scholarly journals On the Multi-Functional Behavior of Graphene-Based Nano-Reinforced Polymers

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5828
Author(s):  
Konstantina Zafeiropoulou ◽  
Christina Kostagiannakopoulou ◽  
Anna Geitona ◽  
Xenia Tsilimigkra ◽  
George Sotiriadis ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Impact Resistance ◽  
Reinforced Polymers ◽  
Impact Performance ◽  
Impact Tests ◽  
Weight Content ◽  
Roll Mill ◽  
Doped Polymers ◽  
The Impact

The objective of the present study is the assessment of the impact performance and the concluded thermal conductivity of epoxy resin reinforced by layered Graphene Nano-Platelets (GNPs). The two types of used GNPs have different average thicknesses, <4 nm for Type 1 and 9–12 nm for Type 2. Graphene-based polymers containing different GNP loading contents (0.5, 1, 5, 10, 15 wt.%) were developed by using the three-roll mill technique. Thermo-mechanical (Tg), impact tests and thermal conductivity measurements were performed to evaluate the effect of GNPs content and type on the final properties of nano-reinforced polymers. According to the results, thinner GNPs were proven to be more promising in all studied properties when compared to thicker GNPs of the same weight content. More specifically, the glass transition temperature of nano-reinforced polymers remained almost unaffected by the GNPs inclusion. Regarding the impact tests, it was found that the impact resistance of the doped materials increased up to 50% when 0.5 wt.% Type 1 GNPs were incorporated within the polymer. Finally, the thermal conductivity of doped polymers with 15 wt.% GNPs showed a 130% enhancement over the reference material.

scholarly journals Impact Resistance of Epoxy Composites Reinforced with Amazon Guaruman Fiber: A Brief Report

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2264
Author(s):  
Raphael H. M. Reis ◽  
Fabio C. Garcia Filho ◽  
Larissa F. Nunes ◽  
Veronica S. Candido ◽  
Alisson C. R. Silva ◽  
...  
Keyword(s):  
Fiber Composite ◽  
Impact Resistance ◽  
Fiber Composites ◽  
Epoxy Composites ◽  
Impact Performance ◽  
Electron Microscopy Analysis ◽  
Ballistic Properties ◽  
Microscopy Analysis ◽  
Izod Impact ◽  
The Impact

Fibers extracted from Amazonian plants that have traditionally been used by local communities to produce simple items such as ropes, nets, and rugs, are now recognized as promising composite reinforcements. This is the case for guaruman (Ischinosiphon körn) fiber, which was recently found to present potential mechanical and ballistic properties as 30 vol% reinforcement of epoxy composites. To complement these properties, Izod impact tests are now communicated in this brief report for similar composites with up to 30 vol% of guaruman fibers. A substantial increase in impact resistance, with over than 20 times the absorbed energy for the 30 vol% guaruman fiber composite, was obtained in comparison to neat epoxy. These results were statistically validated by Weibull analysis, ANOVA, and Tukey’s test. Scanning electron microscopy analysis disclosed the mechanisms responsible for the impact performance of the guaruman fiber composites.

scholarly journals Effect of Thermal Ageing on the Impact Damage Resistance and Tolerance of Carbon-Fibre-Reinforced Epoxy Laminates

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 160 ◽  
Author(s):  
Irene García-Moreno ◽  
Miguel Caminero ◽  
Gloria Rodríguez ◽  
Juan López-Cela
Keyword(s):  
Carbon Fibre ◽  
Residual Strength ◽  
Composite Structures ◽  
Impact Resistance ◽  
Thermal Ageing ◽  
Low Velocity Impact ◽  
Impact Tests ◽  
Compression After Impact ◽  
Structural Applications ◽  
The Impact

