analyzed using scanning electron microscopy (SEM), dynamic scanning calorimetry (DSC), dynamical mechanical analyzer (DMA), and thermogravimetric analysis (TGA). The results show that the −NH2 groups on the chitosan can act as an active crosslinking position and hydrogen bonding. The SEM micrographs reveal good compatibility between the blend components. Furthermore, the values of glass transition temperatures, char yields, and storage moduli of the cured blends are found to be increased with the increase of CTS contents to reach 191℃, 34%, 4.3 GPa, respectively, at 10% of CTS content.

A novel furan-containing tetrafunctional fluorene-based benzoxazine monomer with bisphenol- and diamine-type oxazine rings was successfully prepared. The resulting polybenzoxazine exhibits extremely higher glass transition temperature (440 °C) and better thermal stability than difunctional furan-containing fluorene-based and traditional multifunctional benzoxazine resins.