Rheological,thermal, and mechanical characterization of fly ash‐thermoplastic composites with different coupling agents

Composite materials were prepared by mixing fly ash obtained from biomass combustion as filler and isotactic polypropylene (PP) as matrix. Three silane‐type coupling agents mainly differing in the size of their functional groups were used to improve the compatibility between both components. Uniaxial tensile tests showed that the incorporation of untreated ash into PP led to stiffer but also more brittle and weaker materials, as Young's modulus significantly increased and tensile strength and elongation at break decreased. Furthermore, an enhancement in storage and loss moduli as well as in composite viscosity was observed with the addition of fly ash. Hardness tests and thermal and fracture surface analyzes revealed tensile test results similar to those mentioned earlier. In summary, after analyzing the effects of the three silanes on mechanical, thermal, morphological, and rheological properties, the silane containing the vinyl functional group (XL10) was selected as the most appropriate for the PP/ash composites investigated. POLYM. COMPOS., 31:1722–1730, 2010. © 2010 Society of Plastics Engineers.     

The nanocomposites of zinc oxide/L‐amino acid‐based chiral poly(ester‐imide) via an ultrasonic route: Synthesis,characterization, and thermal properties

In this investigation, a chiral poly) ester‐imide) (PEI) via direct polyesterification of N,N′‐(pyromellitoyl)‐bis‐(L ‐tyrosine dimethyl ester) and N‐trimellitylimido‐L ‐methionine was prepared using the tosyl chloride/pyridine/N,N′‐dimethylformamide system as a condensing agent. This approach allows the insertion of two natural amino acids into the polymer backbone and the creation of a bioactive polymer. From the chemical point of view, the ester groups impart to the polymer's main and side chain increased sensibility to hydrolysis that can cause chain breaking. Therefore, this polymer is expected to be biodegradable and could be classified as an eco‐friendly polymer. The polymer also had a useful level of thermal stability associated with excellent solubility. PEI/zinc oxide bionanocomposites were subsequently prepared by an ultrasonic method as a simple and inexpensive route, using ZnO nanoparticles (ZnO‐NPs) modified by 3‐aminopropyltriethoxylsilane (KH550) as a coupling agent. The structure and properties of the obtained BNC polymers were confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The direct proofs for the formation of the true BNC polymers were provided by TEM. Also, the morphology study of the synthesized polymer‐based BNCs showed well‐dispersed ZnO‐NPs in the polymer matrix by FE‐SEM analysis. TGA studies indicated that an increase of the NP content led to an enhancement of the thermal stability of the new BNC polymers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Structure and property of tetrafluoroethylene‐propylene elastomer‐OVPOSS composites

Tetrafluoroethylene‐propylene elastomer‐octavinyl‐polyhedral oligomeric silsesquioxane (TFE/P‐OVPOSS) composites containing various percentages of OVPOSS are prepared via room temperature milling and heat vulcanization at 170°C. The composites are characterized by FTIR, ¹³C‐NMR, ²⁹Si‐NMR, XRD, DSC, SEM, tensile test, DMA, and TGA. The crosslink bond formation between TFE/P and OVPOSS conforms to the structural characterization of the composites. The OVPOSS cages aggregate when the OVPOSS dosage is more than 6 as observed from the XRD curves and SEM images. The swelling test shows that the experimental crosslink density is lower than the calculated crosslink density, indicating that not all reacted vinyl groups are converted into crosslink bonds. Meanwhile, the incorporation of OVPOSS significantly enhances the mechanical property and elevates the glass temperature of the composites. However, the thermal property is only improved slightly. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1281‐1288, 2013     

Synthesis,structural characterization,and photocatalytic activity of Bi‐based nanoparticles

Bi‐based nanoparticles were successfully synthesized (500°C/2 h) following two intermediate‐temperature routes, Pechini and a combined method of mechanical milling/molten salts. Herein, α‐Bi₂O₃/Bi₂O₂CO₃ heterostructures were identified. These types of heterostructures have shown advantages to improve the visible light responsive activity of Bi‐based nanoparticles to facilitate the separation of photogenerated electron‐hole pairs. By fixing the experimental parameters, the synthesis route and Ag contents showed to play a very important role in the phase composition of the Ag‐containing samples; the formation of Bi/Ag‐Bi₂O₃/Bi₂O₂CO₃ and Ag/Ag‐Bi₂O₃/Bi₂O₂CO₃ complex hybrid structures were revealed. The α‐Bi₂O₃/Bi₂O₂CO₃ heterostructure prepared by combined method exhibited higher photocatalytic efficiency (66.84%) for degrading methylene blue (MB) depending on Bi₂O₂CO₃ component proportion. For the Ag‐containing hybrid structures, the performance of their catalytic activity did not show an increase with respect to α‐Bi₂O₃/Bi₂O₂CO₃. However, in these samples, the degradation efficiency was slightly enhanced with the efficient doping of Ag into the α‐Bi₂O₃ structure and the existence of Bi when the Pechini method was used. Also, a possible photocatalytic process for degrading MB is presented.     

