This research work investigates a new type of polymer-based magnetocaloric composite. Using PMMA as polymeric matrix and the magnetocaloric material Gd5.09Ge2.03Si1.88 as reinforcement,no influence of the presence of polymer on the magnetic properties of Gd5.09Ge2.03Si1.88 were observed. Three types of composites with different PMMA content were fabricated by mixing the components and curing the composite. The composites were evaluated by their mechanical, physicochemical and morphological properties.The proposed PMMA composite MC10 presented the smallest elastic modulus but highest Vickers hardness (6.61 ± 0.08 GPa and 22.10 ± 1.29 HV, respectively). The composites showed asatisfactorymagnetocaloriceffect (MCE)“peak” of -7 J/kgK. With the results, this composite can be a potential candidate for applications as Active Magnetic Regenerator in magnetic heat pumps.

Gd5(Ge1-xSi x), x < 4 based alloys are potential candidates for magnetic refrigeration in the range ~20 - ~290 K. However, one of the greatest obstacles for the use of that technology in large scale is the utilization of high pure Gd metal (99.99 wt. (%)) to produce the GdGeSi alloys, since the impurity elements decrease the intensity of the magnetocaloric effect (EMC)¹. In this work, we prove that annealing of the Gd5Ge2Si2 can promote remarkable values for the EMC in comparison to those obtained for the alloy with high pure Gd. Also, the as cast alloy and the annealed alloy are not monophasic, but have at least two crystalline phases in their microstructure. Results for X-ray analysis, optical and electronic microscopy and magnetization measurements are reported.