Mechanical Characterization of Core-Shell Rubber/Epoxy Polymers for Automotive Structural Adhesives as a Function of Operating Temperature

Automotive structural adhesives must show a steady toughness performance in the temperature range of −40 °C to 80 °C, considering their actual usage environments. Core-shell rubber (CSR) nanoparticles are known to enhance the toughness of epoxy systems. In this study, a CSR, pre-dispersed, diglycidyl epoxy of bisphenol A (DGEBA) mixture at 35 wt % (KDAD-7101, Kukdo Chemical, Seoul, Korea) was used as a toughener for an automotive structural epoxy adhesive system. A simple, single-component, epoxy system of DGEBA/dicyandiamide with a latent accelerator was adopted, where the CSR content of the system was controlled from 0 to 50 phr by the CSR mixture. To determine the curing conditions, we studied the curing behavior of the system by differential scanning calorimetry (DSC). Modulus variations of the cured bulk epoxies were studied using a dynamic mechanical analyzer (DMA) in the dual cantilever mode. The flexural modulus of the cured epoxies at various temperatures (−40, −10, 20, 50, and 80 °C) showed the same tendency as the DMA results, and as the flexural strength, except at 0 phr. On the other hand, the strain at break exhibited the opposite tendency to the flexural modulus. To study the adhesion behavior, we performed single-lap joint (SLJ) and impact wedge-peel (IWP) tests. As the CSR content increased, the strength of the SLJ and dynamic resistance to the cleavage of the IWP improved. In particular, the SLJ showed excellent strength at low temperatures (32.74 MPa at 50 phr @ −40 °C (i.e., an 190% improvement compared to 17.2 MPa at 0 phr @ −40 °C)), and the IWP showed excellent energy absorption at high temperatures (21.73 J at 50 phr @ 80 °C (i.e., a 976% improvement compared to 2.07 J at 0 phr @ 80 °C)). The results were discussed in relation to the changes in the properties of the bulk epoxy depending on the temperature and CSR content. The morphology of the fracture surface was also provided, which offered useful information for composition studies using the CSR/epoxy system.

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Star-shaped arylacetylene resins derived from silicon

Journal of Polymer Engineering ◽

10.1515/polyeng-2020-0083 ◽

2020 ◽

Vol 40 (8) ◽

pp. 676-684

Author(s):

Niping Dai ◽

Junkun Tang ◽

Manping Ma ◽

Xiaotian Liu ◽

Chuan Li ◽

...

Keyword(s):

High Performance ◽

Room Temperature ◽

Mechanical Test ◽

Flexural Modulus ◽

Mechanical Analysis ◽

Reinforced Composites ◽

Scanning Calorimetry ◽

Chemical Structures ◽

Structures And Properties ◽

High Performance Resin

AbstractStar-shaped arylacetylene resins, tris(3-ethynyl-phenylethynyl)methylsilane, tris(3-ethynyl-phenylethynyl) phenylsilane, and tris (3-ethynyl-phenylethynyl) silane (TEPHS), were synthesized through Grignard reaction between 1,3-diethynylbenzene and three types of trichlorinated silanes. The chemical structures and properties of the resins were characterized by means of nuclear magnetic resonance, fourier-transform infrared spectroscopy, Haake torque rheomoter, differential scanning calorimetry, dynamic mechanical analysis, mechanical test, and thermogravimetric analysis. The results show that the melt viscosity at 120 °C is lower than 150 mPa⋅s, and the processing windows are as wide as 60 °C for the resins. The resins cure at the temperature as low as 150 °C. The good processabilities make the resins to be suitable for resin transfer molding. The cured resins exhibit high flexural modulus and excellent heat-resistance. The flexural modulus of the cured TEPHS at room temperature arrives at as high as 10.9 GPa. Its temperature of 5% weight loss (Td5) is up to 697 °C in nitrogen. The resins show the potential for application in fiber-reinforced composites as high-performance resin in the field of aviation and aerospace.

