Effect of functionalized elastomer addition on mechanical and interfacial properties of poly (butylene terephthalate)/glass fiber composites

In this study the effect of incorporation of ethylene‐co‐glycidylmethacrylate (GMA)‐co‐n‐butyl acrylate (nBA) terpolymer with an epoxy functional group, on the mechanical performance of short glass fiber (SGF)/Poly (butylene terephthalate) (PBT) composites has been investigated. Tensile test showed that incorporation of rubber phase in PBT/SGF composites results in loss of strength. However impact measurement exhibited an increase in impact strength with an increase in rubber content. Tensile and impact properties are discussed in terms of interfacial shear strength and morphology of composites. Morphological observation by SEM revealed a thin layer of polymer adhering to the surface of glass fibers indicating that epoxy functional group in the modifier reacts with fiber surface and PBT matrix. This reactivity of epoxy functional group is also supported by FTIR observations. The composites are also analyzed for % crystallinity using DSC and a strong correlation is found to exist between interfacial shear strength and % crystallinity. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Effect of hydroxyl content on the morphology and properties of epoxy/poly(styrene-co-allylalcohol) blends

Blends based on epoxy resin and random copolymers, poly(styrene-co-allylalcohol) (PS-co-PA), were studied. Two PS-co-PA copolymers, with different hydroxyl content, and a polyallylalcohol (PA) homopolymer were used to analyze the effect of polyalcohol content. The polymers presented similar values of molar mass. The miscibility of noncured mixtures and the thermal transition behavior of cured blends were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Its morphology was studied using both scanning and transmission electron microscopy (SEM and TEM). While the epoxy/PA blends are homogenous materials, because of the epoxy/hydroxyl reaction, PS-co-PA/epoxy blends shows separated phases. In these blends, the presence of a third glass transition, whose value is an intermediate between those of pure components, and the presence of a well-defined interfacial layer between PS-co-PA domains and epoxy matrix indicates a secondary epoxy/hydroxyl reaction. The modification of epoxy resin with PS-co-PA provides significant increase in the storage modulus measured by DMTA. POLYM. ENG. SCI., 47:1580–1588, 2007. © 2007 Society of Plastics Engineers     

Multilayered epoxy/glass fiber felt composites with excellently acoustical and thermal insulation properties

In this article, a series of epoxy composites consisting of multilayered ultra-fine glass fiber felts (GFFs) were produced by a hand lay-up process. The incorporation of GFFs greatly enhances the sound-absorption and sound-insulation properties of epoxy composites. It can be mainly attributed to great numbers of voids introduced into the matrix and the increasing interfacial area between glass fiber and epoxy resin, which is confirmed by scanning electron microscopy results. Furthermore, the thermal insulation performance of epoxy/glass fiber felt (EP/GFF) composites is continuously improved with the growing GFF layer, and meanwhile EP/GFF composites exhibit the satisfactory mechanical property. Such novel EP/GFF composites can serve as promising structural, heat-insulated, and soundproof materials in many multifunctional systems including buildings, aircrafts, constructions, vehicles, etc. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46935.     

Simultaneously Increasing Impact Resistance and Thermal Properties of Epoxy Resins Modified by Polyether-Grafted-Epoxide Polysiloxane

In this paper, polyether-grafted-epoxide polysiloxane (FEPMS) was synthesized via hydrosilylation among poly(methylhydrosiloxane) (PMHS), allyl polyoxyethylene polyoxypropylene ether (F6) and allyl glycidyl ether to modify Diglycidyl Ether of Bisphenol A (DGEBA). The morphology, thermal properties, and toughness of all cured samples were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and impact testing. Results indicated that grafted polysiloxane can be well dispersed in epoxy matrix, and the epoxy resin modified with FEPMS at relatively low addition levels exhibited higher thermal properties and improved toughness than the neat epoxy resin.     

