Synthesis and characterization of granite dust microparticles reinforced bio-benzoxazine composites

Abstract

In the current work, an effort has been made to create polymer composite materials using polybenzoxazine (PBz), which is synthesis from sustainable natural ingredients like furfurylamine (Fu), cardanol (Ca) and reinforced with granite dust made from industrial waste. Varied analytical approaches were used to examine the thermal, morphological, chemical structure, flame retardant and electrical properties of Ca-Fu-PBZ composites reinforced with granite dust at varied weight percentages (5, 10, 15 and 20 wt%). According to the weight percentage concentration of granite dust, the differential scanning calorimetry (DSC) data suggest that the value of Tg increased from 105 to 139°C. A pure Ca-Fu-PBZ benzoxazine matrix was found to have a dielectric constant of 3.97 at 1 MHz. Whereas 5, 10 and 20 wt percentages of reinforced Ca-Fu-PBZ composites with granite dust had dielectric constants of 3.54, 3.05, 2.51 and 2.02 at 1 MHz, respectively. For granite dust reinforced Ca-Fu-PBZ polybenzoxazine composites, the value of the limiting oxygen index (LOI) determined for the char yield obtained thermogravimetric analysis (TGA) shows greater values than those of the neat Ca-Fu-PBZ matrices. Using water contact angle, the hydrophobic behavior of polybenzoxazine composites reinforced with granite dust was investigated, and it was concluded that the hydrophobic behavior increased with the weight % of granite dust. Data from several investigations show that the thermally stable electrical insulation applications can employ the granite dust reinforced sustainable cardanol-furfurylamine based polybenzoxazine composites as potting compounds, sealants and composites.

Keywords

Cardanol fufuryl amine bio-benzoxazines thermal stability morphology hydrophobic behavior thermal applications

Introduction

Rapid industrialization and continued increase of human population, generation of wastes are correspondingly increased day by day.¹ Among the varied nature of solid industrial wastes produced granite dust wastes is one of the most important solid wastes² generated during the cutting and shaping of granites stones throughout the world, which contributes to environmental pollution³ in the form of particulate matter.⁴ Further, granite wastes are non-biodegradable⁵ material and cause serious environmental pollution and disrupt ecological systems when dumped on land.⁶ The granite waste dust is predominantly consists of large percentage content of silica (SiO₂) with constituents of mica, feldspar (plagioclase), amphiboles (plagioclase feldspar, quartz and biotite) and other elements.⁷ Currently, the utilization of granite waste was used as additives and fillers for the preparation of masonry products viz., bricks, tiles, paver blocks, etc to avoid pollution problems as well as to exploit its inherent properties and to reduce the cost products.⁸ Granite waste⁹ is also used as reinforcements for the preparation of polymeric resin based composites due to its higher flame retardant ability and thermal stability.

Benzoxazines are synthesized via condensation reaction of phenol, formaldehyde and primary amines.¹⁰ Polybenzoxazines (PBz) can be obtained by the ring opening polymerization of benzoxazine monomer under heat treatment in the absence of any catalysts or curatives and forms no by-product.¹¹ Polybenzoxazines are a kind of thermosetting resin become evident for its superior properties such as molecular design flexibility, thermally stable, near-zero shrinkage upon polymerization, low dielectric constant and low melt viscosities also have much higher hydrophobicity with potential corrosion resistant behavior.¹² PBz materials¹³ become an attractive substitute to conventional thermosetting polymers such as phenolic resins, epoxies,¹⁴ unsaturated polyesters,^15,16 vinyl ester resin, bismaleimides¹⁷ and cyanate esters.^18,19 The reinforcement of polybenzoxazines with organic-inorganic hybrid frame materials,²⁰ like carbon materials²¹ (carbon black,²² CNT and GO²³), silica materials²⁴ (POSS and SiO₂),^25,26 mesoporous materials (mobil composition of matter no. 41 and Santa Barbara Amorphous-15) metal oxides (TiO₂,²⁷ Al₂O₃²⁸ and ZnO^29,30) and bio resource materials³¹ (rice husk and palm flower carbon), act as fillers to improve the properties of the base materials.³² For instance, Amalorpavadoss et al³³ studied the GPTMS functionalized mesoporous silica (F-SBA-15) composites. Kurinchyselvan et al.³⁴ Reported the Cardanol benzoxazine-functionalized graphene oxide (GO-C-aps)-reinforced fluorinated benzoxazine (BAF-a) hybrid composites poly (GO-BAF-a) composites.

