The use of nanotechnology is rapidly growing in various fields for different applications such as aerospace, electronics, construction, biomedicine, cosmetics etc. Nanomaterials posses unique size dependent material properties and can manipulate the host material properties to a greater extent compared to the micron sized particles of the same composition, and make them suit the requirements. Various kinds of nanomaterials with different size and shapes such as particulate, fibrous, layered, tube and foam when added to the host matrix material in composites will tailor the properties of the matrix material to a greater extent making nanocomposites a good alternative to conventional composites. In this research, more emphasis is made on improving mechanical and other physical properties of recycled high-density polyethylene (HDPE) polymer by adding graphene nanoplatelets at different concentrations. Recycled HDPE graphene nanocomposites were prepared using a solvent method assisted by a sonication method where samples are processed in to dog bone shaped specimens by using an injection molding process. For comparision, samples of plain recycled HDPE without graphene nanoplatelets were prepared. The samples were tested to evaluate the improvement in physical properties as function of the graphene concentrations in the polymer matrix. Physical properties of these samples were determined using different techniques: a) thermal conductivity which is found by using axial flow comparative cut bar method, b) dielectric constant is found by measuring capacitance of parallel plate capacitor setup using a capacitance bridge, c) water contact angle is found by optical angle goniometer, and d) tensile modulus is found by uniaxial tensile testing. The morphological characterization of PMN samples is performed using SEM technique to observe the type of distribution and dispersion of graphene nanoplatelets in the polymer matrix. The test results showed that adding graphene into recycled matrix drastically changed the physical properties of the materials. This may improve the value of the recycled materials for various applications.