Study On Preparation And Flame Retardant Modification Of TPU/PVC Alloy

Thermoplastic polyurethane(TPU)has good mechanical properties,such as cold resistance,fatigue resistance and oil resistance.However,its poor processing fluidity,high permanent deformation,poor flame retardancy and high production cost limit its application.Polyvinyl chloride(PVC)is one of the most productive general plastics.It has the advantages of low cost,good processability,easy hardness adjustment and good combustion performance.However,its toughness,thermal stability and low temperature mechanical properties are poor.Therefore,TPU and PVC have complementary advantages in performance,and they have good coMPatibility.Therefore,the preparation of TPU/PVC alloy with excellent properties can effectively broaden the application scope of both.In order to optimize the formulation and prepare TPU/PVC alloy materials with excellent properties,three kinds of plasticizers,Dioctyl Phthalate(DOP),Epoxy Soybean Oil(ESO)and Trimethylphenyl Phosphate(TCP),were firstly used to plasticize the alloy,and the types of plasticizers most suitable for TPU/PVC alloy and their additives were determined.Secondly,the blending ratio of TPU and PVC was adjusted to synthesize different plasticizers.The best blending ratio of the alloy was obtained by testing the properties of the blending ratio alloy.Finally,two different intumescent flame retardant(IFR)systems were studied to modify the alloy,and the optimum flame retardant system and its dosage were determined.Specific research contents are as follows:(1)Compared with DOP and ESO,TCP can improve the mechanical properties and processing fluidity of TPU/PVC alloy,while effectively improving the thermal stability of alloy materials.The comprehensive test results show that when the TCP content is 30 phr,the comprehensive performance of TPU/PVC alloy is the best.(2)When TCP is used as plasticizer and the addition amount is 30 phr,with the increase of the proportion of PVC components,the combustion performance and processing fluidity of the alloy are improved,but its thermal stability is reduced.The mechanical properties of the alloy increase first and then decrease.The peak value is reached when the PVC component is 30%(wt).According to its properties,the optimum blending ratio(mass ratio)of TPU and PVC is 70:30,and the tensile strength of the material is obtained.With tear strength of 14.76 MPa and 96.17 N/mm,MFR increased to 15.64 g/10 min,thermal stability was better and LOI could reach 22.98%,and flame retardancy reached HB level.(3)Apart from good flame retardant effect,the mechanical properties,low temperature thermal stability and processing properties of TPU/PVC alloy were improved by APP/PER flame retardant system.When the ratio of APP/PER was 5:3 and the addition amount was 24 phr,the flame retardant TPU/PVC alloy with the best comprehensive properties could be prepared.At this time,the limiting oxygen index(LOI)and smoke density grade(SDR)of the alloy reached 31.23% and 53.23%,respectively.The burning grade(UL-94)is V-0.The tensile strength and tear strength of the alloy materials are 16.52 MPa and 105.23 N/mm,respectively.In addition,the toughness,processing fluidity and thermal stability of the alloy are good.(4)The nano-kaolin modified by silane coupling agent has better synergistic effect on IFR system based on APP/PER and improves the flame retardant efficiency of IFR system.The flame retardant TPU/PVC alloy with the best comprehensive properties can be prepared when the ratio of APP/PER/modified kaolin is 5:3:2 and the addition amount is 20 phr.At this time,the limit oxygen index(LOI)and smoke density grade(SDR)of the alloy reach 36.14% and 36.04 respectively,the combustion grade(UL-94)reach V-0,and the tensile strength and tear strength of the alloy material reach respectively.To 17.15 MPa and 110.23N/mm,the toughness,processing fluidity and thermal stability of the alloys are good.