Effect Of Composite Foaming Agent On Foaming Properties Of EPDM

EPDM rubber-based foaming materials have excellent cold resistance,heat resistance and aging resistance and other advantages,are widely used in transportation,packaging,construction and other fields,with good prospects for application.Blowing agent is one of the most important components of the production of rubber foaming materials,the current industry is mainly divided into two categories of blowing agent:physical blowing agent and chemical blowing agent,chemical blowing agent can be divided into inorganic and organic blowing agent.Foamed rubber usually uses organic blowing agents with good processing stability and stable gas generation,such as blowing agents AC,OBSH,H.These blowing agents have their own advantages,such as blowing agent AC gas production,non-polluting,non-smelly,relatively inexpensive,etc.blowing agent OBSH is characterized by fine and uniform pore structure,no coloring,can be used in almost all rubber and plastic foaming products.But these blowing agents also have their own disadvantages,such as high temperature of decomposition of blowing agent AC,easy to agglomerate the product foaming uneven;blowing agent OBSH is more expensive,limiting its use.Therefore,the blowing agent will be compounded,modified to meet the needs of different foaming products is an important development trend of today's blowing agent.In this paper,the compound blowing agent was prepared by compounding,modifying and using the blowing agent AC and its activator,and its effect on the foaming performance of EPDM rubber was investigated.AC/ZnO compound blowing agent was prepared by compounding blowing agent AC with its activator ZnO,and the effects of foaming temperature and foaming time on its foaming performance were investigated.The experimental results show that ZnO is a strong activator of foaming agent AC,and when the ratio of AC/ZnO is only 1:0.1,the decomposition temperature of foaming agent can be reduced to about 180?,and the gas production is increased.With the increase of foaming temperature,the density of foaming material first decreases and then increases,and at 180?,the prepared EPDM foaming material has the smallest density and the best bubble pore uniformity.The effect of foaming time on EPDM foaming material is similar to that of foaming temperature,and the density of the prepared EPDM foaming material is the smallest and the uniformity of pores is the best when the foaming time is 10 min.The foaming agent AC was compounded with the foaming agent OBSH,and the AC/OBSH compound foaming agent with different compounding ratios was prepared,and its effect on the foaming performance of EPDM rubber was investigated.The experimental results show that:compared with pure AC,the decomposition temperature of blowing agent AC and OBSH decreases after compounding,and the amount of gas generation decreases,and the amount of heat release decreases after compounding,which provides favorable conditions for the preparation of foaming materials.As the amount of OBSH in the compound blowing agent increases,the vulcanization rate of the system is accelerated,and the E_L and V_fof the foaming material are reduced.When using blowing agent AC alone,the pores were mainly open pores with large difference in pore size and uneven distribution.With the increase of OBSH content in the compound blowing agent,the average diameter of pores decreased,the number increased,the distribution of pores was more uniform,and the pores showed a mixed pore structure with mainly closed pores.The chemically and physically modified silica foaming agent AC was prepared by chemically and physically modified methods,and the effect of its dosage on the foaming performance of EPDM rubber was investigated.The results showed that the decomposition temperature of the modified blowing agent was reduced and there was no adverse effect on the gas production per unit of blowing agent compared with the unmodified blowing agent AC.The effect of silica particles in the modified blowing agent on the process of vulcanization was not significant,and the apparent density of the foamed material decreased with the increase of the amount of blowing agent.The EPDM foam with unmodified blowing agent AC is mostly open pore structure with large pore size and uneven distribution,while the EPDM foam with silica modified blowing agent AC is mostly closed pore structure,and with the increase of modified blowing agent dosage,the average pore size decreases,the distribution becomes narrower and the uniformity of pores becomes better.As the apparent density of EPDM foam decreases and E_Land V_f increase,the tensile strength and elongation at break of the foam decreases.