In the present work the sustainable polymeric binder namely benzoxazine was synthesized using cardanol with hetero-structured furfurylamine and paraformaldehyde through Mannich condensation in the absence of solvent at appropriate experimental conditions. The developed cardanol benzoxazines (Ca-Fu-PBZ) was analyzed using Fourier transform infrared (FTIR) studies. The varying weight percentages (5, 10, 15 and 20 wt%) of conditioned granite dust have been reinforced with Ca-Fu-PBZ bio-based benzoxazine to obtain composites in order to ascertain its suitability for industrial applications. Data resulted from thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy and EDAX (SEM), X-ray diffraction (XRD) and water contact angle studies are reported and discussed.

Experimental

Materials and methods

Sodium sulphate, chloroform, paraformaldehyde and sodium hydroxide were procured from Fine Chemicals (Alpha Chemicals Pvt. Ltd, Maharashtra). Cardanol and Eugenol were received from Satya Cashew Chemicals Pvt. Ltd (Tamil Nadu, India) and Avra Synthesis Pvt. Ltd (Hyderabad, India). Cardanol based benzoxazines was prepared as per the reported procedure.^35,36

Conditioning of granite dust

Granite slurry waste generated during re-sizing of granite rocks by ACY granites, Sivagangai, Tamil Nadu, India was collected and used. The granite powder was washed well with plenty amount water and followed by acetone and dried in an air-oven at 110°C for overnight. The obtained granite powder was dried for a month in normal sunlight and the adsorbed moisture and low volatiles are removed by heating at 200°C in an oven for 48 h. The dried powder was then sieved with 425 μ mesh and the uniform size of the granite particles was collected and used as reinforcement.

Preparation of polymer composites

5 g of cardanol benzoxazine monomer and different weight percentages of 5 wt%, 10 wt%, 15 wt% and 20 wt% of granite dust were mixed separately and dispersed well in 15 mL of 1,4-dioxane. The cardanol benzoxazine and granite dust (Ca-Fu-PBZ)/GD were thoroughly mixed with efficient sonication and agitation and then they were separately poured into a Teflon coated silane treated glass plate. Then, the samples obtained were cured from 30°C to 220°C for 1 h time interval and post-cured at 240°C for 2 h to obtain (Ca-Fu-PBZ)/GD bio-benzoxazine composites. The cured composite samples were washed and cleaned with hexane solvent and then preserved for further characterization studies.³⁷

Characterization

The FTIR spectra of the benzoxazine monomers and Ca-Fu-PBZ bio-composites were recorded in the wave number range of 4000–400 cm⁻¹ using SHIMADZU spectrometer by KBr pellet technique. Differential scanning calorimeter (DSC) and Thermogravimetric analysis (TGA) was recorded using a Netzsch STA 409 analyzer. The value of dielectric constant was evaluated by means of an impedance analyzer at room temperature using a platinum electrode from 1 Hz to 1 MHz using Solartron Impedance Analyzer 1260, UK. The powder XRD pattern of benzoxazines and polybenzoxazine bio-composites was obtained using a Bruker X-ray diffractometer with the Cu ka radiation (λ=1.5406 Å) at the scanning rate of 0.02° S⁻¹ (2θ), in the range of 0–80°. The surface morphology of bio-polymer composite thin films was analyzed by means of a scanning electron microscope (SEM; JEOL JSM Model 6360). The surface of the composite films was covered with gold using Auto Fine Coater (JEOL JFC-1600) at a high vacuum pressure of 8 Pa/20 mA for 95 s. The value of water contact angle on the composite film surface was measured by means of a Kwoya goniometry, DMs 200, Japan with 5 μL of water as probe liquid. All the measurements are repeated twice.

