Thermoplastique Degradation under Heat and Irradiation

2021 ◽  
Vol 904 ◽  
pp. 196-201
Author(s):  
Sonya Redjala ◽  
Said Azem ◽  
Nourredine Ait Hocine
Keyword(s):  
Mechanical Characteristics ◽  
Low Cost ◽  
Impact Resistance ◽  
Ultra Violet ◽  
Analytical Techniques ◽  
Mechanical Tests ◽  
Ultraviolet Rays ◽  
Technical Material ◽  
Effects Of Temperature ◽  
The Impact

The aim of the article is to highlight the effect of the environment on the properties of a polycarbonate (PC). It consists in aging this material under Ultra-violet (UV) combined with temperature for different periods of time, and to reveal the physicochemical and mechanical changes caused by aging. PC is a highly valued technical material for its various important characteristics and low cost. It finds its application in various fields but mainly in those whose requirements are the transparency and the impact resistance. The physicochemical and mechanicals characterizations of the marketed polycarbonate are necessary in order to highlight its intrinsic properties and to develop strategies that can improve its lifespan. In this work, we highlight the physicochemical and mechanical characteristics of virgin and aged polycarbonate. For this, analytical techniques and mechanical tests were used. A comparison of the characteristics revealed the combined effects of temperature and ultraviolet rays.

scholarly journals Towards Sustainable Concrete Composites through Waste Valorisation of Plastic Food Trays as Low-Cost Fibrous Materials

2021 ◽  
Vol 13 (4) ◽  
pp. 2073 ◽  
Author(s):  
Hossein Mohammadhosseini ◽  
Rayed Alyousef ◽  
Mahmood Md. Tahir
Keyword(s):  
Compressive Strength ◽  
Low Cost ◽  
Impact Resistance ◽  
Food Tray ◽  
World Population ◽  
Fibrous Materials ◽  
Palm Oil Fuel Ash ◽  
Waste Plastic ◽  
Compressive Strength Of Concrete ◽  
The Impact

Recycling of waste plastics is an essential phase towards cleaner production and circular economy. Plastics in different forms, which are non-biodegradable polymers, have become an indispensable ingredient of human life. The rapid growth of the world population has led to increased demand for commodity plastics such as food packaging. Therefore, to avert environment pollution with plastic wastes, sufficient management to recycle this waste is vital. In this study, experimental investigations and statistical analysis were conducted to assess the feasibility of polypropylene type of waste plastic food tray (WPFT) as fibrous materials on the mechanical and impact resistance of concrete composites. The WPFT fibres with a length of 20 mm were used at dosages of 0–1% in two groups of concrete with 100% ordinary Portland cement (OPC) and 30% palm oil fuel ash (POFA) as partial cement replacement. The results revealed that WPFT fibres had an adverse effect on the workability and compressive strength of concrete mixes. Despite a slight reduction in compressive strength of concrete mixtures, tensile and flexural strengths significantly enhanced up to 25% with the addition of WPFT fibres. The impact resistance and energy absorption values of concrete specimens reinforced with 1% WPFT fibres were found to be about 7.5 times higher than those of plain concrete mix. The utilisation of waste plastic food trays in the production of concrete makes it low-cost and aids in decreasing waste discarding harms. The development of new construction materials using WPFT is significant to the environment and construction industry.

scholarly journals A Molecular Dynamics Investigation of the Temperature Effect on the Mechanical Properties of Selected Thin Films for Hydrogen Separation

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 241
Author(s):  
Sunday Temitope Oyinbo ◽  
Tien-Chien Jen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Mechanical Characteristics ◽  
Loading Rate ◽  
Indentation Load ◽  
Nanoindentation Test ◽  
Film Hardness ◽  
Loading And Unloading ◽  
Effects Of Temperature ◽  
The Impact

