PET/纳米蒙脱土复合材料的制备及连续挤出发泡

采用熔融共混法制备了聚对苯二甲酸乙二醇酯(PET)/纳米蒙脱土(OMMT)复合材料.研究了不同用量的OMMT对复合材料性能的影响.对熔融插层效果和PET/OMMT复合材料的热性能和流变性能进行了表征,并研究了复合材料的挤出发泡行为.结果表明:熔融共混后,OMMT的层间距得到有效提高,形成了“插层结构”;OMMT的加入可以有效提高PET的结晶速率,但对其熔融行为的影响并不显著;OMMT的加入能够可以提高PET的熔体弹性,同时在挤出发泡过程中具有气泡成核剂的作用,从而可以增强对PET挤出发泡的有效控制.     

聚乳酸/纳米蒙脱土纳米复合材料的制备与挤出发泡研究

采用熔融插层法制备了聚乳酸/有机改性纳米蒙脱土（PLA/OMMT）复合材料,对其复合结构、力学性能、热性能、动态流变性能进行了测试和表征,并研究了复合材料的挤出发泡行为。结果表明,不同含量的OMMT与PLA进行熔融插层会形成不同的插层与剥离结构;3 %的OMMT可以提高PLA的力学性能、改善热性能;OMMT能够提升PLA的熔体强度,同时在挤出发泡过程中起到成核剂的作用,并且能够减弱发泡剂气体向PLA熔体外部的扩散,从而提高PLA挤出发泡的效果。     

反应挤出制备高熔体强度PP

采用反应挤出方法制备高熔体强度聚丙烯,通过凝胶渗透色谱仪、差示扫描量热仪、偏光显微镜等研究了改性产品的结构与性能,并进行挤出发泡应用实验。结果表明：采用特殊的过氧化物引发剂和支化促进剂,与聚丙烯基础树脂共混后通过双螺杆挤出机熔融连续反应挤出,可以直接制备具有长链支化结构的聚丙烯,熔体强度提高300％;挤出发泡试样泡孔均匀,发泡倍率达到50倍,具有较好的可发性能。     

PP/HMS-PP/Nano-OMMT复合材料挤出发泡的研究

利用线性聚丙烯(PP)和有机化处理的纳米蒙脱土(nano-OMMT)在双螺杆挤出机上熔融插层法制备了PP/nano-OMMT复合材料。通过在PP/nano-OMMT复合材料中加入少量的高熔体强度聚丙烯(HMS-PP)以及复合发泡剂,通过连续挤出制备了PP/HMS-PP/nano-OMMT发泡棒材。利用扫描电镜观察了不同HMS-PP和不同的OMMT含量对发泡棒材发泡行为的影响,并利用透射电镜观察了OMMT在发泡制品中的分散及分布状况。结果表明:适量加入HMS-PP可以改善复合材料的发泡性能,所得发泡制品的泡孔密度增大,泡孔的合并现象明显改善;nano-OMMT在靠近泡孔壁面的位置有取向分布的趋势,这有利于得到闭孔形式的泡孔结构。     

开孔型聚合物微发泡材料研究进展

通过回顾目前几种微孔材料成型的主要方法,介绍了微发泡成型技术用于制备开孔型微孔材料的必要性。讨论了关于开孔型聚合物微发泡材料制备技术及研究方法的几种思路,分别是不相容聚合物共混、泡孔合并模型、熔融挤出发泡、开孔剂法和气体浓度阈(值)等方法,这些方法的微孔成型机理各不相同,所制备的材料微观结构也各有特点。文献分析表明:微发泡成型方法用于开孔型微孔材料的制备是一种非常有前景的技术。     

微孔发泡聚碳酸酯片材的制备与性能研究

在聚碳酸酯(PC)的玻璃化温度(tg)和熔融温度(tm)之间，采用模压法制备出用挤出、注射和常规发泡难以加工成型的薄型微孔发泡PC片材。模压法有制备周期短、工艺简单、操作容易、价格低廉等优点。通过热性能及力学性能测试．表明用模压法制备的微孔发泡PC片材性能优异。     

