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Composites are fabricating by reinforcing waste bambara nut shell powder (BNSP) as a bio-filler into an epoxy resin matrix. The composite is fabricated by varying the mass fractions of filler in the range of 5–35 wt%. The effects of bio-filler content on physical, mechanical, and thermal properties are evaluated. The studies reveal that the tensile strength, tensile modulus, flexural strength, and impact strength increased with increasing bio-filler content. The highest mechanical properties of BNSP-loaded epoxy composites are achieved at bio-filler mass content of 15 wt%, whereas hardness increased for 5–35 wt% with peak value at 35 wt%. The water absorption and thickness swelling of the BNSF/epoxy composites increased with increasing bio-filler contents, while the density decreased with an increase in bio-filler content. The TGA results revealed that an increasing bio-filler content decreased thermal stability, whereas the Tg and Tm of the composites increased with increasing bio-filler content. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of the addition of hexagonal boron nitride (hBN) and/or graphene nanoplatelets (GnP) to basalt fiber (BF)-reinforced polyphenylene sulfide (PPS) matrix composites at different weight ratios, both alone and hybrid, on the composite properties. Mechanical, tribological, thermal, and thermomechanical properties of the composites were evaluated using analyses such as tensile test at different ambient temperatures (23 °C and 70 °C), adhesive wear test, thermogravimetric analysis, differential scanning calorimeter analysis, and dynamic mechanical analysis. The results of the tensile test at 70 °C showed that the addition of 0.3 wt% GnP and 1 wt% hBN to the BF-reinforced composites resulted in a 40% increase in tensile strength. In addition, the composite containing 0.3 wt% GnP and 10 wt% hBN showed a 25% increase in high-temperature tensile strength, a 37% decrease in COF value, and a 10 °C improvement in T40% thermal decomposition temperature. Furthermore, the analysis results showed that the hybrid inclusion of GnP and hBN to the BF-reinforced PPS matrix composites improved the high-temperature tensile strength, adhesive wear resistance and thermal resistance properties. As a result, it is concluded that the hybrid use of GnP and hBN provides superior properties to the composites for advanced composite applications where mechanical, tribological and thermal performance is required along with electrical properties. [ABSTRACT FROM AUTHOR]

The scope of the work is to develop in-organic–organic hybrid epoxy nanocomposites using a combination of DGEBA (CY 230) epoxy resin and areca fibre (Af) mixture in the ratio of 70:30, respectively. The mixture was reinforced with varying weight percentages (1 and 2 wt%) of surface-modified nanozinc oxide (M-nZnO) and cured with triethylene-tetra-amine (HY951) at room temperature. 3-aminopropyltriethoxysilane was used as a coupling agent to introduce amine groups on the surface of ZnO and its structure was confirmed by FT-IR. The thermal stability and mechanical properties of in-organic–organic hybrid epoxy nanocomposites having different weight percentages of M-nZnO are investigated by thermogravimetric analysis. Their surface morphology of in-organic–organic hybrid epoxy nanocomposites was analysed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The introduction of M-nZnO improved the mechanical and thermal properties of the in-organic–organic hybrid epoxy nanocomposites. The mechanical characteristics and thermal stability analyses yielded the best results with a 2 wt% addition of M-nZnO nanoparticles. The study's findings clearly suggest that 2 wt% M-nZnO with Af/DGEBA epoxy resin can be used in a wide range of high-performance applications. Interestingly, the Af/DGEBA/M-nZnO epoxy nanocomposites displayed an excellent antibacterial action against high concentrations of Gram-negative bacteria like Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) was synthesized from the graphite powder by modified Hummer's method. Functionalized multi-walled carbon nanotubes (f-MWCNTs) containing –COOH groups were prepared to improve the compatibility of carbon nanotubes with the polymer matrix. Polyethylene terephthalate (PET) hybrid nanocomposites were made by melt blending by micro-compounding. In all compositions, the investigation was done at a constant filler amount of 2 wt%. Fourier transform infrared spectroscopy (FT-IR) and Raman studies revealed that there have been only physical interactions between PET matrix, GO and f-MWCNT fillers. Both water absorption and Shore hardness D increased with increase in GO content or decrease in f-MWCNT till both the nanofillers are equal and decreased upon further increase of GO content or decrease in f-MWCNT. Morphological studies were carried out by FE-SEM and AFM. Tensile and flexural modulus, impact strength, glass transition, melting temperature and thermal conductivity of hybrid nanocomposites were higher than the neat PET. It was also observed that wettability increased with increase in surface roughness. The 3D geometrical bridge between GO (2D) and f-MWCNT (1D) made the hybrid more dispersible and effective for different applications, and a 3D model is proposed. [ABSTRACT FROM AUTHOR]

