Release And Control Of VOCs For Polypropylene Applied In Automobile

Polypropylene,as the third largest universal polymer in the world,has the characteristics of low density,easy processing and excellent mechanical properties.Therefore,it has been widely used in the fields of household appliances,electronic appliances,textile machinery,non-woven materials,automotive materials and so on.Especially in recent years,under the developing trend of using plastic instead of steel to achieve whole vehicle lightweight in automobile industry,substitution of metal material with modified polymers,especially modified polypropylene,is one of the key points for the vehicle matching enterprises.However,the modified polypropylene materials have the natural weakness in the release of VOCs and low molecular volatile will be released from the materials in the period of processing and later use,causing deterioration of the vehicle environment.Therefore,the VOCs release of modified polypropylene materials is one of the hottest research topics in the recent.In this paper,the VOCs release of the polypropylene materials produced with different raw materials,different antioxidant systems and different processing conditions were studied so as to prepare low VOCs polypropylene materials which met the requirements of the automotive industry.Firstly,the effects of polypropylene materials produced by different processes on the VOCs release of modified polypropylene materials were studied.The experimental results showed that the VOCs release of polypropylene products produced by hydrogen modulation method was lower than that of polypropylene products produced by degradation method.Therefore,the polypropylene product produced by the hydrogen modulation method is more advantageous in the control of VOCs release.Secondly,on the basis of using hydrogen modified polypropylene to produce modified polypropylene materials,different antioxidant systems were selected to modify it.After comparing the protective effects of the number of different hindered phenolic groups and melting temperature on polypropylene materials,it was found that the more hindered phenol groups in the same molecule and the higher the melting temperature,the better protective effect of antioxidant.However,UV absorbent and hindered amine light stabilizer had no obvious effect on VOCs release of modified polypropylene materials.Thirdly,physical and chemical adsorbents were introduced into the modified polypropylene materials.The experimental results showed that VOCs release of modified polypropylene materials was improved by using alone physical adsorbent zeolite or chemical adsorbent aldehyde absorption agent,while the aldehyde absorption agent had a beneficial adsorption effect on formaldehyde and acetaldehyde.When two kinds of adsorbents are used at the same time,the adsorption effect of two kinds of adsorbents can be superimposed,the adsorption effect is better,and VOCs release of the modified polypropylene material can be controlled more effectively.Finally,the effect of the processing technology of modified polypropylene materials on the VOCs release was studied.By selecting three factors and three horizontal orthogonal experiments on the processing temperature,the screw speed and the host load during the period of processing,the data analysis of these orthogonal experiments were performed.The best VOCs release effect can be obtained under the production conditions of processing temperature 180-200℃,screw speed 300r/min and main engine load 75%.