Result and discussion

Spectral studies of (Ca-Fu-PBZ) and bio-composites

The granite dust reinforced Ca-Fu-BZ monomer was subjected to ring opening polymerization in the absence of any catalyst with heating to obtain the corresponding polybenzoxazine composites. The formation of Ca-Fu-PBZ matrices and its composites were ascertained from FTIR spectral analysis and the results obtained are presented in Figure 1. In the FTIR spectra the peak observed at 1247 cm⁻¹ infers the formation of the aromatic ether (C-O-C) stretching and the disappearance of peak at 949 cm⁻¹ confirms the ring opening polymerization occurred in the oxazine ring group and the peak observed at 1468 cm⁻¹ evidences the transformation of tri substituted to tetra-substituted aromatic ring which in-turn confirms the development of polybenzoxazine network.³⁸ Further, the very low intensity peaks were observed at 1587, 999 and 751 cm⁻¹ may be accredited to the extra cross-linking provided by furan moiety present in the Ca-Fu-PBZ. The broad absorption peak appeared at 1067 cm⁻¹ ascertains the presence of Si-O-Si linkage in the granite dust and Ca-Fu-PBZ hybrid composites. The symmetric and asymmetric stretching vibrations of aliphatic chain of cardanol are observed at 2970 and 2871 cm⁻¹ respectively.

Thermal studies

Data obtained from DSC analysis for Ca-Fu-PBZ and Ca-Fu-PBZ composites are presented in Table 1 and Figure 2. The enhanced thermal behavior of granite dust reinforced Ca-Fu-PBZ composites may be explained due to the restricted chain movement as a result of the chemical interaction exit between the silica rich granite dust and Ca-Fu-PBZ. The glass transition temperature (T_g) of neat Ca-Fu-PBZ possess lower value (90°C) than that of granite dust reinforced polybenzoxazine composites. The value of glass transition temperature (T_g) of composite materials is prejudiced by inter-crosslinking density of Ca-Fu-PBZ and interaction of granite dust particles. The DSC data illustrate that an increment in the weight percentage of granite dust into Ca-Fu-PBZ enhances the value of T_g according to the weight percentage (5, 10, 15 and 20 wt%) viz., 105, 117, 126 and 139°C respectively. This may be arises owing to the interaction of silica rich granite dust with Ca-Fu-PBZ by the formation of interpenetrating network, which hinders the chain mobility within the network that resulted in higher T_g.³⁹

Table 1.

Thermal stability, and dielectric constant and contact angle of Ca-Fu-PBZ reinforced GD composites.

Sample	T_g (°C)	Thermal stability		Char yield (%) at 800 (°C)	LOI	Dielectric constant	Water contact angle (°)
Sample	T_g (°C)	10% weight loss (°C)	T_d (°C)	Char yield (%) at 800 (°C)	LOI	Dielectric constant	Water contact angle (°)
Neat Ca-Fu-PBZ	90	310	423	19.8	25.4	3.97	89
5% GD/Ca-Fu-PBZ	105	321	429	32.5	30.5	3.54	93
10% GD/Ca-Fu-PBZ	117	342	432	45.7	35.8	3.05	99
15% GD/Ca-Fu-PBZ	126	347	435	59.4	41.3	2.51	104
20% GD/Ca-Fu-PBZ	139	351	437	68.3	44.9	2.02	112