Reactive melt mixing of recycled polyethylene terephthalate (r-PET) and recycled polycarbonate (r-PC) blends in presence of various concentration of Cobalt(II) acetylacetonate catalyst was studied to obtain optimum of catalyst content. r-PET/r-PC blends in presence of catalyst exhibit enhanced mechanical properties in comparison to without catalyst. XRD patterns reveals decreasing crystallite of samples also miscibility of blend will increase in presence of 0.1 wt.% of catalyst. Melt flow index (MFI) analysis demonstrated a decreasing in molecular weight with increasing catalyst concentration. Mechanical properties in samples contain 0.1 wt.% of transesterification catalyst are improved, in which Tensile analysis test showed an improvement in elongation at break, modulus and tensile strength of samples in comparison with r-PET/r-PC. Izod impact test showed that catalyst in blends caused higher impact strength in samples. [ABSTRACT FROM AUTHOR]

The aim of the study was to study the effect of cheap bio-based monomer 2,5-thiophenedicarboxylic acid on poly(butylene furandicarboxylate). Bio-based copolyesters were successfully synthesized by two-step melt polycondensation using 2,5-thiophenedicarboxylic acid (TDCA), 2,5-furandicarboxylic acid (FDCA) and 1,4-butanediol (BDO). Compared with FDCA, the price of TDCA is lower. The main purpose of this study is to add different amounts of TDCA to reduce the cost of polyester and to investigate the effect of TDCA on the properties of poly(butylene furandicarboxylate) (PBF). It can be determined that the expected copolymers were indeed synthesized by FTIR and 1H NMR spectra. DSC and WAXD results suggested that PBFTF27, PBFTF51 and PBFTF77 show isodimorphism behaviors. Because the angle between two carboxyl groups in TDCA is larger than that of FDCA, and the electronegativity of sulfur atom is weaker than that of oxygen atom, the glass transition temperature decreases due to the increase in the flexibility of the chain with the increase in TDCA. Compared with PBF, the toughness of poly(butylene 2,5-thiophenedicarboxylate) (PBTF) and copolyesters increased significantly. Poly(butylene furandicarboxylate-co-butylene 2,5-thiophenedicarboxylate) can be used in the packaging applications. [ABSTRACT FROM AUTHOR]

The molecular dynamics simulations based study of graphene (Gr) reinforced polymer nanocomposite (PNC) is a very intense research field due to the enormous range of possible applications involving such materials. Current review focuses on the reinforcing mechanisms behind the enhancement of the mechanical, thermal, and tribological properties of Gr-based PNC based on molecular dynamics (MD) simulations. It also reviews the capabilities of MD simulations to reproduce the experimentally measured materials properties and behaviour of Gr-based PNC. This review-based investigation summarizes the current literature of the MD simulation studies as well as comparisons for the tribo-thermo-mechanical properties of Gr-based PNC and identification of the suitable simulation protocols for model development, characterization, and mechanism analysis. The careful review of published MD simulation-based articles indicates that two important factors help to reproduce the experimentally measured materials properties and behaviour of Gr-based PNC. They are mainly (a) simulation models (material used for reinforcement, e.g. Gr and Gr derivatives) development and (b) simulation run parameters. In this review, details about those factors have been discussed keeping major consideration of Gr effect (e.g. shape or length, orientation, clustering, weight fraction, different layer, functionalization, and defective condition). Finally potential applications, current challenges and future prospects are discussed which can be useful to the research community. [ABSTRACT FROM AUTHOR]

