Application of a microcellular injection molding process (MuCell®) to produce an implant with porous structure

Wu, Hongbin; Krampe, Erhard; Schlicht, Henning; Wintermantel, E.

doi:10.1007/978-3-642-03900-3_18

Cited by 5 publications

(5 citation statements)

References 2 publications

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“…FIM can be achieved via a chemical blowing agent (CBA) or physical blowing agent (PBA) [11]. Essentially, in both techniques the cellular structure formed via the blowing agent reduces the material cell density which in turn reduces the resulting polymer component weight [36]. When using PBA as the agent, (super critical nitrogen or carbon dioxide) it causes a contact action, whereas CBAs release inert gas upon heating, into the polymer [37].…”

Section: Introductionmentioning

confidence: 99%

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

et al. 2019

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Unfilled and talc-filled Copolymer Polypropylene (PP) samples were produced through low-pressure foam-injection molding (FIM). The foaming stage of the process has been facilitated through a chemical blowing agent (C6H7NaO7 and CaCO3 mixture), a physical blowing agent (supercritical N2) and a novel hybrid foaming (combination of said chemical and physical foaming agents). Three weight-saving levels were produced with the varying foaming methods and compared to conventional injection molding. The unfilled PP foams produced through chemical blowing agent exhibited the strongest mechanical characteristics due to larger skin wall thicknesses, while the weakest were that of the talc-filled PP through the hybrid foaming technique. However, the hybrid foaming produced superior microcellular foams for both PPs due to calcium carbonate (CaCO3) enhancing the nucleation phase.

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Section: Introductionmentioning

confidence: 99%

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

et al. 2019

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“…The injection mould was custom-made. The production details and parameters have been investigated and described elsewhere and are therefore not further elaborated [30,36].…”

Section: Implant Productionmentioning

confidence: 99%

“…Medical grade thermoplastic polyurethane (TPU, Texin® 985, Bayer, Pa, USA) was selected as raw material owing to its outstanding elastic properties, biocompatible and bioinertness [31][32][33][34]. Although it has been shown that it is possible to produce a highly porous GORD implant with the SCF with porosity up to 75% and acceptable in vitro response [30,35,36], the gastric implant has not been tested in vivo condition. SCF is a popular method to provide open porous in medical polymers [37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Long-Term In Vivo Response of a Polyurethane Gastric Implant for Treating Gastro-Oesophageal Reflux Diseases: A Comparison of Different Surface Treatments

Haugen

Schneider

Schlicht

et al. 2022

Biomedical Materials & Devices

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Gastro oesophagael reflux disease (GORD) is common in the Western hemisphere. Patients with regurgitated reflux are typically treated with fundoplication surgery. We present a newly designed polyurethane implant which passively aids the sphincter in reducing gastric fluids within the oesophagus. The gastric implant has an open porous inner side which allows for tissue ingrowth from the oesophagus and thus allows for fixation around the sphincter. In addition, a device for minimally invasive surgery of this implant was developed and used in a pig model. The unmodified GORD implant was placed around the pig’s oesophagus with unsatisfactory results, leading to insufficient fixation at the implantation site and scarring tissue leading to dysphagia. In addition, two surface modifications, plasma activation and TiO2 deposition were used to improve the implant’s host tissue response. The biocompatibility effects of the surface treatments and sterilisation method on the implant were investigated in vitro and in vivo. In vitro tests found that the plasma activation and TiO2 deposition have effectively enhanced the surface hydrophilicity and, consequently, the cell response to the implant. In addition, the gamma sterilisation harmed the plasma-activated implant. The plasma activation was more effective than TiO2 deposition as a surface treatment method for improving the tissue response of this implant in vivo. In addition, the in vivo experiment proved tissue ingrowth as deep as 1 mm into the porous structure of the implant. The GORD implants were encapsulated wholly in fibrous tissue; however, the capsule thickness diminished over time. Finally, the TiO2-coated implants showed the poorest histocompatibility, contradictory to the in vitro findings. This study shows that it is possible to produce a plasma-treated porous polyurethane gastric implant that allows for fibrous tissue ingrowth, reduced in vivo encapsulation, and enhanced chemical properties. Graphical Abstract Model of the implant with an inner porous and an outer non-porous surface. The hypothesis was that the porous surface allows for fibroblastic infiltration into the porous structure (A) and fixation by scarring at the point of implantation, the lower oesophageal sphincter (LOS). The outer side is smooth (B), which hinders neighbouring tissue attachments. In addition, a Nitinol ring (C) aids the implant in exerting pressure around the LOS, thus reducing sphincter volume. In addition, this metal ring aids visualisation with, e.g. X-ray or CT during post-therapy follow-ups. The open, flexible design eases the freeing of the ring in a stretched position and placement around the cardia (D-F). The internal diameter of 28 mm prevents stenosis but markedly reinforces the lower oesophagal sphincter. In addition, its size allows for minimally invasive surgery.

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“…Some studies have investigated the relations between the key process parameters in MuCell Õ technology and produced cellular foam structure [1,5,6]. It was found that the pore morphology in MuCell Õ process could be adjusted through varying the process parameters.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Mold Design on the Pore Morphology of Polymers Produced with MuCell ^®Technology

Wintermantel

Haugen

2010

Journal of Cellular Plastics

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In this study two molds were designed and used in MuCell Õ technology to generate implants with a porous structure. To arrive the desired pore structure many process parameters were investigated for indicating the effects of process parameters on the pore morphology. This process parameter investigation was performed on each mold respectively, so that the influences of the mold design on the pore morphology have been researched by the same process parameter setting. It was found that the mold design also had effects on the pore structure in MuCell Õ technology. A proper mold design could improve the generated pore structure, such as porosity, pore diameter, and interconnectivity.

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Application of a microcellular injection molding process (MuCell®) to produce an implant with porous structure

Cited by 5 publications

References 2 publications

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Long-Term In Vivo Response of a Polyurethane Gastric Implant for Treating Gastro-Oesophageal Reflux Diseases: A Comparison of Different Surface Treatments

The Effects of Mold Design on the Pore Morphology of Polymers Produced with MuCell ^®Technology

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Application of a microcellular injection molding process (MuCell®) to produce an implant with porous structure

Cited by 5 publications

References 2 publications

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Long-Term In Vivo Response of a Polyurethane Gastric Implant for Treating Gastro-Oesophageal Reflux Diseases: A Comparison of Different Surface Treatments

The Effects of Mold Design on the Pore Morphology of Polymers Produced with MuCell ®Technology

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The Effects of Mold Design on the Pore Morphology of Polymers Produced with MuCell ^®Technology