The thermal degradation characteristic of the renewable⁴⁰ Ca-Fu-PBZ and granite dust reinforced Ca-Fu-PBZ composites was analyzed by thermogravimetric analysis and the results obtained are presented in Figure 3 and Table 1. The 10% and maximum mass loss (T_d¹⁰ and T_max) the amount of char yield at 800°C are calculated and are presented Table 1. The initial degradation and char residue of the composites were enhanced appreciably with increasing silica rich granite dust content. The value of char yield obtained for the neat matrix and for the 20 wt% granite dust reinforced Ca-Fu-PBz systems are 19.8% and 68.3% respectively. Consequently, the thermal stability and granite dust reinforced Ca-Fu-PBZ composites are higher than that of neat Ca-Fu-PBZ matrices. The significant improvement of thermal stability of polybenzoxazine composites may be explained due to the effective chemical interaction occurred between granite dust particles and polybenzoxazine matrix.⁴¹

The flame retardant property⁴² of granite dust reinforced Ca-Fu-PBZ composites was determined by using van Krevelen’s equation⁴³ from the char yield values of the polybenzoxazine composites and the results obtained are presented in Figure 4 and Tables 1. In the present work, Ca-Fu-PBZ and silica rich granite dust composites were fruitfully developed using renewable raw materials such as cardanol and furfurylamine. The LOI values of granite dust reinforced Ca-Fu-PBZ composites calculated are in the range of 30.5 to 44.9. The calculated LOI value of Ca-Fu-PBz matrix is 25.4 and that of 5, 10, 15 and 20 wt% of granite dust reinforced polybenzoxazine composites are 30.5, 35.8, 41.3 and 44.9 respectively. The LOI values of granite dust reinforced Ca-Fu-PBZ polybenzoxazine composites have higher values contrast with unmodified Ca-Fu-PBZ matrices. The increased LOI values may be due to the retarded and diminished formation of combustible gases which in turn reduce the exothermic nature of pyrolysis reaction and there by inhibits the combustion of the burning organic moieties.⁴⁴ In addition, the granite dusts dispense additional heat capacity which stabilizes the polymeric chains against thermal decomposition. The flame-retardant behavior of granite dust reinforced polybenzoxazine composites was significantly improved according to the percentage incorporation of granite dust in to polybenzoxazine matrices.

Electrical studies

The dielectric constant⁴⁵ of neat Ca-Fu-PBZ benzoxazine matrix and varying weight percentages of granite dust incorporated Ca-Fu-PBZ benzoxazine composites as a function of frequency at room temperature and the values obtained are presented in Table 1. It is pragmatic that the dielectric constant vale of neat Ca-Fu-PBZ benzoxazine matrix was found to be 3.97 at 1 MHz are shown in Figure 5. The 5, 10, 15 and 20 wt percentages of granite reinforced Ca-Fu-PBZ materials possess the dielectric constant values of 3.54, 3.05, 2.51 and 2.02 at 1 MHz respectively. The dielectric constant value infers that the incorporation of granite dust will decrease the dielectric constant proportional to its content, may be as a result of effective interaction between the granite dust and Ca-Fu-PBZ matrix leading to the formation of non-polar insulating network throughout matrix.⁴⁶

Water contact angle (WCA) studies

The results of water contact angle measurements on neat matrix Ca-Fu-PBZ and 5, 10, 15 and 20 wt% granite dust reinforced Ca-Fu-PBZ are presented in Figure 6 and Table 1. From the Figure, it was inferred that the values of water contact angle obtained for granite dust reinforced composites are gradually enhanced according the increase in weight percent of granite dust in addition to the presence of long aliphatic chain moiety which synergistically contributes to better hydrophobic nature.⁴⁷

Chemical resistance test

Chemical resistance of the Ca-Fu-PBZ matrix and its composites were studied as per ASTM D 543 method.⁴⁸ For this purpose, three strong acids such as H₂SO_4, HCl, and HNO₃; weak acids namely CH₃ COOH, HCOOH and H₃PO₄; strong bases such as NaOH and KOH; weak bases such as ammonia and aniline were selected. The pre-weighed samples were immersed in sufficient quantity of chemicals for 24 h, removed and washed with plenty of distilled water and then dried. The samples are reweighed and the difference in weight was determined.