Natural fibers and reinforcing elements are gaining attention from academicians and researchers to be utilized as the reinforcements in composites because of their environment friendly nature and sustainability. The aim of this study is to characterize and analyze the influence of eggshell particles on the mechanical, morphological and thermal properties of jute/cotton fiber reinforced epoxy composites. Composites were analyzed using UTM, SEM, XRD, UV, FTIR, and surface topology (2D and 3D). These experimental results show that addition of more eggshell particles increases the tensile strength but reduces the bending strength. Good thermal stability (300 °C) is obtained for the Jute/cotton/jute/cotton (JCJC) eggshell composites. SEM images confirmed the reinforcement of fibers in resins. FTIR data shows the presence of different active bands in JCJC eggshell composites. EDS analysis reveals the percentage of different compounds present in the composites. Absorption peaks are visualized by UV analysis in composites. The jute/cotton fiber reinforced epoxy composite without eggshell particles are also investigated for better understanding when eggshell particles are available. The findings experimentally prove that the produced composite can be used as an alternative to traditional materials. Beside this, the results of this study would be a noteworthy contribution for designing high performance bio-based composites over synthetic materials in numerous applications such as household products, vessels, and even in the aerospace industry. [ABSTRACT FROM AUTHOR]

In this research, CuO2@SiO2@polythiophene nanospheres are fabricated through a facile and stepwise synthesis process. Cu@polythiophene yolk–shell nanoparticles are obtained after converting Cu2O to Cu and removing the middle layer of SiO2 by using dilute acid. Transmission electron microscopy (TEM) confirms that the movable Cu cores are encapsulated in the interior of the hollow polythiophene nanospheres. The structure, morphology and optical properties of the synthesized nanoparticles are characterized by X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and ultraviolet–visible absorption spectroscopy. Uniform Cu@polythiophene nanoparticles with yolk–shell structure are applied as conductive filler in the poly(vinyl alcohol) matrix, and the effect of various nanofiller contents on the electrical, mechanical and thermal properties of the flexible polymer thin films is investigated. The FE-SEM images indicate that no agglomerates are seen on the surface of poly(vinyl alcohol) by adding the nanofiller amount up to 4 wt.%. Moreover, an increase in the direct current conductivity of nanocomposites is observed from 2 to 10 S/cm, as a result of the increase in contents of Cu@polythiophene nanoparticles from 0.2 to 3.6 wt.%. Tensile test of thin films reveals that the mechanical properties of the nanocomposites are improved by increasing the content of nanofillers, so that when compared with the pure poly(vinyl alcohol) film, the poly(vinyl alcohol) with 4 wt.% of Cu@polythiophene shows a 238% and 23% increase in Young's modulus and tensile strength, respectively. Besides, the results of the thermogravimetric analysis (TGA) indicate that the composite thin films are thermally more stable than the pure poly(vinyl alcohol) films. [ABSTRACT FROM AUTHOR]

