Research On Properties Of Bio-based Polyurethane Porous Composites In Vehicle

With the development of society,the automobile ownership in China is further advanced,and people’s eagerness for capability of the automobile becomes stronger too.Among them,the NVH(noise,vibration,harshness)performance is indispensible.Noise is an important part of NVH performance,which has a negative impact on the physical and mental health of drivers and passengers.Polyurethane materials are widely used as automotive acoustic packaging because of low density,ease of molding,ease of production,and excellent acoustic properties.At present,polyurethane materials are generally made of pure petroleum based polyurethane.Pure petroleum-based polyurethane not only consumes non-renewable resources,but also has problems such as poor low-frequency sound absorption performance,poor mechanical strength,difficult degradation,and easy to cause white pollution.Bio-based polyurethane uses renewable materials to replace some of the reactants in the process of preparing pure petroleum-based polyurethane,which has the characteristics of environmental protection.Therefore,it is of great significance to study the bio-based polyurethane porous composites in vehicle.In this paper,castor oil,soybean oil-based polyols,and tung acid polyols are used to study the preparation process of castor oil-based polyurethane,soybean oil-based polyurethane,and tung oiled-based polyurethane.The properties of the three bio-based polyurethanes were being conducted studied and compared by FTIR,SEM,acoustic,mechanical,and degradation measurement.It was found that the low-frequency sound absorption performance,sound insulation performance,compression performance,and degradation performance of the three bio-based polyurethanes were better than those of pure petroleum-based polyurethanes.Then,castor oil-based polyurethane foam was selected,and further research was conducted through flame retardancy test and volatile organic compound test.The results showed that castor oil-based polyurethane has better flame retardancy,lower volatility and less formaldehyde than pure petroleum-based polyurethane.The contents of ionized water,MDI and A33 were used as design variables to design the response surface experiment for optimization.Based on the experimental results,mathematical models of the average sound absorption coefficient and average sound insulation of castor oil-based polyurethane were established according to the contents of deionized water,MDI,and A33.Considering the sound absorption and sound insulation properties of castor oil-based polyurethane,these three components were optimized based on the NSGA-Ⅱ algorithm.When 2.05 g of deionized water,42.60 g of MDI and 1.25 g of A33 were used,the acoustic properties of the samples were the best.The castor oil-based polyurethane was modified with jute fiber,peanut shell powder and carbon powder filler.It has been studied that the acoustic and mechanical properties of castor oil-based polyurethanes modified respectively by adding 4.0,3.5,3.0,and 1.5 g fillers.The effects of hemp fiber filler treated with 5% NaOH solution and untreated hemp fiber filler on the properties of castor oil-based polyurethane were also studied,respectively.The results show that adding treated and untreated hemp fiber can improve the sound insulation and compressive resistance of the sample,but reduce the sound absorption performance.Among them,the addition of treated jute fiber has a more significant decrease in the sound absorption performance of the sample.Adding 1.0 g and 1.5 g jute fiber filler can improve the sound absorption performance of castor oil polyurethane in the range of 500-1000 Hz.Adding a certain amount of powder filler can increase the open cell ratio of castor oil-based polyurethane unit cells and improve its sound absorption performance.The addition of 1.0g peanut shell powder had the most significant effect on sound absorption of samples,and the sound absorption coefficient was up to 0.551.Porous material models with different opening characteristics were established according to the characteristics shown in the SEM pictures of polyurethane porous materials.The finite element method and JCA acoustic model were used to simulate the sound absorption performance of these models.The results show that the sound absorption performance of the porous material with oval hole is weaker than that of the porous material with circular hole,and the sound absorption performance of the porous material with half hole is better than that of the porous material with small hole.Castor oil-based polyurethane and castor oil-based polyurethane modified by peanut shell powders were applied to the acoustic package of the automobile roof and firewall,and compared with pure petroleum-based polyurethane,using statistical energy analysis.The results show that both bio-based materials can reduce the interior noise and both materials can improve the sound absorption performance of the firewall,ceiling acoustic packaging of the automobiles in the range of 400-630 Hz and the sound insulation performance in the range of 400-6300 Hz.