Flame-Retardant and Tensile Properties of Polyamide 12 Processed by Selective Laser Sintering

This research was funded by the European Regional Development Fund within Measure 1.1.1.1 “Industry-Driven Research” of the Specific aid objective 1.1.1 “To increase the research and innovation capacity of scientific institutions of Latvia and their ability to attract external funding by investing in human resources and infrastructure” of the Operational Program “Growth and Employment” (Project No. 1.1.1.1/19/A/143). A.S. and A.Z. are grateful to funding received from the European Union Horizon 2020 Framework programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.Composite materials are becoming widely applied in fire-critical conditions such as, e.g., aviation interior parts. Environmental considerations motivate the use of additive manufacturing due to the decrease of polymer wastes, and therefore additional fuel sources. The aim of this work was to evaluate the effect of printing direction on flame retardancy and the tensile properties of 3D-printed test samples of polyamide 12 manufactured by selective laser sintering. The effects of printing parameters on the flammability of 3D-printed samples were investigated using vertical burn tests with varied specimen thicknesses and printing directions. It was found that these effects were substantial for the flammability at a low thickness of the test samples. No significant effects of printing direction were revealed for the tensile characteristics of polyamide 12. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.ERDF project 1.1.1.1/19/A/143; Institute of Solid-State Physics, University of Latvia has received funding from the European Union's Horizon 2020 Framework Pro gramme H2020-WIDESPREAD-01-2016-2017-Teaming Phase 2 under grant agreement No. 739508, project CAMART2.

Surface Wettability Regulation for Prosthetic Applications

UV radiation is used to engineer wettability of prosthetic PMMA, for eye prostheses applications

UV ietekme uz PMMA virsmas lādiņu

UV starojums diapazonā 200-400nm var tikt izmantots acu protezēšanā PMMA virsmas īpašību modificēšanai

UV Radiation Influence on Prosthetic PMMA Surface Charge

Nowadays in eye prosthetics and eye lenses produc-tion mostly poly methyl metha acrylate (PMMA) is used be-cause the material excellently fulfills biomedical and aesthetic functions. Peculiarities of PMMA material determines that under influence of mechanical impact (wind, sand, eye lid movements) and degradation in time, surface properties alter and wetting between supplementary aid and eye lid declines. Reduced biocompatibility follows, discomfort and inflammations in the eye socket region occur. Therefore, the aim of this research is to decrease/avoid complications by regulating surface charge that would result in wettability alterations, possibly altered to patients gain. It is presumed that applying small enough energy, will influence properties at surface level without changing bulk properties since only the first are responsible for interaction between eye prosthesis or lens and eye socket. For that reason non-ionizing Ultra Violet radiation is used in range 200- 400nm. Processed material was examined by means of detecting electron work function, contact angle and absorption spectra to find correlation between surface charge and other surface properties, e.g., wettability. Results demonstrate, that UV radiation influences PMMA surface electrical charge and also wettability in non-linear manner. UV radiation could be used to functionalize PMMA surface by not influencing its structure with UV exposures under 60 minutes

International Symposium on Biomedical Engineering and Medical Physics

This volume presents the proceedings of the International Symposium on Biomedical Engineering and Medical Physics and is dedicated to the 150 anniversary of the Riga Technical University, Latvia. The content includes various hot topics in biomedical engineering and medical physics

Commercial and Prosthetic PMMA Surface Wettability Regulation

The subject of current research is modification of surface properties in nano scale with aim to improve poly methyl metha acrylate performance for biomedical applications where interaction between material and surrounding environment is critical, e.g. contact lenses, dental applications, bone cement and many others

Commercial and Prosthetic PMMA Surface Wettability Regulation

The subject of current research is modification of surface properties in nano scale with aim to improve poly methyl metha acrylate performance for biomedical applications where interaction between material and surrounding environment is critical, e.g. contact lenses, dental applications, bone cement and many others. Charge on materials surface is strongly related to surface energy which in turn influences surface adhesion property and wettability property. Prosthetic PMMA surface properties including related biocompatibility are affected during time due to mechanical impact – wear between eye lense and eye lid; surrounding factors – wind, sand, sun. Mentioned factors lead to discomfort, inflammations for patients in case of eye lenses; to poor attachment capability in case of dental applications therefore many are trying to improve PMMA material.Results show that it might be possible to regulate surface properties also of commercial PMMA that would open new possibilities in both medical and non-medical fields

Ultra Violet Radiation Regulates Wettability Property on PMMA

The contact angle depends on UV exposure. The UV radiation could be employed to functionalize PMMA wettability, the structure uninfluenced radiation mode being available at exposure < 60 min

Wettability of the PMMA Surface Caused by Its Polarization due to UV Radiation

Wettability of the poly methyl methacrylate (PMMA) surface defines its biocompatibility being essential factor for biomedical applications. The processed surface degrades in time therefore the prostheses/lens should be repaired to keep the patient at a high life quality level. However the most common methods can be considered as sophisticated (plasma treatment, laser treatment, etc.). The research presents novel result on the PMMA surface wettability engineering by means of non-ionizing ultraviolet radiation (200-400nm). Results (electron work function (), photoelectron emission spectra, optical absorption) show alteration from hydrophobic to hydrophilic surface behaviour. Both the surface (photoelectron emission) and the bulk (optical absorption) interacting centres were influenced by radiation showing maximum effect after 45 minutes of irradiation