| With the rapid socio-economic development and improved people’s living standards, residential comfort of insulation has been further demanded for community. In this study, ultra-light weight foam core prefabricated board was produced with fire-retardant medium density fiber(FR-MDF) boards for the faces and phenolic foam(PF) as the core. Due to the cladding panel of FR-MDF, the sandwich panels not only overcome the defect of taking off powder, but also had overall good performance, good insulation effect, excellent mechanical properties. The sandwich panels were evaluated by these properties of mechanic, fire-retardant, thermal and sound insulation, in order to opt suitable structural units for different purposes. The main content and conclusions are as follows:(1)Flame retardant fiberboard and phenolic foam of B1 level were selected as the sandwich units through preferring by preliminary tests. Polyvinyl scetate adhesive was choosed to manufacture this new type of foam sandwich panels for its inexpensive price. The specific gluing process was preferably coated on one side of the fiberboard, 90 g/m2 resin content consumption and the relative pressure 0.01 MPa of second molding pressure. The two materials had good adhesive properties, tensile failure occured on the foam itself when adoptted tensile test.(2)The flame resistance of phenolic foam sandwich was characterized by oxygen index, smoke density, cone calorimeter test. The peak heat release rate of foam sandwich with 20 mm,50 mm foam core between 5 mm FR-MDF face was 99.6 kW/m2,112.5 kW/m2, and the total heat release within 5 min was 7.48 MJ/m2,15.67 MJ/m2, respectively, the maximum smoke density 23.0 %. The combustion and smoke released is superior to polyurethane foam or polystyrene foam sandwich, with excellent charring, flame retardant and low smoke properties.The peak heat release rate reduced with the increase of the thickness of fire-retardant fibreboard within a certain range of thickness(3 mm~5 mm), what’s more, the second peak of heat release time later. The peak heat release rate of 5 mm FR-MDF reduced by about 51.67 kW/m2 with respect to the 3 mm plate, the time to second peak heat release rate corresponding delayed about 180 s. Therefore 5 mm thick FR-MDF showed more stable, lower heat release rate, time to peak heat release rate later. The phenolic foam of different thickness presented heat release rate more consistent trend preliminary, the overall heat release rate was low, just only 15 kW/m2~25 kW/m2. Ignition test of the entire phenolic foam did not appear, the heat release rate increased slightly, but not significant with the increasing thickness of the foam.The heat release rate of foam sandwich with 5 mm FR-MDF faces was significantly lower than 3 mm. What’s more, 5 mm FR-MDF face could effectively block the heat further down along the core material, which apperring more complete carbon layer after cone calorimeter test, and the foam did not completely carbonized in thickness direction after 1200 s.The phenolic foam core sandwich showed excellent flame retardant properties.(3)The mechanical properties and failure modes of composite panels under load were evaluated by mechanical tests of three-point bending, compression and lateral pressure, etc. The results of foam sandwich panel with 5 mm FR-MDF face and 20 mm~50 mm core showed that compressive strength 0.22 MPa, bending strength of 1.0 MPa ~ 3.3 MPa, edgewise compressive strength 5.42 MPa, toughness 6.80 k J / m2 ~ 8.95 kJ / m2.(4)The heat transfer performance of foam core sandwich panels was analyzed through ANSYS finite element software, the thermal resistance of 60 mm sandwich board was 1.47 m2·K/W, and thermal conductivity was 0.041 W/(m·k) by thermal conductivity test. The transfer time of 60 mm sandwich required 180 min with respect to 30 mm sandwich of 60 min from the cold side of 20℃ to 34.4℃~36.1℃, the heat transfer rate was greatly reduced in contrast with thinner foam core, which was helpful to save energy and reduce energy consumption.(5)Sound insulation of foam sandwich panels was tested by acoustic impedance tube, then the structure of sandwich was preferred. The results showed that the fiberboard increased by the average of 2 dB ~ 3 dB with increasing thickness of 1 mm. Also phenolic foam board increased by nearly 2 dB ~ 5 dB with increasing thickness of 10 mm. Sound insulation of foam sandwich panels were improved than the single-layer structure unit, thereinto, foam sandwich with 20 mm, 50 mm foam core increased more significantly in acoustics, increased by about 8 dB relative to fiberboard and 3 dB relative to phenolic foam board, the performance of 60 mm foam sandwich panel(≥35 dB) could meet indoor bedroom wall insulation standard at residential buildings of GB 50118-2010 for civil insulation design.(6)Currently foam sandwich panels faced with non-metallic board have not yet relevant reference standards and norms. Several practical suggestion for engineering applications of the foam core sandwich panels were proposed basing on the test results by mechanics, fire-retardant, thermal and acoustic properties. |
