选区激光烧结PS/AF复合粉末材料的初步实验研究

为了解决聚苯乙烯(PS)选区激光烧结(SLS)成型件质量较差的问题,使用不同工艺下的芳纶纤维(AF)作为增强改性材料制备了两种PS/AF复合粉末材料;在激光功率30 W,轮廓扫描速度2 200 mm/s等条件下,通过控制变量法分别研究了预热温度、分层厚度及填充扫描速度对两种PS/AF复合粉末材料SLS成型件精度及弯曲强度的影响规律。结果表明,PS/AF复合粉末材料SLS成型件的X、Y向尺寸精度不受工艺参数变化的影响;以聚合球磨AF为填料的PS/AF复合粉末材料成型件整体上的Z向成型精度较好,但其弯曲强度值低于以短切AF为填料的PS/AF复合粉末材料;在试验范围内,得到预热温度、分层厚度及填充扫描速度较优工艺参数范围为85～95℃,0. 20～0. 24 mm和1 400～1 800 mm/s。     

SLS工艺制造的高分子原型材料选择

面向快速铸造工艺的激光选择性烧结（SLS）工艺制造可以制造可烧蚀的高分子快速原型，结合熔模铸造工艺能够实现金属零件的无模快速铸造。选择既适合激光烧结工艺又满足铸造要求的高分子材料是快速铸造工艺的前提。在系统地比较和分析了常用高分子材料的特性．并进行了粉末激光烧结实验后，选择了聚苯乙烯（PS）材料作为快速铸造用SLS原型的粉末原材料。     

尼龙12/OMMT纳米复合粉末的制备及性能

利用十八烷基三甲基溴化铵(OTAB)对蒙脱土(MMT)进行有机改性,并通过溶液插层法制备尼龙12/有机蒙脱土(PA12/OMMT)纳米复合粉末。利用X射线衍射、傅立叶变换红外光谱、扫描电子显微镜等手段对改性后的MMT及PA12/OMMT纳米复合粉末的结构和微观形貌进行表征,并将复合粉末热压成型制成标准件,测试其力学性能和热性能。结果表明,经过有机改性,MMT的层间距由1.24 nm增加到了2.13 nm,且改性后的MMT能均匀地分散在PA12基体中,PA12/OMMT纳米复合粉末的成型件在拉伸强度、弯曲强度、冲击强度和热性能方面都优于纯PA12粉末。PA12/OMMT纳米复合粉末为选择性激光烧结技术(SLS)提供了一种性能良好的粉末材料。     

尼龙12/氧化石墨烯纳米复合粉末的制备及性能

在高分子材料中引入纳米填料制备选择性激光烧结(SLS)复合粉末能够有效增强烧结件的性能。通过改进的Hummers方法辅以超声剥离制备氧化石墨烯(GO),通过溶剂沉淀法制备尼龙12/氧化石墨烯(PA12/GO)纳米复合粉末。利用傅立叶变换红外光谱、透射电子显微镜、X射线衍射、扫描电子显微镜等手段对材料结构进行了表征,并对复合粉末的力学性能和热学性能进行了测试。结果表明,GO能均匀分散在PA12基体中,PA12/GO纳米复合材料的拉伸强度、弯曲强度、弯曲弹性模量、维卡软化温度分别提高了18.9%,8.3%,5.4%,6.8%,热失重曲线显示当温度为450℃时,PA12/GO质量保持率为85.25%,而纯PA12仅为65.17%。PA12/GO纳米复合粉末为选择性激光烧结提供了一种性能良好的粉末材料。     

选择性激光烧结用聚合物粉末材料研究进展

选择性激光烧结(SLS)是一项重要的3D打印技术，目前已广泛应用于各个高新技术领域。本文首先介绍了三种聚合物粉末的制备方法及原理，主要包括机械粉碎法、溶剂沉淀法和相分离法，并分析总结了三种制备方法的优缺点。其次，重点论述了聚合物粉末特性对SLS工艺的影响，如粉末材料的粒径大小、表面形貌以及材料的表面张力。最后，分析总结了SLS工艺参数对烧结制件性能的影响因素。本文的研究内容可为从事聚合物粉末SLS技术的相关生产技术人员和科研人员提供参考借鉴。     

激光选区烧结(SLS)3D打印尼龙材料的专利综述

SLS用尼龙粉末作为非常重要的3D打印高分子材料,现有专利主要采用深冷粉碎法、溶剂沉淀法、合成共聚法三种方法为主衍生的各种制备技术来满足SLS要求的高流动性、低收缩型、低熔点、阻燃、抗静电等性能。综述了SLS用尼龙粉末现有专利涉及到的制备技术以及功能性技术研究。     

