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UVC & Dr Frédéric LUIZI – UV Expert

IoTCo sa Avenue du Pré Aily, 24 4031 Angleur [email protected]

UVC & Polymers Version A1

Table of contents

1 Introduction 3 1.1 3 1.2 3 2 The problem of polymers 5 3 Tests and observations performed by UVmastercare 9 4 Conclusions 12

© IoTco sa - UVmastercare 2

UVC & Polymers Version A1

1 Introduction

1.1 Background The Covid-19 pandemic has created an unprecedented situation for health practitioners who receive patients in their offices. The disinfection of the environment where successive patients are treated has become infinitely more critical than before. This is especially true for dental offices, where "open mouth" procedures result in the diffusion of particles containing potentially pathogenic microorganisms from the patient into the air. After the procedure, the air is therefore inevitably charged with aerosols and droplets of all kinds of substances, including some concentration of coronavirus if the patient is infected. These substances are deposited on the surrounding surfaces, which are therefore potentially contaminated. The aim of UV-MasterCare is to quickly destroy all organic particles in the air, on the walls and on the surface of objects in the dental practice where the procedure is performed, including the dreaded coronavirus. The system carries out a disinfection between the interventions on two successive patients. This phase, which must imperatively take place without human occupation of the practice, lasts only a few minutes. The process therefore allows the practice to maintain a normal operating rate. 1.2 Principle The infectious agents contained in the air and deposited on the surfaces are eliminated by the effect of a particular ultraviolet radiation, the UV-C. As a reminder, ultraviolet radiation, or UV, is a type of light that extends the spectrum of visible light on the short wavelength side. The wavelength is a fundamental characteristic of the light wave, and the shorter it is, the more energy the constituent photons of light carry. For visible light, the wavelength is also what determines the color we perceive when the radiation reaches our eye. The spectrum of colors extends from red to purple, for corresponding wavelengths of 780 to 400 nanometers. The nanometer, abbreviated "nm", is one billionth of a meter. Light with a wavelength of less than 400 nm, known as ultraviolet light, is invisible to us. However, it is not without effect on us, because being more energetic, it is likely to cause damage in the organic molecules of which we are made. The danger of UV-C for the health is however to be tempered by the fact that their rate of penetration in the living tissues is very weak. One can usefully consult on this subject: https://www.prevent.be/fr/banque_de_connaissance/rayons-uv-risque-invisible-et-souvent-sous- estim%C3%A9 It is the ability to affect the molecules of biological beings that is the basis of the disinfecting power of ultraviolet radiation. Scientific studies show that DNA molecules easily absorb UV rays with a wavelength of 260 nm. When subjected to a certain dose of such radiation, the molecules break up. This is how viruses, which are microscopic reservoirs of RNA (close to DNA), are killed. In the UV spectrum, which extends from 400 to 100 nm, there is a range of variants called UV-A, UV-B, UV-C and extreme UV. The UV that most effectively destroys the DNA or RNA of coronaviruses is the UV-C type. There are dedicated lamps that produce ultraviolet light in the region of the spectrum of interest. These lamps are tubular and have similarities with the fluorescent lighting tubes we know, which are often called (although improperly) "neon tubes". The lamps that make up the UVmastercare system are germicidal lamps called "amalgam" because their operation involves the presence of mercury amalgam in their structure. It is

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UVC & Polymers Version A1

not useful to understand the details of the functioning of these lamps, except that their emission spectrum presents a peak centered on 254 nm, which makes them perfect virus killers. The principle of UVmastercare can then be stated as follows: After having placed one or more germicidal lamps inside the practice, they are switched on without any human presence for a sufficient amount of time to ensure that the air and surfaces are reached by a sufficient dose of UV-C radiation to eliminate any coronavirus that may have been present.