In this study, we performed nanoindentation test using the molecular dynamic (MD) approach on a selected thin film of palladium, vanadium, copper and niobium coated on the vanadium substrate at a loading rate of 0.5 Å/ps. The thermosetting control is applied with temperature variance from 300 to 700 K to study the mechanical characteristics of the selected thin films. The effects of temperature on the structure of the material, piling-up phenomena and sinking-in occurrence were considered. The simulation results of the analysis and the experimental results published in this literature were well correlated. The analysis of temperature demonstrated an understanding of the impact of the behaviour. As the temperature decreases, the indentation load increases for loading and unloading processes. Hence, this increases the strength of the material. In addition, the results demonstrate that the modulus of elasticity and thin-film hardness decreases in the order of niobium, vanadium, copper and palladium as the temperature increases.

Solutions for hematocrit bias in dried blood spot hormone analysis

Bioanalysis ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 1293-1308
Author(s):  
Vera de Kleijne ◽  
Isabelle Kohler ◽  
Annemieke C Heijboer ◽  
Mariëtte T Ackermans
Keyword(s):  
Low Cost ◽  
Analytical Techniques ◽  
Dried Blood Spot ◽  
Significant Interest ◽  
Alternative Approaches ◽  
The Impact ◽  
Hormone Analysis ◽  
Blood Spot

Over the last years, dried blood spot (DBS) sampling has gained significant interest due to development of analytical techniques combined with DBS, the simplicity and low cost of the method. Despite its wide use, DBS sampling can lead to inaccurate results due to the impact of the hematocrit (Hct) on the analysis. Some analytes have shown to be hardly impacted by Hct values. However, in other cases, a significant impact of Hct is observed, which requires the use of alternative approaches to circumvent this issue. This review describes the possible impact of Hct-related bias in DBS sampling in the context of hormone analysis and discusses the different methodologies that can be used to overcome this bias to ensure accurate results.

Reconditioning by Welding of Rims Manufactured from Nonferrous Alloys

2014 ◽  
Vol 1029 ◽  
pp. 61-66 ◽  
Author(s):  
Nicoleta Bularda ◽  
Teodor Heput
Keyword(s):  
Automotive Industry ◽  
Mechanical Characteristics ◽  
Mechanical Tests ◽  
Base Metals ◽  
Adequate Quality ◽  
Nonferrous Alloys ◽  
The Impact ◽  
Unsprung Mass ◽  
Co Emission

At present, in the automotive industry, the trend on the world plane is to fit on the wheels with rims made from nonferrous alloys, based on aluminum, magnesium or titanium. These rims have the advantage that they are lighter than the same rims made from steel, reducing the unsprung mass of the vehicle, and increasing the vehicle performances, that lead to the better handling, the faster braking and the better acceleration. Also, by using the rims made from nonferrous alloys, the increasing of the fuel consumption efficiency and the reducing of the carbon monoxide (CO) emission are obtained. During the traffic, the wheels (rim + tyre) can be subjected to accidental collisions, such as the impact with the pavement, leading to damages of the rims, which must be reconditioned. The paper presents the results of structural examinations and mechanical tests, made on car rims made from nonferrous alloys, degraded and reconditioned by specific welding technologies. The structural and mechanical characteristics determined in the zones reconditioned by welding are at the level of the base metals used to made the investigated rims, that confirm the adequate quality of them, and a low risc to cracking.

Effect of adhesive interlayers on protective performance of bio-inspired building ceramic covering

2020 ◽  
Vol 23 (16) ◽  
pp. 3446-3455
Author(s):  
Yuyan Sun ◽  
Sheng Wang ◽  
Ziguo Wang
Keyword(s):  
Penetration Depth ◽  
Low Cost ◽  
Impact Resistance ◽  
Epoxy Adhesive ◽  
Building Ceramic ◽  
Ballistic Performance ◽  
Silicone Sealant ◽  
Brick And Mortar ◽  
Maximum Penetration ◽  
The Impact

