scholarly journals Viscoelastic Polyurethane Foams with Reduced Flammability and Cytotoxicity

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 151
Author(s):  
Małgorzata Okrasa ◽  
Milena Leszczyńska ◽  
Kamila Sałasińska ◽  
Leonard Szczepkowski ◽  
Paweł Kozikowski ◽  
...  
Keyword(s):  
Polyurethane Foams ◽  
Test Results ◽  
Scanning Calorimetry ◽  
Simultaneous Reduction ◽  
Protective Devices ◽  
Respiratory Protective Devices ◽  
The Face ◽  
Foam Properties ◽  
Risk Of Exposure ◽  
The Impact

Consistent and proper use of respiratory protective devices (RPD) is one of the essential actions that can be taken to reduce the risk of exposure to airborne hazards, i.e., biological and nonbiological aerosols, vapours, and gases. Proper fit of the facepiece and comfort properties of RPDs play a crucial role in effective protection and acceptance of RPDs by workers. The objective of the present paper was to develop viscoelastic polyurethane foams for use in RPD seals characterised by proper elasticity, allowing for the enhancement of the device fit to the face and the capability of removing moisture from the skin in order to improve the comfort of RPD use. Moreover, it was pivotal to ensure the non-flammability of the foams, as well as a simultaneous reduction in their cytotoxicity. The obtained foams were characterised using scanning electron microscopy, infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. Measurements also involved gel fraction, apparent density, compression set, rebound resilience, wettability, flammability, and cytotoxicity. The results are discussed in the context of the impact of modifications to the foam formulation (i.e., flame-retardant type and content) on the desired foam properties. The test results set directions for future works aimed to develop viscoelastic polyurethane foams that could be applied in the design of respiratory protective devices.

Protective Efficiency of Filtering Respirators

2017 ◽  
Vol 25 ◽  
pp. 88-95
Author(s):  
Sergiy Cheberiachko ◽  
Olena Yavors’ka ◽  
Olena Stolbchenko ◽  
Dmytro Radchuk
Keyword(s):  
High Efficiency ◽  
Protective Device ◽  
Protective Efficiency ◽  
Protective Devices ◽  
Respiratory Protective Devices ◽  
The Face ◽  
The Relationship ◽  
Protective Effectiveness ◽  
Penetration Coefficient

In the article the dependence of protective efficiency of the respiratory protective devices on the filter penetration coefficient and leakage of the polluted air through sealing band was established. The leakage was determined by the ratio of the filter resistance and the sealing band. The relationship between increasing the filter resistance and worsening the protective effectiveness of respiratory protective device was established. Factors that worsen the respirator quality were determined: the gaps between the face and half-mask, weak tension of the head harness. Filter parameters that will ensure high efficiency for respirators of the second protection class were established.

The impact of dust in filter materials of respiratory protective devices on the microorganisms viability

2017 ◽  
Vol 58 ◽  
pp. 109-116 ◽  
Author(s):  
Katarzyna Majchrzycka ◽  
Małgorzata Okrasa ◽  
Justyna Szulc ◽  
Beata Gutarowska
Keyword(s):  
Protective Devices ◽  
Filter Materials ◽  
Respiratory Protective Devices ◽  
The Impact

THE IMPACT OF THE TYPE OF CUTTING FLUID ON THE TURNING PROCESS

Tribologia ◽  
2018 ◽  
Vol 273 (3) ◽  
pp. 119-126 ◽  
Author(s):  
Dariusz OZIMINA ◽  
Joanna KOWALCZYK ◽  
Monika MADEJ ◽  
Łukasz NOWAKOWSKI ◽  
Andrzej KULCZYCKI
Keyword(s):  
Cutting Tools ◽  
Mineral Oil ◽  
Cutting Fluid ◽  
Test Results ◽  
Turning Process ◽  
Surface Textures ◽  
The Face ◽  
Disc Configuration ◽  
The Impact ◽  
Ball On Disc

