The Research Of Poly-Dioxanone And Its Blends

Aliphatic polyesters, with outstanding biodegradability bioabsorbability and biocompatibility, have attracted great interest of researchers in recent decades. Poly(p-dioxanone)PPDO is a linear aliphatic polyester with good biocompatibility, biodegradability and mechanical properties. It has been used in medical field, such as monofilament sutures, bone and tissue fixation devices. However, its application was restricted because the rigorous synthetic condition needed in order to obtain high molecular weight products by common ring opening polymerization. What’s more, the poor thermal stability and melt viscosity of PPDO decrease significantly during processing are also disadvantage for production.Firstly, PPDO with higher molecular weight (intrinsic viscosity=1.16dl/g) was obtained via solid-state polymerization (ssp) in different condition. Then non-isothermal crystallization kinetics, rheology and the thermal degradation behavior have been utilized to investigate the physical property of PPDO. Another research of this work was the studies on property of PLLA/PPDO blends. The crystallization, thermal behavior, thermal stability and vitro degradation of PLLA/PPDO blends were studied by IR, DSC, TG.Results showed that:1) The appropriate conditions for melt solid-state polycondensation of PPDO were studied. The correlations among the molecular weight and the reaction temperature,N2flow speed were studied. Under the ssp experimental conditions of pre-crystallization temperature50℃, the N2flow20ml/min, reaction temperture80℃, and reaction time48h, the Ⅳ increased from0.77dl/g to1.16dl/g.2) Non-isothermal crystallization kinetics of different kinds of PPDO showed that the Ozawa equation could describe the non-isothermal crystallization of PPDO process well, the ozawa index were2.34,2.26and2.27.Kissinger equation was used to analyzed the crystallization activation energy, we concluded the crystallization activation energy were-201.43kJ/mol,-149.03kJ/mol and-148.61kJ/mol.3)The kinetics of the thermal degradation and oxidative degradation of PPDO have been investigated by TG Kissinger method, Friedman method and Flynn-Wan-Ozawa method to determine the activation energies of PPDO.The results showed that the thermal the correlation coefficient of Flynn-Wan-Ozawa was more close to1, indicating that this method was more accurate. At150℃the life time was rather shorter than123minutes.4) The solubility parameter of PLLA/PPDO blends suggested that PPDO and PDLLA are certain degree of compatibility. The strength and modulus of blends decreased, but the flexibility significantly improved. With the increase of PPDO in blends systerm while Tm closed to each other. At the same time all results suggested that PLLA in this system influence crystalline structure of PPDO and consideraly promote PPDO crystallzation. TG results indicated that the thermal stability of the blend system reduced with the increases of PPDO.5In the vitro degradation process, the hydrogen bonding of carbonyl group and water promoted the degradation of ester group. Subsequently, the ester bond degradation, the molecular weight of PPDO decreased. During the49days, PPDO fiher changed significant, weight loss reached about17.56%at7th week, the elongation changed from33.92%to14.44%. The vitro degradation of blends performance showed that:with the increase of PPDO, the degradation speed accelerate.