Preparation and characterization of bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane)–unsaturated polyester modified epoxy intercrosslinked matrices

An intercrosslinked network of unsaturated polyester–bismaleimide modified epoxy matrix systems was developed. Epoxy systems modified with 10, 20, and 30% (by weight) of unsaturated polyester were made by using epoxy resin and unsaturated polyester with benzoyl peroxide and diaminodiphenylmethane as curing agents. The reaction between unsaturated polyester and epoxy resin was confirmed by IR spectral studies. The unsaturated polyester toughened epoxy systems were further modified with 5, 10, and 15% (by weightt) of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of the matrix samples were performed to determine the glass transition temperature (T_g) and thermal degradation temperature of the systems, respectively. Mechanical properties, viz: tensile strength, flexural strength, and plain strain fracture toughness of intercrosslinked epoxy systems, were studied by ASTM methods. Data obtained from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improves toughness but with a reduction in glass transition, whereas the incorporation of bismaleimide into epoxy resin improved both mechanical strength and thermal behavior of epoxy resin. The introduction of bismaleimide into unsaturated polyester‐modified epoxy resin altered thermomechanical properties according to their percentage concentration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2853–2861, 2002     

长玻璃纤维增强聚丙烯复合材料的力学性能研究

采用熔体浸渍技术制备了长玻璃纤维母料(LGF/PP-g-MAH/PP)增强聚丙烯(PP)复合材料(LGF/PP)。通过双螺杆挤出机制备了同等配比的短玻纤增强聚丙烯(SGF/PP)复合材料。研究了LGF含量、环氧树脂(EP)和固化剂(2E4MZ)对LGF/PP复合材料的力学性能影响。结果表明:当LGF质量分数为35%～40%时,LGF/PP的综合力学性能最好,且明显优于同样组成的SGF/PP复合材料。EP和含固化剂(2E4MZ)的EP对LGF/PP复合材料的力学性能提高有一定的作用。SEM照片分析表明:EP的加入能改善玻纤与聚丙烯基体的界面粘接。     

A Study of the Interphase Region in Carbon Fibre/Epoxy Composites using Dynamic Mechanical Thermal Analysis

We have examined the effect of fibre addition on the glass transition temperature (T _g ) of two epoxy resin systems (an amine cured and an anhydride cured epoxy system) using dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC). The presence of fibres changes the glass transition temperature (T _g ) of an anhydride cured epoxy resin but does not affect that of an amine cured epoxy. The data suggest that two counteracting mechanisms are responsible for these changes: firstly, the presence of fibres causes a restriction of the molecular motion in the resin system, and secondly, the presence of carboxyi and keto-enol groups on the fibre surface inhibit curing of the resin close to the fibre, i.e. in the interphase region. The former increases the T _g and is a long range effect whereas the latter decreases the T _g and is a localised phenomenon. Changes in the dynamic properties of the interphase region are only detected when the samples are loaded in the longitudinal direction and not in the transverse direction where bulk matrix properties dominate. Sizing the fibres before their incorporation into the epoxy resin eliminates the variation in interfacial properties arising from differences in fibre surface chemistry.     

Synthesis and characterization of hybrid materials based on graphene oxide and silica nanoparticles and their effect on the corrosion protection properties of epoxy resin coatings

This study focuses on the use of tetraethyl orthosilicate (TEOS) as a silica source to decorate the surface of graphene oxide (GO) nanosheets and the use of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (Z-6020) as a coupling agent through a one-step in-situ sol-gel process. The results of the Fourier transform infrared spectroscopy (FT-IR), UV-visible, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) revealed that fine SiO₂ nanoparticles have successfully been synthesized on the basal plane of GO by covalent bonding. The dispersion of GO sheets and GO–SiO₂ nanohybrids within the epoxy matrix was studied using XRD and SEM techniques. Then, the effect of incorporating 0.1?wt% GO sheets and GO–SiO₂ nanohybrids on the corrosion protection and barrier performance of the epoxy coating was also investigated. The results showed that the incorporation of GO–SiO₂ into the epoxy matrix improved its thermal stability. The electrochemical impedance spectroscopy (EIS) test, potentiodynamic polarization and cathodic disbonding test showed that the corrosion protection performance was significantly enhanced by the incorporation of GO–SiO₂ hybrids into the epoxy resin compared to epoxy/GO and neat epoxy resin, respectively. The water contact angle (CA) results confirmed the reduction of the hydrophobic nature of the surface after the incorporation of GO–SiO₂ hybrids.     

