Research On Thermal And Aging Resistance Of Polyurethane Core Of Polyurethane-Steel Composite Materials

The Sandwich Plate System (SPS) is a kind of composite structure material that is madeup of two layers of steel plate injected polyurethane elastomer. SPS has excellent physicalcharacteristics such as lighter weight, higher strength, fatigue resistance, corrosion resistance,shorter processing cycle and so on. All of these excellent performance make SPS, as astructural material instead of steel have a wide range of applications, for example, shipbuilding and repairing, reinforcement and construction of the bridge panel, replacement ofconcrete bridge deck, stand of entertainment venues, bailey bridge, high-rise building and soon. The design service life of SPS is generally required to achieve one hundred year. In thispaper, the polyurethane core of SPS was prepared, and its mechanical properties, thermal andaging resistance performance were characterized and analyzed as well as its service lifetime.Polyurethane elastomer is mainly composed of polyols, diisocyanate and chain extender.In this paper, one-step method was used in order to prepare polyurethane elastomersbased on different soft segments (PPG, PTMG, PCL). And mechanical and processingproperties as well as thermal and aging properties were characterized by TG, DSC and agingin the oven. The relationship between the soft segment structure and mechanical property,processing property, thermal and aging resistance and so on were discussing. The resultshowed that PPG based polyurethane elastomer can meet the requirements of SPS corematerial on performance and technology.Then, in the condition that PPG was as soft segment and BDO was as chain extender,polyurethane elastomers based on different hard segments (PAPI, U-MDI, C-MDI) wereprepared. The relationship between the hard segment structure and mechanical property,processing property, thermal and aging resistance and so on were also discussing. The resultshowed that PAPI based polyurethane elastomer was suitable for the research of this paper.Based on the above, the structure and performance of polyurethane elastomer based on PPG/PAPI/BDO were characterized and analyzed. The result showed that its performance hasreached requirements of Lloyd’s register of shipping (LR) to the polyurethane core material ofSPS. Finally, three pieces of SPS plates of2250mm x1560mm x15mm size were casted, inorder to analyze the performance of SPS.At last, the apparent activation energy (Ea) was calculated through the analysis of thedynamics of the degradation of polyurethane elastomer. On this basis, the service lifetime ofpolyurethane elastomer based on PPG/PAPI/BDO system was predicted using Kissingermethod and Arrhenius model as well as ageing resistance varying with temperature. All theresults showed that at room temperature, the service lifetime of the polyurethane elastomercan achieve1.6x1010min, and at60℃, it can reach5.1x107min. Considering the error ofthe prediction model and the real condition of SPS plates, the service lifetime of polyurethanecore of SPS can reach fifty to one hundred years, within the scope of the safety factor.