The Ca-Fu-PBZ matrix and granite dust incorporated Ca-Fu-PBZ composites is immersed in some strong and weak acids, strong and weak bases. Form these studies, we have noticed more or less weight gain is observed depending on acids and bases concentration. The weight gain observed in the entire polybenzoxazine composites systems is understandable, as inter-crosslinked matrices form three-dimensional networks that are chemically more stable.

H₂SO₄>HCl>HNO₃

CH₃ COOH> HCOOH > H₃PO₄

NaOH> KOH Ammonia > Aniline

Morphological studies

The X-ray diffraction patterns of Ca-Fu-PBZ benzoxazine based intercrossed linked matrices and various weight percentage (5, 10, 15 and 20) composition of granite dust loaded composites are displayed in Figure 7. The amorphous nature of broad diffraction patterns are appeared at 2θ = 20.61°. From this broad and amorphous diffraction patterns confirms that the uniform distribution of granite dust homogenously in the benzoxazine matrices.

The SEM morphology and photographs of Ca-Fu-PBZ benzoxazine matrices and different compositions (5, 10, 15 and 20 wt%) of granite dust embedded PBz composites are accessible in Figures 8(a)–(f). The neat C-Fu-PBz benzoxazine matrices show a continuous and smooth structure [Figure 8(a)]. From the SEM photographs evidences that the homogeneous dispersion of the granite dust in the PBz matrix without any aggregation of granite dust, which resulted in a smooth surface morphology. The SEM studies indicated the existence of good interfacial bond between granite dust and the polymer with a homogeneous and denser structure.

EDAX spectroscopy was conducted to ascertain the composition of composites and the EDX spectrum of the of Ca-Fu-PBZ benzoxazine matrices and different compositions (5, 10, 15 and 20 wt%) of granite dust loaded PBz composites are offered in Figures 9(a)–(e). The neat Ca-Fu-PBz benzoxazine matrix elemental analysis confirmed that the presence of C = 71.32%, O = 24.46% and Si = 0.40%. The neat Ca-Fu-PBz benzoxazine matrix possesses the higher values of carbon, oxygen with traces of silicon impurity was observed. The EDX spectrum of various weight percentages of granite dust reinforced composites provides the composition of carbon, oxygen, and silicon. Consequently, the atomic percent of the 5% granite dust reinforced polybenzoxazine composites was found as C = 52.20%, O = 31.64%, Si = 11.21% and traces of some metal oxides like alumina, calcium, potassium and iron.⁴⁹ Figure 9(e) represents the elemental analysis of 20 wt% of granite dust reinforced polybenzoxazine composites possess the higher values of carbon, oxygen and silicon (C = 43.85%, O = 34.93%, Si = 15.76%). The composition values were strongly dependent upon the percentage of the granite dust in the in situ polymerization.

Conclusion

In the current work, the potential use of industrial waste and bio-based sustainable polymeric resin matrix for the production of composite materials with improved thermal stability, flame retardant behavior, and hydrophobic behavior is presented. All these benefits help to explain why research on cardanol polybenzoxazine composites has increased recently. Cardanol polybenzoxazine composites have a number of advantages, including one-pot solvent less atom-economized synthesis, polymers with good thermal stability, and low viscosity of benzoxazines expanding the range of potential applications. The process ability of the related resin may be hampered by certain restrictions like a high curing temperature. Numerous modifications, including the addition of fillers, the creation of blends, the functionalization of monomers, etc., have been tried to address these shortcomings.

