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

Liparoti, Sara; Speranza, Vito; Pantani, Roberto

doi:10.3390/ma11081442

Cited by 15 publications

(14 citation statements)

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“…In the injection molding process, one of the main operating parameters that affect the properties of the final object is the mold temperature [17,18]. Surface finishing, morphology distribution, and possibility to produce micro and nano-structures on the molded surface strongly depend on the temperature adopted in the mold and, in particular, on the cavity surface [19][20][21][22][23]. The mechanical properties have been found to be dependent on the mold temperature; in particular, the tensile strength of moldings made of polyether-ether-ketone increases with the mold temperature [24].…”

Section: Introductionmentioning

confidence: 99%

Effect of Rapid Mold Heating on the Structure and Performance of Injection-Molded Polypropylene

et al. 2020

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The tailoring by the process of the properties developed in the plastic objects is the more effective way to improve the sustainability of the plastic objects. The possibility to tailor to the final use the properties developed within the molded object requires further understanding of the relationship between the properties of the plastic objects and the process conduction. One of the main process parameters that allow adjusting the properties of molded objects is the mold temperature. In this work, a thin electrical heater was located below the cavity surface in order to obtain rapid and localized surface heating/cooling cycles during the injection molding process. An isotactic polypropylene was adopted for the molding tests, during which surface temperature was modulated in terms of values and heating times. The modulation of the cavity temperature was found able to control the distribution of relevant morphological characteristics, thus, properties along the sample thickness. In particular, lamellar thickness, crystallinity distribution, and orientation were analyzed by synchrotron X-ray experiments, and the morphology and elastic modulus were characterized by atomic force microscopy acquisitions carried out with a tool for the simultaneous nanomechanical characterization. The crystalline degree slightly increased with the cavity temperature, and this induced an increase in the elastic modulus when high temperatures were adopted for the cavity surface. The cavity temperature strongly influenced the orientation distribution that, on its turn, determined the highest values of the elastic modulus found in the shear layer. Furthermore, although the sample core, not experiencing a strong flow field, was not characterized by high levels of orientation, it might show high values of the elastic modulus if temperature and time during crystallization were sufficient. In particular, if the macromolecules spent adequate time at temperatures close to the crystallization temperature, they could achieve high levels of structuring and, thus, high values of elastic modulus.

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Section: Introductionmentioning

confidence: 99%

Effect of Rapid Mold Heating on the Structure and Performance of Injection-Molded Polypropylene

et al. 2020

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“…[ 5,14 ] In general, pattern structures, such as pattern size, shape, and aspect ratio, and molding conditions, such as melting temperature, mold temperature, injection pressure, and injection speed, affect the precision of replication. [ 15–19 ] Improved replication precision has been reported by adjusting molding methods such as rapid heating of mold surface, [ 20,21 ] vacuum molding, [ 22 ] and injection compression molding. [ 23,24 ]…”

Section: Introductionmentioning

confidence: 99%

Improvement in nano‐pattern replication of injection molding by polyamide/dendrimer blend

Kang

Kim

2021

Polymer Engineering & Sci

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In general, lower viscosity of materials leads to desirable nano‐pattern replication characteristics in injection molding processes. However, such materials do not meet the properties required for manufacturable products owing to their poor mechanical properties. In this study, we blended a small amount of dendrimer with high‐viscosity polyamide 6 to lower viscosity and enhance flowability of the polymer blend while maintaining desirable mechanical properties. It was observed that the flowability of the polyamide 6/dendrimer blend increased significantly with an increase in dendrimer content without affecting the mechanical properties of high‐viscosity polyamide 6. To investigate the nano‐pattern replication characteristics of the blend, injection molding process and the mold of metal stamp were used to manufacture a nano‐pattern specimen. Blending more than 0.6 wt% of dendrimer with high‐viscosity polyamide 6 significantly improved its nano‐pattern replication characteristics and flowability.

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“…Replication is highly influenced by process parameters (mold temperature, melt temperature, injection velocity and holding pressure) and mold design (e.g., distance of the patterned area from the gate and part thickness) [34,35]. In the literature, many experimental studies have focused on the optimization of the µIM process and auxiliaries to overcome the manufacturing issues driven by the replication of high aspect ratio structures [36,37]. Rapid Heat Cycle Molding (RHCM) is commonly used to increase mold temperatures above the polymer glass transition temperature (T g ) during the injection phase.…”

Section: Introductionmentioning

confidence: 99%

Functionalization of Plastic Parts by Replication of Variable Pitch Laser-Induced Periodic Surface Structures

et al. 2020

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Surface functionalization of plastic parts has been studied and developed for several applications. However, demand for the development of reliable and profitable manufacturing strategies is still high. Here we develop and characterize a new process chain for the versatile and cost-effective production of sub-micron textured plastic parts using laser ablation. The study includes the generation of different sub-micron structures on the surface of a mold using femtosecond laser ablation and vario-thermal micro-injection molding. The manufactured parts and their surfaces are characterized in consideration of polymer replication and wetting behavior. The results of the static contact angle measurements show that replicated Laser-Induced Periodic Surface Structures (LIPSSs) always increase the hydrophobicity of plastic parts. A maximum contact angle increase of 20% was found by optimizing the manufacturing thermal boundary conditions. The wetting behavior is linked to the transition from a Wenzel to Cassie–Baxter state, and is crucial in optimizing the injection molding cycle time.

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

Cited by 15 publications

References 50 publications

Effect of Rapid Mold Heating on the Structure and Performance of Injection-Molded Polypropylene

Effect of Rapid Mold Heating on the Structure and Performance of Injection-Molded Polypropylene

Improvement in nano‐pattern replication of injection molding by polyamide/dendrimer blend

Functionalization of Plastic Parts by Replication of Variable Pitch Laser-Induced Periodic Surface Structures

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