工艺参数对PS/改性滑石粉SLS烧结件力学性能的影响

利用硅烷偶联剂KH560对滑石粉进行表面改性,之后将其与聚苯乙烯(PS)粉机械共混,制备PS/改性滑石粉复合粉末。在预热温度85℃和8层网格支撑等条件下,采用选择性激光烧结(SLS)工艺将粉末制备成烧结件。采用扫描电子显微镜观察了滑石粉与PS的界面,发现通过对滑石粉进行表面改性,不仅可以使其均匀地分散于PS粉中,而且两者的相容性也得到了改善。通过正交实验法研究了SLS工艺参数对PS/改性滑石粉烧结件力学性能的影响。利用极差分析法与综合平衡法得到了多指标下的最优工艺参数组合,即单层厚度0.18 mm,扫描间距0.28 mm,激光功率27 W,扫描速度1 200 mm/s,此时PS/改性滑石粉烧结件的拉伸强度为4.29 MPa,弯曲强度为14.4 MPa,冲击强度为4.4 k J/m~2,相比纯PS粉烧结件分别提高了4.9%,10%和56%。     

SLS高分子粉末材料的成型工艺参数及质量的比较研究

介绍了选用PS基3种高分子粉末材料,在AFS-320快速成型机上采用正交试验法研究预热温度、激光功率、分层厚度、扫描速度等工艺参数对可烧结性能和烧结件质量的影响,获得了各材料的优化烧结工艺参数。并测试试样拉伸强度,比较了3种粉体的工艺性能、成型质量、优缺点和用途范围,可为合理选用SLS高分子粉末材料提供参考依据。     

松香改性高分子材料的研究和应用进展

综述了国内外松香改性制备高分子材料的研究现状,分别介绍了松香改性酚醛树脂、聚氨酯、聚丙烯酸、醇酸树脂等高分子材料的制备和应用现状,比较了一步法和两步法制备松香改性酚醛树脂的优缺点,详述了半连续种子乳液聚合法/细乳液聚合法制备松香改性聚丙烯酸酯类高分子材料;对松香综合改性高分子材料的发展趋势进行展望,指出了基于松香双键和羧基综合改性制备色泽浅、软化点高的高分子材料及松香改性其它生物质基类高分子材料的发展潜力,以期促进松香改性高分子材料的制备和应用研究。     

PS/CF复合粉末激光选区烧结工艺研究

为提高聚苯乙烯粉末烧结件的强度,制备了聚苯乙烯/碳纤维(PS/CF)复合粉末,采用正交实验方法研究了不同工艺参数对PS/CF复合粉末SLS烧结件弯曲强度的影响,确定了最优工艺参数。结果表明,复合粉末试样的弯曲强度最高可达7.49 MPa,比纯PS粉提高2.88倍;弯曲强度随扫描速度和层厚的增大而减小,随预热温度的增加而增大;PS/CF复合粉末的最优工艺参数为扫描速度1 800 mm/s,预热温度85℃,层厚0.18 mm。     

选择性激光烧结用聚合物基材料制备研究进展

选择性激光烧结（selective laser sintering, SLS）是一种重要的3D打印加工技术,可制备传统加工无法制备的任意复杂形状的制件,广泛应用于航空航天、国防装备、医疗器械以及汽车等高新技术领域。本文介绍了SLS技术的加工原理和优势,综述了SLS技术加工成形用材料种类及聚合物基粉体材料的制备方法,主要包括相分离法、机械粉碎法、溶液法和喷雾干燥法。重点对SLS技术制备聚合物基压电复合材料及制品的国内外研究现状进行总结。虽然SLS打印制造技术面临聚合物原料种类少、功能缺乏、粉体生产成本高以及难以批量制备等瓶颈问题,但经过不断地创新与发展,SLS打印技术将成为高性能多功能高分子复合材料及其大型复杂制件的极佳制造方法。     

High-performance ceramic parts with complex shape prepared by selective laser sintering: a review

ABSTRACT

Selective laser sintering (SLS) is an additive manufacturing technology which has shown great advantages in direct formation of the polymer, metal and their composites. However, ceramic parts prepared by the SLS still exhibit some fatal defects, including low density and poor mechanical properties. In this respect, recent advances for preparing ceramics have improved the final density and performance by adopting post-processing methods. In this review, three commonly used powder preparation approaches (i.e. mechanical mixing, solvent evaporation and dissolution-precipitation process) and two powder sintering mechanisms for the SLS are introduced. Porous ceramic parts are prepared directly through the SLS by virtue of their high porosity. And dense, high-performance Al₂O₃, ZrO₂, kaolin and SiC ceramic parts with complex shape are prepared by introducing CIP technology into the SLS, indicating that the hybrid technology could be the promising route for preparing high-performance ceramic parts used in various fields.     

