Mechanical properties of 3D parts fabricated by fused deposition modeling: Effect of various fillers in polylactide

Weak mechanical strength and serious mechanical anisotropy are two key limiting factors for three-dimensional (3D) parts prepared by fused deposition modeling (FDM) in industrial applications. In this work, we investigated the relationships between mechanical properties and surface quality of FDM parts with the properties of materials used. Three kinds of polylactide (PLA) filaments, composed of the same PLA matrix but different fillers (carbon fibers and talc), were used to prepare FDM specimens. Due to the nature of FDM process, FDM parts exhibited tensile properties weaker and more anisotropic than their injection-molding counterparts. The presence of fillers affected the tensile properties of FDM parts, especially the degree of mechanical anisotropy. It is found that the interlayer bond governing the mechanical performance of FDM parts was improved since the fillers added in the polymer materials facilitates the molecular diffusion across the bond interface. Also, the surface quality of FDM parts varied with fillers. Neat PLA parts exhibited surface quality superior to the 3D parts printed with composites filaments. This work is believed to provide highlights on the development of polymer composites filament and improvement of mechanical properties of FDM parts. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47824.     

Inkjet printing of polylactic acid on substrates prepared by fused deposition modeling and its potential for selective surface finishing

Fused deposition modeling (FDM) is an additive manufacturing technology commonly used for prototyping. One limiting aspect for the use in functional prototyping and small‐lot production is the achievable surface roughness. The aim of this work was to investigate a potential method of processing polylactic acid (PLA), as it is commonly used for FDM printing, via inkjet technology. PLA solvent inks with different concentrations were prepared by dissolving PLA in 1,4‐dioxane. The tested PLA substrates were prepared by FDM with different layer thicknesses and the change in surface roughness after multilayer inkjet printing was measured by a stylus profilometer. The surface roughness was reduced by up to 50% and further increasing the number of inkjet layers caused voids and PLA accumulations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43527.     

Effect of IR-laser treatment parameters on surface structure,roughness, wettability and bonding properties of fused deposition modeling-printed PEEK/CF

In this study, laser surface treatment was applied to alter the surface texturing and chemical compositions of fused deposition modeling (FDM)-printed PEEK/CF samples to improve the deficiency of inert surface of PEEK as adherend substrate. The influence of IR-laser parameters including treatment gaps, single pulse energy and pulse widths on surface properties and shear bond strength were discussed. The results indicated that surface roughness was enhanced with decreasing treatment gap or increasing pulse energy, which reached the highest value of Ra = 32.44 μm at 0.4*0.4 mm² treatment gap and 300 mJ single pulse energy. By adjusting laser pulse width, surface wettability changed from hydrophobicity to hydrophilicity. After micro-second laser ablation, the texturing structure was changed and acted as mechanical interlocking effect, and therefore make the shear bond strengths improve from 3.28 to 6.42 MPa compared with the untreated groups. On the other hand, functional groups on substrate surface were activated after nano-second laser ablation, which contributes to an enhancement of shear bond strength through chemical interaction between adhesives and substrates. Therefore, our work highlights an efficient method of laser surface treatment on the adhesion property of FDM-printed substrates.     

Fabrication and characterization of polylactic acid/natural fiber extruded composites

In this work, the fabricated polylactic acid (PLA) and hybrid natural fiber (NF) biocomposites via a melt extrusion method were investigated. NFs from locally grown plants were utilized as fillers. Polyethene glycol (PEG) was used as the plasticizer to improve the processability of the PLA. The effect of PLA/NF biocomposite processing was assessed by mechanical characterization (tensile, modulus, strain at break, and impact tests), and thermal properties (thermogravimetric analysis and differential scanning calorimetry [DSC] analysis). The dynamic mechanical analysis (DMA), and thermo-mechanical analysis (TMA) of the samples were also analyzed. The mechanical properties of PLA/NF biocomposites improved as compared with that of PLA. The DMA findings show that the storage modulus and loss modulus exhibited a slight reduction for PLA/NF biocomposites compared with the PLA sample. In opposite, the glass transition temperature (T_g) from DSC thermogram results showed no obvious changes in values compared with the PLA sample. Furthermore, the findings of TMA showed a significant decrease in coefficient of thermal expansion values of PLA/NF biocomposites compared with those of PLA samples. The overall findings from this work indicated that PLA/NF biocomposites have the potential to make novel biocomposites and suitable for further application especially in biomedical applications due to its good stiffness, tensile strength, and dimensional stability.     