Fracture and toughening behavior of aramid fiber/epoxy composites

The effect of short Aramid fibers on the fracture and toughening behavior of epoxy with high glass transition temperature has been studied. Fine dispersion of the fibers throughout the matrix is evidenced by optical microscopy. Compared with neat epoxy resin, the fracture toughness (K_IC) of the composites steadily increases with increasing fiber loading, indicating that addition of Aramid fibers has an effective toughening effect to the intrinsically brittle epoxy matrix. Scanning electron microscopy (SEM) indicates that formation of numerous step structures for fiber‐filled epoxy systems is responsible for the significant toughness improvement. SEM and transmitted optical microscopy show that fiber pullout and fiber breakage are the main toughening mechanisms for the Aramid fiber/epoxy composites. POLYM. COMPOS. 26:333–342, 2005. © 2005 Society of Plastics Engineers.     

Thermal and toughness property studies on a polybenzimidazole‐modified epoxy resin system

The effect of polybenzimidazole (PBI) on a silica‐filled epoxy resin matrix has been investigated. Polybenzimidazole (PBI) was incorporated into a difunctional epoxy resin matrix to the extent of 10 %, before being cured with an anhydride hardener. The effects of PBI on the curing reaction and glass transition temperature (T_g) and on the toughness of the cured epoxy matrix have been studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and a universal testing machine (Instron). The results indicate that the PBI modifier enhanced not only the glass transition temperature of the difunctional epoxy matrix but also its toughness, by its catalytic action. Further investigations have been carried out on the fractured specimens, using scanning electron microscopy (SEM) to support the enhanced toughness property of the epoxy matrix. © 2000 Society of Chemical Industry     

Synthesis and characterization of bis(4‐cyanato 3,5‐dimethylphenyl) naphthyl methane/epoxy/glass fiber composites

Bis(4‐cyanato 3,5‐dimethylphenyl) naphthylmethane was prepared by treating CNBr with bis(4‐hydroxy 3,5‐dimethylphenyl) naphthylmethane in the presence of triethylamine at −5 to 5°C. The dicyanate was characterized by FT‐IR and NMR techniques. The prepared dicyanate was blended with commercial epoxy resin in different ratios and cured at 120°C for 1 hr, 180°C for 1 hr, and post cured at 220°C for 1 hr using diamino diphenyl methane (DDM) as curing agent. Castings of neat resin and blends were prepared and characterized by FT‐IR technique. The morphology of the blends was evaluated by SEM analysis. The composite laminates were also fabricated from the same composition using glass fiber. The mechanical properties like tensile strength, flexural strength, and fracture toughness were measured as per ASTMD 3039, D 790, and D 5528, respectively. The tensile strength increased with increase in cyanate content (3, 6, and 9%) from 322 to 355 MPa. The fracture toughness values also increased from 0.7671 kJ/m² for neat epoxy resin to 0.8615 kJ/m² for 9% cyanate ester epoxy modified system. The thermal properties were also studied. The 10% weight loss temperature of pure epoxy is 358°C and it increased to 398°C with incorporation of cyanate ester resin. The incorporation of cyanate ester up to 9% loading level does not affect the T_g to a very great extent. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Synthesis and characterization of siliconized epoxy-1,3-bis(maleimido)benzene intercrosslinked matrix materials

