scholarly journals Durability of flax/bio-based epoxy composites intended for structural strengthening

2018 ◽  
Vol 199 ◽  
pp. 07014
Author(s):  
Karim Benzarti ◽  
Robert Chlela ◽  
Wendlamita Zombré ◽  
Marc Quiertant ◽  
Laurence Curtil
Keyword(s):  
Natural Fibers ◽  
Adhesive Bond ◽  
Tensile Tests ◽  
Accelerated Ageing ◽  
Scanning Calorimetry ◽  
Major Drawback ◽  
Sorption Behaviour ◽  
Frp Composites ◽  
Externally Bonded ◽  
Interlaminar Shear

Environmentally friendly FRP composites, made of natural fibres and bio-based polymer matrices, may be used as externally bonded reinforcement for civil structures or buildings subjected to moderate outdoor conditions, in replacement of traditional carbon/epoxy systems. However, a major drawback of natural fibers is their sensitivity to moisture, which can affect both the mechanical properties of FRP composites and their adhesive bond with concrete. This research, funded by the French National Research Agency (ANR Project MICRO), aims at studying the influence of hygrothermal ageing on the performances of “green composites” manufactured by hand lay-up process using unidirectional flax fabrics and a bio-based epoxy matrix. The test program consists in subjecting FRP laminates and FRP strengthened concrete slabs to accelerated ageing conditions under various combinations of temperature and humidity. Aged laminates are then periodically characterized by tensile tests and interlaminar shear tests, while the bond properties of concrete/composite assemblies are assessed by pull-off tests. This paper presents the first results of this ongoing program which is scheduled over a period of 2 years. Results are discussed in the light of complementary investigations (water sorption behaviour, microscopic observations and evaluation of the glass transition temperature by differential scanning calorimetry – DSC) in order to relate observed performance evolutions to actual microstructural changes or damage processes taking place in the material.

Experimental Response of RC Beams Strengthened in Shear by FRP Sheets

2013 ◽  
Vol 7 (1) ◽  
pp. 127-135 ◽  
Author(s):  
E. Grande ◽  
M. Imbimbo ◽  
A. Rasulo
Keyword(s):  
Slenderness Ratio ◽  
Shear Capacity ◽  
Rc Beams ◽  
Fiber Reinforced Plastic ◽  
Frp Composites ◽  
Reinforced Plastic ◽  
Externally Bonded ◽  
Experimental Response ◽  
Transverse Steel ◽  
Cracking Pattern

The paper discusses the results of an experimental investigation carried out on reinforced concrete (RC) beams strengthened in shear by externally bonded fiber reinforced plastic (FRP) sheets. The study is devoted to analyze the role that the transverse steel reinforcement and the beam slenderness ratio could play on the resistant mechanism of RC beams strengthened in shear by FRP composites. The results are summarized and analyzed in detail in the paper in terms of shear capacity, cracking pattern and shear resisting contribution of FRP.

scholarly journals Wastes from Agricultural Silage Film Recycling Line as a Potential Polymer Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1383
Author(s):  
Jerzy Korol ◽  
Aleksander Hejna ◽  
Klaudiusz Wypiór ◽  
Krzysztof Mijalski ◽  
Ewelina Chmielnicka
Keyword(s):  
Vinyl Acetate ◽  
Thermal Performance ◽  
Mechanical Performance ◽  
Ethylene Vinyl Acetate ◽  
Tensile Tests ◽  
Solid Particles ◽  
Polymer Materials ◽  
Slight Reduction ◽  
Scanning Calorimetry ◽  
Crystallinity Degree

The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.

scholarly journals Characterization of Beeswax, Candelilla Wax and Paraffin Wax for Coating Cheeses

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 261
Author(s):  
Adolfo Bucio ◽  
Rosario Moreno-Tovar ◽  
Lauro Bucio ◽  
Jessica Espinosa-Dávila ◽  
Francisco Anguebes-Franceschi
Keyword(s):  
Physical And Mechanical Properties ◽  
Tensile Tests ◽  
Paraffin Wax ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Absorption Bands ◽  
Dimensional Changes ◽  
Ductile Behavior ◽  
Candelilla Wax

A study on the physical and mechanical properties of beeswax (BW), candelilla wax (CW), paraffin wax (PW) and blends was carried out with the aim to evaluate their usefulness as coatings for cheeses. Waxes were analyzed by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), permeability, viscosity, flexural and tensile tests and scanning electron microscopy. Cheeses were coated with the waxes and stored for 5 weeks at 30 °C. Measured parameters were weight, moisture, occurrence and degree of fractures, and dimensional changes. The crystal phases identified by XRD for the three waxes allowed them to determine the length of alkanes and the nonlinear compounds in crystallizable forms in waxes. FTIR spectra showed absorption bands between 1800 and 800 cm−1 related to carbonyls in BW and CW. In DSC, the onset of melting temperature was 45.5 °C for BW, and >54 °C for CW and PW. Cheeses coated with BW did not show cracks after storage. Cheeses coated with CW and PW showed microcraks, and lost weight, moisture and shrunk. In the flexural and tensile tests, BW was ductile; CW and PW were brittle. BW blends with CW or PW displays a semi ductile behavior. Cheeses coated with BW blends lost less than 5% weight during storage. The best waxes were BW and the blends.