Two series of polyurethanes (PUR) were synthesized in a one-step procedure, using a polydimethylsiloxane (Mn ~ 2000 g/mol) in different molar ratios (10, 15, and 20 mol%) as soft segments, hexamethylene diisocyanate, and isophorone diisocyanate as a part of hard segments. Butane-1,4-diol was used as a chain extender in polyurethane synthesis. Obtained PURs were thoroughly studied and used for the preparation of blends with commercial thermoplastic polyurethane elastomer. In combination with commercial PUR, some synthesized samples behave as plasticizers, increasing the breaking strain and decreasing the Young's modulus values. Blends with commercial PUR and 10 wt% of sample synthesized using an isophorone diisocyanate have shown an increase in strain values, but also values of break and Young's modulus, resulting in materials with fully improved mechanical properties, and mostly higher hydrophobicity. The greatest values of breaking strain (1712.72%) and max strain (1637.09%) were recorded for the blend which contains 10 wt% of PUR sample based on isophorone diisocyanate and 20 mol% of polydimethylsiloxane, while blend which contains 10 wt% of PUR sample synthesized using isophorone diisocyanate and 10 mol% of polydimethylsiloxane has the greatest value of Young's modulus (3.55 N/mm2). Prepared blends possess a lower surface tension values in comparison with the commercial PUR. The lowest value of surface tension (13.23 mN/m) was recorded for blend which contains 30 wt% of PUR sample synthesized using the isophorone diisocyanate and 20 mol% of polydimethylsiloxane. [ABSTRACT FROM AUTHOR]

Nanoparticles are central to the development of novel hybrid composites for various technological applications. As a sequel, in the present investigation, 5, 10 and 15 wt% of MgO filler were, respectively, dispersed in 95, 90 and 85 wt% of PVA matrix to fabricate pore-free PVA@MgO nanocomposite films using solution casting technique. The filler MgO powder was synthesised by Starch-Assisted Combustion method. Structural, optical, thermal, mechanical, dielectric and biodegradable properties of PVA@MgO films were gauged. X-ray diffractometry (XRD) revealed the increasing amorphous nature of the PVA@MgO films on MgO loading. Interaction between –OH group of PVA with MgO through hydrogen bonding is obvious from Fourier transform infrared spectroscopy (FTIR) analysis. Scanning electron microscopy (SEM) confirmed homogeneous dispersion of MgO throughout the films with flower or crochet like structures. UV absorbance as well as Eg of the films increased with the increasing MgO loading. Impedance study indicated the increased ionic conductivity of the films with filler content. The real part of dielectric permittivity (ε′) of the films decreased with increasing frequency and increased with MgO loading in PVA matrix. Enhancement in mechanical, biodegradable and thermal properties of film is the obvious result of incorporating MgO in the PVA matrix and could increase the performance of PVA as a support base material for 3D printing industry thereby further widening the scope of PVA@MgO nanocomposites in future power electronics, optoelectronics and semiconducting devices. [ABSTRACT FROM AUTHOR]

Microcomposites based on polyamide 66 (PA66) reinforced with bronze powder in low contents (3, 5 and, 7 wt%) were prepared in a co-rotating twin-screw extruder. Mechanical performance, including tensile characteristics, impact resistance, and Shore D hardness, was evaluated. The results indicated that the elongation at break and impact strength decreased with the increase in bronze loading, while the hardness reached a maximum (15% enhancement) when using 7 wt% of bronze powder. Scanning electron microscopy (SEM) was utilized to analyze the fracture surface and study the toughening mechanisms. The thermal expansion coefficient, as a good indicator of dimensional stability, was measured by applying thermomechanical analysis (TMA). The experimentally measured mechanical and thermal properties were modeled by an artificial neural network (ANN) method. The network was trained by Levenberg–Marquardt back-propagation (LMBP) in a single hidden layer which is consist of five neurons. Based on the excellent consistency between the ANN predictions and empirical results, ANN models can be considered as a reliable tool to estimate and evaluate material properties before synthesis and manufacturing. [ABSTRACT FROM AUTHOR]