Intercrosslinked network of siliconized epoxy-1,3-bis(maleimido)benzene matrix systems have been developed. The siliconization of epoxy resin was carried out by using various percentages of (5-15%) hydroxyl-terminated polydimethylsiloxane (HTPDMS) with γ-aminopropyltriethoxysilane (γ-APS) as crosslinking agent and dibutyltindilaurate as catalyst. The siliconized epoxy systems were further modified with various percentages of (5-15%) 1,3-bis(maleimido)benzene (BMI) and cured by using diaminodiphenylmethane (DDM). The neat resin castings prepared were characterized for their mechanical properties. Mechanical studies indicate that the introduction of siloxane into epoxy resin improves the toughness of epoxy resin with reduction in the values of stress-strain properties whereas, incorporation of bismaleimide into epoxy resin improves stress-strain properties with lowering of toughness. However, the introduction of both siloxane and bismaleimide into epoxy resin influences the mechanical properties according to their percentage content. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of heat distortion temperature were also carried out to assess the thermal behavior of the matrix samples. DSC thermogram of the BMI modified epoxy systems show unimodel reaction exotherms. The glass transition temperature (T_g), thermal degradation temperature and heat distortion temperature of the cured BMI modified epoxy and siliconized epoxy systems increase with increasing BMI content and this may be due to the homopolymerization of BMI rather than Michael addition reaction. The morphology of the BMI modified epoxy and siliconized epoxy systems were also studied by scanning electron microscopy.     

Thermo mechanical behaviour of unsaturated polyester toughened epoxy–clay hybrid nanocomposites

The intercrosslinked networks of unsaturated polyester (UP) toughened epoxy–clay hybrid nanocomposites have been developed. Epoxy resin (DGEBA) was toughened with 5, 10 and 15% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4,4′-diaminodiphenylmethane as a curing agent at appropriate conditions. The chemical reaction of unsaturated polyester with the epoxy resin was carried out thermally in presence of benzoyl peroxide-radical initiator and the resulting product was analyzed by FT-IR spectra. Epoxy and unsaturated polyester toughened epoxy systems were further modified with 1, 3 and 5% (by wt) of organophilic montmorillonite (MMT) clay. Clay filled hybrid UP-epoxy matrices, developed in the form of castings were characterized for their thermal and mechanical properties. Thermal behaviour of the matrices was characterized by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Mechanical properties were studied as per ASTM standards. Data resulted from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improved the thermal stability and impact strength to an appreciable extent. The impact strength of 3% clay filled epoxy system was increased by 19.2% compared to that of unmodified epoxy resin system. However, the introduction of both UP and organophilic MMT clay into epoxy resin enhanced the values of mechanical properties and thermal stability according to their percentage content. The impact strength of 3% clay filled 10% UP toughened epoxy system was increased by 26.3% compared to that of unmodified epoxy system. The intercalated nanocomposites exhibited higher dynamic modulus (from 3,072 to 3,820 MPa) than unmodified epoxy resin. From the X-ray diffraction (XRD) analysis, it was observed that the presence of d ₀₀₁ reflections of the organophilic MMT clay in the cured product indicated the development of intercalated clay structure which in turn confirmed the formation of intercalated nanocomposites. The homogeneous morphologies of the UP toughened epoxy and UP toughened epoxy–clay hybrid systems were ascertained from scanning electron microscope (SEM).     

Mechanical,morphological, and tribological behavior of Eulaliopsis binata fiber epoxy composites

This study is aimed at the potential use of a new natural fiber in polymer based composites (Eulaliopsis binata fiber) as a reinforcing material whose potential for tribological applications is still an unexposed area of research. The characterization studies of the fiber has been carried out with XRD, EDS, and Scanning electron microscope (SEM). Different weight percentages (10, 20, 30, and 40%) of short fiber were taken as reinforcement with epoxy polymer resin and hardener to study the tensile, flexural, and impact strength as well as the abrasive wear behavior of the developed composites. The experimental results indicate significant improvement in the mechanical and wear properties of epoxy with the incorporation of Eulaliopsis binata (EB) fiber. The composites containing 30 and 20 weight fraction of Eulaliopsis binata fiber exhibit optimum mechanical properties and abrasion resistance, respectively. The fractured and worn surfaces of the composites were studied under SEM to find out the failure mechanisms.     