Indirect selective laser sintering of epoxy resin-Al2O3 ceramic powders combined with cold isostatic pressing

To fabricate Al₂O₃ ceramic components with complex shape, selective laser sintering (SLS) combined with cold isostatic pressing (CIP) process was used to consolidate Al₂O₃ powder with additive of epoxy resin E06 (ER06) and polyvinyl alcohol (PVA). The starting material preparation combined spray drying with mechanical mixing to formulate compound powder consisting of PVA (1.5 wt%), ER06 (8 wt%) and Al₂O₃ and provide a good fluidity for SLS. Experimental investigations were carried the shrinkage, relative density, bending strength of Al₂O₃-ER06 SLS specimens in order to optimize the laser sintering parameters. It was found that Al₂O₃-ER06 SLS specimens represented acceptable shrinkage, high density and bending strength when laser power, scanning speed, scanning space and layer thickness were, respectively, 21 W, 1600 mm/s, 100 μm and 150 μm. Following that, the SLS specimens were processed through CIP to eliminate the pores in green ceramics. Finally, the optimized SLS/CIP Al₂O₃ specimens were debinded, sintered to produce crack-free Al₂O₃ bodies. The final Al₂O₃ components achieved a relative high density of more than 92% after furnace sintering. The study shows a novel and promising approach to fabricate complex ceramic matrix and ceramic components via indirect SLS and CIP process.     

A novel method to prepare high-resistivity polymer composites

A novel method was developed for the preparation of high-resistivity conductive polymer composites reproducibly. The conventional method which involves the simple mixing of a conductive filler and a polymer usually produces a conductive polymer composite having a loading curve with a region in which the resistivity changes rapidly as the filler concentration changes. Hence, it is very difficult to obtain reproducible materials in that region. This newly developed method involves the preparation of a conventional conductive polymer composite, which is prepared by the simple mixing of carbon black and a polymer as the first step. The resulting compound, which is crosslinked by either electron-beam radiation or a chemical-crosslinking agent, is ground into a fine powder (composite filler) with the particle size less than 250 microns. The composite filler is mixed with another polymer to form a conductive particulate composite which has a loading curve showing a more gradual change of resistivity as a function of filler concentration. The modification of the loading curve is controlled by the resistivity, the shape, and the size of the composite filler.     

Structure and thermal behavior of poly(L‐lactic acid) clay nanocomposites: Effect of preparation method as a function of the nanofiller modification level

The structural and thermal characteristics of poly(L ‐lactic acid)/layered‐silicate hybrid materials that were produced via two different routes, namely by solvent casting and by melt mixing, were compared in association with the degree of clay modification. Investigation of the produced materials' structure revealed that, at low modification levels, melt blending is necessary in dispersing the amine‐treated clay into the polymer matrix. At intermediate degrees of modification, both techniques are capable of swelling the silicate clay with the solution casting to be a more effective method. Thermal measurements showed that the clay modification level influences significantly the thermal stability of both solution and melt processed hybrids. Moreover, the material derived from melt mixing displayed a higher onset decomposition temperature. The glass transition temperature of the polymer was not significantly affected by the preparation method followed. However, the crystallization process was found to be strongly dependent on both the preparation method and the degree of clay modification. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

聚酰亚胺(PI)/无机纳米复合材料的制备、结构与性能

依据国内外聚酰亚胺（PI）／纳米复合材料的最新研究进展，重点阐述PI复合材料的制备、结构、性能及应用，展望了PI复合材料的发展趋势。列举了几种常用纳米粉体的特性，介绍了聚酰亚胺（PI）纳米复合材料的3种制备方法：溶胶一凝胶法、插层复合法、直接分散法，由于纳米粉体在PI材料中的分散性良好，使整个聚合物基体形成新的网络结构，利用纳米粉体改变了PI材料的性能，如力学性能、热学性能、加工流动性等，插层剂的加入对PI纳米复合材料的复合体系有明显改善作用。     

核壳聚合物增韧环氧树脂的研究进展

核壳聚合物(CSP)用来增韧环氧树脂的最大优点,在于提高韧性的同时而不降低材料的玻璃化转变温度(Tg)和加工性能。综述了核壳聚合物增韧环氧树脂的特点,核壳聚合物的制备方法、微观结构及形态,以及增韧环氧树脂及其复合材料的性能及影响因素。     

固体表面改性及其应用：第二讲 表面改性方法和机理

本文主要介绍无机粉体和增强材料的表面改性,也适当介绍高聚物基体的表面改性。文中通过几种典型的和某些有前途的改性方法(如硅烷偶联和等离子体处理等)来说明改性机理。     

含氟水性聚氨酯制备工艺概述及其研究进展

含氟聚氨酯(FPU)材料因氟碳类化合物的低表面能特性而成为一类新型高分子功能材料。氟的引入可大幅度改善涂膜的表面性能,提升涂膜的品质,弥补原有聚氨酯材料在涂膜性能方面的不足。重点阐述了含氟水性聚氨酯的制备工艺,以有机含氟官能团作为含氟改性剂制备含氟水性聚氨酯,概述了近年来国内外在制备含氟水性聚氨酯中所采用的改性方法和主要的表征手段,综合比较了各种制备方法在工艺上的异同之处以及改性产物的优缺点,并对水性聚氨酯氟化研究的广阔前景进行了展望。