微孔注塑发泡制备聚乳酸-天然橡胶多孔材料方法及材料

正本发明属于微孔注塑发泡技术领域,公开了一种微孔注塑发泡制备聚乳酸天然橡胶多孔材料方法及材料,通过乳液聚合制备接枝物;将干燥的聚乳酸粒料与甲基丙烯酸缩水甘油酯天然橡胶接枝物按比例混合,采用双螺杆挤出机熔融共混,挤出造粒;将共混物粒料采用配备有气体压缩单元的注塑机进行微孔注塑发     

多层包覆核壳结构的石头纸功能性母粒及制备

石头纸是以无机粉体为主要原材料,经与树脂载体混炼熔融、挤压及薄膜化处理而成的,具有抗拉力强、耐水性好和耐腐蚀等优异特性和环保特性的新型复合材料。传统的表面改性技术无法实现无机填料与有机载体树脂的均匀共混,通过填料层、载体层、偶联层、分散层、增容层、特殊功能层进行核-壳多层包覆结构设计和制备,解决了高填充无机粉体团聚、界面相容性和加工流动性差等技术难题。     

AC/LDHs插层复合材料的制备及其在挤出发泡成型中的应用

以苯甲酸插层改性LDHs纳米粉体为交换前体,采用插层置换的方法,制备出一种AC/LDHs新型纳米复合发泡材料.采用XRD、TG-DTA等手段对新材料进行了表征.结果表明pH值是影响插层效果的一个关键因素,且pH=4时,插层效果最好.利用pH=4条件下制备的新型插层复合材料在适当条件下进行挤出发泡成型,可以得到孔径为20～40μm左右的泡孔分布均匀的发泡制品.     

发泡特性优异的挤出成型用PP

据“プラスチックスエ -ジ ,2 0 0 0 ,4 6 ( 1) :83”报道 ,日本グランド·ポリマ -公司开发成功一种发泡特性极好的挤出成型用PP—V -PP。该制品是采用该公司的催化剂技术和聚合工艺技术控制分子结构的超高结晶性材料。该材料的主要特点有 :( 1)高熔融张力。比原PP的熔融张力高 2倍以上 ,发泡片材成型时的气体保持率高 ,可以形成细密的泡孔 ,成型原PP不可能得到的高发泡倍率、表面外观良好的发泡片材。另外 ,该发泡片材的真空成型性好 ,加热时的收缩性及深拉性等性能接近PS树脂。 ( 2 )高刚性及高耐热性。与原PP相比 ,刚性及耐热性有…     

非溶剂致相分离3D打印聚合物的成型工艺研究

采用自行搭建的湿度可控的气辅式三维（3D）打印机,基于非溶剂致相分离原理,实现了常温下、高精度、低成本3D打印耐高温的聚合物材料。以聚醚酰亚胺（PEI）为例,探究了挤出压力、喷头直径、打印速度、打印环境相对湿度、打印层高等打印参数对成型质量的影响。结果表明,挤出丝料的宽度与打印速度、环境相对湿度有关,随打印速度和环境相对湿度的增大而减小;打印层高与挤出丝料的厚度有关,打印层高约等于挤出丝料的厚度的时,成型质量最好;通过多层沉积实验,得到最优的打印参数,成型了表面质量良好、精度高的PEI坯体。     

Potentials with small‐angle neutron scattering technique for understanding structure–property relation of 3D‐printed materials

Carbon fiber (CF)‐embedded acrylonitrile butadiene styrene polymer composites printed on the large‐scale printer at Oak Ridge National Laboratory were investigated by small‐angle neutron scattering to correlate the microstructure of the composites with their mechanical strength. The microstructure of the polymer domains and the alignment of CF were characterized across the interfaces between layers of the hot‐melt extruded material and were compared with CF‐free ABS. The small‐angle neutron scattering data show that the CF‐containing material displays strong anisotropic scatterings suggesting molecular alignment along the printing direction that is not present in the CF‐free ABS. Scattering data analysis across the interfacial layer revealed enhanced molecular alignment along the printing direction near the boundaries and inhomogeneous size distribution of polymer domains upon the addition of CF. We attribute the compromised strength across interfacial layers from CF‐containing material to this inhomogeneous size distribution which prevents effective lateral interaction between layers. POLYM. ENG. SCI., 59:E65–E70, 2019. © 2018 Society of Plastics Engineers     

Fabricating ceramics with embedded microchannels using an integrated additive manufacturing and laser machining method

