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Most of the experiments on additively manufactured polymers are on a small scale, and it remains uncertain whether findings at a small scale can be extrapolated to their larger-scale counterparts. This uncertainty mainly arises due to the limited studies on the effect of size on three-dimensional (3D)-printed polymers, among many others. Given this background, this preliminary study aims to investigate the effect of geometric dimensions (i.e., the size effect) on the mechanical performance of four representative types of 3D-printable polymers, namely, (1) polycarbonate acrylonitrile butadiene styrene (PC/ABS), (2) acrylonitrile-styrene-acrylate (ASA), (3) polylactic acid (PLA) as a bio biodegradable and sustainable material, and (4) polyamide (PA, nylon), based on compression, modulus of elasticity, tension, and flexural tests. Eight different sizes were investigated for compression, modulus of elasticity, and tension tests, while seven different sizes were tested under flexure as per relevant test standards. A material extrusion technique was used to 3D-print the polymers in a flat build orientation and at an infill orientation angle of 45°. The results have shown that the mechanical properties of the 3D-printed polymers were size-dependent, regardless of the material type, with the most significant being flexure, followed by tension, compression, and modulus of elasticity; however, no clear general trend could be identified in this regard. All the materials except for nylon showed a brittle failure pattern, characterized by interfacial failure rather than filament failure. PLA outperformed the other three polymer specimens in terms of strength, irrespective of the type of loading. [ABSTRACT FROM AUTHOR]

Additive manufacturing technology has been developed in the manufacturing industry; however, limited choice of materials and low printing speeds in large-scale production make 3D printing challenging in the industry. Wood and cellulose-based materials have recently drawn a lot of attention for use as 3D printing materials due to their unique properties such as environmental friendliness, cost-effectiveness and abundancy. However, because these compounds are derived from various natural sources, their different particle sizes can result in low 3D printing quality. The objective of this study is to resolve the mentioned deficiencies in the packaging industry by designing a novel 3D printer nozzle based on the material extrusion method (FDM technique), which provides higher printing speed and enhanced quality for wood and cellulose-based materials. The packaging industry can significantly benefit from 3D printing technology for cellulose-based materials by producing high-quality recyclable economical packaging on a large scale according to the clients’ demand. The proposed nozzle design enables selecting different geometrical cross-sections of the nozzle dies and any number of extrusion points along the nozzle die simultaneously during the 3D printing process. These capabilities lead to advanced performance and improved speed of 3D printing in large scale manufacturing. The proposed nozzle design provides a novel technique for 3D printing of plant-derived compounds with remarkable advantages such as providing selective variable extrusion and multiple nozzle dies. Compared to other existing 3D printing techniques, the proposed nozzle abilities make it a promising option with higher speed and better functionality for the packaging industry.

Despite the wide-spectrum and effective anti-cancer activity of paclitaxel (PTX), their low solubility and side effects are the main challenges in their clinical application. In this study, a model paclitaxel-encapsulated nanoliposome (NLips-PTX) carrier was synthesized to enhance PTX solubility and increase its passive accumulation at the tumor site. Soy lecithin and cholesterol at a 9:1 ratio were used to prepare the nano-sized liposomes through the thin-film hydration followed by extrusion technique. The prepared spherical NLips-PTX liposomes with an average size of about 150 nm and high uniformity were characterized by DLS and TEM. PTX load efficiency of NLips was determined at about 85% by HPLC. NLips-PTX also showed a therapeutic effect toward breast cancer cells (MCF-7) in a dose- and time-dependent manner via in vitro cellular uptake and a cytotoxicity study. This research indicates that extrusion is a simple and convenient method for nano-sizing and homogenising liposome suspension for potentially effective delivery of drug to target tumor sites. [ABSTRACT FROM AUTHOR]

The recent year's calcium phosphate ceramics have gained more attention in biomedical applications due to their biocompatibility with the living system. In the recent past, BCP was widely used in orthopedics and dentistry. However, the usages of ceramic materials in cardiovascular applications are limited. In this work, an attempt was made to explore the possibility to utilize the advantages of biphasic calcium phosphate in the development of cardiovascular devices using simple conventional techniques. [ABSTRACT FROM AUTHOR]

