| Polymethyl methacrylate is the most commonly used denture base material in stomatology,and the room curing PMMA has the advantages of easy processing?economical and time saving,and is usually used in the clinical production of denture relining?mandibular inclined guide?individual trays?temporary substrates and orthodontic retainers.However,oral pathogenic bacterias are easy to adhere because of it does not have antibacterial properties,and the surface is rough and porous nature,which is easy to cause denture stomatitis.In addition,compared with the heat curing PMMA,the room curing PMMA has high brittleness and poor toughness,which makes it impossible to fully satisfy all clinical requirements.Therefore,it is of great significance to develop an enhanced room curing PMMA material with antibacterial properties.Previous experimental studies of our research group have showed that the room curing PMMA with 2wt%nano-silver inorganic antibacterial agent RHA-1 has good antibacterial and biocompatibility,but has no significant reinforcing effect on the mechanical properties.This experiment is aimed at improving the mechanical properties and is divided into two parts.In the first part,the nano-silver inorganic antibacterial agent RHA-1 was modified by silane coupling agent KH-570 to investigate the dispersibility of silane coupling agent KH-570 on the nano-silver inorganic antibacterial agent in the room curing PMMA matrix and its effect on the flexural performance of room curing PMMA,determines the optimal amount.In the second part,based on the first part of the experiment,the effects of modified potassium titanate whiskers on the mechanical properties of room curing PMMA with nano-silver base inorganic antibacterial were investigated by adding different amounts of modified potassium titanate whiskers.The influence mechanism was analyzed by scanning electron microscopy.To provide reference data for the study of the enhanced room curing PMMA material with antibacterial and theoretical basis for clinical promotion and application.Nano-silver base inorganic antibacterial agent has high surface energy and strong agglomeration tendency,and its interfacial compatibility with organic matrix has a great influence on the mechanical properties of the composites.In the first part of the experiment,the nano-silver inorganic antibacterial agent RHA-1 was surface modified with silane coupling agent KH-570 to improve the compatibility between the antibacterial agent and the room curing PMMA matrix,so that it can be uniformly dispersed in the matrix and form a good bond.The modification effect was characterized by FTIR then the modified antibacterial agent was ball milled to room curing PMMA powder in a ratio of 2wt%.The flexural strength and modulus of elasticity of the specimens were tested,and the fracture surfaces of specimens were observed by scanning electron microscopy.The results showed:FTIR confirmed that the silane coupling agent KH-570 successfully formed chemical coupling on the surface of the antibacterial agent.When the content of the coupling agent was 2%of the mass fraction of the antibacterial agent,the flexural strength and modulus of elasticity of the PMMA reached the maximum value.The fracture surface scanning electron microscopy showed that the antibacterial agent modified by 2wt%silane coupling agent dispersed well in the PMMA matrix.The nano-silver base inorganic antibacterial agent modified at this concentration were applied to the subsequent experiments.Potassium titanate whiskers have become the most important reinforcement materials in recent years due to their excellent mechanical properties?chemical stability and high cost performance.The properties of the composite material are related to the properties of the matrix itself,the properties of the filler and the processing technology,as well as the content of the filler.The content of the filler is an important factor affecting the mechanical properties of the composite.Low content may not play the role in enhancing filler,high content may affect the dispersion of the filler and the compatibility with the matrix,which is easy to reduce the mechanical properties.In this experiment,the modified potassium titanate whiskers were added to the room curing PMMA with nano-silver base inorganic antibacterial agent according to the mass ratio of 0%?5%?10%?15%and 20%.The flexural strength?modulus of elasticity and Vickers hardness of each specimens were tested,and the fracture surfaces were observed by scanning electron microscopy.The results showed that when the content of potassium titanate whiskers was 10wt%,the flexural properties and Vickers hardness of room curing PMMA composites with nano-silver base inorganic antibacterial agent were significantly improved,SEM showed the whiskers were well dispersed in PMMA matrix.Through the above test results,the following conclusions are drawn from the comprehensive analysis of this experiment:1.The modification effect of silane coupling agent KH-570 on nano-silver inorganic antibacterial agent RHA-1 was determined.2.The amount of silane coupling agent has a significant effect on the flexural strength and modulus of elasticity of room curing PMMA with nano-silver base inorganic antibacterial agent.The flexural strength and elastic modulus of room curing PMMA with nano-silver base inorganic antibacterial agent are the largest when the amount of coupling agent is 2wt%.3.The modified potassium titanate whiskers have an enhanced effect on the flexural properties and hardness of room curing PMMA with nano-silver base inorganic antibacterial agent.4.The addition of modified potassium titanate whiskers have a significant effect on the mechanical properties of room curing PMMA with nano-silver base inorganic antibacterial agent,and the optimum mechanical strength of the composites is achieved when the addition amount is 10wt%with the method used in this experiment. |
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