Continuous fiber‐reinforced thermoplastic composites: influence of processing on fire retardant properties

Fiber‐reinforced thermoplastic composite materials can find numerous applications in the transportation sector and replace thermoset composites. However, they have to comply with strict standards, particularly with those concerning their fire behavior. In this frame, composites based on an acrylic resin Elium^® (Arkema), a woven fiberglass, (taffetas tissue Chomarat G‐Weave 600 P/A) and Exolit OP930 (Clariant) as fire retardant were prepared by using three processes. The thermal stability and fire behavior were studied by means of thermogravimetric analysis and cone calorimetry. The obtained results allowed to highlight the drawbacks of each processing method and to select the most appropriate. The improvement of the fire behavior by combining post‐curing of the composites, addition of a cross‐linking agent, and addition of aluminum trihydroxide was also investigated. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and characterization of a lactic acid‐based thermoset resin suitable for structural composites and coatings

A new biobased polyester resin was developed for thermoset composite applications. The resin is potentially inexpensive and can be produced industrially by relatively simple means. The resin consists of star‐shaped methacrylated oligomers of lactic acid (LA). LA oligomers were synthesized in a two‐step process: in the first step, oligomers of LA were polymerized by direct condensation of LA. In the second step, the oligomers were end‐functionalized by methacrylic anhydride. The resin was characterized by differential scanning calorimetry, Raman spectroscopy, NMR, rubber process analyzer, and TOF‐SIMS. Tests show that the resin can be crosslinked into a rigid network within a couple of minutes upon thermal initiation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of acrylic‐based processing aids on processibility,rheology, thermal and structural stability,and mechanical properties of PVC/wood–sawdust composites

Methyl methacrylate and ethylacrylate (MMA‐co‐EA) and methyl methacrylate and butylacrylate (MMA‐co‐BA) copolymeric processing aids were introduced into poly(vinyl chloride) (PVC)/33.3 wt % wood–sawdust composites containing 0.6 and 2.4 phr of calcium stearate lubricant. The properties of the composites were monitored in terms of processibility, rheology, thermal and structural stability, and mechanical properties. It was found that the mixing torque, wall shear stress, and extrudate swell ratio increased with increasing processing aid content because of increased PVC entanglement. MMA‐co‐BA (PA20) was found to be more effective than MMA‐co‐EA (K120 and K130), this being associated with the flexibility of the processing aids, and the dipole–dipole interactions between sawdust particles and polymeric processing aids. The sharkskin characteristic of the composite extrudate at high extrusion rate was moderated by the presence of processing aids. Adding the acrylic‐based processing aids and lubricant into PVC/sawdust composites improved the thermal and structural stability of the composites, which were evidenced by an increase in glass transition and decomposition temperatures and a decrease in polyene sequences, respectively. The changes in the mechanical properties of the composites involved a composite homogeneity, which was varied by degree of entanglement and the presence of wood sawdust, and un‐reacted processing aids left in the composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 782–790, 2004     

Novel elastomer‐dumbbell functionalized POSS composites: Thermomechanical and Morphological Properties

Nanocomposites consisting of poly(styrene‐b‐butadiene‐b‐styrene) (SBS) and polyhedral oligomeric silsesquioxanes (POSS) were prepared using a solvent dispersion method. Dumbbell‐shaped POSS fillers were prepared using diacyl chlorides to bridge the POSS molecules. Infrared spectroscopy confirmed functionalization. Scanning electron microscopy revealed an increase in filler aggregation with concentration, with preferential phase selectivity. Polydispersity increased with filler concentration while d spacing was influenced by phase selectivity and domain‐filler compatibility. Functionalized POSS improved thermal stability by imparting restrictions of SBS chain motions. Tensile stress–strain analysis revealed an increase in modulus, yield strength, and strain hardening with filler concentration, while creep deformation decreased and permanent strain increased with POSS content. Storage modulus, loss modulus, and glass transition temperature increased with filler content due to effective SBS–POSS interaction. Nanocomposite properties were influenced by filler concentration, the phase of the filler was dispersed throughout and the length of the alkyl “barbell” on the dumbbell‐shaped POSS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of surface modification of zinc oxide nanoparticles on thermal behavior and hydrophilic property of PET–PEG composites

