Synthesis of bromo-cardanol novolac resins and evaluation of their effectiveness as flame retardants and adhesives for particleboard

Substitution of urea-formaldehyde by renewable phenolic compound for environmentally appropriate production of particleboards

In recent years, research has been conducted in search of alternative adhesives that are less harmful to human health and the environment. Cardanol derived from cashew nut shell liquid (CNSL) has attracted considerable attention due to its chemical and specific characteristics (antioxidant activity, flame resistance, and hydrophobicity). In this sense, this study aimed to evaluate the quality of particleboards using cardanol instead of urea-formaldehyde (UF) adhesive. Different percentages of cardanol were used (0, 20, 40, 60 and 80%) in which its physicochemical properties were evaluated. The panels were produced with particles of Pinus oocarpa and nominal density of 0.75 g/cm³, their physical and mechanical properties were evaluated, wood-adhesive interface evaluation with scanning electron microscopy (SEM), and the combustibility test. It is concluded that the maximum replacement of UF by cardanol is 5%, since, in this situation, the mentioned properties reach the established norms for the commercialization of the boards.

Comparative Study of Different Methods of Synthesis and Their Effect on the Thermomechanical Properties of a Halogenated Epoxy-Based Flame-Retardant Resin

The work presented in this paper deals with the comparative synthesis of diglycidyl ether-based tetrabromobisphenol-A(TBBPA) using both conventional and nonconventional methods in order to explore materials for better industrial applications with respect to effective yield, cost, and time consideration. The conventional method involved the polycondensation of TBBPA and epichlorohydrin in the presence of an alkali catalyst. The nonconventional routes adopted for the synthesis of the material involved ultrasonication, microwave irradiation, and UV light exposure. The Fourier transform infrared spectroscopy spectra of all the synthesized materials of the resin were found to be identical, and the X-ray diffraction analysis showed the material as amorphous. The mechanical studies of the resins revealed that all these resins synthesized by different methods are strong and possess high viscosity. Based on the overall thermal, rheological, and excellent hydrophobic properties, it can serve as an excellent flame retardant.

Synergistic Effect of APP and TBC Fire-Retardants on the Physico-Mechanical Properties of Strandboard

This study explored the feasibility of fabricating fire-retardant strandboard with low mechanical properties deterioration to the physico-mechanical properties. A hybrid fire-retardant system of ammonium polyphosphate (APP) and 1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazinane-2,4,6-trione (TBC) was investigated. Thermogravimetric analysis results show that both APP and TBC enhance the thermal stability and incombustibility of wood strands. An infrared spectrum was applied to investigate the effect of flame retardants on the curing behaviors of polymeric diphenylmethane diisocyanate (PMDI) resin. Based on the results of limiting oxygen index (LOI) and Cone calorimetry (CONE), APP and TBC both lead to a higher fire retardancy to strandboard. It is worth mentioning that the two flame retardants lead to evidently differential influences on the modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), and water-soaking thickness swelling (TS) properties of strandboard. Hence, a hybrid flame retardant is prominent in manufacturing strandboard with both good fire retardant and satisfying physico-mechanical properties.

Synthesis and Properties of Organosilicon-Grafted Cardanol Novolac Epoxy Resin as a Novel Biobased Reactive Diluent and Toughening Agent

The aim of this work is to develop a biobased functional reactive diluent for thermosetting epoxy resins suitable for high-performance applications. An advanced organosilicon-grafted cardanol novolac epoxy resin (SCNER) was synthesized from cardanol novolac epoxy resin and heptamethyltrisiloxane. After the chemical structure of SCNER was identified by Fourier transform infrared, ¹H NMR, and ¹³C NMR, it was used to modify the diglycidyl ether of the bisphenol A (DGEBA)/methylhexahydrophthalic anhydride system. The SCNER showed unique advantages, reducing the viscosity of DGEBA and improving the properties of the cured resin. With 10 wt % SCNER, the cured resin exhibited a higher tensile strength (78.84 MPa) and impact strength (32.36 kJ·m^-2). The single glass transition temperature (T _g) step proved the homogeneous phase structure of the cured resin. Inevitably, the T _g of the cured resin decreased for the addition of SCNER. The dynamic mechanical analysis results indicated that the storage modulus of the cured resin decreased with the increasing content of SCNER. The morphology showing the ductile fracture of the cured resin was testified by scanning electron microscopy. The dilution and toughening properties of SCNER paves the way to a wide range of possible "eco-friendly" applications, especially in the fields of coatings, paintings, and adhesives.