The brick-and-mortar microstructure of nacre is usually considered as a source of inspiration for the development of strong and tough artificial materials. In this article, a nacre-inspired layered-and-staggered structural building ceramic protective covering was fabricated, and the effect of four types of adhesive materials on the ballistic performance of the protective covering was investigated through the ballistic test. The experimental results showed that under the impact of the 7.62-mm ordinary rifle bullet at a speed of 790–820 m/s, the average crater diameter in the concrete targets with protective covering was reduced by 40%–72%, and the penetration depth in the concrete was reduced by 70%–100%, compared with those of unprotected concrete targets. For the concrete targets with protective covering, that adopting the silicone sealant interlayers exhibited a smaller crater area but a maximum penetration depth, while that adopting the epoxy adhesive interlayers showed a larger crater area but a minimum penetration depth. Since the targets with the low-cost polyurethane sealant interlayers presented the smallest crater area and the shallower penetration depth, it can be concluded that the concrete with the protective covering using polyurethane sealant interlayers showed the better projectile impact resistance.

scholarly journals Effect of Wood Fiber Surface Treatment on the Properties of Recycled HDPE/Maple Fiber Composites

2021 ◽  
Vol 5 (7) ◽  
pp. 177
Author(s):  
Roberto C. Vázquez Fletes ◽  
Denis Rodrigue
Keyword(s):  
Surface Treatment ◽  
Low Cost ◽  
Flexural Modulus ◽  
Wood Fiber ◽  
Impact Resistance ◽  
Tensile Modulus ◽  
Fiber Surface ◽  
Treated Fiber ◽  
Fiber Surface Treatment ◽  
The Impact

This work reports on the production and characterization of recycled high density polyethylene (R-HDPE) composites reinforced with maple fibers. The composites were produced by a simple dry-blending technique followed by compression molding. Furthermore, a fiber surface treatment was performed using a coupling agent (maleated polyethylene, MAPE) in solution. FTIR, TGA/DTG, and density analyses were performed to confirm any changes in the functional groups on the fiber surface, which was confirmed by SEM-EDS. As expected, the composites based on treated fiber (TC) showed improved properties compared to composites based on untreated fiber (UC). In particular, MAPE was shown to substantially improve the polymer–fiber interface quality, thus leading to better mechanical properties in terms of tensile modulus (23%), flexural modulus (54%), tensile strength (26%), and flexural strength (46%) as compared to the neat matrix. The impact resistance also increased by up to 87% for TC as compared to UC. In addition, the maximum fiber content to produce good parts increased from 15 to 75 wt% when treated fiber was used. These composites can be seen as sustainable materials and possible alternatives for the development of low-cost building/construction/furniture applications.

scholarly journals Microbial degradation of polychlorinated biphenyls

2007 ◽  
Author(s):  
◽  
Shubnum Mustapha
Keyword(s):  
Polychlorinated Biphenyls ◽  
Microbial Degradation ◽  
Carbon Sources ◽  
Environmental Pollutants ◽  
Industrial Effluent ◽  
Ultra Violet ◽  
Analytical Techniques ◽  
Pcb Metabolites ◽  
The Impact ◽  
Layer Chromatography

The aromatic compounds Polychlorinated Biphenyls (PCBs) are one of the largest groups of environmental pollutants. The greatest concern is the release of PCBs in the water systems by industrial effluent, accidental spillages or leaks. PCBs are able to bioaccumulate in the fatty tissues of animals, fish and humans. The impact on human health due to PCBs has prompted interest in their degradation. The application of microbial degradation of PCBs can transform many PCB metabolites. There are a wide variety of microorganisms that can degrade PCBs or utilise them as sole carbon sources. This study focused on isolating microrganisms from industrial wastewater capable of aerobic degradation of PCBs. The degradation potential of the selected isolates were investigated by using different analytical techniques viz. ultra violet or visible spectrophotometer (UV/Vis), thin layer chromatography (TLC) and gas chromatography electron capture detector (GC-ECD).

scholarly journals Improving the Shock Resistance of Agricultural Composite Units Using Visco-Elastic Fluids

