Research in manufacturing of micro-structured injection molded polymer parts

Lucyshyn, Thomas; Struklec, Tobias; Burgsteiner, Martin; Graninger, Georg; Holzer, Clemens

doi:10.1063/1.4937292

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…Because of the small part thickness, the process is subjected to filling difficulties caused by premature freezing of the polymer inside the cavity . Furthermore, high temperature and elevated injection speed are applied to reproduce small features in the conventional process to reduce melt viscosity . Consequently, the materials experience high stresses and shear rates.…”

Section: Introductionmentioning

confidence: 99%

Dynamic local temperature control in micro‐injection molding: Effects on poly(lactic acid) morphology

Meo

Santis

Pantani

2017

Polymer Engineering & Sci

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Microinjection molding is one of the most efficient processes for wide‐scale production of thermoplastic polymer microparts. The injection molding process with a cold mold suffers from drawbacks, that is, the premature solidification, caused by the small thickness and large temperature difference between the surface of the mold and the incoming polymer. In this work, an original and versatile system to dynamically control the local temperature of the cavity surfaces in microinjection molding was developed. The system was used to investigate the effects of rapid variations of the temperature of a 200 μm thick cavity on the reachable flow length and study the morphology of microinjection molded parts of poly(lactic acid). For the rapid mold temperature control, electrical resistive thin components are located very near the surface of the impression to change the temperature by some tens of degrees per second. This study also demonstrates that the system is able to influence the final morphology of the part with a semicrystalline thermoplastic material. Changing the annealing time and temperature, the effects on the morphology of the part, in the mold and immediately after the injection, were investigated by microscopy analysis and X‐ray diffraction. POLYM. ENG. SCI., 58:586–591, 2018. © 2017 Society of Plastics Engineers

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Section: Introductionmentioning

confidence: 99%

Dynamic local temperature control in micro‐injection molding: Effects on poly(lactic acid) morphology

Meo

Santis

Pantani

2017

Polymer Engineering & Sci

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“…A variotherm process was implemented by electrical resistance heating based on previous results showing that variotherm processes are very useful for high aspect ratio microstructure replication [39, 42, 43]. Molded slide sterility was maintained by aseptic packaging in sterile containers.…”

Section: Methodsmentioning

confidence: 99%

Cell Morphology on Poly(methyl methacrylate) Microstructures as Function of Surface Energy

Katschnig

Maroh

Andraschek

et al. 2019

International Journal of Biomaterials

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Whilst the significance of substrate topography as a regulator of cell function is well established, a systematic analysis of the principles underlying this is still unavailable. Here we evaluate the hypothesis that surface energy plays a decisive role in substrate-mediated modulation of cell phenotype by evaluation of cell behaviour on synthetic microstructures exhibiting pronounced differences in surface energy. These microstructures, specifically cubes and walls, were fabricated from a biocompatible base polymer, poly(methyl methacrylate), by variotherm injection molding. The dimensions of the cubes were 1 μm x 1 μm x 1 μm (height x width x length) with a periodicity of 1:1 and 1:5 and the dimensions of the walls 1 μm x 1 μm x 15 mm (height x width x length) with a periodicity of 1:1 and 1:5. Mold inserts were made by lithography and electroplating. The surface energy of the resultant microstructures was determined by static contact angle measurements. Light scanning microscopy of the morphology of NT2/D1 and MC3T3-E1 preosteoblast cells cultured on structured PMMA samples in both cases revealed a profound surface energy dependence. “Walls” appeared to promote significant cell elongation, whilst a lack of cell adhesion was observed on “cubes” with the lowest periodicity. Contact angle measurements on walls revealed enhanced surface energy anisotropy (55 mN/m max., 10 mN/m min.) causing a lengthwise spreading of the test liquid droplet, similar to cell elongation. Surface energy measurements for cubes revealed increased isotropic hydrophobicity (87° max., H2O). A critical water contact angle of ≤ 80° appears to be necessary for adequate cell adhesion. A “switch” for cell adhesion and subsequently cell growth could therefore be applied by, for example, adjusting the periodicity of hydrophobic structures. In summary cell elongation on walls and a critical surface energy level for cell adhesion could be produced for NT2/D1 and MC3T3-E1 cells by symmetrical and asymmetrical energy barrier levels. We, furthermore, propose a water-drop model providing a common physicochemical cause regarding similar cell/droplet geometries and cell adhesion on the investigated microstructures.

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“…36 For the molds, we used metal ceramic heating (MCH) elements because of their thin profiles and high wattage; they have also been previously described for variotherm heating. [83][84][85][86] The portions of both A and B plates behind the cavities were hollowed out to enable the variotherm process (Fig. 2C).…”

Section: Injection Molding Assembly Design and Fabricationmentioning

confidence: 99%

Rapid microfluidics prototyping through variotherm desktop injection molding for multiplex diagnostics

Suarez¹,

Bayer²,

Suarez³

et al. 2023

Lab Chip

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Research in manufacturing of micro-structured injection molded polymer parts

Cited by 5 publications

References 18 publications

Dynamic local temperature control in micro‐injection molding: Effects on poly(lactic acid) morphology

Dynamic local temperature control in micro‐injection molding: Effects on poly(lactic acid) morphology

Cell Morphology on Poly(methyl methacrylate) Microstructures as Function of Surface Energy

Rapid microfluidics prototyping through variotherm desktop injection molding for multiplex diagnostics

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