The project consisted of developing a technology for the manufacture of MFC with controlled polarity, for its subsequent application as a reinforcing additive in both hydrophilic and hydrophobic resins. For this purpose, the surface of the CBMs was esterified in a controlled manner, by means of acetylation, to change their surface polarity and optimize their compatibility with matrices of diverse chemical nature. Then, the reinforcing capacity of the reinforced CBMs on urea-formaldehyde (UF) adhesive resins and polypropylene (PP) plastic resins was demonstrated.

• LThe physical and chemical characteristics of the CBMs produced during the project allow them to be homogeneously dispersed in hydrophobic polymeric matrices, unlike conventional CBMs, whose polarity makes them incompatible with these materials. Although there are similar proposals mentioned in the technical literature, the product developed stands out for its low cost and better reinforcing performance in polymers of different polarity.
• As for the developed process, its main differentiating attribute is that it allows a homogeneous substitution of hydroxyl groups present in CBMs, unlike conventional processes that are difficult to control. In fact, an acetylation of macrofibrils is usually heterogeneous, with preferential substitution at the surface level, which impairs the properties of microfibrils. On the other hand, fibrillation at the micro and nanometric level increases the homogeneity of the material, improving its properties and facilitating its dispersibility in thermosetting and thermoplastic resins.
• The plastics reinforced with the developed product show greater elasticity than their unmodified counterparts, whose incorporation into plastic matrices usually deteriorates the mechanical properties of the material.
• The CBMs are capable of significantly improving the adhesive properties of commercial ureic resins. This makes it possible to reduce the dosage of adhesive required for the manufacture of particleboard, without impairing its mechanical properties.

Plastics processing industry
The addition of acetylated CBMs improves the tensile strength characteristics of the material, which translates into higher breaking strength. This improvement is of particular interest to plastics processors and users who require PP with improved mechanical performance. The only PP producer in the country, Petroquim S.A., has expressed interest in this technology.

Adhesive resin industries
An increase in the degree of acetylation improves the reinforcing effect of CBMs, resulting in an increase in the mechanical strength of adhesive resins. This effect has attracted the attention of the company Resinas del Bío-Bío S.A., which has shown interest in the product. Its intention is to take advantage of the reinforcing effect and the low cost of CBM, to generate a new product that will reduce the dosage of adhesive resin required in the manufacture of reconstituted wood panels.