Summary: To enhance the rehydration and palatability characteristics of extruded noodles, a new type of instant noodles with a well‐developed porous structure was successfully created by cooperating medium temperature α‐amylase (MTA) with extrusion technique. To explain the formation reason of the porous structure, a detailed mechanism analysis was firstly carried out. It turned out that a portion of starch was degraded into water‐soluble dextrin during the enzymatic extrusion treatment. Besides, a slight restriction of the excessive MTA on the starch gelatinisation was demonstrated. The appearance of the well‐developed porous structure was attributed to the leaching of dextrin and loosely bound starch fragments. Therefore, the extruded noodles with 0.40‰ MTA concentration were recommended based on the results of cooking quality, textural characteristics and sensory evaluation. [ABSTRACT FROM AUTHOR]

An improved extrusion spraying technique was employed for encapsulation of mixed bacteria culture of Streptococcus thermophilus and Lactobacillus bulgaricus using sodium alginate as the coating material for the purpose of better survival during spray drying of sweetened yoghurt. The effects of nozzle air pressure (200, 300, 400 and 500 kPa), sodium alginate concentration (1%, 1.5%, 2%, 2.5% and 3% w/v ), calcium chloride concentration (0.1, 0.2, 1 M) and hardening time (15, 30, 45 and 60 min) on the viability of encapsulated bacteria were investigated. Alginate concentration increased the microcapsule size whereas, nozzle air pressure decreased the size. The encapsulation efficiency increased with the size of microcapsules. Hardening time exhibited a positive effect up to 30 min then the effect was non-significant. Increased level of sodium alginate significantly increased the survival ratio of encapsulated bacteria cells. The survival ratio of bacteria cells during spray drying of sweetened yoghurt were 2.48 × 10 −1 and 2.36 × 10 −3 for encapsulated and free cells of S. thermophilus , respectively and 7.26 × 10 −1 and 8.27 × 10 −3 for L. bulgaricus . This study demonstrated that microencapsulation of yoghurt culture in sodium alginate is an effective technique of protecting bacterial cells against extreme drying conditions. [ABSTRACT FROM AUTHOR]

In this study, for the first time honeycomb β-tricalcium phosphate (β-TCP) scaffolds were fabricated through an extrusion technique. The physicochemical properties and cell behaviors of the honeycomb β-TCP scaffolds were investigated. The results showed that scaffolds were characterized by ordered channel-like macropores and unidirectional interconnection. The pore structure and mechanical strength could be tailored by changing the parameters of extrusion molds. The pore size of scaffolds was in the range of 400–800 µm approximately, while their compressive strength parallel to the pore direction and porosity ranged from 14 to 20 MPa and 60–70%, respectively. The in vitro cell behavior demonstrated that cells could well attach on the surfaces and grow into the inner channel-like pores of the scaffolds; the scaffolds with higher porosity showed better cell proliferation but poorer cell differentiation. The honeycomb scaffolds fabricated by extrusion technique are potential candidate for bone tissue engineering. [ABSTRACT FROM AUTHOR]

Preform design plays a significant role in forging design especially for parts with complex shapes. Conventional preform design approaches include trial-and-error approach, electric field method, and shape optimization-based approaches. In this paper, by introducing the structural design optimization concept, a 3D topological preform design optimization method has been developed. In this method, a new criterion for element elimination and addition is proposed and employed for plastic deformation problems in blade forging. Based on the finite element (FE) simulation combined with optimization, the optimized preforms with and without equal cross-section constraint can be obtained. Using the optimized preform, physical experiment on forging of a blade has been implemented to validate the optimization result. Other preform-related issues, such as the feasible approaches for preparation of optimized preforms, are also discussed in detail. The result suggested that the optimized preforms could improve the deformation uniformity during forging processes with better die-filling rate and reduced waste of raw materials. [ABSTRACT FROM AUTHOR]