2020 ◽  
Vol 30 (2) ◽  
pp. 268-286
Author(s):  
Mikhail V. Astakhov ◽  
Ekaterina V. Slavkina
Keyword(s):  
Mechanical Characteristics ◽  
Layer Structure ◽  
Impact Resistance ◽  
Statistical Processing ◽  
Polymer Composite Material ◽  
Relative Deformation ◽  
Shock Loads ◽  
Additional Layer ◽  
Applied Forces ◽  
The Impact

Introduction. The use of composite materials in agricultural engineering is known as one of the recommended ways to reduce the weight of the structure and protect against corrosion. The main disadvantages of such products are their low resistance to shock loads that occur during operation. The aim of this study is to develop a glass composite multi-layer structure of the trailer side, capable of withstanding shock loads along with statically applied forces, without including additional reinforcing metal elements in the zones of the possible impacts. Materials and Methods. To increase the impact resistance of the product (after an analysis of modern design solutions) the use of visco-elastic non-Newtonian fluids based on polysilicon by introducing an additional layer into the power element to compensate for impact effects is proposed. Results. On the basis of laboratory testing using statistical processing of the obtained data, the basic mechanical characteristics of non-Newtonian fluid (polysilicon) during impact tests (density, Poisson’s ratio, Young’s modulus, shear modulus) are determined, and graphs of the obtained dependencies are constructed. The temperature of the tested polysilicon samples did not significantly affect their mechanical properties. It is established that starting from the value of relative deformation 0.042, during the impact polysilicon shows linearly elastic properties. Discussion and Conclusion. Based on the received mechanical characteristics, the conclusions about resistance to shock loads of polysilicon as a component of a trailer board element are made. The variant of arrangement of the trailer board structural solution as a multilayer sandwich element with external parts made of polymer composite material with internal filling with fiberglass cells and polysilicon placed in large cells is offered.

Intermediate Velocity Impact Response of Carbon/Epoxy Composites with Polycarbonate Facing

2003 ◽  
Vol 11 (6) ◽  
pp. 421-432 ◽  
Author(s):  
U.K. Vaidya ◽  
C.A. Ulven ◽  
M.V. Hosur ◽  
J. Alexander ◽  
L. Liudahl
Keyword(s):  
Composite Structures ◽  
Low Cost ◽  
Impact Resistance ◽  
Woven Fabrics ◽  
Impact Response ◽  
Woven Fabric ◽  
Velocity Impact ◽  
Out Of Autoclave ◽  
Processing Techniques ◽  
The Impact

Woven fabric composites are increasingly being used in composite structures for applications in the aircraft, marine, and automotive industries. With emerging low-cost processing techniques for composite materials, the role of fabric architectures in sustaining low, intermediate, and high velocity impact loads is a subject of interest. An example of a low-cost process is the out-of-autoclave, vacuum assisted resin transfer molding (VARTM) technique. The present study evaluates the intermediate velocity impact response of two commonly used structural carbon fabric laminates produced from plain and 2/2 twill woven fabrics, processed using VARTM. A series of impact tests have been performed on the all plain, all twill and hybrid plain-twill weave carbon/epoxy laminates. All laminates studied were covered with a polycarbonate facing in order to enhance the impact resistance of the carbon/epoxy laminates. The perforation mechanism, ballistic limit, and damage evolution of each laminate has been studied. The results from the experiments are reported.

PRODUÇÃO E CARACTERIZAÇÃO MECÂNICA DO COMPÓSITO DE POLIPROPILENO E CASCA DE EUCALIPTO

2017 ◽  
Vol 32 (4) ◽  
pp. 342
Author(s):  
Maria Beatriz Sartor ◽  
Helen De Matos Prosdocini ◽  
Maurício De Oliveira Gondak ◽  
Giovana Roberta Francisco Bronzato ◽  
Alcides Lopes Leão
Keyword(s):  
Maleic Anhydride ◽  
High Performance ◽  
New Technologies ◽  
Low Cost ◽  
Impact Resistance ◽  
Mechanical Tests ◽  
Natural Fibres ◽  
Forest Residues ◽  
Eucalyptus Bark