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The influence of adding long basalt fiber on the mechanical and thermal properties of composites based on poly(oxymethylene)

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705718806549 ◽

2018 ◽

Vol 33 (4) ◽

pp. 435-450 ◽

Cited By ~ 4

Author(s):

Patrycja Bazan ◽

Stanisław Kuciel ◽

Mariola Sądej

Keyword(s):

Mechanical Properties ◽

Thermal Properties ◽

Average Length ◽

Flexural Modulus ◽

Basalt Fiber ◽

Charpy Impact ◽

Mechanical And Thermal Properties ◽

Gravimetric Analysis ◽

Scanning Calorimetry ◽

Atr Spectroscopy

The work has evaluated the possibility of the potential reinforcing of poly(oxymethylene) (POM) by basalt fibers (BFs) and influence of BFs addition on thermal properties. Two types of composites were produced by injection molding. There were 20 and 40 wt% long BFs content with an average length of 1 mm. The samples were made without using a compatibilizer. In the experimental part, the basic mechanical properties (tensile strength, modulus of elasticity, strain at break, flexural modulus, flexural strength, and deflection at 3.5% strain) of composites based on POM were determined. Tensile properties were also evaluated at three temperatures −20°C, 20°C, and 80°C. The density and Charpy impact of the produced composites were also examined. The influence of water absorption on mechanical properties was investigated. Thermal properties were conducted by the differential scanning calorimetry, thermal gravimetric analysis, and fourier transform infrared (FTIR)-attenuation total reflection (ATR) spectroscopy analysis. In order to make reference to the effects of reinforcement and determine the structure characteristics, scanning electron microscopy images were taken. The addition of 20 and 40 wt% by weight of fibers increases the strength and the stiffness of such composites by more than 30–70% in the range scale of temperature. Manufactured composites show higher thermal and dimensional stability in relation to neat POM.

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Optimization of Curing Conditions and Nanofiller Incorporation for Production of High Performance Laminated Kevlar/Epoxy Nanocomposites

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2018-85067 ◽

2018 ◽

Author(s):

Abdel-Hamid I. Mourad ◽

Mouza S. Al Mansoori ◽

Lamia A. Al Marzooqi ◽

Farah A. Genena ◽

Nizamudeen Cherupurakal

Keyword(s):

Oil And Gas ◽

Mechanical Performance ◽

Thermo Gravimetric Analysis ◽

Applied Pressure ◽

Curing Temperature ◽

Gravimetric Analysis ◽

Epoxy Nanocomposites ◽

Scanning Calorimetry ◽

Curing Conditions ◽

Weight Percentage

Kevlar composite materials are getting scientific interest in repairing of oil and gas pipelines in both offshore and onshore due to their unique properties. Curing is one of the major factor in deciding the final mechanical performance of laminated Kevlar/epoxy nanocomposites. The parameters such as curing time, temperature and applied pressure during the hot pressing will affect chemistry of crosslinking of the epoxy matrix and interaction of epoxy with the Kevlar fiber. The present study is carried out to evaluate the optimal curing conditions of the Kevlar/epoxy nanocomposites. Three different nanofillers (namely Multi walled Carbon nanotubes (MWCNT), Silicon Carbide (SiC) and Aluminum Oxide (Al2O3)) are incorporated in different weight percentage. Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA) tests are carried out to determine the thermal stability and optimal curing conditions. Mechanical performance is investigated by conducting flexure, and drop weight tests. The results show that, the optimal curing temperature for maximizing the mechanical properties is at 170°C. Peeling off the Kevlar layers are observed for nanocomposite samples cured under 100°C. Mechanical strength of the composites is enhanced by optimizing the curing conditions and nanofiller contents.

