Preparation And Mechanical Properties Analysis Of Shape Memory Polyurethane Reinforced With Glass Fiber For Orthodontics Application

The polymer material with shape memory effect(SMPs,shape memory ploymers),which is a new type of smart materials,has good recovery rates and biocompatibility,such as polyurethane(PU),can be used in orthodontics.However,the elastic modulus of this material is relatively low,and the shape recovery force is relatively small.In order to improve the feasibility of the application of PU material in the orthodontics,the glass fiber is used as reinforcement for the polyurethane matrix.The work mainly includes the following aspects:(1)Based on the literature analysis and preliminary experiments,the filler is selected,the synthetic process of GFRSMPU composites is explored,and then,the rectangular spline samples are fabricated.(2)In order to evaluate whether the mechanical properties of GFRSMPU composites meet the requirements of orthodontics,the elastic modulus value of GFRSMPU composites is measured by static tensile test,the glass transition temperature of GFRSMPU composites is measured by DSC,the flexural modulus of GFRSMPU composites is measured by three-point bending test and the stress release of GFRSMPU composites is tested by stress relaxation test and the uniformity of dispersion of glass fiber in polyurethane matrix is observed by SEM.Finally,the shape memory performance and the appearance of GFRSMPU are evaluated.The results show that,compared with SMPU material,the elastic modulus of GFRSMPU composites increased by 381% when temperature is 36 ? and the glass fiber mass fraction is35%.The glass transition temperature of GFRSMPU is 36.25 ?,the material have shape memory performance and aesthetic function,so the mechanical properties of GFRSMPU areimproved greatly,as well as the possibility of using this material in orthodontics is improved obviously.(3)The GFRSMPU wire orthodontic finite element model is established.The maxillary lateral incisors is chosen as research object,the process of SMPU archwire and GFRSMPU archwire fixed into bracket of orthodontics patient's teeth have the direction of the lip and cheek or lingual dislocation are simulated,the initial orthodontic forces are obtained from the finite element analysis and the two orthodontic force values are compared.The results show that the initial orthodontic force provided by the GFRSMPU archwire is about 2 times that of the pure SMPU archwire.The results show that the effect of glass fiber reinforced the mechanical properties of SMPU material is more obvious.The effect of glass fiber on the glass transition temperature,shape memory performance and appearance of GFRSMPU are not significant.The results of experiment and simulation analysis showed that the GFRSMPU with the glass fiber mass fraction of 35% is suitable for the preparation of orthodontic archwire for tooth malocclusion...