This article compares the test results concerning the wear of cutting tools after face turning under dry friction conditions and lubricated friction conditions with biodegradable cutting fluid or mineral-oil based emulsion. The turning was performed using a CTX 310 ECO machine tool. The wear of the cutting tools was measured by means of stereo zoom microscopy (SX80), while the elements were identified through scanning electron microscopy (JSM 7100F). The tribological tests were conducted for a ball-on-disc configuration in sliding contact using a T-01M tribometer. The surface textures of the face turned specimens were measured with a Talysurf CCI Lite optical profiler. The study also involved determining the foaming tendency and corrosive effects of both cutting fluids. The use of the biodegradable cutting fluid with low foaming tendency resulted in lower wear and higher corrosion resistance of the tool.

scholarly journals Application of Walnut Shells-Derived Biopolyol in the Synthesis of Rigid Polyurethane Foams

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2687 ◽  
Author(s):  
Sylwia Członka ◽  
Anna Strąkowska ◽  
Agnė Kairytė
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Characteristics ◽  
Cell Structure ◽  
Weight Ratio ◽  
Polyurethane Foams ◽  
Maximum Temperature ◽  
Walnut Shells ◽  
Foam Properties ◽  
The Fourier Transform ◽  
The Impact

This study aimed to examine rigid polyurethane (PUR) foam properties that were synthesized from walnut shells (WS)-based polyol. The Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the liquefaction of walnut shells was successfully performed. The three types of polyurethane (PUR) foams were synthesized by replacement of 10, 20, and 30 wt% of a petrochemical polyol with WS-based polyol. The impact of WS-based polyol on the cellular morphology, mechanical, thermal, and insulating characteristics of PUR foams was examined. The produced PUR foams had apparent densities from 37 to 39 kg m−3, depending on the weight ratio of WS-based polyol. PUR foams that were obtained from WS-based polyol exhibited improved mechanical characteristics when compared with PUR foams that were derived from the petrochemical polyol. PUR foams produced from WS-based polyol showed compressive strength from 255 to 310 kPa, flexural strength from 420 to 458 kPa, and impact strength from 340 to 368 kPa. The foams that were produced from WS-based polyol exhibited less uniform cell structure than foams derived from the petrochemical polyol. The thermal conductivity of the PUR foams ranged between 0.026 and 0.032 W m−1K−1, depending on the concentration of WS-based polyol. The addition of WS-based polyol had no significant influence on the thermal degradation characteristics of PUR foams. The maximum temperature of thermal decomposition was observed for PUR foams with the highest loading of WS-based polyol.

scholarly journals Changes in the Strength Properties and Phase Transition of Gypsum Modified with Microspheres, Aerogel and HEMC Polymer

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3486
Author(s):  
Justyna Ciemnicka ◽  
Karol Prałat ◽  
Artur Koper ◽  
Grzegorz Makomaski ◽  
Łukasz Majewski ◽  
...  
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Compressive Strength ◽  
Bending Strength ◽  
Strength Properties ◽  
Test Results ◽  
Strength Parameters ◽  
Scanning Calorimetry ◽  
Binding Material ◽  
The Impact

The paper presents an assessment of the impact of using additives on the strength of a binding material, i.e., building gypsum, and also the phase transformation that takes place in it. Microspheres, aerogel and polymer (HEMC) additives were added to a building gypsum slurry with a water to gypsum ratio of 0.75. In order to investigate their influence on bending strength, compressive strength, and the effect of high temperatures, differential scanning calorimetry (DSC), as well as tests of the multicomponent binder, were carried out in accordance with the applicable PN-EN 13279-2:2005 standard. The obtained test results allowed to determine that the used additives influenced the strength parameters of the obtained composites. It was shown that the applied additives decreased the compressive and bending strength of the modified gypsum. Despite these properties, the obtained gypsum materials are environmentally friendly because they reuse wastes, such as microspheres. Out of all the applied additives, the use of microspheres in an amount of 10% caused a decrease in the bending strength by only 10%, and an increase in the compressive strength by 4%.

scholarly journals Viscoelastic Polyurethane Foams for Use in Seals of Respiratory Protective Devices

