Studies On Synthesis, Characterization And Applications In Rubber As Vulcanizing Properties Of Metal Complexes With Organic Ligands Containing Sulphur Atoms

1. In this thesis, the studies on complexes of IIB and rare earth metals with organic ligands containing sulphur atoms have been reviewed. Synthetic methods, structural characterization and analytic methods of these complexes are discussed in detail. At the same time, the application of vulcanization acceleration for these complexes has been described.2. Two new metal complexes, which were shown as [Cd(DBTC)2]2 (1) [Zn(DBTC)2]2(bipy) (2) (where DBTC = N,N-dibenzyl dithiocarbamate; bipy = 4,4'-bipyridine), were synthesized in mixture of ethanol and water at room temperature and characterized by IR spectra, TGA analysis and X-ray crystallographic analysis. The complex (1) is centrosymmetric dinuclear structure. There are two tridentate dithiocarbamate ligands which bridge via one sulfur atom each to two cadmium atoms leading to the formation of a Cd2S2 core. Each cadmium atom is coordinated to five sulphur atoms from three ligands and it results in the formation of a tetragonal pyramidal geometry. Crystal data were listed as following: C30H28CdN2S4 M = 657.18, monoclinic, space group of P21/n, a = 1.11098(4) nm, b = 1.56325(5) nm, c = 1.66695(5) nm, p = 97.9220(10), V = 2.86743(17) nm3, Z = 4, Rl [I>2( I)] =0.044, wR2 (all reflections) = 0.099. The complex (2) shows centrosymmetric dinuclear structure. Zn(II) ions, which is five-coordinated to sulphur atoms from two bidentate dithiocarbamate ligands and one nitrogen atom from bipy, has a trigonal bipyramidal geometry. In each cell, two identical Zn(II) units are linked by bipy to form a dimer. It is triclinic, space group of P-l, with Z= 1. Its lattice parameters: C70 H64 N6 S8 Zn2, M = 1376.5, a = 1.06878(7) nm, b = 1.26278(8) nm, c = 1.32586(8) nm; a = 93.090(1), β = 104.488(1), γ = 108.270(1). Rl [I>2( I)] = 0.046, wR2 (all reflections) = 0.119.3. Very crucial synthetic conditions for preparing the ligand Na(DBTC), such as the mole radio of reactants and reaction time, et al, have been discussed in this thesis. In view of the product's yield and purity, the optimal synthesis conditions are obtained. Then, the complex [Nd(DBTC)3(HMPA)2] was synthesized by changing the syntheticconditions.4. Vulcanizing properties of the Cd(II) complex [Cd(DBTC)2]2 as vulcanizing accelerator in natural rubber were studied. Compared with traditional accelerators NOBS and CZ/TMTD etc, the results show that the cross-linked rubber accelerated by the complex [Cd(DBTC)2]2 has more excellent physical mechanical properties on tensile strength and tear strength than that by the others.5. Additive capacity of the Nd(III) complex [Nd(DBTC)3(HMPA)2] in natural rubber have been studied. With the dosage of the complex increase, modulus and Shore hardness of cross-linked rubber increase. Their tensile strength and elongation at break increase with the content of the accelerant in the beginning, and the optimal properties are obtained at 2.5 percent, and it would decrease with the increase of the content. It has also been similarly changed on tear strength and the optimal conditional appears at 2.0 percent.With fixing the dosage of sulphur, the crosslink density changes with the increase of the accelerator, and same changes on the modulus and Shore hardness have been taken place with crosslink density, but tensile strength and tear strength would come to head with certain crosslink density. The optimal content of [Nd(DBTC)3(HMPA)2] as an accelerator on the natural rubber would be determined on the basis of considering various properties.