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The Effect of POSS Type on the Shape Memory Properties of Epoxy-Based Nanocomposites

Molecules ◽

10.3390/molecules25184203 ◽

2020 ◽

Vol 25 (18) ◽

pp. 4203

Author(s):

Avraham I. Bram ◽

Irina Gouzman ◽

Asaf Bolker ◽

Noam Eliaz ◽

Ronen Verker

Keyword(s):

Transition Temperature ◽

Shape Memory ◽

Crosslinking Density ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Space Environment ◽

Scanning Calorimetry ◽

Space Applications ◽

Curing Conditions ◽

Oligomeric Silsesquioxane

Thermally activated shape memory polymers (SMPs) can memorize a temporary shape at low temperature and return to their permanent shape at higher temperature. These materials can be used for light and compact space deployment mechanisms. The control of transition temperature and thermomechanical properties of epoxy-based SMPs can be done using functionalized polyhedral oligomeric silsesquioxane (POSS) additives, which are also known to improve the durability to atomic oxygen in the space environment. In this study, the influence of varying amounts of two types of POSS added to epoxy-based SMPs on the shape memory effect (SME) were studied. The first type contained amine groups, whereas the second type contained epoxide groups. The curing conditions were defined using differential scanning calorimetry and glass transition temperature (Tg) measurements. Thermomechanical and SME properties were characterized using dynamic mechanical analysis. It was found that SMPs containing amine-based POSS show higher Tg, better shape fixity and faster recovery speed, while SMPs containing epoxide-based POSS have higher crosslinking density and show superior thermomechanical properties above Tg. This work demonstrates how the Tg and SME of SMPs can be controlled by the type and amount of POSS in an epoxy-based SMP nanocomposite for future space applications.

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Preparation and Processing Characterization of Glass/Phenolic Prepregs

Polymers and Polymer Composites ◽

10.1177/096739111101900909 ◽

2011 ◽

Vol 19 (9) ◽

pp. 789-796 ◽

Cited By ~ 2

Author(s):

Mohammad Rajaei ◽

Mohammad Hosain Beheshty ◽

Mehran Hayaty

Keyword(s):

Differential Scanning Calorimetry ◽

Phenolic Resin ◽

Flexural Modulus ◽

Resin Flow ◽

Effective Parameters ◽

Scanning Calorimetry ◽

Cure Cycle ◽

Cure Behaviour ◽

Structural Parts

Glass/phenolic prepreg is one of the most applicable prepregs used for making composites for structural parts. To investigate the effective parameters on the processing and properties of these prepregs, thirty samples of glass/phenolic prepregs containing about 50 wt.% resins were prepared by using a resole type phenolic resin and satin glass fibre fabric. They were B-staged or pre-cured at 110 °C and 120 °C for different times from 15 to 50 min, to control the flow behaviour and tack properties. Tack and resin flow were characterized, in order to determine the conditions in which flow and tack properties are optimum. Results show that the levels of pre-cure or conversion were between 2% and 55%. The maximum tack was achieved at 5.3% conversion. Cure behaviour and rheological properties of these prepregs were studied by using differential scanning calorimetry and rheometry. An appropriate cure cycle is presented with the aid of these results. After curing the prepregs on the basis of this cure cycle, a flexural strength of 172.6 MPa and flexural modulus of 17 GPa were obtained.

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Controlled Release of Metformin Hydrochloride from Core-Shell Nanofibers with Fish Sarcoplasmic Protein

Medicina ◽

10.3390/medicina55100682 ◽

2019 ◽

Vol 55 (10) ◽

pp. 682 ◽

Cited By ~ 1

Author(s):

Sena ◽

Sumeyra ◽

Ulkugul ◽

Sema ◽

Betul ◽

...

