## 2 _Introduction_  
Although polymeric methylene diphenyl disisocyanate (pMDI) resins have been successfully used as non-formaldehyde binders in the manufacture of wood panel products such as particle board (PB) and medium density fiberboard (MDF), their use in the manufacture of plywood panels (PW) has been limited for a number of reasons. These include the difficulty of cleaning with water the equipment used to apply pMDI resins to veneers, the reaction of the NCO group in PMDI with the hydroxyl groups in wood, resulting in premature curing prior to hot pressing, the tendency of pMDI resin to stick to the caul plates during pressing making the plywood difficult to remove, and the incompatibility of pMDI with water-based adhesives commonly used in plywood production due to its high reactivity with water. A solution to overcome these drawbacks is to mix pMDI adhesives with starch to control their reactivity by forming urethane bonds between starch and pMDI, making them easier to apply to plywood [1]. The starch used industrially to make plywood is usually derived from wheat. However, in the context of a sustainable economy, it is desirable to use other lower value biomasses or wastes for this application. In this study, residues of soybeans, hemp seeds, and olive fruit and leaves were investigated as pMDI resin fillers in the manufacture of plywood panels. All these materials are found in large quantities as wastes, and their use in this application gives them added value. Soybean cultivation in Europe has grown steadily in recent years, reaching a record high of 11.5 million tonnes in 2023 [2], and is expected to increase by a further 5-10% in 2024 [3]. Soybeans are rich in protein and also contain fiber and oligosaccharides, making them a valuable food source for both humans and animals. However, soy has been studied for many applications beyond food, such as health products [4], dietary supplements, cosmetics [5; 6; 7], and chemical formulations. In the case of adhesives for plywood panels, [PERSON] et al., 2012 [8], investigated a mixture of soy protein hydrolysate, different resins (phenol-formaldehyde, melamine-formaldehyde, phenol-melamine-formaldehyde, methylenediphenyl diisocyanate, and epoxy) and an amine polymer-epichlorohydrin adduct. It was found that the plywood panels were not successful in all cases, with the degree of hydrolysis of the soy playing a significant role. [PERSON] et al., 2014 [9], improved the water resistance of a soy-based adhesive by mixing it with epoxy resin or melamine-formaldehyde resin or a mixture thereof, making it suitable for plywood production. Other researchers have investigated the performance of non-formaldehyde mixtures of soybean flour with cardanol-based epoxy resin or citric acid [10; 11]. The results of these studies have shown the potential of such binders for plywood panel production. [PERSON] et al., 2022 [12], evaluated the potential of using soy flour (among other materials) as a partial replacement of pMDI resin for the production of both hardwood and softwood plywood panels. The results showed that replacing 30% of the pMDI resin with soy flour significantly improved its adhesion properties. Following this, it has been considered that the partial substitution of soy flour in pMDI should not exceed that of 30% because of the poor waterproof properties of soy flour itself [13; 14]. Industrial hemp is another crop that is attracting increasing research interest due to its rapid growth and diverse applications in commercial products such as textiles, paper, medicine, food, animal feed, paints, biofuel, biodegradable plastics, and construction materials. Industrial hemp seeds, which are the fruits of _Cannabis sativa_, represent another valuable but underutilized biomass resource after the extraction of nutritional ingredients. Specifically, hemp seeds are covered by a thin, two-layered pericarp and contain an endosperm and two cotyledons. They contain approximately 25-30% oil, 25-30% protein, 30-40% fiber, and 6-7% moisture [15; 16; 17].