scholarly journals Metallization of Thermoplastic Polymers and Composites 3D Printed by Fused Filament Fabrication

Technologies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 49
Author(s):  
Alessia Romani ◽  
Andrea Mantelli ◽  
Paolo Tralli ◽  
Stefano Turri ◽  
Marinella Levi ◽  
...  
Keyword(s):  
Physical Vapor Deposition ◽  
Test Sample ◽  
Tensile Tests ◽  
Layer By Layer ◽  
Post Processing ◽  
Thermoplastic Polymers ◽  
Fused Filament Fabrication ◽  
Scanning Calorimetry ◽  
3D Printed ◽  
Manufacturing Technologies

Fused filament fabrication allows the direct manufacturing of customized and complex products although the layer-by-layer appearance of this process strongly affects the surface quality of the final parts. In recent years, an increasing number of post-processing treatments has been developed for the most used materials. Contrarily to other additive manufacturing technologies, metallization is not a common surface treatment for this process despite the increasing range of high-performing 3D printable materials. The objective of this work is to explore the use of physical vapor deposition sputtering for the chromium metallization of thermoplastic polymers and composites obtained by fused filament fabrication. The thermal and mechanical properties of five materials were firstly evaluated by means of differential scanning calorimetry and tensile tests. Meanwhile, a specific finishing torture test sample was designed and 3D printed to perform the metallization process and evaluate the finishing on different geometrical features. Furthermore, the roughness of the samples was measured before and after the metallization, and a cost analysis was performed to assess the cost-efficiency. To sum up, the metallization of five samples made with different materials was successfully achieved. Although some 3D printing defects worsened after the post-processing treatment, good homogeneity on the finest details was reached. These promising results may encourage further experimentations as well as the development of new applications, i.e., for the automotive and furniture fields.

scholarly journals Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1242
Author(s):  
Olga Mysiukiewicz ◽  
Paulina Kosmela ◽  
Mateusz Barczewski ◽  
Aleksander Hejna
Keyword(s):  
Mechanical Properties ◽  
Melt Flow Index ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Metal Composites ◽  
Pre Treatment ◽  
The Impact ◽  
Properties Of Composites

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

NON-DESTRUCTIVE EVALUATION OF MECHANICAL DAMAGE OF ADHESIVES USING MAGNETO-ELECTRIC NANOPARTICLES

2021 ◽  
Author(s):  
GONZALO SEISDEDOS ◽  
BRIAN HERNANDEZ ◽  
JULIETTE DUBON ◽  
MARIANA ONTIVEROS ◽  
BENJAMIN BOESL ◽  
...  
Keyword(s):  
Adhesive Joint ◽  
Adhesive Bonding ◽  
Mechanical Damage ◽  
Adhesive Bond ◽  
Tensile Tests ◽  
Adhesive Joints ◽  
Adhesive Bonds ◽  
Magnetic Signatures ◽  
Looper System ◽  
Lock In

Adhesive bonding has been shown to successfully address some of the main problems with traditional fasteners, such as the reduction of the overall weight and a more uniformly distributed stress state. However, due to the unpredictability of failure of adhesive bonds, their use is not widely accepted in the aerospace industry. Unlike traditional fastening methods, it is difficult to inspect the health of an adhesive joint once it has been cured. For adhesive bonding to be widely accepted and implemented, there must be a better understanding of the fracture mechanism of the adhesive joints, as well as a way to monitor the health of the bonds nondestructively. Therefore, in-field structural health monitoring is an important tool to ensure optimal condition of the bond is present during its lifetime. This project focuses on the advancement of a non-invasive field instrument for evaluation of the health of the adhesive joints. The tool developed is based on a B-H looper system where coils are arranged into a noise-cancellation configuration to measure the magnetic susceptibility of the samples with a lock-in amplifier. The B-H looper system can evaluate the state of damage in an adhesive bond by detecting changes in surface charge density at the molecular level of an epoxy-based adhesive doped with magneto-electric nanoparticles (MENs). Epoxy-based adhesive samples were doped with MENs and then scanned using the B-H looper system. To evaluate the health of the adhesive joint, microindentation and tensile tests were performed on MENs-doped adhesive samples to understand the relationship between mechanical damage and magnetic signal. Correlations between magnetic signatures and mechanical damage were minimally observed, thus future studies will focus on refining the procedure and damaging methodology.