Effects of Nickel Oxide (NiO) nanoparticles on the performance characteristics of the jatropha oil based alkyd and epoxy blends

Plant oil based alkyd resin was prepared from jatropha oil and blended with epoxy resin. Subsequently, alkyd/epoxy/NiO nanocomposites with different wt % of NiO nanoparticles have been prepared by mechanical mixing of the designed components. The structure, morphology, and performance characteristics of the nanocomposites were studied by UV‐visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and universal testing machine (UTM). The alkyd/epoxy/NiO nanocomposites showed the gradual increase in thermal stability with increasing NiO content. With 3 wt % NiO content the tensile strength of the nanocomposite increased by 19 MPa (more than twofold) when compared with the pristine polymer. Limiting oxygen index (LOI) value of the nanocomposites indicate that the incorporation of NiO nanoparticles even in 1 wt % can greatly improves the flame retardant property of the nanocomposites. This study confirms the strong influence of NiO nanoparticles on the thermal, mechanical, and flame retardant properties of the alkyd/epoxy/NiO nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41490.     

The Curing Behavior and Adhesion Strength of the Epoxidized Natural Rubber Modified Epoxy/Dicyandiamide System

The curing properties and adhesive strengths of the epoxidized natural rubber (ENR, 25 mole percent epoxidation) modified epoxy systems are studied with differential thermal calorimetry (DSC), scanning electron microscopy (SEM), and lap shear strength (LSS) measurement. The results of DSC analyses indicate that the curing exotherm, the curing rate, the reaction order, and the glass transition temperature of the epoxy system are affected by the presence of reactive ENR. From SEM micrographs, it is obtained that a second spherical rubber phase is formed during cure and the particle size of the rubber phase is increased by increasing the curing temperature and the ENR content. The changes of the volume fraction of the rubber phase and the T_g of the cured systems indicate that the mutual dissolution between epoxy resin and ENR happens and which changes with the curing temperature and the ENR content. The LSS of adhesive joints prepared with the ENR modified adhesives are all lower than those of the unmodified epoxy system, and decrease with increasing the amount of ENR added because of the limited compatibility of the ENR with the epoxy matrix.     

Epoxy compositions cured with aluminosilsesquioxanes: Thermomechanical properties

The aim of this study was to verify the influence of bis(heptaphenylaluminosilsesquioxane) (AlPOSS), used as a curing agent, on the thermomechanical properties of epoxy resin. Moreover, various curing conditions were taken into account. Epoxy casts were prepared from epoxy resin based on bisphenol A cured with different amounts of bis(heptaphenylaluminosilsesquioxane). The thermomechanical properties were investigated during dynamical mechanical thermal analysis (DMTA) in two cycles of heating. The storage modulus G′ of the epoxy casts was found to be higher in comparison to the reference epoxy sample and significantly dependent on the POSS content. A correlation between the glass transition temperatures (T_g), the curing conditions and the amount of curing agents were closely related. The occurrence of the crosslinking process in epoxy matrix was proved by the FTIR spectroscopy. The structure of the epoxy casts was investigated using scanning electron microscopy (SEM). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40672.     