A variety of 5, 10, 15 and 20 wt percent amounts of granite dust reinforced cardanol polybenzoxazine composites were prepared. By using the proper analytical procedures, the bio-benzoxazines (Ca-Fu-PBZ) and bio-benzoxazine composites thermal stability, morphology, and water contact angle were investigated. The acquired results from thermal experiments using techniques like DSC and TGA showed that the granite dust enhanced composites have better thermal stability than a plain Ca-Fu-PBZ based matrix. According to the findings of LOI experiments, benzoxazine matrices and composites based on cardanol exhibit better thermal behavior than clean benzoxazine matrix. The thermal, electrical and hydrophobic behavior of Ca-Fu-PBZ matrix and granite dust contained composites is superior to that of composites and standard synthetic benzoxazines. It has been achieved that the Ca-Fu-PBZ/granite dust is taken into account for the creation of high performance composite materials for a variety of industrial applications, as well as for efficient solid waste management. As a result, modified cardanol polybenzoxazine composites have demonstrated a noticeable improvement in characteristics as well as a broad range of applicability, including composites, adhesives, self-healants, etc. Due to this, cardanol polybenzoxazine composites' monomers and polymers occupy a unique position among other polybenzoxazines, necessitating further research on both the synthetic and application levels.

Footnotes

Acknowledgements

One of the authors (Dr.A.Chandramohan) acknowledges the financial support of Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam, Tamil Nadu.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the SSN Trust.

ORCID iD

Parthiban Rangasamy

References

Wiśniewska

Hejna

Saeb

. Recycling and Processing of Waste Materials. Materials 2023; 16: 508.

Howell

. Efficient biobased oligomeric plasticizers from the renewable biomonomers, glycerol and adipic acid. Polym Renew Resour 2023; 12: 20412479231182700.

Pawar

Patnaik

Ravindra

. Investigation on mechanical and thermo-mechanical properties of granite powder filled treated jute fiber reinforced epoxy composite. Polym Compos 2015; 38: 1–13.

Nurhania

Syarifuddin

Armynah

, et al. Fiber-reinforced polymer composite: Higher performance with renewable and eco-friendly plant-based fibers. Polym Renew Resour 2023; 14: 215–233.

Shujit

Muhammed

Abdul

, et al. Study of thermal properties of granite powder (scrap) reinforced polyester resin composite. J Adv Chem Eng 2017; 7: 1–50.

Wiśniewska

Haponiuk

Colom

, et al. Green Approaches in Rubber Recycling Technologies: Present Status and Future Perspective. ACS Sustain Chem Eng 2023; 11: 8706–8726.

Nallusamy

Karthikeyan

. Synthesis and wear characterization of reinforced glass fiber polymer composites with epoxy resin using granite powder. JNanoR 2017; 49: 1–9.

Khan

Rahamathbaba

Mateen

, et al. Effect of NaOH treatment on mechanical strength of banana/epoxy laminates. Polym Renew Resour 2019; 10: 19–26.

Mathavan

Amar

. Analysis of wear properties of granitedust filled polymer composite for wind turbine blade. Results Mater 2020; 5: 1–4.

10.

Lyu

Ishida

. Natural sourced benzoxazine resins, homopolymers, blends and composites: A review of their synthesis, manufacturing and applications. Prog Polym Sci 2019; 99: 101168.

11.

Luo

. A novel benzoxazine/cyanate ester blend with sea-island phase structures. Phys Chem Chem Phys 2015; 17: 19255–19260.

12.

Jouyandeh

Tikhani

Shabanian

, et al. Synthesis, characterization, and high potential of 3D metal–organic framework (MOF) nanoparticles for curing with epoxy. J Alloys Compd 2020; 829: 154547.

13.

Zhang

Wang

Pang

, et al. High residual mechanical properties at elevated temperatures of bamboo/glass reinforced-polybenzoxazine hybrid composite. Polym Eng Sci 2019; 59: 1818–1829.

14.

Movahedifar

Vahabi

Saeb

, et al. Flame retardant epoxy composites on the road of innovation: An analysis with flame retardancy index for future development. Molecules 2019; 24: 3964.

15.

Kamble

Rajput

Abed

Thermosetting blends of acid modified polybenzoxazine and unsaturated polyester: study on intermolecular specific interactions and their thermal, mechanical properties. Inter J Materi Sci Eng 2016; 4: 104–112.

16.

Karikal Chozhan

Chandramohan

Alagar

. Benzoxazine modified diglycidyl ether of bisphenol-a/silicon/siliconized epoxy hybrid polymer matrices: Mechanical, thermal, electrical and morphological properties. J Macromol Sci Part: Pure Appl Chem 2019; 56: 1–16.