Keyword(s):

Cell Attachment ◽

Metformin Hydrochloride ◽

Core Shell ◽

Order Kinetic ◽

Drug Release Profile ◽

Scanning Calorimetry ◽

Electrospinning Technique ◽

Sarcoplasmic Protein ◽

Enhance Cell Attachment ◽

Diabetic Wound Healing

Background and Objectives: A coaxial electrospinning technique was used to produce core/shell nanofibers of a polylactic acid (PLA) as a shell and a polyvinyl alcohol (PVA) containing metformin hydrochloride (MH) as a core. Materials and Methods: Fish sarcoplasmic protein (FSP) was extracted from fresh bonito and incorporated into nanofiber at various concentrations to investigate the influence on properties of the coaxial nanofibers. The morphology, chemical structure and thermal properties of the nanofibers were studied. Results: The results show that uniform and bead-free structured nanofibers with diameters ranging from 621 nm to 681 nm were obtained. A differential scanning calorimetry (DSC) analysis shows that FSP had a reducing effect on the crystallinity of the nanofibers. Furthermore, the drug release profile of electrospun fibers was analyzed using the spectrophotometric method. Conclusions: The nanofibers showed prolonged and sustained release and the first order kinetic seems to be more suitable to describe the release. MTT assay suggests that the produced drug and protein loaded coaxial nanofibers are non-toxic and enhance cell attachment. Thus, these results demonstrate that the produced nanofibers had the potential to be used for diabetic wound healing applications.

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Resistance to Cleavage of Core–Shell Rubber/Epoxy Composite Foam Adhesive under Impact Wedge–Peel Condition for Automobile Structural Adhesive

Polymers ◽

10.3390/polym11010152 ◽

2019 ◽

Vol 11 (1) ◽

pp. 152 ◽

Cited By ~ 6

Author(s):

Jong-Ho Back ◽

Dooyoung Baek ◽

Jae-Ho Shin ◽

Seong-Wook Jang ◽

Hyun-Joong Kim ◽

...

Keyword(s):

Pore Size ◽

Epoxy Composite ◽

Impact Resistance ◽

Expansion Ratio ◽

Core Shell ◽

Scanning Calorimetry ◽

Composite Foam ◽

Foaming Agent ◽

Epoxy Foam ◽

The Impact

Epoxy foam adhesives are widely used for weight reduction, watertight property, and mechanical reinforcement effects. However, epoxy foam adhesives have poor impact resistance at higher expansion ratios. Hence, we prepared an epoxy composite foam adhesive with core–shell rubber (CSR) particles to improve the impact resistance and applied it to automotive structural adhesives. The curing behavior and pore structure were characterized by differential scanning calorimetry (DSC) and X-ray computed tomography (CT), respectively, and impact wedge–peel tests were conducted to quantitatively evaluate the resistance to cleavage of the CSR/epoxy composite foam adhesives under impact. At 5 and 10 phr CSR contents, the pore size and expansion ratio increased sufficiently due to the decrease in curing rate. However, at 20 phr CSR content, the pore size decreased, which might be due to the steric hindrance effect of the CSR particles. Notably, at 0 and 0.1 phr foaming agent contents, the resistance to cleavage of the adhesives under the impact wedge–peel condition significantly improved with increasing CSR content. Thus, the CSR/epoxy composite foam adhesive containing 0.1 phr foaming agent and 20 phr CSR particles showed high impact resistance (EC = 34,000 mJ/cm2) and sufficient expansion ratio (~148%).

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Effect of Kenaf Alkalization Treatment on Morphological and Mechanical Properties of Epoxy/Silica/Kenaf Composite

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.35.22743 ◽

2018 ◽

Vol 7 (4.35) ◽

pp. 258 ◽

Cited By ~ 9

Author(s):

Che Nor Aiza Jaafar ◽

Muhammad Asyraf Muhammad Rizal ◽

Ismail Zainol

Keyword(s):