ABS的3D打印制品表面质量研究

采用熔融沉积成型(FDM)三维(3D)打印技术成形丁二烯-丙烯腈-苯乙烯共聚物(ABS)制件,探究喷嘴挤出温度及层高变化对制件表面质量的影响.针对不同的挤出温度、层高等打印工艺参数,制备形状、尺寸一致的多组制件,使用形状测量激光显微镜对制件的表面形貌数据进行了采集并对分析,得出了算术平均高度(Sa)、最大高度(Sz)、...     

用于FDM的PLA共混改性

采用酰胺成核剂(NT–C)和聚乙二醇(PEG2000)对聚乳酸(PLA)进行熔融共混改性,制备了用于3D打印的PLA/NT–C/PEG2000共混物,并在200℃的温度下通过熔融沉积成型(FDM)工艺制备了共混物FDM打印件。研究了NT–C的用量对PLA/NT–C打印件结晶性能的影响,并在此基础上研究了PEG2000用量对共混物流变性能、共混物打印件的结晶性能和力学性能的影响。差示扫描量热分析表明NT–C可在一定程度上提高PLA/NT–C打印件的结晶度,一定用量的PEG2000的添加进一步提高了共混物打印件的结晶性能,当NT–C和PEG2000的质量分数分别为2%和5%时,打印件的结晶度达到17.1%,相比PLA提高了12倍;流变性能测试表明PEG2000提高了共混物的熔体流动速率,降低了共混物储能模量和损耗模量对温度的依赖性,扩宽了PLA在FDM工艺中的成型温度;力学性能测试表明PEG2000显著提高了PLA/NT–C/PEG2000共混物的缺口冲击强度,降低了打印中断丝的几率,FDM打印件弯曲和拉伸强度相比于PLA也有显著提高,当NT–C和PEG2000的质量分数分别为2%和5%时,打印件的弯曲和拉伸强度分别达到了注塑件的80%和70%以上,扩宽了PLA在FDM中应用。     

豌豆淀粉/聚乳酸双层膜的制备与性能表征

采用溶液流延法以豌豆淀粉（PS）和聚乳酸（PLA）为原料制备了豌豆淀粉/聚乳酸（PS/PLA）双层薄膜。通过对双层薄膜的吸水性、溶解性、水蒸气透过性、拉伸性能、表面形貌等进行测试,研究了薄膜的力学性能、疏水性能以及水蒸气阻隔性能。结果表明：随着双层膜中聚乳酸层的比例增加,双层薄膜的吸水性、溶解性和水蒸气透过性逐渐降低,拉伸强度和拉伸模量逐渐增加,断裂伸长率逐渐下降,表明水蒸气阻隔效果明显,增加了膜的韧性,降低了膜的强度。当PLA和PS的质量比为50：50时,PS/PLA双层膜的拉伸强度为（13.47±0.75）MPa,拉伸模量为（0.848±0.002）GPa;断裂伸长率为（16.11±0.16）%,水蒸气透过系数为0.27×10^-10 g·cm/（cm²·s·Pa）。     

Study of processing parameters in fused deposition modeling based on mechanical properties of acrylonitrile‐butadiene‐styrene filament

Four processing parameters, layer thickness, printing speed, raster angle, and building orientation were investigated in terms of their effects on mechanical properties, surface quality, and microstructure of acrylonitrile‐butadiene‐styrene (ABS) samples in fused deposition modeling (FDM) by orthogonal experiments. The results show that both the building orientation and the printing layer thickness have a great influence on the mechanical properties of ABS specimens. When the layer thickness is 0.1 mm, samples printed in horizontal direction have the best mechanical performance. The vertical‐direction‐built parts generally have the worst tensile strength and impact resistance. Moreover, the layer surface quality of the products becomes worse with the increasing of layer thickness and printing speed. The influence of layer thickness on the roughness of FDM samples is still very significant. These researches are of great significance to explore the FDM molding mechanism and optimize processing parameters to meet the performance demands. POLYM. ENG. SCI., 59:120–128, 2019. © 2018 Society of Plastics Engineers     