17.

Jiang

Yan

Chen

, et al. Preparation, characterization, and properties of silanized graphene oxide reinforced biobasedbenzoxazine bismaleimide resin composites. J Adhes Sci Technol 2019; 33: 1974–1988.

18.

Chozhan

Chandramohan

Alagar

. Development and characterization of 1,1-bis(3-methyl-4-hydroxyphenyl) cyclohexane-based benzoxazine and cyanate ester hybrid polymer matrices: Thermal and morphological properties. Polym Polym Comp 2019; 27: 609–618.

19.

Chozhan

Chandramohan

Alagar

. Influence of multi-walled carbon nanotubes on mechanical, thermal and electrical behavior of polybenzoxazine-epoxy nanocomposites. Polym Plast Technol Eng 2015; 54: 68–80.

20.

Seidi

Jouyandeh

Taghizadeh

, et al. Metal-Organic Framework (MOF)/Epoxy Coatings: A Review. A review. Materials 2020; 13: 2881.

21.

Yarahmadi

Didehban

Sari

, et al. Development and curing potential of epoxy/starch-functionalized graphene oxide nanocomposite coatings. Prog Org Coat 2018; 119: 194–202.

22.

Mohamed

Kuo

. Functional Silica and Carbon Nanocomposites Based on Polybenzoxazines. Macromol Chem Phy 2018; 220: 1800306.

23.

Jouyandeh

Yarahmadi

Didehban

, et al. Cure kinetics of epoxy/graphene oxide (GO) nanocomposites: Effect of starch functionalization of GO nanosheets. Prog Org Coat 2019; 136: 105217.

24.

Asrafali

Periyasamy

Haldhar

, et al. Fabrication of SiO₂-reinforced polybenzoxazine composites and their thermal and dielectric properties. J Polym Res 2022; 29: 176.

25.

Chandramohan

Shanavas

Arunkumar

, et al. Thermal and morphological properties of Octa (maleimido phenyl) silsesquioxane (OMPS) reinforced polybenzoxazine hybrid nanocomposites. Int J Polym Anal Char 2013; 18: 269–279.

26.

Jouyandeh

Jazani

Navarchian

, et al. Surface engineering of nanoparticles with macromolecules for epoxy curing: Development of super-reactive nitrogen-rich nanosilica through surface chemistry manipulation. Appl Surf Sci 2018; 447: 152.

27.

Wang

Kao

Cheng

, et al. Reversible manipulation of the adhesive forces of TiO₂/polybenzoxazine nano assembled coatings through UV irradiation and thermal treatment. Appl Surf Sci 2015; 357: 1634–1646.

28.

Lakshmikandhan

Chandramohan

Sethuraman

, et al. Development and characterization of functionalized Al₂O₃ and TiO₂ reinforced polybenzoxazine nanocomposites. Desig Monom Polym 2016; 19: 67–76.

29.

Rajamanikam

Pichaimani

Kumar

, et al. Optical and thermomechanical behavior of benzoxazine functionalized ZnO reinforced polybenzoxazine nanocomposites. Polym Compos 2017; 38: 1881–1889.

30.

Karami

Jouyandeh

Ali

, et al. Epoxy/layered double hydroxide (LDH) nanocomposites: Synthesis, characterization, and Excellent cure feature of nitrate anion intercalated Zn-Al LDH. Prog Org Coat 2019; 136: 105218.

31.

Hashem

Al-Askar

Saeb

, et al. Sustainable biosynthesized bimetallic ZnO@ SeO nanoparticles from pomegranate peel extracts: antibacterial, antifungal and anticancer activities. RSC Adv 2023; 13: 22918.

32.

Zarrintaj

Seidi

Youssefi Azarfam

, et al. Biopolymer-based composites for tissue engineering applications: A basis for future opportunities. Compos Part B: Eng 2023; 258: 110701.

33.