In this paper, we demonstrate the feasibility of an innovative method to fabricate flexibly embedded microchannels in bulk ceramics of complex geometries. This innovative method is an integration of extrusion freeforming (EFF) and picosecond (PS) laser machining. The bulk ceramic green body of complex geometries was fabricated using the extrusion method. After one green layer was extruded, in-plane microchannels with variable cross-section sizes and aspect ratios were fabricated using a picosecond laser. After the microchannels were fabricated, a cover layer was extruded. The green state processed structures ceramics were pressurelessly sintered to a bulk density of ~94%. In this paper, sinuous channels, channel networks, and patterns have been demonstrated. Vertical channels can also be drilled using the picosecond laser layer-by-layer with uniform diameters. The wall between the neighboring channels can be as thin as ~60 μm without any observable defects after firing. With the correct paste rheology, the cover layer did not sag into the microchannels and the bonding between layers was excellent. We did not observe any debonding between layers. During extrusion, the gaps between the adjacent filaments can be eliminated by controlling the filament spacing and the distance between needle tip and substrate. After firing, microchannels did not distort or collapse. The laser can cut through multiple layers without damage to the bonding between layers. Due to the uniform shrinkage during pressureless sintering, the green shapes of the microchannels were well preserved.     

First printing of continuous fibers into ceramics

This article reports a novel method for three-dimensional (3D) printing of continuous fibers into ceramics to improve the mechanical properties of printed ceramics, which is difficult in other 3D printing technologies. The ceramics were derived by pyrolysis of thermoplastic ceramic precursor feedstocks, which were prepared by two methods. One is homogeneously mixing thermoplastic resins and ceramic precursors. The feedstocks prepared by this method exhibit good thermoplastic properties and can be extruded into filaments. Ceramics were obtained by heating the feedstocks to 1100°C in argon atmosphere. The ceramics were amorphous and remained stable during 1100-1300°C; at 1400°C they decomposed into β–SiC with simultaneous volatile gas generation. Above 1400°C, their quality decreased significantly due to cracking of ceramic skeletons. The other method is directly heating, extruding and printing the ceramic precursor. The precursors showed good printability and complex ceramic structures were printed with continuous carbon fibers inside. The continuous carbon fibers improved the flexural strength of pyrolytic ceramics, which is about 7.6 times better than that of the ceramics without fibers. The novel method unravels the potential of 3D printing of continuous fibers into ceramics with complex lightweight structures to improve the strength.     

Mechanical behaviour of multi-layer half-cells of microtubular solid oxide fuel cells fabricated by the co-extrusion process

Multi-layer micro-tubes consisting of four anode layers of NiO and YSZ mixture, and an electrolyte layer, YSZ, were fabricated by co-extrusion. The die designed in this study is able to extrude 5 layers around a sacrificial core, which eliminates the difficulties from the use of mandrel in processing tubes. Scanning electron microscopy (SEM) results revealed that this technique can be used for the successful fabrication of multi-layer microtubes with good bonding between the layers. 3-point bending was used to evaluate the mechanical properties of these co-extruded multi-layer samples. Moreover, thermal shock resistance of the tubes was investigated by water quenching from an elevated temperature. The results were compared with those obtained for conventionally extruded single layer samples. The co-extruded samples were found to have the highest average strength and also the highest weibull modulus and reliability. It was also found that multi-layer anode can significantly improve thermal shock resistance.     

A Novel Polymeric Substrate with Dual-Porous Structures for High-Performance Inkjet-Printed Flexible Electronic Devices

Inkjet printing has emerged as a promising low-cost and high-performance method for manufacturing printing-based devices. However, the development of optimized substrates for inkjet printing using novel materials is limited. In this study, a novel polymeric substrate optimized for flexible electronic devices is fabricated using thin-film processing and phase inversion of polyethersulfone (PES). The PES film consists of two layers of pores; the upper layer has nano-sized pores that filter the nanoparticles in the conductive ink and allow for high-density aggregation on the substrate, while the lower layer contains micro-scale pores that quickly absorb and drain the ink solvent. The two porous structures lead to higher conductivity and high-resolution printed patterns by minimizing solvent lateral diffusion. Additionally, the PES printing substrate can undergo high-temperature curing of metal nanoparticles, enabling high-resolution pattern printing with low resistance. The PES substrate is highly transparent and flexible, allowing for the fabrication of various printed electronic patterns and the production of high-performance flexible electronic devices.     

