Synthesis Of Nylon 12 Composite Powder For Selective Laser Sintering And Pilot Scale Production

Selective Laser Sintering which rely on laser as heat source is a rapid prototyping technology,the technology has a very broad application prospects.Polymer Materials is the most widely used in SLS technology,wherein the semi-crystalline polyamide 12 composite powder material and its superior performance,has become one of the largest demand for SLS powders.Currently,the required of PA12 in domestic market mainly rely on imports.Therefore,this study aims to develop a high performance as SLS PA12 powder,and through the study of the pilot scale production to chieve industrial production.In this paper,we studied formula composition,preparation and sintering properties of PA12 powder and coposite powder which ia used in SLS,and provides a feasible production equipment for pilot scale production.Choose the solvent precipitation method preparation the PA12 powder,study on the process and formulation,analyzes and contrasts the properties of PA12 powder by varying the reaction temperature,holding time,crystallization temperature,stirring speed and other process conditions,and change the type and amount of aid.Electron microscopy were used to characterize the shape and size of PA12 powder,and using laser particle size analyzer to analyze the particle size of the powder.The thermal degradation kinetics and thermal oxidation resistance PA12 by measuring the whiteness of the powder,TG curve method,the effects of antioxidants on the amount and ratio of PA12 aging properties was discussed,and determine the optimum use of antioxidants.The conclusionis that the most appropriate solution temperature for PA12 particles is 145-147?,within the temperature,the range of the powder particle size is small,the color of the powder is white;PA12 powders into nucleation temperature control in 120-125? of the powder particle size distribution is the best,white carbon black as a adding nucleating agent of PA12 powders greatly affects the growth.Addition of antioxidants can improve the thermal oxidative stability of PA12 powder,the main antioxidant 1098,antioxidant 168 supplemented by,when the main and secondary antioxidant content is 0.5% and the proportion is 2:1,the best effect;PA12/GF composite powder was prepared by the method of solvent precipitation.In the three PA12 / GF composite powders,the content of glass fiber was 30 wt.%,40 wt.%,50 wt.%.The micro morphology of composite powder was observed by microscope,the particle size distribution of composite powder were measured,and the thermal properties of the composite powders were analyzed.The results show that the size distribution of the composite powders with different glass fiber content is different,when the glass fiber content is 40%,the size of the composite powder is mainly distributed in the vicinity of 50 ?m,which is more favorable to the process of selective laser sintering process.Powder morphology presented by nylon-coated glass fiber and nylon particles together form.Compared with pure PA12 powder,the melting temperature of composite powder gradually decreases with increasing glass fiber content.The mechanical properties of the composite powder were determined by the moulding of the composite powder,the tensile properties of the composite powders increased with the increase of the glass fiber content,and the impact strength decreased with the increase of the glass fiber content.This study on the basis of small scale experiment,has carried on the preliminary test study to complete the installation of 10 L and 200 L reactor production process design and equipment.Study on the pilot scale production's conditions of the reactor,The difference analysis of morphology,test products and products were compared in small particle size distribution,thermodynamic properties.The pilot application of PA12 powder production in SLS,mechanical properties of the sintering process and sintered PA12 powder,and the test results and the imported PA12 powder were compared.Conclusion: In the process of test,the PA12 powder with high spherical degree,the size of the particle size and the suitable of distribution,SLS powder was prepared by optimizing the process conditions,the SLS process parameters set the preheating temperature of 160?,laser power by 20%,scanning rate 4000 mm / s,and printing temperature is 167?,the size of the sintered parts appearance quality,forming high precision and good mechanical performance.