Composite structures are particularly vulnerable to impact, which drastically reduces their residual strength, in particular, at high temperatures. The glass-transition temperature (Tg) of a polymer is a critical factor that can modify the mechanical properties of the material, affecting its density, hardness and rigidity. In this work, the influence of thermal ageing on the low-velocity impact resistance and tolerance of composites is investigated by means of compression after impact (CAI) tests. Carbon-fibre-reinforced polymer (CFRP) laminates with a Tg of 195 °C were manufactured and subjected to thermal ageing treatments at 190 and 210 °C for 10 and 20 days. Drop-weight impact tests were carried out to determine the impact response of the different composite laminates. Compression after impact tests were performed in a non-standard CAI device in order to obtain the compression residual strength. Ultrasonic C-scanning of impacted samples were examined to assess the failure mechanisms of the different configurations as a function of temperature. It was observed that damage tolerance decreases as temperature increases. Nevertheless, a post-curing process was found at temperatures below the Tg that enhances the adhesion between matrix and fibres and improves the impact resistance. Finally, the results obtained demonstrate that temperature can cause significant changes to the impact behaviour of composites and must be taken to account when designing for structural applications.

scholarly journals Experimental Tests and Reliability Analysis of the Cracking Impact Resistance of UHPFRC

Fibers ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 74
Author(s):  
Hussain A. Jabir ◽  
Sallal R. Abid ◽  
Gunasekaran Murali ◽  
Sajjad H. Ali ◽  
Sergey Klyuev ◽  
...  
Keyword(s):  
High Performance ◽  
Steel Fiber ◽  
Impact Resistance ◽  
High Strength ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Fiber Types ◽  
Impact Performance ◽  
High Performance Fiber ◽  
The Impact

Ultra-high performance (UHP) concrete is a special type of fibrous cementitious composite that is characterized by high strength and superior ductility, toughness, and durability. This research aimed to investigate the resistance of ultra-high performance fiber-reinforced concrete (UHPFRC) against repeated impacts. An adjusted repeated drop mass impact test was adopted to evaluate the impact performance of 72 UHPFRC disc specimens. The specimens were divided into six mixtures each of 12 discs. The only difference between the mixtures was the types of fibers used, while all other mixture components were the same. Three types of fibers were used: 6 mm micro-steel, 15 mm micro-steel, and polypropylene. All mixtures included 2.5% volumetric content of fibers, however with different combinations of the three fiber types. The test results showed that the mixtures with the 15 mm micro-steel fiber absorbed a higher number of impact blows until cracking compared to other mixtures. The mixture with pure 2.5% of 15 mm micro-steel fiber exhibited the highest impact resistance, with percentage increases over the other mixtures ranging from 25 to 140%. In addition, the Weibull distribution was used to investigate the cracking impact resistance of UHP at different levels of reliability.

Study of the Impact Performance of Solder Joints by High-Velocity Impact Tests

2010 ◽  
Vol 39 (12) ◽  
pp. 2536-2543 ◽  
Author(s):  
Ning Zhang ◽  
Yaowu Shi ◽  
Fu Guo ◽  
Fuqian Yang
Keyword(s):  
High Velocity ◽  
Solder Joints ◽  
High Velocity Impact ◽  
Velocity Impact ◽  
Impact Performance ◽  
Impact Tests ◽  
The Impact

Flexural and Creep Performances of Wood Fiber Reinforced Polymer Composite

2016 ◽  
Vol 850 ◽  
pp. 91-95
Author(s):  
Yan Cao ◽  
Wei Hong Wang ◽  
Hai Long Xu ◽  
Qing Wen Wang
Keyword(s):  
Wood Fiber ◽  
Impact Resistance ◽  
Fiber Reinforced Polymer ◽  
Creep Recovery ◽  
Fiber Reinforced ◽  
Impact Performance ◽  
Reinforced Polymer ◽  
Fiber Size ◽  
Resistance Performance ◽  
The Impact