PBS/PLA/滑石粉3D打印线材制备及熔融沉积成型工艺研究

以聚丁二酸丁二醇酯(PBS)为基体,滑石粉和聚乳酸(PLA)为改性剂,采用熔融挤出法制备了PBS/PLA/滑石粉三维 （3D）打印线材,并对其进行了熔融成型研究。通过分析结晶性能、流变性能、力学性能、断面形貌和打印效果对PBS/PLA/滑石粉体系进行了探究。结果表明,PLA的加入使PBS的结晶温度下降了5 ℃;随着PLA含量的增加,材料的复数黏度、储能模量和损耗模量均得到提高;而拉伸强度则随PLA含量的增加下降了1.71 MPa,缺口冲击强度下降了2.63 kJ/m2;PLA含量的增加使断面逐渐粗糙;在打印效果上复合材料的打印模型随PLA含量的增加而变得美观规整,当底板温度高于110 ℃时,打印制件的翘曲度较低,同时拉伸强度随着打印温度的升高而增加。     

Development of fish scale particle reinforced PLA filaments for 3D printing applications

This study investigated incorporating fish scale powder (FSP) as a bio-filler into polylactic acid (PLA) raw material for polymeric 3D printing. The PLA/FSP filaments were evaluated for various properties (tensile strength, tensile modulus, elongation, diameter deviation, thermogravimetric analysis, surface roughness, and SEM analysis) at different compositions (PLA, PLA/FSP10, PLA/FSP20, and PLA/FSP30 wt%). The results revealed that PLA filaments reinforced with 20 wt% FSP achieved the highest tensile strength, and modulus is 44.49 MPa and 2.83 GPa. The filaments reinforced with neat PLA and PLA with 10 wt% fish scale powder exhibited minor diameter deviations of +0.002 and −0.002. The surface roughness of the neat PLA filament is notably higher, registering a value of 1.459 μm. This finding highlights the importance of considering surface characteristics in filament selection for 3D printing applications. The microscopic analysis confirmed a uniform distribution of FSP particles in the 20 wt% composition PLA/FSP filaments. These results suggest that PLA/FSP (20 wt%) is an optimal feedstock for 3D printing, especially in developing biomaterials like bio-scaffolds.     

基于田口试验法的熔融沉积成型PLA制品工艺优化

为了提高熔融沉积成型(FDM)制品的质量,采用田口试验法研究填充密度、沉积方向和填充图案三个因素对聚乳酸(PLA)制品拉伸性能的影响。结果表明,加工工艺参数对拉伸弹性模量和拉伸强度的影响程度均为沉积方向>填充密度>填充图案,其中拉伸弹性模量最优化的参数组合为填充密度100%、沉积方向45°、填充图案网格形状,拉伸强度最优化的参数组合为填充密度70%、沉积方向45°、填充图案网格形状。通过扫描电子显微镜对拉伸试验失效断面进行观察分析,探究了FDM打印工艺参数之沉积方向、填充密度对PLA试样拉伸失效的影响及其失效机理,其表征分析与试验结果高度吻合,表明该研究结果具有较好的借鉴意义。     

Thermal and mechanical properties of polyamide 12/graphene nanoplatelets nanocomposites and parts fabricated by fused deposition modeling

The printable polyamide 12 (PA12) nanocomposite filaments with 6 wt % graphene nanoplatelets (GNPs) for fused deposition modeling (FDM) were prepared by melting compounding and smoothly printed via a commercial FDM three‐dimensional (3D) printer. The thermal conductivity (λ) and elastic modulus (E) of 3D printed PA12/GNPs parts along to the printing direction had an increase by 51.4% and 7% than that of compression molded parts, which is due to the GNPs preferentially aligning along to the printing direction. Along with these improved properties, ultimate tensile strength of 3D printed PA12/GNPs parts was well maintained. These results indicate that FDM is a new way to achieve PA12/GNPs parts with enhanced λ over compression moulding, which could contribute to realize efficient and flexible heat management for a wide range of applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45332.     

