Influence Of PEO Molecular Weight On Structures And Properties Of Cu/PEO/LDPE Contriceptive Material

In this paper,a novel copper-containing composite based on polymer alloy of polyethylene oxide(PEO)and low-density polyethylene(LDPE),i.e.,Cu/PEO/LDPE composite,is developed for copper-containing intrauterine devices(Cu-IUDs).After various samples of Cu/PEO/LDPE composite with different PEO molecular weight has been prepared by using a combined technique of melt blending and injection molding,influences of PEO molecular weght on structures,non-isothermal crystallization behavior,mechanical properties,thermal stability,rheological properties,dynamic mechanical properties,hydrophilicity and copper ion release rate of this composite were investigated.Results of study on the structures of Cu/PEO/LDPE composite show that this composite is a simple mixture of pure Cu,pure PEO and pure LDPE,and the change of PEO molecular weight does not affect the micromorphology,distribution and valence of copper of this composite.Results of study on the non-isothermal crystallization behavior of Cu/PEO/LDPE composite show that the PEO molecular weight has no effect on the nucleation and growth mode of the crystallization of LDPE matrix,but the increase of PEO molecular weight will lower the non-isothermal crystallization rate of the LDPE matrix and increase the activation energy required for the diffusion of LDPE molecule chains during crystallization,lead to the decrease of the crystallinity of LDPE.The calculation of non-isothermal crystallization kinetics by using different models found that the Avrami-Ozawa method and the iso-conversional method modified by Vyazovkin are more suitable to this composite.Results of study on the properties of Cu/PEO/LDPE composite show that PEO molecular weight has a significant effect on many properties of this composite except for its thermal stability.As the PEO molecular weight increases,the mechanical properties of the Cu/PEO/LDPE composite deteriorate,the loss modulus,storage modulus and viscosity of the Cu/PEO/LDPE composite increase,and the contact angle between this composite and the simulated uterine solution increase,the glass transition temperatures of its LDPE matrix decrease.The copper ion release rate of the prepared Cu-IUDs increase firstly and then decrease with the increase of the PEO molecular weight.and its maximum is appeared around the PEO molecular weight of 4.3×10~5.These results indicate that the properities of this novel composite can be easily regulated by the change of its PEO molecular weight.