The concept of zero-energy building is one of the promising ways to improve energy efficiency, resulting in the reduction of greenhouse gas emissions. The use of rigid polyurethane foam (RPUF) has been widely used as insulation material in building panels because of its excellent properties including light-weight, durability, and lower thermal conductivity. This study aimed to determine the effect of mixing conditions on the production of RPUF at varied mixing speeds (300, 500, 1000 rpm) corresponding to its density, mechanical, and insulation properties. It was observed that the well-defined physical structure of RPUF was obtained at the minimum mixing speed of 500 rpm. The foam density changed with the increasing mixing speed, from 39.8 kg/m3 at 500 rpm to 51.30 kg/m3 at 1000 rpm. This might be because of the possible loss of the blowing agent due to excessive mixing speed as noted by the constrained foam expansion and the shorter time for the free-rise process. The thermal insulation property of obtained RPUF was significantly lower than that of conventional building materials like concrete. This research is one of the key technologies to reduce the energy consumption for heating-cooling buildings and thus create a potential strategy for climate change mitigation.

Previous studies on the physical properties of each Polyethylene (PE) or Ethylene Vinyl Acetate (EVA) foam have been widely reported. The current challenge is how to understand the combination of PE and EVA foam in order to obtain appropriate properties in various applications. Therefore, an experimental breakthrough in order to understand the physical mechanism on the PE:EVA mixed foam in order to maintain many appropriate properties due to their applications was studied. The physical properties of a combination of PE and EVA foam with Azodicarbonamide (ADC) as blowing agent and the addition of Zinc Oxide (ZnO) as accelerated agent in foaming process have been investigated in this study. The foams were prepared via two steps. Firstly, the various content of PE and EVA resins with combination of various content of ZnO and the addition of ADC, stearic acids and antioxidants were mixed by a single screw extrusion as the results of pellets. Furthermore, this intermediate product was pressed by compression moulding at the temperature of 175 °C and pressure of 30 bar for 5 minutes, then the pressure was released for the foaming process. The effect of the addition of ZnO were observed on the density and the mechanical properties of the foams. The density decreased with increasing of ZnO content up to 4 per hundred resin (phr) on the foam with PE content maximum of 20 phr. Interestingly the density of the foam increased with the addition of 6 phr of ZnO. Due to the increasing number of ZnO, we found the formation of foams completely. We observed the approval of the hardness, tensile and compression properties of each formulation, respectively. Furthermore, the morphology observation of the foams was conducted by scanning electron microscopy (SEM) to measure the size and homogeneous of the cells. We observed large size of cells at low density of foams, meanwhile uniform of cell was obtained at the high density of foams. Finally, the Fourier transform infrared (FTIR) spectroscopy confirmed that in general the intensity of the absorption peak at around 2216 cm-1 - 2223 cm-1 of each formulation decreased with the addition of ZnO up to 4 phr of ZnO and increased again at 6 phr of ZnO.