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1600
Author(s):  
Małgorzata Okrasa ◽  
Milena Leszczyńska ◽  
Kamila Sałasińska ◽  
Leonard Szczepkowski ◽  
Paweł Kozikowski ◽  
...  
Keyword(s):  
Water Content ◽  
Apparent Density ◽  
Recovery Time ◽  
Elastic Recovery ◽  
Air Permeability ◽  
Polyurethane Foams ◽  
Time Compression ◽  
Protective Devices ◽  
Compression Set ◽  
Respiratory Protective Devices

A key factor in effective protection against airborne hazards, i.e., biological and nonbiological aerosols, vapors, and gases, is a good face fit of respiratory protective devices (RPDs). Equally important is the comfort of use, which may encourage or discourage users from donning RPDs. The objective of the work was to develop viscoelastic polyurethane foams for use in RPD seals. The obtained foams were characterized using scanning electron microscopy, infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. Measurements also involved gel fraction, apparent density, air permeability, elastic recovery time, compression set, rebound resilience, and sweat uptake. The results were discussed in the context of modifications to the foam formulation: the isocyanate index (INCO) in the range of 0.6–0.9 and the blowing agent content in the range of 1.2–3.0 php. FTIR analysis revealed a higher level of urea groups with increasing water content in the formulation. Higher INCO and water content levels also led to lower onset temperatures of thermal degradation and higher glass-transition temperatures of the soft phase. A decrease in apparent density and an increase in mean pore sizes of the foams with increasing INCO and water content levels was observed. Functional parameters (air permeability, elastic recovery time, compression set, rebound resilience, and sweat uptake) were also found to be satisfactory at lower INCO and water content levels.

scholarly journals Multifunctional Polymer Composites Produced by Melt-Blown Technique to Use in Filtering Respiratory Protective Devices

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 712 ◽  
Author(s):  
Agnieszka Brochocka ◽  
Aleksandra Nowak ◽  
Katarzyna Majchrzycka ◽  
Michał Puchalski ◽  
Sławomir Sztajnowski
Keyword(s):  
Production Method ◽  
Absorption Capacity ◽  
Respiratory Protection ◽  
Breathing Zone ◽  
Scanning Calorimetry ◽  
Protective Devices ◽  
Poly Ethylene Terephthalate ◽  
Respiratory Protective Devices ◽  
Poly Ethylene ◽  
Materials Used

In this work, a multifunctional polymer composite is made using melt-blowing technology from polypropylene (88 wt.%) and poly (ethylene terephthalate) (12 wt.%) with the addition of functional modifiers, that is, 3 g of a superabsorbent polymer and 5 g of a biocidal agent (Biohaloysite). The use of modifiers is aimed at obtaining adequate comfort when using the target respiratory protection equipment (RPE) in terms of microclimate in the breathing zone and protection against harmful aerosols including bioaerosols. The developed production method is innovative in that the two powdered modifiers are simultaneously applied in the stream of elementary polymeric fibers by two independent injection systems. Aerosols of the modifiers are supplied via a specially designed channel in the central segment of the die assembly, reducing the amount of materials used in the production process and saving energy. The results show that the proposed method of incorporating additives into the fiber structure did not adversely affect the protective and functional properties of the resulting filtration nonwovens. The produced nonwoven composites are characterized by SEM, FTIR, and differential scanning calorimetry (DSC). Given their high filtration efficiency at 5%, satisfactory airflow resistance (~200 Pa), very good antimicrobial activity, and excellent water absorption capacity, the obtained multifunctional nonwoven composites may be successfully used in filtering respiratory protective devices.

scholarly journals The use of the respiratory protective devices by the population during the COVID-19 pandemic

2021 ◽  
Vol 65 (6) ◽  
pp. 527-532
Author(s):  
Ekaterina A. Shashina ◽  
Denis V. Shcherbakov ◽  
Tatiana S. Isiutina-Fedotkova ◽  
Valentina V. Makarova ◽  
Vitaly A. Sukhov ◽  
...  
Keyword(s):  
Face Mask ◽  
Grocery Stores ◽  
Protective Equipment ◽  
Respiratory Protection ◽  
Protective Devices ◽  
Different Types ◽  
Respiratory Protective Devices ◽  
The Face ◽  
Almost All ◽  
Spread Of Infection