Amalorpavadoss

Kumar

Pavunkumar

, et al. Synthesis, Characterization and anti-corrosion property of GPTMS functionalized mesoporous silica (F-SBA-15) incorporated aliphatic chain containing polybenzoxazine nanocomposites. Compos Interf 2022; 29: 833.

34.

Kurinchyselvan

Chandramohan

Hariharan

, et al. Cardanol-based benzoxazine-terminated graphene oxide-reinforced fluorinated benzoxazine hybrid composites for low K applications. Compo Interf 2020; 27: 737.

35.

Shukla

Mahata

Pathak

, et al. Cardanol benzoxazinesinterplay of oxazine functionality (mono to tetra) and properties. RSC Adv 2015; 5: 78071–78080.

36.

Ayyavu

Rangasamy

Senthilkumar

, et al. Thermal, electrical, morphological and hydrophobic properties of bio-silica reinforced bio-benzoxazine nanocomposites. Appl Nanosci 2023; 13(6): 4193–4205.

37.

Kurinchyselvan

Chandramohan

Hariharan

, et al. Mesoporous silica MCM-41 reinforced cardanol based benzoxazine nanocomposites for low-k applications. Polym Bull 2021; 78: 2043–2065.

38.

Chozhan

Chandramohan

Alagar

. Studies on thermal, mechanical, electrical and morphological behavior of organoclay reinforced polybenzoxazine-epoxy nanocomposites. High Perform Polym 2013; 25: 1007–1021.

39.

Jinyue

Yang

Teng

, et al. Synthesis of eugenol-based silicon-containing benzoxazines and their applications as biobased organic coatings. Coatings 2018; 8: 88–101.

40.

Nonahal

Saeb

Hassan Jafari

, et al. Design, preparation, and characterization of fast cure epoxy/amine functionalized graphene oxide nanocomposites. Polym Compos 2018; 39: E2016–E2027.

41.

Rucigaj

Alic

Krajnc

, et al. Curing of bisphenol A-aniline based benzoxazine using phenolic, amino and mercapto accelerators. Express Polym Lett 2015; 9: 647–657.

42.

Vahabi

Saeb

Formela

, et al. Flame retardant epoxy/halloysite nanotubes nanocomposite coatings: Exploring low-concentration threshold for flammability compared to expandable graphite as superior fire retardant. Prog Org Coat 2018; 119: 8–14.

43.

Chozhan

Chandramohan

Alagar

. Surface Modified Clay Reinforced Silicon Incorporated Epoxy Hybrid Nanocomposites: Thermal, Mechanical, and Morphological Properties. Polym Renew Resour 2018; 9(1): 1–22.

44.

Vahabi

Jouyandeh

Cochez

, et al. Short-lasting fire in partially and completely cured epoxy coatings containing expandable graphite and halloysite nanotube additives. Prog Org Coat 2018; 123: 160–167.

45.

Ghiyasi

Sari

Shabanian

, et al. Hyperbranched poly (ethyleneimine) physically attached to silica nanoparticles to facilitate curing of epoxy nanocomposite coatings. Prog Org Coat 2018; 120: 100–109.

46.

Zhang

Zhuang

Liu

, et al. A new benzoxazine containing benzoxazole-functionalized polyhedral oligomeric silsesquioxane and the corresponding polybenzoxazine nanocomposites. Macromolecules 2013; 46: 2696–2704.

47.

Huang

Pei

Wang

, et al. Design and synthesis of organosoluble and transparent polyimides containing bulky substituents and noncoplanar structures. J Appl Polym Sci 2016; 133: 43266–43275.

48.

Ramakrishna

Priya

Rai

(2007). Flexural, compression, chemical resistance, and morphology studies on granite powder-filled epoxy and acrylonitrile butadiene styrene-toughened epoxy matrices. J Appl Polym Sci. 2007; 104: 171-177.

49.

Ashraf

Kausar

Siddiq

. Preparation and properties of multilayered polymer/nanodiamond composites via an in situ technique. Polym Eng 2014; 34: 415–429.