###### Abstract  
GlycidylI methacrylate (GMA) was grafted onto (recycled) polyethylene (PE) to design a new adhesive with better mechanical properties compared to non-grafted PE. The effects of the amount of GMA, the amount of dicumyl peroxide (DCP) and the use of supercritical carbon dioxide (s\(\mathrm{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\  
reactions (at the interface) with other functional groups, such as hydroxyl groups. This results in effective compatibilizers that are usable for blends of polyolefins with immiscible nonpolar and polar polymers [5; 6; 7; 8; 9; 10; 11]. The advantages of using GMA are their faster grafting reactions, the non-formation of water or other side products, and a reduction in crosslinking due to the bulky molecular structure of GMA compared to MAH or acrylic acid (AA) [8]. The grafting of GMA onto the polymer backbone would enable the design of a new product out of (recycled) PE with better mechanical properties and compatibility compared to non-grafted PE. The main chain (-CH\({}_{2}\)-CH\({}_{2}\)-)\({}_{2}\) is non-polar, while the grafted GMA is polar, and it can help to form multilayer composite films or act as a hot melt adhesive between metal plates. [PERSON] et al. (2019) [12] successfully performed melt grafting experiments in a torque rheometer with GMA, AA, and RPE. The tensile strength improved by 70% and the elongation at break increased by five times. Furthermore, the melt index decreased, indicating that longer polymer chains were formed. Furthermore, the crossover frequency decreased as well, due to the increased degree of chain entanglements in the grafted polymer. The mechanical properties of grafted RPE significantly improved compared to the un-grafted RPE. A study performed by [PERSON] et al. (2013) [13], focused on the reuse of plastic waste, used PE-g-MAH as one of the compatibilizers for blending waste polypropylene and polyethylene in a twin-screw extruder. The usage of PE-g-MAH led to an improvement in impact strength but a decline in tensile strength. Nevertheless, the use of compatibilizers improved the blending of waste PE and waste PP due to the improved crystallization of the blend. This resulted in a temperature decrease in the PP melting peak and an increase in the PE melting peak, leading to a smaller temperature difference between the two melting peaks for the mixed PP/PE samples. This in turn suggests that the compatibilization of blending was improved. On the other hand, the grafting reactions of GMA and MAH often result in relatively low grafting degrees and efficiencies [7; 14]. One of the upcoming techniques that has been used for several grafting processes is the use of supercritical CO\({}_{2}\)[15; 16; 17; 18; 19; 20; 21] because of its attractive properties. ScCO\({}_{2}\) is non-flammable, nontoxic, and relatively cheap, and it has moderate critical parameters (T\({}_{\rm c}\) = 31.3 \({}^{\circ}\)C, P\({}_{\rm c}\) = 7.38 MPa) [22]. Furthermore, scCO\({}_{2}\) has the advantage of lowering the viscosity of the melt phase due to its swelling effect, which leads to an increase in the specific volume of the polymer and the mobility of the chains. This results in a lower processing temperature, which ensures less chain degradation or side reactions in general [21]. Moreover, scCO\({}_{2}\) has a plasticizer effect, which results in a lower glass transition temperate (T\({}_{\rm g}\)) and a more flexible and softer polymer. The plasticizer effect combined with the swelling effect of scCO\({}_{2}\) enables interactions not only on the polymer surface, but also into the polymer matrix [23; 24; 25; 26; 27]. Several researchers found a higher grafting degree, less crosslinking, and lower processing temperatures when grafting under scCO\({}_{2}\) conditions [3; 15; 16; 17; 18; 19; 20; 21; 28; 29; 30; 31; 32]. Overall, it can be said that there is already a significant amount of research information available about polymer grafting and blending, even with the use of scCO\({}_{2}\).