## 1 Introduction  
Within the world of adhesives for wood, Polyvinyl Acetate (PVAc) adhesive is a water-based adhesive, which is considered more environmentally acceptable comparedto solvent-based adhesives. PVAc is most often used as an adhesive for porous materials such as wood and paper, but it is also a good adhesive for plastics, metal foil, leather, cloth, and as a general building adhesive. The main advantages of PVAc are its easy and wide application, elasticity, resistance to aging, low cost and availability, resistance to bacterial and fungicidal attack, and non-toxicity. Nevertheless, this adhesive also has some disadvantages related to its thermal and mechanical properties. PVAc has a thermoplastic nature and a linear amorphous structure, which makes it poorly resistant to temperature and relative humidity changes, affecting the adhesive bond quality. Also, due to its poor thermal stability, with a heat presence, this adhesive can yield because of a continuous load effect over time. To overcome these advantages, some studies evaluate the modification of PVAc, by adding different nanoparticles or additives, for example: nano clay (NC), cellulose nanofibrils (CNFs), silica (SiO\({}_{2}\)), titanium dioxide (TiO\({}_{2}\)) nanoparticles, and multi wall carbon nanotubes (MWCNTs) [1; 2; 3; 4; 5; 6]. Unfortunately, unmodified polymers do not have ideal flame-retardant properties, however, flame-retardant polymer materials can be developed. This mechanism is intended to decrease the material's flammability and slow the flame's spread. When the flame is removed, it will quickly self-extinguish, halting the burning process. Flame retardant polymer materials can be classified into halogen, inorganic, organic, intumescent, and nano-filler flame retardants according to the type of fillers [7]. Halogenated fire retardants work by continuously releasing free radicals, interrupting the emission of gases. During the combustion of the substrate, high-energy OH and H radicals are generated, which react with the free radicals of the halogenated compounds, thus stopping the spread of fire [7; 8]. Halogenated fire retardants have been in use for more than 40 years due to their good flame retardant performance [9]; however, there is great concern in the scientific and industrial environment, because their use generates negative impacts on the health of human beings and the environment [10; 11]. Therefore, the challenge at the scientific and industrial level is related to the development of fire retardant products, free of halogen compounds, for the protection of a wide variety of materials, with high flame-retardant efficiency and economic convenience [12]. Intumescent fire-retardant systems (IFR) are among the existing efficient and very low-toxicity fire-retardant solutions. Fire retardant products, of an intumescent nature, with flame retardant applications, are composed of three fundamental elements:  
1. [label=()]
2. Coking agent. These are generally polyatomic alcohols or polyols (containing organic hydroxyl), i.e., compounds with a high carbon content. 3. Catalysts (acid components). Here, inorganic acids or substances that release acid at a temperature between 100 and 250 \({}^{\circ}\)C are possible. 4. Foaming agents. Mainly organic amines or amides, although some inorganic salts can release significant amounts of non-combustible gases after thermal decomposition (carbonates of alkali metals and ammonium salts, among others) [13]. In general, the most common synthetic fire-retardant intumescent systems (out of the commercial types), present three fundamental elements: carbon, nitrogen, and phosphorus. These decompose in the presence of heat into: a carbon part, which serves as a thermal insulator; a gaseous part, which with these gases dilutes the combustible gases in the combustion process; and, finally, an acidic part (phosphoric acid), which catalyzes or retards the advance of fire.