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UVC & Polymers Version A1

2 The problem of polymers

The resistance of polymers to UV-C is very variable, even though the vast majority of UVCs do not cause significant deterioration. The objective of this note is to provide information on these impacts to the users of the system so that they can take the appropriate measures according to the materials present in their practice. The following website from which our data was obtained provides a lot of additional information: https://omnexus.specialchem.com/polymer-properties/properties/uv-light-resistance The table below summarizes the impacts observed according to the nature of the polymers:

Polymer Name UV Light resistance ABS - Acrylonitrile Butadiene Styrene Poor ABS Flame Retardant Fair ABS Flame Retardant Poor ABS High Heat Poor ABS High Impact Poor ABS/PC Blend - Acrylonitrile Butadiene Styrene/ Blend Fair ABS/PC Blend 20% Glass Fiber Fair ABS/PC Flame Retardant Poor ASA - Acrylonitrile Styrene Acrylate Good ASA/PC Blend - Acrylonitrile Styrene Acrylate/Polycarbonate Blend Good ASA/PC Flame Retardant Poor ASA/PVC Blend - Acrylonitrile Styrene Acrylate/ Blend Good CPVC - Chlorinated Polyvinyl Chloride Fair ECTFE - Ethylene Chlorotrifluoroethylene Good ETFE - Ethylene Tetrafluoroethylene Good EVA - Ethylene Vinyl Acetate Poor FEP - Fluorinated Ethylene Propylene Good HDPE - High Poor HIPS - High Impact Poor HIPS Flame Retardant V0 Poor Ionomer (Ethylene-Methyl Acrylate ) Good LCP - Liquid Crystal Polymer Good LCP Carbon Fiber-reinforced Good LCP Glass Fiber-reinforced Good LCP Mineral-filled Good LDPE - Low Density Polyethylene Fair LLDPE - Linear Low Density Polyethylene Fair MABS - Transparent Acrylonitrile Butadiene Styrene Fair PA 11 - ( 11) 30% Glass fiber reinforced Fair

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UVC & Polymers Version A1

PA 11, Conductive Fair PA 11, Flexible Fair PA 11, Rigid Fair PA 11 or 12 Fair PA 12 (Polyamide 12), Conductive Fair PA 12, Fiber-reinforced Fair PA 12, Flexible Fair PA 12, Glass Filled Fair PA 12, Rigid Fair PA 46 - Polyamide 46 Fair PA 46, 30% Glass Fiber Fair PA 6 - Polyamide 6 Fair PA 6-10 - Polyamide 6-10 Fair PA 66 - Polyamide 6-6 Poor PA 66, 30% Glass Fiber Poor PA 66, 30% Mineral filled Poor PA 66, Impact Modified, 15-30% Glass Fiber Poor PA 66, Impact Modified Poor Polyamide semi-aromatic Fair PAI - Polyamide-Imide Excellent PAI, 30% Glass Fiber Excellent PARA (Polyarylamide), 30-60% glass fiber Good PBT - Terephthalate Fair PBT, 30% Glass Fiber Fair PC - Polycarbonate Fair PC (Polycarbonate) 20-40% Glass Fiber Fair PC (Polycarbonate) 20-40% Glass Fiber, Flame Retardant Poor PC - Polycarbonate, high heat Fair PC/PBT Blend - Polycarbonate/Polybutylene Terephthalate Blend Fair PC/PBT blend, Glass Filled Fair PCTFE - Polymonochlorotrifluoroethylene Good PE - Polyethylene 30% Glass Fiber Fair PEEK - Polyetheretherketone Good PEEK 30% Carbon Fiber-reinforced Good PEEK 30% Glass Fiber-reinforced Good

