**5. Resveratrol based polybenzoxazine for flame resistant applications**

Hatsuo Ishida and Kan Zhang group reported [45, 48] the series of thermally stable and flame resistant resveratrol-based tri-functional benzoxazine monomers

**Figure 18.** *Synthesis of resveratrol-based tri-functional benzoxazine monomers.*

*Development of Halogen Free Sustainable Polybenzoxazine Matrices and Composites for Flame… DOI: http://dx.doi.org/10.5772/intechopen.98470*

#### **Figure 19.**

Further, poly(GU-fa) infers the THR value of 6.5 KJ/g, whereas poly(FBP-fa) displays a fairly lower THR value of 5.8 KJ/g. The data of flame related properties of both PBz's are presented in **Table 5**. Unexpectedly, the HRC value of developed poly(FBP-fa) gives significantly lower value than that of earlier reported polymers. Furthermore, poly(FBP-fa) displays very lower flammability characteristics than that of many other reported PBz's. It is well-known that the HRC value less than 300 J/gK can be observed as self-extinguishing while, whereas the HRC values less

M. Sarojadevi research group have also synthesized [51] the BGF and BGF-based

benzoxazin-6-yl] methane and bis[(3-octadecyl)-3,4-dihydro-2H benzoxazin-6-yl] methane as an substitute to BPA. The LOI values (**Table 2**) of the BGF-FPbz and BGF-SPbz was found to be 38.5 and 32.8 respectively indicating the high flame retardancy. As expected, the developed PBz's with these LOI values are greater than

**5. Resveratrol based polybenzoxazine for flame resistant applications**

Hatsuo Ishida and Kan Zhang group reported [45, 48] the series of thermally stable and flame resistant resveratrol-based tri-functional benzoxazine monomers

benzoxazines (**Figure 17**) viz., bis[(3-(furan-2-yl) methyl)-3,4-dihydro-2H

than 100 J/gK are designated as non-ignitable materials.

*Synthesis of bisguaiacol-F (BGF) and BGF based benzoxazine monomers.*

*Flame Retardant and Thermally Insulating Polymers*

**Figure 17.**

**Figure 18.**

**54**

26 endorsing outstanding flame resistant property.

*Synthesis of resveratrol-based tri-functional benzoxazine monomers.*

*Schematic representation of proposed thermal behaviors of RES-ac.*

(**Figure 18**) have been produced using resveratrol, different amines (aniline, 4 chloroaniline, 3-aminophenylacetylene, and furfurylamine) and paraformaldehyde. The thermal and flammability performances of the developed PBz's are studied using TGA and MCC respectively. Among the benzoxazine studied, resveratrolbased, tri-functional benzoxazines containing acetylene possesses the highest thermal stability with a value of Tg over the 350°C, 10% weight loss at 465°C, and char yield of 74%. Further, the developed polybenzoxazine infers the extremely low heat release capacity of 30.7 J/gK and total heat release value of 6.0 kJ/g.

MCC analysis was performed to analyse the quantitative features of flame resistance of PBz's. Usually, the extreme value of specific HRR can be used to assess the HRC, which is considered as unique best single interpreters for the flame resistance of materials. Here, poly(RES-a), poly(RES-ch), poly(RES-ac) (**Figure 19**), and poly (RES-fa) were analysed at the heating rate of 1°C/s over the temperature range 100 750°C. As illustrated in MCC results (**Table 5**) of poly(RES-a), poly(RESch), poly(RES-ac) and poly(RES-fa) indicate HRC values of 79.7, 73.4, 30.7, and 54 J/gK, respectively. Moreover poly(RES-a), poly(RES-ch), and poly(RES-fa) exhibit THR values of 15.9, 14.2, and 9.3 KJ/g, while poly(RES-ac) shows a lower THR value of 6.0 KJ/g. The data obtained from thermal and flame resistant properties for PBz's are presented in **Table 5**. The value of HRC for poly(RES-ac) is significantly lesser than those of other polymers. Moreover, the HRC value of poly (RES-ac) is even lower than that of the thermosets from ortho-amide and orthoimide benzoxazines, which exhibited one of the lowest HRC values of all polymers. Obviously, the PBz formed from the ring opening polymerization along with the cyclo trimerization of acetylene results in a considerable HRC reduction. Thus, the newly developed resveratrol-based tri-benzoxazine monomer containing acetylene group has greatest prospective applications as anti-flammable and fire resistant matrix for advanced composites.