Optimization of 3D printing parameters for high-performance biodegradable materials

Developing 3D printing high-performance biodegradable materials is important to protect the environment and deal with emergencies such as COVID-19. Fused deposition modeling (FDM), one of the 3D printing methods, has many advantages, such as low cost and wide range of materials. However, the weak interlayer adhesion is an important factor restricting the development of FDM. In addition to the influence of material properties, the optimization of 3D printing parameters is also an important means to give full play to the inherent properties of materials. The optimal 3D printing parameters are conducive to the diffusion and entanglement of molecular chains between adjacent layers. PLA/PBAT/PLA-g-GMA (70/30/10 wt%, PLA-g-GMA was a compatibilizer synthesized in our lab) was used as the research object. This work aims to analyze the mechanical properties response of biodegradable polymers products manufactured through FDM. Herein, the effect of 3D printing parameters including layer thickness, nozzle temperature, printing speed and platform temperature have been systematically investigated by orthogonal experimental design. The result showed that the excellent performance of 3D printing specimen was obtained when the layer thickness was 0.15 mm, the printing speed was 50 mm·s⁻¹, the nozzle temperature was 200°C and the platform temperature was 50°C. The SEM images showed that the optimal 3D printing products had the best interlayer adhesion and the lowest porosity. Undergoing optimization of 3D printing processing, the yield strength and elongation at break of specimen increased by 115% and 229%, respectively. In this paper, the interlayer adhesion and mechanical properties of 3D printing products can be significantly improved by simply optimizing the 3D printing parameters without complex material modification. This work provided a new method for improving the interlayer adhesion of FDM and the mechanical properties of FDM products.     

挤出机头内流场对玻纤取向和分布的影响

本文分析了平直和发散两种挤出机头内的流场,推得发散流道内熔体周向拉伸应变速率的表达式;研究了两种挤出流率下由这两种机头挤出的制品壁内玻纤的取向和分布,并通过流道内的剪切和周向拉伸应变速率,对玻纤取向和分布的形成机理进行解释。结果表明：经平直机头挤出的制品内,玻纤在剪切作用下基本沿流动方向排列。发散机头内熔体受剪切和周向拉伸的共同作用,使制品壁厚方向形成了“表层-次表层-芯层-次表层-表层”的五层结构,并首次发现芯层呈“W”形排列。玻纤的排列不仅受流动过程中的应变影响,更取决于应变速率的大小。     

Cocoa Shell Waste Biofilaments for 3D Printing Applications

In this study, biofilaments based on cocoa shell waste, a by‐product of the chocolate industry, and biodegradable poly(ε‐caprolactone), PCL, have been prepared using a single‐screw extruder. Micronized cocoa shell waste is compounded in the polymer up to 50% by weight without significant alteration of its crystalline structure. Resultant elastic (Young's) modulus of biofilaments remains close to that of pure PCL. Scanning electron microscopy results indicate that micronized cocoa shell waste is homogeneously dispersed in the polymer during the extrusion process. Detailed thermal characterization measurements on the extruded filaments allow tuning of the fused deposition modeling 3D printing parameters. 3D printed items display a well‐defined structure with good adhesion between deposition layers and fine resolution. Hence, with this simple and solvent‐free fabrication technique, uniformly structured cocoa shell waste biofilaments can be produced in a very reproducible manner and can be used in 3D printing of diverse objects with potential household and biomedical applications.     

直接涂膜技术用于质子交换膜燃料电池膜电极制备(Ⅱ)

研究了直接涂膜过程中,催化剂液组成对电池性能的影响.异丙醇在催化剂墨水中起到溶剂和造孔剂的作用,当催化剂墨水中催化剂、异丙醇的质量比为1∶10时电池性能最好.Nafion是催化剂层中良好的黏结剂和质子传导载体.由于直接涂膜,使Nafion液与Nafion膜直接接触,从而增加了质子传导性.实验结果表明,最佳的Nafion含量（干基）为NFP=33%.通过对不同金属含量的Pt/C催化剂的研究发现,金属含量不同,异丙醇和Nafion的最优含量亦随之改变.考察了催化剂层不同制备工艺对电池性能的影响,表明催化剂层数越多电池性能越好,但是差异并不是很大.