Study On Dynamic Mechanical Properties Of Polyborosiloxane Modified Natural Rubber And Thermoplastic Elastomer

Polyborosiloxane(PBDMS)is a strain rate sensitive material,which possesses relaxation effect under dynamic alternating load and has strong ability to dissipate external energy.Thus it has potential application in the fields of impact protection,vibration damping,etc.However,it is difficult to be applied in practical applications because of its fluidity.In order to solve this problem,three different elastomer materials,natural rubber(NR),hydrogenated styrene-butadiene-styrene block copolymer(SEBS)and ethylene-vinyl acetate copolymer(EVA),were blended with PBDMS respectively to prepare a series of modified elastomer materials.And the dynamic mechanical behaviors of the samples were herein studied.The results are as follows:During the blending process of PBDMS and NR,there was no chemical reaction between the two materials but only physical crosslinking.In the composites,when the mass fraction of PBDMS is 10%,the composites have good compatibility.Furthermore,the addition of PBDMS improves the tensile strength,storage modulus and loss factor of the composite material,and the enhancement effect is better when the addition ratio is 10%.Compared with pure NR,the composite modified by PBDMS has higher strain rate sensitivity.During the blending process of PBDMS and SEBS,there was no chemical reaction between the two materials but only physical crosslinking.With the increase of PBDMS content in the composite system,glass transition zone,cold crystallization peak and melting peak of PBDMS gradually appear in the DSC curve.In the composites,when the mass fraction of PBDMS is 25%and 35%,the glass transition platform of polystyrene block on DSC curve disappears.When the hydroxyl number of hydroxyl-terminated polydimethylsiloxane(PDMS-OH)is 1%,the tensile strength,storage modulus and loss factor properties of PBDMS/SEBS composites are improved,and the mechanical properties of the composites also increase with the increase of PBDMS contentThe experimental results of blending and foaming of PBDMS with ethylene-vinyl acetate copolymer show that when the mass fraction of PBDMS is 5%,the composite material has the best performance,the uniformity and density of inner cells of the modified material are improved,and the cell wall thickness is obviously increased.The tear strength of the composite material is increased from 1.6N/mm before modification to 3.4N/mm,and the damping performance was significantly better than that of pure EVA material.The storage modulus was increased from 0.03MPa to 0.07MPa,and the loss factor was increased from 0.27 to 0.51.The glass transition temperature of the modified EVA material decreases somewhat,but the transition temperature region widens.