Zinc oxide (ZnO) nanoparticles were successfully prepared by a one‐step precipitation reaction in an aqueous solution of zinc acetate and sodium hydroxide with stearic acid (SA) as the modifying agent. Hydrophilic composites of poly(ethylene terephthalate) (PET), poly(ethylene glycol), and ZnO nanoparticles were prepared further by in situ polymerization. The surface modification of ZnO and the microstructure and properties of prepared nanoparticles were investigated by relative contact angle measurements (CA), Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy, and thermogravimetric analysis (TGA). Measurements of CA and XRD indicated that the surface‐treated ZnO was hydrophobic and had a significant improvement in crystallinity with SA. Compared with the nanocomposites filled with the pure ZnO, the modified ZnO exhibits a better dispersion in PET–PEG matrix. TGA results showed that the presence of modified ZnO nanoparticles can improve the thermal stability of PET–PEG matrix. CA and low field nuclear magnetic resonance methods were used to investigate the hydrophilic behavior of nanocomposites. The results revealed that modified nanoparticles had a positive effect on the bound water absorption. A simple model for the interactions between ZnO, SA, and PET–PEG matrix was proposed. POLYM. COMPOS., 37:1830–1838, 2016. © 2015 Society of Plastics Engineers     

Properties of thermoplastic composites based on wheat‐straw lignocellulosic fillers

Lignocellulosic fractions from wheat straw were used as natural fillers in composites of a polyolefin (a copolymer of polyethylene and polypropylene) and a biodegradable polyester [poly(butylene adipate‐co‐terephthalate)]. The mechanical properties of these injected composites were investigated with tensile and impact testing. A reinforcing effect of wheat‐straw residues was found for both types of composites. Compared with the polyester‐based composites, the polyolefin composites were more brittle. The addition of compatibilizing agents (γ‐methacryloxypropyltrimethoxysilane, maleic anhydride modified polypropylene, and stearic acid) did not improve the properties of the polyolefin composites. The surface properties were studied with contact‐angle measurements, and poor interfacial adhesion was found between the hydrophilic lignocellulosic filler and the hydrophobic polyolefin matrix. Thermal characterization revealed the formation of low intermolecular bonds between the polyester matrix and the lignocellulosic filler, in agreement with the surface tensions results and scanning electron microscopy observations. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 428–436, 2004     

Effect of nanostructures of modified clay–carbon black on physico‐mechanical,electrical, and acoustic properties of elastomer‐based composites

Elastomeric composites based on nitrile rubber (NBR), carbon black (CB), and organically modified nanoclay (NC) were prepared using a laboratory two‐roll mixing mill. Influences of the hybrid filler system (CB+NC) on various properties of NBR compound were analyzed. It was found that the addition of hybrid filler (CB+NC) over only carbon black enhances various properties. It was also found that the addition of nanoclay to the rubber matrix effectively improved key properties. Acoustics and electrical properties were modified with reduced water absorption because of layered clay platelets. The lower volume resistivity of NBR composites reflected better electrical conductivity attributed to the presence of nanoclay leading to effective filler connectivity. X‐ray diffraction and transmission electron microscopy measurements revealed that nanoclays were mostly intercalated and were uniformly dispersed. Use of calcium stearate facilitated dispersion of nanoclay in the rubber matrix which was observed through the formation of nanostructures including “nano” and “halo” units. Time temperature superposition in dynamic mechanical analysis test of the composites indicated lower mechanical loss in the frequency range of interest. The advantages accruing due to overall property enhancement, including lower water absorption, and better electrical and excellent acoustic properties of NBR composites make it suitable as underwater acoustic transparent materials for transducer encapsulation application. POLYM. COMPOS., 37:1786–1796, 2016. © 2014 Society of Plastics Engineers     

DGEBA‐grafted polyaniline: Synthesis,characterization and thermal properties

The utilization of conducting emeraldine salt (PANI‐ES) and intrinsic leucoemeraldine polyaniline (PANI‐LEB) in the synthesis of DGEBA‐grafted PANI via anionic copolymerization is described. The structures of copolymers obtained were characterized by FTIR, ¹³C and ¹H NMR. The extent of grafting was verified by THF Soxhlet (solvent extraction). The thermal properties of these new copolymers were described and their conductivities were reported. Results obtained indicated that the graft copolymer exhibited higher electrical and thermal conductivities than that of the blend counterpart. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microstructural characterization of corn starch‐based porous thermoplastic composites filled with multiwalled carbon nanotubes

