Modification Study On Nylon Composite Powder Used In Selective Laser Sintering

Compared with common plastics, nylon can be made into mock-up or function element for new products quickly by selective laser sintering with high wearability and great tenacity, and directly provides tests in product design and performance for the deviser. However, the traditional nylon powder, used in sintering function element directly, always brings about heavy shrinking and bending in the course of sintering, which can not meet the using demand. Therefore, the purpose of the article is to select proper nylon to produce nylon composite powder with high performance through physical and chemical modification, which is suitable for selective laser sintering. The content and result of the article are as follows.The article has studied the selective laser sintering mechanism of nylon power through heating nylon powder and sintering nylon powder by laser, and qualitatively analyzed nylon's fluidity, granularity distributing, granule appearance, thermal performance and soakage, which have effect on precision and quality of technology and product in laser sintering.According to the feature and demand of selective laser sintering, PA 12 has been selected as sintering material and it can be made into test material through adding proper surface active agent, light absorption agent, antistatic agent and mobile agent. But through the test of laser sintering molding, it has been discovered that the sintering part has heavier shrinking and bending, poor dimension precision and lower mechanical performance.Compared with glass fiber, wollastonite, talc and glass bead has been selected as inorganic filler to mix and modify. Then, it will be managed on its surface with silane coupling agent and mixed with PA 12 to produce test material and carry through laser sintering molding test and performance test. It has been discovered that mixing materials can improve shrinking and bending of PA 12 and adding proper glass bead can increase mechanical performance of sintering part of PA 12.PA 12 can be mixed and modified through producing EVALM as consistence and selecting polystyrene as alloy material. The experiment has showed that mixing polystyrene into PA 12 can greatly improve the distortion of shrinking and bending in the course of laser sintering, but the mechanical performance of sintering part is quite poor. However, soaking colophony can improve such disadvantage.Mixed with proper inorganic filler of glass bead, PA 12 can be made into compound material after chemical modification. The experiment has showed that the prepared compound material powder has excellent performance in spreading powder and molding, and the sintering part can be directly used in test and assembly with tensile strength of 45.2 Mpa, flexural strength of 56.5Mpa and elongation of 7% in the condition of optimized technology.