Synthesis And Properties Of The Type Of (DA-EG)_m-(DA-PG)_n Block Polyester Material

Unsaturated polyester resin is an important sorts of thermosetting resin. It has been widely used in many fields because of its good comprehensive properties and multiple shaping techniques. In recent years, with the sustained and rapid development of our economy, the new requirements which were proposed about variety and performance of unsaturated polyester resin. In order to satisfy these needs, the unsaturated polyester resin which had better performances urgent need to develop.In this paper, the type of (DA-EG)m-(DA-PG)n block polyester was synthesized using C36 dimer fatty acid (DA), ethylene glycol (EG), propylene glycol (PG) and cis-butenedioic anhydride (cBA) as materials. And the type of (DA-EG)m-(DA-PG)n block polyester resin was synthesized using the polyester. Regularity of the synthesis of (DA-EG)m-(DA-PG)n block polyester was studied. Proportion of the mechanics, water resistance, oil resistance, fire resistance of the (DA-EG)m-(DA-PG)n block polyester resin were studied, The results were as follows:Mark-Houwink equation constants of the new types of dimer fatty acid based polyester was obtained at 30℃in tetrahydrofuran, the equation constants is K=0.7978, a=0.01698. And the relationship between the inherent viscosity of polyester and average molecular weight was as follows: [η] = 0.01698M0.7978.Frist, the prepolymer of DA-EG was synthesized using dimer fatty acid and ethylene glycol at 170℃, vacuum conditions; Second, the prepolymer of DA-PG was synthesized using dimer fatty acid and propylene glycol at the same condition; finally, the type of (DA-EG)m-(DA-PG)n block polyester was synthesized using the prepolymers and cis-butenedioic anhydride. The optimum reaction conditions of polyester were as follows: the molar ratio dimer fatty acid: cis-butenedioic anhydride is 1:0.8, the preferable catalyst is p-toluene sulfonic acid and the amount is 1.0% of the mass of materials, reaction tempertion is 160℃, reaction time is 4 h. And the target product was proved by IR and H NMR spectra, the molecular structure of polyester has a good regularity.The type of (DA-EG)m-(DA-PG)n block polyester resin was synthesized using (DA-EG)m-(DA-PG)n block polyester, styrene and benzoyl peroxide as materials. The performance of (DA-EG)m-(DA-PG)n block polyester resin which was influenced by proportion of styrene, proportion of benzoyl peroxide, curing time and curing temperature was studied. A preferably proportion for the new types of polyester with better property of mechanics, water resistance, fire resistance was obtained. The molar ratio styrene: cis-butenedioic anhydride is 2.5:1～4:1, the amount of benzoyl peroxide is 1.0 % of the mass of polyester, curing time is 6 h, curing temperature of 100℃.The result of thermal analysis showed that the type of (DA-EG)m-(DA-PG)n block polyester resin had perfected thermodynamic stability. The decomposition temperature was above 240℃, and the percentage of lost weight was at 450℃. The new types of polyester which was obtained by experiments had excellent properties, such as tensile strength, impact strength, flame resistance and water resistance and so on.