Microstructural characterization of corn starch‐based porous thermoplastic (TPS) composites containing various contents (0.1, 0.5, and 1 wt %) of multiwalled carbon nanotubes (MWCNTs) was performed. Corn starch was plasticized with a proper combination of glycerol and stearic acid. TPS composites with MWCNT were prepared conducting melt extrusion followed by injection molding. TPS containing 1 wt % of MWCNTs exhibited higher tensile strength and elastic modulus values than neat TPS. Moreover, TPS electrical conductivity was determined to increase with increasing content of MWCNTs. X‐ray diffraction measurements revealed that incorporation of MWCNTs increased the degree of TPS crsystallinity to some extent. Scanning electron microscopy examination revealed that MWCNT altered TPS surface morphology and tensile failure modes, significantly. Transmission electron microscopy investigation showed that dispersion characteristics of MWCNTs within TPS were in the form of tiny clusters around micro pores of TPS, which is considered influential on electrical conductivity of the resulting composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of short Grewia optiva fiber‐based polymer composites

Natural fibers, such as Flax, Sisal, Hibiscus Sabdariffa, and Grewia optiva (GO) possess good reinforcing capability when properly compounded with polymers. These fibers are relatively inexpensive, easily available from renewable resources, and possess favorable values of specific strength and specific modulus. The mechanical performance of natural fiber‐reinforced polymers (FRPs) is often limited owing to a weak fiber‐ matrix interface. In contrast, urea–formaldehyde (UF) resins are well known to have a strong adhesion to most cellulose‐containing materials. This article deals with the synthesis of short G. optiva fiber‐reinforced UF polymer matrix‐based composites. G. optiva fiber‐reinforced UF composites processed by compression molding have been studied by evaluating their mechanical, physical, and chemical properties. This work reveals that mechanical properties such as: tensile strength, compressive strength, flexural strength, and wear resistance of the UF matrix increase up to 30% fiber loading and then decreases for higher loading when fibers are incorporated into the polymer matrix. Morphological and thermal studies of the matrix, fiber, and short FRP composites have also been carried out. The swelling, moisture absorbance, chemical resistance, and water uptake behavior of these composites have also been carried out at different intervals. The results obtained lay emphasis on the utilization of these fibers, as potential reinforcing materials in bio‐based polymer composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Synthesis and characterization of thermoplastic composites filled with γ‐boehmite for fire resistance

This paper explores the use of boehmite as a fire retardant in low‐density polyethylene and polyamide 6. The structure and morphology of the filler are characterized by X‐ray diffraction and scanning electron microscopy. The water content of our boehmite is estimated about 30% by thermogravimetric analysis. The filler/matrix interactions in nanocomposites are investigated by means of thermo‐physical measurements: differential scanning calorimeter and thermogravimetry. The resulting morphology shows particles individually dispersed in the matrix. The fire tests present a fire‐resistance effect at low filler content despite a different behavior as a function of the matrix. For instance, with only 2% volume of boehmite, the burning time of LDPE composite is significantly increased by 15%. At the same filler content in PA6, the burning time is solely increased by 4.5%. On the other hand, the limiting oxygen index is increased by +7.0% (only 2.6% with LDPE composites). Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation of nano‐zinc oxide/EPDM composites with both good thermal conductivity and mechanical properties

In this article, nano‐zinc oxide (ZnO) filled ethylene propylene diene monomer (EPDM) composites are prepared, and the mechanical (static and dynamic) properties and thermal conductivity are investigated respectively, which are further compared with the traditional reinforcing fillers, such as carbon black and nano‐silica. Furthermore, influence of in‐situ modification (mixing operation assisted by silane at high temperature for a certain time) with the silane‐coupling agent Bis‐(3‐thiethoxy silylpropyl)‐tetrasufide (Si69) on the nano‐ZnO filled composites is as well investigated. The results indicate that this novel reinforcing filler nano‐ZnO can not only perform well in reinforcing EPDM but can also improve the thermal conductivity significantly. In‐situ modification with Si69 can enhance the interfacial interaction between nano‐ZnO particles and rubber matrix remarkably, and therefore contribute to the better dispersion of filler. As a result, the mechanical properties and the dynamic heat build‐up of the nano‐ZnO filled composites are improved obviously by in‐situ modification, without influencing the thermal conductivity. In comparison with traditioanl reinforcing fillers, in‐situ modified nano‐ZnO filled composites exhibit the excellent performance in both mechanical (static and dynamic) properties and better thermal conductivity. In general, our work indicates that nano‐ZnO, as the novel thermal conductive reinforcing filler, is suitable to prepare elastomer products serving in dynamic conditions, with the longer expected service life. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reactive processing of thermoplastic elastomers based on polyamide-6: preparation and characterization