Em decorrência de preocupações ambientais, o desenvolvimento de novas tecnologias e materiais de alto desempenho vem sendo direcionado para o campo da sustentabilidade, com a utilização de recursos naturais e renováveis. Fibras vegetais estão sendo cada vez mais utilizadas como reforço em termoplásticos em virtude de seu baixo custo, altas propriedades específicas e natureza renovável. A adição de fibras naturais aos compostos poliméricos pode causar alteração nas suas propriedades, características e comportamento mecânico, por isso a necessidade de estudos que tratem da produção e caracterização destes materiais. O polipropileno (PP) modificado com anidrido maléico (PP-MAH) é o compatibilizante mais comumente utilizado para auxiliar na melhora da aderência interfacial entre as fibras de madeira (hidrofílicas) e o polipropileno (hidrofóbico). Sendo assim e, devido a versatilidade e aplicabilidade industrial dos compostos plásticos reforçados com fibras naturais,  o objetivo do presente trabalho foi a produção de um compósito polimérico constituído PP reforçado com casca de eucalipto para avaliação das propriedades mecânicas do material. Para tal, foram utilizadas três formulações para a produção do compósito: a primeira formulação foi composta por polipropileno com a adição de 20 % de casca de eucalipto, 5 % de látex e 2 % de anidrido maléico; a segunda foi composta por PP com 20% de casca de eucalipto, 2% de PP-MAH e 0 % de látex; a terceira formulação, composta por 100% de polipropileno. Os ensaios mecânicos realizados foram de resistência à tração, resistência à flexão e resistência ao impacto. O delineamento experimental utilizado foi o inteiramente casualizado (DIC) e os dados foram submetidos a análise de variância; as médias foram comparadas pelo ensaio de Tukey a 5% de probabilidade, utilizando-se o software Sisvar. Os resultados mostraram uma diminuição das propriedades de resistência a flexão e a tração nos compósitos que contém casca de eucalipto e um aumento nas propriedades de impacto quando comparadas ao PP puro.PALAVRAS-CHAVE: polímeros, resíduo florestal, agente compatibilizante. PRODUCTION AND MECHANICAL CHARACTERIZATION OF POLYPROPYLENE AND EUCALYPTUS BARK COMPOUNDABSTRACT: In consequence of environmental concerns, the development of new technologies and high-performance materials has been directed towards to the field of sustainability, through the use of natural and renewable resources. Natural fibres are increasingly used as reinforcement in thermoplastics because of their low cost, high specific properties and renewable source. The addition of natural fibres to polymeric compounds can cause changes in their properties, characteristics and mechanical behavior, therefore the need for studies that deal with the production and characterization of these materials. Polypropylene (PP) modified with maleic anhydride (PP-MAH) is the compatibilizer most commonly used to improve interfacial adhesion between wood (hydrophilic) fibers and polypropylene (hydrophobic). Thus, and due to the versatility and industrial applicability of the plastic compounds reinforced with natural fibres, the objective of the present work was the production of a polymer matrix composed of eucalyptus bark and PP to evaluate the mechanical properties of the composite. Therefore, three formulations were used to produce the composite: the first formulation was composed of polypropylene with the addition of 20% eucalyptus bark, 5% of latex and 2% of PP-MAH; for the second composition, it was used polypropylene with 20% of eucalyptus bark, 2% of  maleic anhydride and 0% of latex; the third formulation wascomposed of 100% polypropylene. The mechanical tests were of tensile and flexural strength and impact resistance. The experimental design was completely randomized and the data were submitted to analysis of variance; the means were compared by Tukey´s test at 5% probability, using the Sisvar software. According to the results, there is a decrease in flexural and tensile strength properties in composites containing eucalyptus bark and an increase in impact properties when compared to pure PP.KEYWORDS: polymers, forest residues, compatibilizing agent

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