Toughening polylactide with epoxidized styrene–butadiene impact resin: Mechanical,morphological, and rheological characterization

Styrene–butadiene impact resin (SBC) was chosen as the toughening agent to improve the tensile toughness of polylactide (PLA). Epoxidized SBC (ESBC) with different epoxidation degree were prepared by epoxidation using in situ peroxoformic acid method and a series of PLA/SBC(ESBC) blends were prepared by melt blending. The elongation at break of the PLA/ESBC blends was greatly improved, which was reflected in the slight decrease in the tensile strength and tensile modulus. Moreover, the tensile strength and tensile modulus were not significantly affected by the epoxidation degree of ESBC. For example, the incorporation of ESBC28.8% (30 wt %) to PLA caused an obvious increment of elongation at break from 3.5% of pure PLA to 305.0%, while the tensile modulus and tensile strength decreased to 80 and 78% of pure PLA, respectively. Scanning electron microscopy observations of cryo‐fractured surface morphology and particle size analysis demonstrated that the compatibility of the PLA/ESBC blends was improved significantly compared to PLA/SBC blend. PLA/ESBC(70/30) blends exhibited shear‐thinning behavior over the range of the studied shear rate. With an increase in shear rate, the non‐Newtonian index of the blends decreased gradually. Furthermore, the flow behavior of PLA/ESBC(70/30) blends was more sensitive to the shear rate than pure PLA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46058.     

Novel polylactide/vermiculite nanocomposites by in situ intercalative polymerization. I. Preparation,characterization, and properties

Polylactide (PLA)/vermiculite nanocomposites were prepared by in situ intercalative polymerization of L,L ‐lactide (LLA) in the presence of organomodified vermiculite (VMT). The d‐spacings of both the organomodified VMT and the exfoliated nanocomposites were investigated by X‐ray diffraction (XRD) analysis, and the morphology of exfoliated nanocomposites was examined by transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) indicated that there is some enhancement in degradation behavior between the nanocomposites and the PLA matrix. Dynamic mechanical analysis (DMA) confirmed the constraint effect of exfoliated VMT layers on PLA chains, which is beneficial to the increased storage and loss modulus and increased glass transition temperature. The tensile strength showed that the exfoliated nanocomposites are reinforced and toughened by the addition of nanometer‐size vermiculite layers. POLYM. COMPOS., 28:545–550, 2007. © 2007 Society of Plastics Engineers     

陶瓷材料加工表面完整性及其对材料可靠性的影响

采用磨削-抛光加工、金刚石锯片切割加工、超声波加工和电火花线切割加工技术对Al2O3/TiC陶瓷材料进行加工.研究了各加工方法对陶瓷材料的加工表面完整性及其可靠性的影响.结果表明:加工方法对陶瓷材料加工表面完整性和可靠性有很大的影响.磨削-抛光加工的陶瓷试样表面粗糙度小,硬度高,抗弯强度及其可靠性最高.金刚石锯片切割加工和超声波加工次之;电火花加工陶瓷试样表面粗糙大,硬度低,抗弯强度及其可靠性最低.电火花加工陶瓷表面产生一硬度低且表面粗糙的约8μm厚的热影响层,加工表面含有大量的电火花腐蚀凹坑,随电流的增大,电火花加工陶瓷试样的抗弯强度及其可靠性降低.超声波加工陶瓷试样的表面完整性与磨料粒度有关,随磨料粒度的减小,陶瓷试样的抗弯强度及其可靠性增加.     

抗氧剂1010对3D打印用聚乳酸氧化降解性能的影响

为研究抗氧剂1010(KY1010)对3D打印用聚乳酸(PLA)氧化降解性能的影响,以PLA和KY1010为原料,通过挤出成型工艺制得3D打印用PLA丝材,并采用FDM工艺制备复合材料,研究KY1010添加量对PLA丝材拉伸性能、动态热机械性能、氧化诱导期以及复合材料力学性能的影响.结果表明,KY1010可有效改善PL...     