Enhancing the Thermal and Mechanical Characteristics of Polyvinyl Alcohol (PVA)-Hemp Protein Particles (HPP) Composites

2021 ◽  
Vol 36 (2) ◽  
pp. 137-143
Author(s):  
S. A. Awad
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Composite Films ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Solution Casting Method ◽  
Protein Particles

Abstract This paper aims to describe the thermal, mechanical, and surface properties of a PVA/HPP blend whereby the film was prepared using a solution casting method. The improvements in thermal and mechanical properties of HPP-based PVA composites were investigated. The characterization of pure PVA and PVA composite films included tensile tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of TGA and DSC indicated that the addition of HPP increased the thermal decomposition temperature of the composites. Mechanical properties are significantly improved in PVA/HPP composites. The thermal stability of the PVA composite increased with the increase of HPP filler content. The tensile strength increased from 15.74 ± 0.72 MPa to 27.54 ± 0.45 MPa and the Young’s modulus increased from 282.51 ± 20.56 MPa to 988.69 ± 42.64 MPa for the 12 wt% HPP doped sample. Dynamic mechanical analysis (DMA) revealed that at elevated temperatures, enhanced mechanical properties because of the presence of HPP was even more noticeable. Morphological observations displayed no signs of agglomeration of HPP fillers even in composites with high HPP loading.

Initial properties and ageing behaviour of pineapple leaf and palm fibre as reinforcement for polypropylene

2016 ◽  
Vol 30 (2) ◽  
pp. 174-195 ◽  
Author(s):  
Rungsima Chollakup ◽  
Haroutioun Askanian ◽  
Florence Delor-Jestin
Keyword(s):  
Mechanical Properties ◽  
Cost Effective ◽  
Tensile Tests ◽  
Natural Fibre ◽  
Thermal Ageing ◽  
Second Step ◽  
Scanning Calorimetry ◽  
Ultraviolet Exposure ◽  
Palm Fibre

In the furniture, automotive and contruction industries, there is increased demand for cost-effective and lightweight biocomposites. The objective of this work was to develop new natural fibre-based composites with specific properties. Palm and pineapple leaf fibres were chosen in association with polypropylene (PP). The first step was to investigate the effect of these natural fibres as reinforcement for PP. The evolution of chemical structure and crystallinity was proposed with infrared spectroscopy measurements and differential scanning calorimetry thermograms, respectively. The assessments of mechanical properties with tensile tests and melt viscoelastic behaviour were also investigated. The study enabled to distinguish the influence of fibre content. The second step in our work was to assess the composite durability after ultraviolet exposure or thermal ageing. The oxidation level was calculated. The long-term evolution of thermal and mechanical properties was also proposed. As a result, the PP/pineapple leaf composite revealed a promising biocomposite.

Performance of All-Polypropylene Composites at LNG Temperatures

2017 ◽  
Author(s):  
Bilim Atli-Veltin
Keyword(s):  
Composite Materials ◽  
Mechanical Performance ◽  
Cost Effective ◽  
Tensile Tests ◽  
Small Scale ◽  
Failure Behavior ◽  
Polypropylene Composites ◽  
Design Flexibility ◽  
Static Tensile ◽  
Interlaminar Shear

In the small scale LNG infrastructure, composite materials are scarcely employed. Potentially, cost effective solutions for LNG applications could be developed thanks to the advantages of composite materials over metals such as weight savings, design flexibility and recyclability. The research presented in this paper focuses on the mechanical performance of fully recyclable, thermoplastic Polypropylene (PP) composite tapes at cryogenic LNG temperatures. Quasi-static tensile tests performed on [±45] laminates made of plain woven plies of PURE® show that at −196°C the behavior is bilinear with the failure strain of 6.5% and failure stress of 37 MPa. Such non-brittle failure behavior of PP is desirable for cryogenic applications. The other results presented in the paper contains [0/90] laminate results and the interlaminar shear strength characteristics at room and cryogenic temperatures.

scholarly journals CHARACTERISATION OF INCLUSION COMPLEXES BETWEEN BIFONAZOLE AND DIFFERENT CYCLODEXTRINS IN SOLID AND SOLUTION STATE

2017 ◽  
Vol 36 (1) ◽  
pp. 81 ◽  
Author(s):  
Hajnal Kelemen ◽  
Angella Csillag ◽  
Gabriel Hancu ◽  
Blanka Székely-Szentmiklósi ◽  
Ibolya Fülöp ◽  
...  
Keyword(s):  
Inclusion Complexes ◽  
Binary Systems ◽  
Pharmaceutical Formulations ◽  
2D Nmr ◽  
Local Drug Delivery ◽  
Stable Complex ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
2D Nmr Spectroscopy ◽  
Major Drawback

The aim of this study is to confirm the formation of inclusion complexes between bifonazole (BFZ) and different cyclodextrin (CD) derivatives. Bifonazole, an imidazole antifungal derivative,is a very hydrophobic compound, which is a major drawback in obtaining topical pharmaceutical formulations with optimal bioavailability. Cyclodextrins may increase local drug delivery by enhancing the drug release and/or permeation. The binary systems between bifonazole and cyclodextrins were prepared in two molar ratios by physical-mixture methods.The physicochemical properties of these complexes were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) methods. Results showed favourable molecular interaction between the components, in solid state and in solution. 1H NMR -CD titrations and molecular modelling study showed that the most stable complex was obtained when using γ-CD. The Job’s method and 2D NMR spectroscopy sustain the 2:1 stoichiometry of the BFZ:γ-CD complex.

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