Mechanical Properties ◽

Sodium Hydroxide ◽

Mechanical Performance ◽

Flexural Modulus ◽

Charpy Impact ◽

Charpy Impact Test ◽

Curing Temperature ◽

Curing Process ◽

Scanning Calorimetry ◽

Kenaf Fiber

The mechanical performance of silica modified epoxy at various concentration of sodium hydroxide for surface treatment of multi-axial kenaf has been analyzed. Epoxy resin with amine hardener was modified with silica powder at 20 phr and toughened by treated kenaf fiber that immerses in various concentrations of sodium hydroxide (NaOH) ranging from 0% to 9% of weight. The composite was analyzed through differential scanning calorimetry (DSC) to ensure complete curing process. The mechanical properties of the composites were analyzed through flexural test, Charpy impact test and DSC to ensure the complete curing process. DSC analysis results show epoxy sample was completely cured at above 73°C that verifies the curing temperature for preparation for the composite. Hence, 3% NaOH treated composite exhibits the best mechanical properties, with 10.6 kJ/m2 of impact strength, 54.1 MPa of flexural strength and 3.5 GPa of flexural modulus. It is due to the improvement of fiber-matrix compatibility. Analysis by SEM also revealed that a cleaner surface of kenaf fiber treated at 3% NaOH shown cleaner surface, thus, in turn, improve surface interaction between fiber and matrix of the composite. The composites produced in this work has high potential to be used in automotive and domestics appliances.

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Mechanical Properties, Wettability and Thermal Degradation of HDPE/Birch Fiber Composite

Polymers ◽

10.3390/polym13091459 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1459

Author(s):

Agbelenko Koffi ◽

Fayçal Mijiyawa ◽

Demagna Koffi ◽

Fouad Erchiqui ◽

Lotfi Toubal

Keyword(s):

Mechanical Properties ◽

Differential Scanning Calorimetry ◽

Thermal Degradation ◽

Coupling Agent ◽

High Density Polyethylene ◽

Fiber Composite ◽

Flexural Modulus ◽

High Density ◽

Wood Fibers ◽

Scanning Calorimetry

Wood–plastic composites have emerged and represent an alternative to conventional composites reinforced with synthetic carbon fiber or glass fiber–polymer. A wide variety of wood fibers are used in WPCs including birch fiber. Birch is a common hardwood tree that grows in cool areas such as the province of Quebec, Canada. The effect of the filler proportion on the mechanical properties, wettability, and thermal degradation of high-density polyethylene/birch fiber composite was studied. High-density polyethylene, birch fiber and maleic anhydride polyethylene as coupling agent were mixed and pressed to obtain test specimens. Tensile and flexural tests, scanning electron microscopy, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetry analysis and surface energy measurement were carried out. The tensile elastic modulus increased by 210% as the fiber content reached 50% by weight while the flexural modulus increased by 236%. The water droplet contact angle always exceeded 90°, meaning that the material remained hydrophobic. The thermal decomposition mass loss increased proportional with the percentage of fiber, which degraded at a lower temperature than the HDPE did. Both the storage modulus and the loss modulus increased with the proportion of fiber. Based on differential scanning calorimetry, neither the fiber proportion nor the coupling agent proportion affected the material melting temperature.

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HIGH-IMPACT PP NANOCOMPOSITES: INFLUENCE OF CLAY CONTENT ON MECHANICAL AND THERMAL PROPERTIES

International Journal of Nanoscience ◽

10.1142/s0219581x13500397 ◽

2013 ◽

Vol 12 (06) ◽

pp. 1350039

Author(s):

L. G. FURLAN ◽

RICARDO V. B. OLIVEIRA ◽

ANDRÉIA C. E. MELLO ◽

SUSANA A. LIBERMAN ◽

MAURO A. S. OVIEDO ◽

...

Keyword(s):

Thermal Properties ◽

Impact Strength ◽

Flexural Modulus ◽

Clay Content ◽

Mechanical Analysis ◽

High Impact ◽

Mechanical And Thermal Properties ◽

Scanning Calorimetry ◽

Transmission Electron ◽

Izod Impact

The preparation of high-impact polypropylene nanocomposites with different organo-montmorillonite (O-MMT) contents by means of meltprocessing was investigated. The nanocomposite properties were evaluated by transmission electron microscopy (TEM), flexural modulus, izod impact strength, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was noticed that the PP/O-MMT nanocomposites properties were affected by clay content. Exceptional improvements in impact strength were obtained (maximum of 185%) by the use of low O-MMT content. The results showed that higher enhancement on mechanical/thermal properties was obtained by 3 wt.% of O-MMT instead of higher quantities.

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