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UVC & Polymers Version A1

PEI - Polyetherimide Fair PEI, 30% Glass Fiber-reinforced Fair PEI, Mineral Filled Fair PESU - Polyethersulfone Fair PESU 10-30% glass fiber Fair PET - Polyethylene Terephthalate Fair PET, 30% Glass Fiber-reinforced Fair PET, 30/35% Glass Fiber-reinforced, Impact Modified Poor PETG - Polyethylene Terephthalate Glycol Fair PE-UHMW - Polyethylene -Ultra High Molecular Weight Fair PFA - Perfluoroalkoxy Fair PI - Excellent PMMA - Polymethylmethacrylate/Acrylic Good PMMA (Acrylic) High Heat Good PMMA (Acrylic) Impact Modified Fair PMP - Polymethylpentene Fair PMP 30% Glass Fiber-reinforced Fair PMP Mineral Filled Fair POM - (Acetal) Poor POM (Acetal) Impact Modified Poor POM (Acetal) Low Friction Poor POM (Acetal) Mineral Filled Poor PP - Fair PP - Polypropylene 10-20% Glass Fiber Fair PP, 10-40% Mineral Filled Fair PP, 10-40% Talc Filled Fair PP, 30-40% Glass Fiber-reinforced Fair PP (Polypropylene) Copolymer Fair PP (Polypropylene) Homopolymer Fair PP, Impact Modified Poor PPE - Polyphenylene Ether Fair

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UVC & Polymers Version A1

PPE, 30% Glass Fiber-reinforced Fair PPE, Flame Retardant Poor PPE, Impact Modified Poor PPE, Mineral Filled Fair PPS - Polyphenylene Sulfide Good PPS, 20-30% Glass Fiber-reinforced Good PPS, 40% Glass Fiber-reinforced Good PPS, Conductive Good PPS, Glass fiber & Mineral-filled Good PPSU - Polyphenylene Sulfone Good PS - Polystyrene Poor PS - Polystyrene, 30% Glass Fiber Poor PS (Polystyrene) Crystal Poor PS, High Heat Poor PSU - Fair PSU, 30% Glass finer-reinforced Fair PSU Mineral Filled Fair PTFE - Good PTFE, 25% Glass Fiber-reinforced Good PVC - Polyvinyl Chloride Good PVC (Polyvinyl Chloride), 20% Glass Fiber-reinforced Good PVC, Plasticized Fair PVC, Plasticized Filled Fair PVC Rigid Fair PVDC - Fair PVDF - Polyvinylidene Fluoride Good SAN - Styrene Acrylonitrile Poor SAN, 20% Glass Fiber-reinforced Poor SMA - Styrene Maleic Anhydride Flame Retardant V0 Poor SRP - Self-reinforced Polyphenylene Good XLPE - Crosslinked Polyethylene Good

Source : https://omnexus.specialchem.com/polymer-properties/properties/uv-light-resistance

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UVC & Polymers Version A1

3 Tests and observations performed by UVmastercare

The sensitivity of the polymers is illustrated by the fact that the irradiation by UV-C can lead to the formation of free radicals which, themselves, will oxidize the polymer and affect its transparency. This effect is reduced by most of the pigments which will capture part of the UV-C radiation and dissipate it in the form of heat. The sensitivity of the above-mentioned polymers is therefore relevant for their transparent forms. Moreover, the UV-C are very little penetrating. At most, they will penetrate a few hundred microns but never more than one millimeter. Therefore, UV-C does not affect the structure of materials but contributes at most to surface aging. The only exception is for flexible polymers, where the modification of the surface properties potentially affects the elasticity and thus the overall structure. Thus, there are relatively few materials that will be sensitive to UV-C. As an additional validation, we also conducted aging tests on typical dental practice materials.

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UVC & Polymers Version A1

The few pictures below illustrate some of the tests that were performed. Various objects supplied by a dental practice material distributor such as seat parts (shell and fabric), accessories such as lamps, pedals, hoses, and tools were exposed to high doses of UV-C at varying distances and durations. Stickers were placed on the material during the tests to show the effects on the exposed material compared to the material in the shadow of the sticker. No aging could be demonstrated despite exposure for several tens of hours.

Figure 1 – Overview of the test lab

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UVC & Polymers Version A1

Figure 2 – Close-up view & distances in Cm

Figure 3 – Scratchers indicate no impact

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4 Conclusions

These tests have not been reproduced on pipettes, which seem to accumulate all the sensitivities. Indeed, if they are Pasteur pipettes, they are made of transparent polyethylene and therefore fall into the categories of fragile polymers, without pigment and with a high elasticity. The aging of this type of material does not reflect the impact that other materials will undergo.

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