Preparation Of Organic Zinc Salt Vulcanization Agent And Its Application In Rubber Crosslinking

According to the world health organization,there are now 3 billion used rubber tires in the world,and the number is increasing by 1 billion a year.In the crosslinking forming stage,a covalent crosslinking network is formed between rubber molecules,which leads to the difficulty of rubber recovery.At present,the commonly used industrial method is to grind waste rubber into rubber powder and raw rubber for compounding or used in the construction industry.This method has high cost and low added value.Some researchers have also constructed dynamic covalent bonds in the crosslinking network of rubber to give rubber hot pressure recovery performance,but this method has complex steps and low industrialization prospect.Ionic bond is a kind of non-covalent bond,which is completely reversible under appropriate conditions and has a large bond energy.Based on this,a new ionic crosslinking agent was synthesized,and a reversible crosslinking network was constructed with non-covalent ionic bonds as the core,which endowed rubber materials with the characteristics of recyclability,reusability and biodegradability and the main studies are as follows:(1)Zinc thiomethylmethacrylate(S-ZDMA)was prepared from zinc methacrylate(ZDMA)and bis-[poly-(triethoxylsilicon)propyl]tetraculfide(Si-69)by one-pot method.The epoxidation of ZDMA and its ring opening with si-69 were analyzed by Fourier infrared spectroscopy(FT-IR),Raman spectrometer(Raman),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and X-ray diffraction(XRD).The ratio of substances controlling HCOOH:C=C:H2O2 is 1:2:3.5;The mass ratio of Si-69 to ZDMA is 1:1.At 90? for 12 h,the yield of S-ZDMA was 53%.(2)Ion-crosslinked styrene-butadiene rubber was prepared by mechanical melting and molding method with styrene-butadiene rubber as matrix.The mechanical properties of ion-crosslinked styrene butadiene rubber were characterized by FT-IR,XRD,universal material testing machine,densimeter,resilience tester and hardness tester.The results showed that there were spontaneous bubbles in the crosslinking process of S-ZDMA,and the tensile strength,elongation at break and toughness of ion-crosslinked styrene butadiene rubber increased with the content of S-ZDMA.When the content of S-ZDMA was 40 phr,the tensile strength,elongation at break and toughness of the material reached 4.15 MPa,1029%and 23.59 MJ/m3,respectively.Moreover,S-ZDMA can also crosslink natural rubber(NR),nitrile rubber(NBR),neoprene rubber(CR)and ethylene propylene diene diene rubber(EPDM).(3)Ionic crosslinked styrene-butadiene rubber can be dissolved in a mixed solvent of chloroacetic acid/toluene,which breaks the tradition of non-melting and insoluble crosslinked rubber.The solution was transferred to toluene and the liner styrene butadiene rubber was precipitated to recover the crosslinked styrene butadiene rubber.(4)With the recovered styrene-butadiene rubber as the matrix and ZnO as the cross-linking agent,the recovered styrene-butadiene rubber can be reprocessed by means of melt blending and molding,so as to realize the reuse of the styrene-butadiene rubber.The stress,strain and toughness of the reprocessed styrene butadiene rubber reached 3.3 MPa,555%and 9.74 MJ/m3,respectively.(5)Ion-crosslinked styrene butadiene rubber can be degraded by yeast,lactobacillu and lipase.The degradation degree increased first and then decreased with time,and the yeast reached the maximum degradation degree on the fourth day,with the weight loss rate up to 7.5%.Lactic acid bacteria reached the maximum degradation degree on the third day,and the weight loss rate reached 5.7%.Lipase reached its maximum degradation on the second day,with a weight loss rate of 3.0%.Under the yeast/lipase,lactobacillus/lipase complex system,the degradation degree of materials decreased significantly.