Introduction. Wearing a face mask is an important measure against spread of infection during the COVID-19 pandemic. The purpose of the study was to analyze various aspects of the face masks use by the population during the pandemic. The questioner was used. Results. Almost all respondents (96.4%) wore respiratory protective devices during the pandemic; 91.4% respondents worn face masks visiting grocery stores, pharmacies and medical organizations; 64.0% - visiting non-food trade facilities; 76.9% - travelling by surface transport, and 76.1% - being on the subway. Different types of face masks were used, 93.3% of respondents used disposable medical mask, 25.4% - reusable cloth masks. However, only 44.8% of respondents indicated that their protective equipment was made of non-woven material; 26.1% did not know how many layers their protective equipment contained; about a third of respondents (20.1% - 30.21%) were not able to assess the effectiveness of different types of respiratory protection. A third of the respondents (33.6%) wore a disposable medical mask for 2 hours, 35.2% - more than 2 hours in one day, 28.0% - for several days. Conclusions. Most of the respondents wore the face mask. Disposable medical masks were most commonly used. Requirements for the duration of wearing of face masks were met by about third of the respondents, for the handling - half of the respondents. Spontaneous choice of face mask by respondents confirms the importance of the development of hygiene guideline for choosing the most effective respiratory protection.

Particularities of the independent auditor's report on reliability of accounting (financial) statements for 2019: COVID-19 as qualitatively essential information (Part 2)

2020 ◽  
Vol 23 (7) ◽  
pp. 777-799
Author(s):  
O.I. Shvyreva ◽  
Z.I. Kruglyak ◽  
A.V. Petukh
Keyword(s):  
Financial Reporting ◽  
Financial Statements ◽  
Economic Situation ◽  
Risk Disclosure ◽  
Essential Information ◽  
Logical Method ◽  
Annual Reporting ◽  
The Face ◽  
Key Aspects ◽  
The Impact

Subject. This article discusses the issues related to the practice of financial reporting in the face of uncertainties caused by the coronavirus contagion, as well as the specifics of the audit strategy and formation of an audit opinion on this reporting. Objectives. The article aims to identify the quality characteristics of financial reporting prepared in the context of the COVID-19 pandemic and justify the key aspects of assurance engagement completion in an extremely uncertain epidemiological and economic situation. Methods. For the study, we used an abstract-logical method, content analysis techniques, systematization, and classification. Results. Analyzing the impact of the extremely uncertain epidemiological and economic situation on financial statements, the article clarifies aspects of disclosure of events after the reporting date and threats to business continuity in the annual reporting of economic entities. The article identifies possible alternative procedures and algorithms to obtain proper evidence when it is insufficient in the face of the inability to meet certain audit standards requirements in a remote audit environment. The article defines the impact of COVID-19 risk disclosure on the structure of the audit report and opinion. Relevance. The results of the study can be used in the practical activities of economic entities that prepare financial statements in the face of significant uncertainty, as well as auditors and audit organizations.

Safe development of business and national economy in the face of a pandemic and global recession

2020 ◽  
Vol 16 (6) ◽  
pp. 1182-1198
Author(s):  
I.V. Vyakina
Keyword(s):  
Economic Security ◽  
Global Recession ◽  
Graphical Visualization ◽  
National Economic ◽  
Business Support ◽  
The Face ◽  
The Russian Federation ◽  
Business Entities ◽  
Visualization Techniques ◽  
The Impact

Subject. This article deals with the issues related to the national economic security of the State in today's conditions. Objectives. The article aims to develop a set of special measures for additional business support to reduce the impact of restrictions imposed against the background of quarantine and the pandemic spread, and which would help prevent collapse of business entities. Methods. For the study, I used the methods of theoretical, systems, logical, and comparative analyses, and tabular and graphical visualization techniques. Results. The article proposes possible measures to support business aimed at reducing the costs of business entities due to the restrictions caused by the pandemic, that complement and explain the activities proposed by the President and Government of the Russian Federation, taking into account the regional and municipal levels. Conclusions. The uncertain current situation requires constant adjustment and adaptation of public policy in accordance with specific circumstances. Ensuring the country's economic security and sustainability associates with creation of a business organization system that connects public administration tools and business support and development opportunities under the changed environment.

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