This paper presented the experimental results of MOC (magnesium oxychloride cement) with the EP/PA (expanded perlite/paraffin) composite manufactured by extrusion technique. The objective of this study was to improve the thermal insulation and thermal storage capacity of MOC cement with satisfied mechanical properties, which was expected to be used as structural materials with self-thermal insulation and storage in buildings. The DSC (differential scanning calorimetry) results revealed that the paraffin has melting temperature and latent heat of 26.7 °C and 138.0 J/g, respectively. The EP/PA composite can be obtained by absorbing the paraffin into the porous structures of expanded perlite, which showed good thermal storage and thermal stability properties. The incorporation of EP/PA composite caused not only 80% reduction in thermal conductivity, but also 14 min peak load shifting in thermal cycling test due to the improved thermal storage capacity. In addition, the extrusion technique contributed to the higher compressive and flexural strength of MOC cement due to the denser and better fiber alignment of the mixture, varied between 17–45 MPa and 6–8 MPa, respectively. In conclusion, the MOC cement with the EP/PA composite manufactured by extrusion technique has great potential for the sustainable development of energy efficient buildings. [ABSTRACT FROM AUTHOR]

Abstract: A PVA short fiber reinforced fly ash-geopolymer composites manufactured by extrusion technique (SFRGC) is developed in this study. The effects of fly ash content and fiber volume fraction on the rheological and impact behaviors of SFRGC are systemically investigated. Freeze–thaw cycles and sulfuric acid attack tests are also employed to study the durability of SFRGC. The experimental results show that for normally curing SFRGC, the addition of PVA fiber increases greatly the ductility of SFRGC, especially in the case of high volume fraction of fiber, resulting in the change of impact failure mode from brittle pattern to ductile one. As a result, a great increase in the impact toughness is seen in SFRGC with high fiber content. Comparatively the addition of fly ash exhibits obvious influence on the rhelogical and impact behaviors. The spherical shape of fly ash can greatly improve the extrudability of fresh SFRGC pastes. SFRGC without or with low percentage of fly ash possesses very high impact strength and stiffness. However, when too much fly ash is incorporated, the impact resistance of SFRGC is reduced rapidly. For SFRGC undergone freeze–thaw cycles and 1 month of sulfuric acid solution attack, only 5% or less of loss in impact strength is observed. The corresponding microstructure and failure mechanism are also explored by Laser particle size analysis (LSA), X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM), and Mercury intrusion porosimetry (MIP) techniques. [Copyright &y& Elsevier]

This paper studies the phenomenon of fiber alignment during the extrusion process. The fiber alignment is largely dependent on shapes of dies and the compression as well as the shear force generated in the extruder. The fiber alignment orientation, of course, would lead to direction dependency of the tensile properties of fiber-reinforced cement (FRC) extrudates. Such a dependency has been investigated in present study. It is found that when fiber volume ratio is small, say 1% of the glass fiber, the majority of the fiber can be aligned in the extrusion direction. As a result, the tensile strength of the thin plate along the extrusion direction is much higher than that along the transverse direction. When the total fiber volume ratio is increased to 2% or 4%, the fiber volume along the transverse direction is largely increased although the percentage of the fiber aligned along the extrusion direction is still higher. Thus, the tensile strength at a transverse direction can be significantly enhanced. In fact, the tensile strength of the samples along the transverse direction is almost the same as that along the extrusion direction when the fiber volume ratio reaches 2%. Furthermore, the strength of the sample at the extrusion direction does not increase proportionally to the fiber volume ratio. For the comparison purpose, plain sheets without any fibers have been prepared by both casting and extrusion. Mechanical properties of the sheets have also been tested and the test results show that extrusion process and fiber addition do have effects on enhancing the tensile properties. Polymer coating on the surface of the samples has also been used to improve the tensile properties of the extrudates with low fiber volume ratio, which shows some promising results. [Copyright &y& Elsevier]