Surfactant-Assisted Dispersion of MWCNTs in Epoxy Resin Used in CFRP Strengthening Systems

The epoxy resin used as the bonding agent in carbon fiber-reinforced polymer (CFRP) strengthening systems was modified by the infusion of multiwalled carbon nanotubes (MWCNTs). Two types of surfactants, Triton X-100 and C₁₂E₈, were used to disperse the nanotubes in the epoxy resin employing ultrasonic mixing. Dynamic mechanical analysis and tensile tests were conducted to study the effect of the surfactant-assisted dispersion of nanotubes on the thermal and mechanical properties of epoxy composites. The morphology of the epoxy composites was interpreted using scanning electron microscopy (SEM). Moreover, the effect of surfactant treatment on the structure of nanotubes was investigated by Fourier transform infrared (FT-IR). Based on the experimental results, the tensile strength and the storage modulus of the epoxy resin were increased by 32% and 26%, respectively, by the addition of MWCNTs. This was attributed to the homogeneous dispersion of nanotubes in the epoxy resin according to the SEM images. Another reason for the enhancement in the tensile properties was the reinforced nanotube/epoxy interaction as a result of the surfactant anchoring effect which was proved by FT-IR. A moderate improvement in the glass transition temperature (T _g) was recorded for the composite fabricated using Triton X-100, which was due to the restricted molecular motions in the epoxy matrix. To characterize the temperature-dependent tensile behavior of the modified epoxy composites, tensile tests were conducted at elevated temperatures. It was revealed that the MWCNT modification using surfactant substantially improves the tensile performance of the epoxy adhesive at temperatures above the T _g of the neat epoxy.     

Control of resin release from particleboards by gamma irradiation. I. Thermal decomposition behavior and structure morphology

The release or emission of resins from pressed particleboards, modified through gamma radiation, was characterized in terms of the thermal decomposition (TGA) and structure morphology (SEM). Particleboards, based on some farm residues and some polymers as adhesives, were first made by thermal compression in a hot press at 120°C and subsequently exposed to various doses of gamma irradiation. In general, gamma irradiation improves the thermal stability of the particleboards regardless of the type of the farm residues or the type of adhesive. Meanwhile, the thermal stability was found to increase with increasing irradiation dose as shown by the percentage loss in weight at different decomposition temperatures and the temperatures of the maximum values of the rate of reaction. The results showed that the particleboards based on cotton or flax stalks and polystyrene (PS) displayed higher thermal stability than did those based on the epoxy resin (E150). The particleboards based on wood sawdust and the E150 resin showed higher thermal stability than did those based on PS. SEM observations of the fracture surfaces of the different particleboards give further support to the improvement in the thermal properties after exposure to gamma radiation. In this regard, the pores and distances between the base material were coated with radiation‐crosslinked or ‐grafted E150 resin, particularly in the case of wood sawdust boards. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2869–2881, 2001     

Studies on thermal and morphological behavior of siliconized epoxy bismaleimide matrices

Novel bismaleimide‐modified siliconized epoxy intercrosslinked network systems were developed. Siliconized epoxy systems containing 5, 10, and 15% siloxane units were prepared using epoxy resin and hydroxyl‐terminated polydimethylsiloxane (HTPDMS) with γ‐aminopropyltriethoxysilane (γ‐APS) as a compatibilizer and dibutyltindilaurate as a catalyst. The siliconized epoxy systems were further modified with 5, 10, and 15% (wt %) of bismaleimide [(N,N′‐bismaleimido‐4,4′‐diphenylmethane) (BMI)] and cured by diaminodiphenylmethane (DDM). Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and heat‐distortion temperature measurement of the matrix samples were carried out to assess their thermal behavior. DSC thermograms of the BMI‐modified epoxy systems show unimodel reaction exotherms. The glass transition temperature (T_g) of the cured BMI‐modified epoxy and siliconized epoxy systems increases with increasing BMI content. Thermogravimetric analysis and heat‐distortion temperature measurements indicate that the thermal degradation temperature and heat‐distortion temperature of the BMI‐modified epoxy and siliconized epoxy systems increase with increasing BMI content. The morphology of the BMI‐modified siliconized epoxy systems was also studied by scanning electron microscopy (SEM). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2330–2346, 2001