3D-printed polymer packing structures: Uniformity of morphology and mechanical properties via microprocessing conditions

Three-dimensional (3D) printing is an attractive approach to fabricate highly porous extremely lightweight structures for architecture antivibrational packaging. We report 3D printing processing of model packaging structures using biodegradable poly(lactic acid) (PLA) as a source material, with acrylonitrile butadiene styrene (ABS) utilized as a common 3D printing source material as a traditional benchmarked material. The effects of printing temperature, speed, and layer morphology on the layer-by-layer 3D-printed structures and their mechanical properties were considered. Three different characteristic morphologies were identified based on printing temperature; the microscopic surface roughness was dependent on the printing speed and layer height. We demonstrate that the mechanical performances and surface properties of 3D-printed PLA structures could be improved by optimization of printing conditions. Specifically, we evaluate that these PLA-based 3D structures printed exhibited better surface qualities and enhanced mechanical performance than traditional ABS-based structures. Results showed that the PLA-based 3D structures possessed the favorable mechanical performance with 34% higher Young's modulus and 23% higher tensile strength in comparison to the ABS-based 3D structures. This study provides guidelines for achieving high-quality 3D-printed lightweight structures, including smooth surfaces and durable mechanical properties, and serves as a framework to create biodegradable 3D-printed parts for human use.     

Preparation of poly(lactic acid) and pectin composite films intended for applications in antimicrobial packaging

A pectin and poly(lactic acid) (PLA) composite was compounded by extrusion. A model antimicrobial polypeptide, nisin, was loaded into the composite by diffusion. The incorporation of pectin into PLA resulted in a heterogeneous biphasic structure, as revealed by scanning electronic microscopy, confocal laser microscopy, and fracture–acoustic emission. The incorporation of pectin also created a rough and cragged surface, which was hydrophilic and facilitated the access and absorption of nisin. The nisin‐loaded composite suppressed Lactobacillus plantarum growth, as indicated by agar diffusion and liquid‐phase culture tests. The incorporation of pectin at the concentration of ～ 20% of the total mass did not alter the Young's modulus of the film from that of the pure PLA. The composite materials were able to retain their tensile strength, flexibility, and toughness to an extent that satisfied the requirements for packaging materials. Results from this research indicate the potential of pectin/PLA composites for applications in antimicrobial packaging. © 2007 Wiley Periodicals, Inc.? J Appl Polym Sci 2007     

Effect of polishing method on surface roughness and bacterial adhesion of zirconia-porcelain veneer

The purpose of this study was to evaluate the effect of various polishing methods on surface roughness of zirconia-porcelain veneer and to correlate the findings with early bacterial adhesion. The study specimens were glazed (control group), glazed after fine polishing (glazed group) and polished with Exa Cerapol (Cerapol group) or with Shofu porcelain adjustment kit (Shofu group) (n =20). Surface roughness was then measured using profilometer and scanning electron microscope (SEM). After artificial saliva coating, the specimens were incubated in Streptococcus mitis suspension for 4 h at 37 °C. Adherent bacteria were quantified from SEM images. Streptococcal viability was assessed by LIVE/DEAD staining kit and fluorescent microscope. There were significant differences in surface roughness according to polishing method and surface material. Relatively smoother surfaces were found in zirconia surfaces and glazed porcelain surfaces. There were also significant differences in bacterial adhesion according to polishing method and surface material. Cerapol group showed minimal bacterial adhesion with more dead cells when compared to other groups. A positive correlation between surface roughness and bacterial adhesion was found in glazed porcelain surface and a negative correlation in zirconia surface of Cerapol group, both with no statistical significance. Within the limitations of in vitro study, surface roughness and bacteria adhesion were significantly influenced by polishing method and surface material. Also, there was a positive correlation and negative correlation between surface roughness and bacterial adhesion in glazed porcelain surface and in zirconia surface of Cerapol group, respectively.     

Anisotropy of poly(lactic acid)/carbon fiber composites prepared by fused deposition modeling

It is well known that 3D printed parts prepared by fused deposition modeling (FDM) exhibit large anisotropy of mechanical properties. In this article, poly(lactic acid; PLA)/carbon fiber (CF) composites with different built orientations (X, Y, Z) were prepared by FDM. The effects of printing temperature, speed, orientations, and layer thickness on the mechanical properties of the composites were systematically investigated. The mechanical properties of PLA/CF composites show more significant anisotropy. The orientation of the fibers along the printing direction is displayed by scanning electron microscopy. Printing parameters bring almost no effect on mechanical properties of the X-construct oriented specimen, and bring obvious effect on those of the Y-construct oriented specimen and Z-construct oriented specimen. According to the analysis, carbon fiber can amplify this anisotropy from layer fashion, and the key factors from printing parameters are porosity and bond strength between fuses. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48786.