Replication of micro and nano-features on iPP by injection molding with fast cavity surface temperature evolution

Speranza, Vito; Liparoti, Sara; Calaon, Matteo; Tosello, Guido; Pantani, Roberto; Titomanlio, G.

doi:10.1016/j.matdes.2017.08.016

Cited by 29 publications

(31 citation statements)

References 47 publications

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“…In this work, the grating orientation was designed to be aligned with the polymer melt flow to promote filling of the cavity. It had been reported that the air in the grating cavity aligned with the flow direction could partially escape from the cavity, whereas the escape of air is limited when the grating is aligned orthogonal to the flow direction . To investigate the influence of process parameters on the replication fidelity, the range values for mold temperature ( T mold ) and holding pressure ( P holding ) were defined considering the thermal and mechanical properties of the mold insert's material and injection molding plastic material.…”

Section: Resultsmentioning

confidence: 99%

“…To investigate the influence of process parameters on the replication fidelity, the range values for mold temperature ( T mold ) and holding pressure ( P holding ) were defined considering the thermal and mechanical properties of the mold insert's material and injection molding plastic material. In the current work, the relatively low range values for mold temperature (25–40 °C) and holding pressure (100–250 bar) were used for injection molding of sub‐micron surface patterns in comparison with other works ( T mold > 100 °C and P holding > 700 bar), in which the mold inserts were made of nickel shim or silicon. For polymeric mold inserts, patterned structure on the mold underwent deformation when the mold temperature was above 50 °C (i.e., the T g of Digital ABS mold material), whereas a pronounced flash along parting lines was formed when a holding pressure above 400 bar was applied (as shown in Figure S4, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

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Nanostructured Free‐Form Objects via a Synergy of 3D Printing and Thermal Nanoimprinting

Lee

Low

2018

Global Challenges

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High‐resolution surface patterning has garnered interests as a nonchemical‐based surface engineering approach for creating functional surfaces. Applications in consumer products, parts for transportation vehicles, optics, and biomedical technologies demand topographic patterning on 3D net shape objects. Through a hybrid approach, high‐resolution surface texture is incorporated onto 3D‐printed polymers via direct thermal nanoimprinting process. The synergy of geometry design freedom in 3D printing and the high spatial resolution in nanoimprinting is demonstrated to be a versatile fabrication of high‐fidelity surface pattern (from 2 µm to 200 nm resolution) on convex, concave semicylindrical, and hemispherical objects spanning a range of surface curvatures. The novel hybrid fabrication is further extended to achieve a high‐resolution curved mold insert for rapid prototyping via injection molding. The versatility of the fabrication strategies reported here not only provides a post‐3D printing process that enhances the surface properties of 3D‐printed objects but also opens a new pathway to enable future study on the effects of combining microscale and nanoscale surface texture with macroscopic curvature. Both have been known, individually, as an effective approach to tune surface functionalities.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Nanostructured Free‐Form Objects via a Synergy of 3D Printing and Thermal Nanoimprinting

Lee

Low

2018

Global Challenges

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“…The use of polycaprolactone (PCL) seems to be particularly promising, because of its biocompatibility and its capability to prolong the drug release. In the last decades, compression molding has been one of the most diffused processes for polymeric part production [20][21][22][23]. High automation, high geometrical accuracy, and the fast cycle time, which means high productivity, are the main reasons for the diffusion of this process.…”

Section: Introductionmentioning

confidence: 99%

PCL/Mesoglycan Devices Obtained by Supercritical Foaming and Impregnation

et al. 2019

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In this work, a one-shot process for the simultaneous foaming of polycaprolactone (PCL) and impregnation of mesoglycan (MSG) into the porous structure was successfully attempted. Supercritical carbon dioxide plays the role of the foaming agent with respect to PCL and of the solvent with respect to MSG. The main objective is to produce an innovative topical device for application on skin lesions, promoting prolonged pro-resolving effects. The obtained device offers a protective barrier to ensure a favorable and sterilized environment for the wound healing process. The impregnation kinetics revealed that a pressure of 17 MPa, a temperature of 35 °C, and a time of impregnation of 24 h assured a proper foaming of PCL in addition to the impregnation of the maximum amount of MSG; i.e., 0.22 mgMSG/mgPCL. After a preliminary study conducted on PCL granules used as brought, the MSG impregnation was performed at the optimized process conditions also on a PCL film, produced by compression molding, with the final goal of producing medical patches. Comparing the dissolution profiles in phosphate buffered saline solution (PBS) of pure MSG and MSG impregnated on foamed PCL, it was demonstrated that the release of MSG was significantly prolonged up to 70 times. Next, we performed functional assays of in vitro wound healing, cell invasion, and angiogenesis to evaluate the biological effects of the PCL-derived MSG. Interestingly, we found the ability of this composite system to promote the activation of human keratinocytes, fibroblasts, and endothelial cells, as the main actors of tissue regeneration, confirming what we previously showed for the MSG alone.

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“…The electrical heating of the cavity surface is undoubtedly less expensive and requires small additional tool costs [ 29 , 30 , 31 , 32 , 33 ]. The electrical heating of the cavity surface was efficiently applied to the injection-molding process to obtain micro- and nanostructures surfaces of polypropylene [ 34 ].…”

Section: Introductionmentioning

confidence: 99%

Replication of Micro- and Nanofeatures in Injection Molding of Two PLA Grades with Rapid Surface-Temperature Modulation

2018

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The production by injection molding of polymeric components having micro- and nanometrical surfaces is a complex task. Generally, the accurate replication of micro- and nanometrical features on the polymeric surface during the injection-molding process is prevented by of the low mold temperature adopted to reduce cooling time. In this work, we adopt a system that allows fast heating of the cavity surface during the time the melt reaches the cavity, and fast cooling after heater deactivation. A nickel insert with micro- and nanofeatures in relief is located on the cavity surface. Replication accuracy is analyzed by Atomic Force Microscopy under different injection-molding conditions. Two grades of polylactic acid with different viscosity have been adopted. The results indicate that the higher the cavity surface temperature is, the higher the replication accuracy is. The viscosity has a significant effect only in the replication of the microfeatures, whereas its effect results are negligible in the replication of nanofeatures, thus suggesting that the interfacial phenomena are more important for replication at a nanometric scale. The evolution of the crystallinity degree on the surface also results in a key factor on the replication of nanofeatures.

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Replication of micro and nano-features on iPP by injection molding with fast cavity surface temperature evolution

Cited by 29 publications

References 47 publications

Nanostructured Free‐Form Objects via a Synergy of 3D Printing and Thermal Nanoimprinting

Nanostructured Free‐Form Objects via a Synergy of 3D Printing and Thermal Nanoimprinting

PCL/Mesoglycan Devices Obtained by Supercritical Foaming and Impregnation

Replication of Micro- and Nanofeatures in Injection Molding of Two PLA Grades with Rapid Surface-Temperature Modulation

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