A new class of thermoplastic polyamide elastomers was successfully synthesized by polyaddition reactions between amino-terminated polyamide-6 and different diisocyanate-terminated polyether diols or polyester diols in a Haake torque rheometer. The chemical structure, phase separation, static and dynamic mechanical properties, thermal stability and hydrophilicity of TPAEs were characterized by Fourier transform infrared spectroscopy, differential scanning calorimeter (DSC), tensile tests and dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and water contact angle test methods, in the order given. DSC results showed that these synthesized TPAEs exhibited two obvious endothermic peaks associated with melting transition of soft segments and hard segments. The mechanical results revealed that TPAEs possess outstanding mechanical properties with tensile strength of 22.2–35.9 MPa and the elongation-at-break of 360–467 %. TGA results showed TPAEs can be fabricated by traditional thermoplastic processing method without any decomposition once the processing temperature is below 300 °C. Furthermore, the TPAEs only dissolved in acetic acid and methanoic acid at room temperature, showing TPAEs can be applied to some harsh environment due to excellent organic solvent resistance. Especially, this friendly reactive processing can also be used to handle the environmental problems associated with volatile organic compound emission.     

Influence of the processing on the completion of curing in epoxy‐based composites

Differential scanning calorimetry analysis was used to investigate interrelationships between several thermal parameters and the processing conditions of particle‐filled thermosetting resins. On the same piece, obtained by injection molding, epoxy‐based composites exhibited sensible differences within a set of measurements of the glass‐transition temperature, the width of the transition, the difference in the heat capacity, and the conversion degree. Statistical analysis showed a strong intercorrelation between these thermal parameters, but it could not provide any explanation for the disparities. The dispersion of the measured properties could, in a second step, be directly related to a sample's position with respect to the injection point in the mold. Moreover, even the postcuring stage could not erase this topological effect. As a result, a phenomenological model is proposed that fairly describes the experimental trends. This simple polynomial approach can subsequently be used either to determine the thermal parameters of any point of a molded piece or to shed some light on phenomena responsible for the large variations of the measured quantities. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1368–1376, 2005     

Synthesis and characteristics of thermoplastic elastomer based on polyamide‐6

A new class of polyether amide thermoplastic elastomers (TPAE) was synthesized via a three‐step polymerization route. In the first step a binary carboxyl terminated polyamide‐6 (PA6) with relatively low number‐average molecular weight was prepared via a caprolactam hydrolytic ring‐opening process. 4,4′‐Diphenylmethane diisocyanate (MDI) was reacted with the PA6 to produce PA6–MDI hard segments in the second step. Chain extension of the hard segments with poly(tetramethylene glycol) was the last step to furnish a series of new TPAEs. Structural characterization, physical properties and the effects of reaction conditions on the properties of the copolymer were investigated by infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy and other analytical techniques. Possible side reactions and phase separation are reported. Copyright © 2011 Society of Chemical Industry     

Synthesis,characterization, and cure reaction of methacrylate‐based multifunctional monomers for dental composites

The synthesis of 2,2‐bis[(4‐(2‐hydroxy‐3‐methacryloxyethoxy)phenyl]propane (BHEP) and (1‐methacryloxy‐3‐ethoxymethacryloxy‐2‐hydroxy)propane (MEHP) for use as the monomer phase in dental composites are reported. The monomers were prepared by the reaction of 2‐hydroxyethyl methacrylate (HEMA) with diglycidyl‐ether of bisphenol A (DGEBA) and with glycidyl methacrylate (GMA), respectively. The progress of the reaction was followed by measuring the disappearance of the epoxide group peak using FTIR and the structure of the monomers was characterized by ¹H‐NMR. BHEP and MEHP have lower viscosity because of the presence of long aliphatic spacer on both sides of the aromatic ring in BHEP and the absence of aromatic rings and the presence of only one hydroxyl group in each molecule of MEHP. Thermal curing of the monomers was conducted in a DSC using benzoyl peroxide as an initiator. Photopolymerization of the monomers was also conducted with the visible light using camphorquinone and N,N‐dimethylaminoethyl methacrylate as the photoinitiating system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007