In order to optimize the size of wood fiber reinforced polymer, and extend the application field of wood fiber reinforced polymer composites and improve the safety of their use, four size of wood fiber reinforced high-density polyethylene (HDPE) composites were prepared by forming mat-compression molding. The four kinds of fibers of different size include 80-120 mesh, 40-80 mesh, 20-40 mesh and 10-20 mesh fibers. The flexural performance, impact resistance performance and 24 hours creep - 24 hours recovery of the composites are studied. Fiber of 20-40 mesh presents the best flexural and impact resistance performance. The flexural strength, the elastic modulus and the impact strength reach 26.71MPa, 2.73Gpa and 6.88 KJ/m2 respectively. The impact performance of wood fiber/HDPE composites do not change a lot, while the fiber size increases from 10 to 80 mesh. However, the composites containing 80-120 mesh fibers has minimum impact performance. The creep performance of the wood fiber/HDPE composites with 80-120 mesh is the worst. After 24h creep test, the strain of the other three groups is almost the same. Creep recovery of the composites reinforced with 40-80 mesh fiber is the worst (61.74%). The creep recovery of the other three is above seven percent. Therefore, excessively large or small fiber size proves to be negative to improve the mechanical and creep performance, and polymer composites reinforced by them are not suitable for work under long-term load.

scholarly journals Enhanced Impact-Resistance of Aeronautical Quasi-Isotropic Composite Plates Through Diffused Water Molecules in Epoxy

2020 ◽  
Author(s):  
Furqan Ahmad ◽  
Fethi Abbassi ◽  
Mazhar Ul-Islam ◽  
Frédéric JACQUEMIN ◽  
Jung-Wuk Hong
Keyword(s):  
Carbon Fiber ◽  
Impact Resistance ◽  
Composite Plates ◽  
Hot Water ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Segmental Mobility ◽  
Impact Tests ◽  
Isotropic Composite ◽  
The Impact

Abstract In order to elucidate the hygroscopic effects on impact-resistance of carbon fiber/epoxy quasi-isotropic composite plates, low-velocity impact tests are conducted on dry and hygroscopically conditioned plates, respectively, under identical configurations. For the impact tests, plates were immersed in the hot water at 80 °C to absorb a different amount of moisture content (MC). Experimental results reveal that the presence of the MC plays a pivotal role by improving the impact-resistance of composite plates. Plates with higher percentage of MC could behave elastically to a larger strain, yielding larger deflection under impact loading. From SEM fractographies, it is observed that small disbanding grows at the interface of epoxy and carbon fiber due to absorbed MC. After absorbing MC, most of impact enegy is dissipated in hygroscopic conditioned composite plates throught elastic deformation and overall less damage is induced in wet composite plates compare to the dry plate. We can postulate that the presence of MC increases the elastic limit as well as ductility of the epoxy by promoting chain segmental mobility of the polymer molecules, which eventually leads to the enhancement of the impact-resistance of wet quasi-isotropic composite plates in comparison with the dry plate.

scholarly journals Impact Resistance and Sodium Sulphate Attack Testing of Concrete Incorporating Mixed Types of Recycled Plastic Waste

2021 ◽  
Vol 13 (17) ◽  
pp. 9521 ◽  
Author(s):  
Mahmoud Abu-Saleem ◽  
Yan Zhuge ◽  
Reza Hassanli ◽  
Mark Ellis ◽  
Md Mizanur Rahman ◽  
...  
Keyword(s):  
Transport Properties ◽  
Water Transport ◽  
Impact Resistance ◽  
Sodium Sulphate ◽  
Plastic Waste ◽  
Sulphate Attack ◽  
Impact Performance ◽  
Water Transport Properties ◽  
The Impact ◽  
Mixed Types

