Study On Composition Analysis Of Waste Rubber Powder And Its New Recycling Pathways

Waste rubber powder,as the secondary resource of waste rubber,shows a wide range of applications,such as rubber asphalt,retread tires,cement concrete,etc.However,the researches on the composition analysis of waste rubber powder and its recycling methods are still very unclear.On that account,in this paper,the structure and composition of waste rubber powder were studied in detail by means of thermogravimetric analysis and infrared spectroscopy,and then new recycling methods of waste rubber powder were explored.The concrete results are as follows:(1)The composition and relative content of waste rubber powder are analyzed by total reflection infrared spectroscopy and thermography-infrared spectrometer.thecompositions and contents of waste natural rubber powder(WRP-7)and waste nitrile rubber powder(WRP-8)are determined.The volatile non-rubber components in WRP-7 account for13.37%,rubber hydrocarbon components account for 47.46%,carbon black and other filler components account for 34.55%,inorganic components account for 4.62%.The volatile non-rubber component,rubber hydrocarbon component and inorganic component in WRP-8account for 11.22%,43.58%and 45.20%respectively.(2)The reported researcheshaveindicated that,there are still residual unsaturated double bonds in a variety of waste rubber powder.These double bonds can be chemically re-crosslinked to form recycled rubber.In addition,in order to conquer the challenges of traditional vulcanized rubber with irreversible covalent crosslinking,a large number of dynamic covalent bonds have been incorporated into rubber crosslinking network to produce dynamic bond crosslinked and solid phase recyclable rubber.Therefore,in the third chapter,the waste rubber powder(waste natural rubber powder)is chosen as the base materialusing its unsaturated double bond as active sites,thiokol(containing disulfide bonds in its molecule chain and thiol in molecular end)as crosslinking agent,1,8-diazabicyclo[5.4.0]undec-7-ene(DBU)as catalyst.The thiol-ene addition reaction between waste rubber powder and thiokol is fulfilled to develop self-healable and damping recycled rubber.The results are as follows:the conversion of unsaturated double bond is calculated as 84%in the 10/2 samples with the mass ratio of waste rubber powder to polysulfide rubber,and 100%in the 10/4 samples.The damping properties of recycled rubber are tested by DMA.The maximum damping factor of10/5 samples is 0.88,the effective damping temperature ranges from-26.9℃to 34.8℃,meaning that it has certain damping properties at room temperature.The mechanical properties of recycled rubber and self-healing ability are also studied.The tensile strength of10/2 samples was the highest with 1.13MPa.The self-healing efficiency of the 10/6 samples is 94%after being heated at 120℃for 24h,and 72.9%at 100℃for 2h.(3)The UV-curing 3D printing has advantages like fast speed,high accuracy,excellent surface quality,but its developed devicesstill reveals shortcomings such as high brittleness and poor toughness.The waste rubber powder has been widely used to toughen and modify thermosetting resins.Therefore,in the fourth chapter of this paper,the residual unsaturated double bond in the waste rubber powder is also used to modify the waste rubber powder,and the modified rubber powder is compounded with 3D printing photosensitive resin to prepare3D printing photosensitive composite resin.The results are as follows:the structure of modified rubber powder is characterized by IR and Raman spectroscopy.The content of sulfhydryl groups on the surface of modified rubber powder is determined by standard curve method.When the mass ratio of waste rubber powder to modifier is 10/4,10/8 and 10/12,the contents of sulfhydryl groups on the surface are 126,171 and 545μmol/g,respectively.The impact strength of the 3D printed 10/8 samples with 5%modified rubber powder is4.91k J/cm~2,increased by 258%compared with the original sample.The impact strength of the samples with 5%unmodified rubber powder has little change,but its tensile strength is reduced to 6.31MPa.