Impact resistance, water transport properties and sodium sulphate attack are important criteria to determine the performance of concrete incorporating mixed types of recycled plastic waste. Nine mixes were designed with different combinations of the three plastic types; Polyethylene terephthalate (PET), High density polyethylene (HDPE) and Polypropylene (PP). The plastic partially substituted the coarse aggregate (by volume) at various replacement ratios; 10%, 15%, 20% and 30%. The impact resistance and water transport properties were evaluated for nine mixes while sodium sulphate attack test was performed for three mixes. The results showed that the addition of mixed recycled plastic in concrete improved the impact resistance. The highest impact resistance improvement was achieved by R8 (PET + HDPE + PP) at 30% replacement which was 4.5 times better than the control mix. Water absorption results indicated a slight increase in all plastic mixes while contradictory results were observed for sorptivity test. Analysis of sodium sulphate attack results showed that incorporating 30% mixed plastic reduced the sodium sulphate resistance slightly due to the collective effect of plastic entrapping of sulphate ions after 80 cycles. This study has shown some positive results relating to the impact performance of Mixed Recycled Plastic Concrete (MRPC) which enhances its use in a sustainable way.

Influence of the Cellulose and Soft Wood Fibres on the Impact and Tensile Properties in Polypropylene Bio Composites

2021 ◽  
Vol 903 ◽  
pp. 134-139
Author(s):  
Jānis Zicans ◽  
Remo Merijs Meri ◽  
Tatjana Ivanova ◽  
Andrejs Kovalovs ◽  
Piotr Franciszczak
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Resistance ◽  
Tensile Modulus ◽  
Response Surfaces ◽  
Design Parameters ◽  
Cellulose Fibres ◽  
Highest Weight ◽  
Weight Content ◽  
The Impact

Investigation presents an experimental study of mechanical properties of hybrid bio-composites made from man-made cellulose fibres and soft wood microfiller embedded into polypropylene homopolymer matrix at different weight contents. Mechanical properties such as elastic modulus, tensile strength, and impact resistance of the reinforced composites determined for various total weight contents of both biobased fillers were used as the design parameters. The problem was solved by planning the experiments and response surfaces method. The results demonstrate that using the both filler types enhance the mechanical properties. The tensile modulus increases by ~115%. The bio-composite with the highest weight content of man-made cellulose fibres and the lowest content of soft wood microfibers possesses maximum tensile strength (more 66 MPa). Addition of man-made cellulose fibres demonstrate a significant influence on the impact resistance of the investigated composites.

Evaluation of Testing Uncertainties for the Impact Resistance of Machine Guards

2021 ◽  
Author(s):  
Luca Landi ◽  
Eckart Uhlmann ◽  
Robert Hoerl ◽  
Simon Thom ◽  
Giuseppe Gigliotti ◽  
...  
Keyword(s):  
Probabilistic Approach ◽  
Impact Resistance ◽  
Impact Testing ◽  
Ductile Material ◽  
Projectile Energy ◽  
Ballistic Limit ◽  
Worst Case ◽  
Impact Tests ◽  
Velocity Reduction ◽  
The Impact

Abstract Machine guards provide protection against ejection of parts during operation, such as chips or workpiece fragments. They are considered safe if the impact resistance is at least as high as the resulting projectile energy in the worst case of damage. To protect the machine operator, the impact resistance of machine guards is determined according to ISO standards. The bisection method can be used to determine the impact resistance through impact tests. However, this method is inaccurate for a small number of impact tests and does not provide an indication of uncertainties in the determination. Moreover, the result of testing is validated in different ways depending from the standard utilized for testing.Relevant uncertainties affecting impact testing and a new probabilistic approach for assessing the impact resistance using the Recht & Ipson equation are presented. With multiple impact tests at different initial velocities a Recht & Ipson best-fit curve and a confidence interval for a ballistic limit can be obtained, which is used to determine the impact resistance by defining a velocity reduction coefficient. This method can be applied to any machine guard made of ductile material. This paper validates the Recht & Ipson method by performing impact tests with a standardized 2.5 kg projectile on polycarbonate sheets of different thicknesses. Determination of the ballistic limit showed good agreement with experimental results. With the ballistic limits, the velocity reduction coefficients have been found to determine the impact resistances. Therefore, an alternative method for standardized tests to determine the impact resistance was found.

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