A kind of polyurethane rubber (PU)/n-octadecane (n-OD)@silicon dioxide (SiO2)-polymethyl acrylate (PHEMA) form-stable phase change material (PCM) was fabricated in this paper. n-OD@SiO2-PHEMA microcapsules were prepared in one-pot, through interfacial hydrolysis polycondensation of alkoxy silanes and radical polymerization of HEMA. Then, n-OD@SiO2-PHEMA microcapsules were added into PU matrix to obtain PU/n-OD@SiO2-PHEMA composites. SiO2-PHEMA hybrid shell not only provides a shelter for core material, but also increases interfacial bonding between microcapsules with PU and effectively improves the mechanical properties of composites. The morphologies, chemical compositions and crystal structures of microcapsules and composites were characterized by SEM, TEM, FT-IR and XRD methods. The thermal and mechanical properties of the microcapsules and composites were characterized by differential scanning calorimetry and mechanical performance tests. The results show that the thermal and mechanical properties of PU/n-OD@SiO2-PHEMA composites were better than those of neat PU. The PU/n-OD@SiO2-PHEMA composites endow the microcapsules with improved thermal reliability and leakage proof property. The composites were found as form-stable PCM with low leakage rate. The phase change latent heat of the PU/n-OD@SiO2-PHEMA composites was up to 85.1 J/g and the composites can be used for thermal energy storage. [ABSTRACT FROM AUTHOR]

In this work, Opuntia ficus-indica (OFI) fibers were used as natural reinforcement to high-density polyethylene (HDPE) matrix to valorize unexploited Moroccan natural resources in composites applications. Composites specimens were prepared by combining extruder and injection molding processes using various fibers loadings (2.5, 5 and 10 wt%). OFI fibers were alkali treated to clean their surfaces from non-cellulosic compounds, and styrene–(ethylene–butene)–styrene three-block copolymer grafted with maleic anhydride (SEBS-g-MA) is used as coupling agent to graft maleic groups in the surface of matrix. Combined effects of both treatments on thermal and mechanical properties of prepared composites were investigated. Results showed that the alkali treatment proves to be more effective in improving interfacial adhesion between fibers and matrix, which positively influences the hardness and Young's modulus properties of composites without SEBS-g-MA, while the addition of coupling agent increased composites plasticity and thermal stability owing to the chemical bond formation at fibers–matrix interface. [ABSTRACT FROM AUTHOR]

In this research work, the effect of the change in the surface area of silicon dioxide nanoparticles of the same size on mechanical properties of poly(lactic acid) nanocomposites (PLA) was studied, as well as the role of coupling agent amount in the compatibility of these nanomaterials. We consider a spherical silicon dioxide with a surface area of 170–200 m2/g (labeled as S–SiO2) and another considered amorphous with a surface area of 180–600 m2/g (labeled as P-SiO2). This surface areas difference plays an important role in modifying of nanoparticles polarity by incorporating a coupling agent and its integration into partially polar polymers. According to obtained results, for nanomaterials with high surface area, it was observed while increasing coupling agent amount, the elasticity of the composite was observed to increase. In contrast, in nanomaterials with spherical nanoparticles, it was observed that as the amount of coupling agent decreases, the resistance of the material increases, reaching a maximum when a 10:2 ratio is used. It was observed that behaviors for both nanoparticles were different, which gives an idea that the incorporation of nanoparticles in polymers is not an issue of coupling agent or quantity only, it is more important as it is arranged on the surface. This kind of couplings does not only affect mechanical properties, since the thermal behavior of the material was also influenced, where it was observed that particles with low surface area modify the crystallization rate when they have different percentages of coupling agent on the surface. Furthermore, it is observed that the incorporation of nanoparticles with high surface areas area does not modify the crystallization rate significantly. Besides, in both cases, it was observed that the highest crystallization rate is reached when a 10:2 ratio is used. However, the energy required to form crystals remains unchanged. Therefore, it is considered that the incorporation of nanoparticles only affects the crystal formation rate without disturbing the energy requirement for crystal formation. Finally, a maximum in the 10:2 ratio was observed for the compatibility in both particles, which was manifested in an increase in the storage module through a dynamic mechanical analysis. The rate of crystal formation as well as the number of formed crystals have a considerable effect on mechanical properties of nanocomposites when the surface area is modified. [ABSTRACT FROM AUTHOR]

Environmental pollution due to non-biodegradable packaging materials is a menace. Hence, with a societal concern, an attempt was made through this paper to fabricate and evaluate pore-free nanocomposite films with PVA as the matrix with various wt% CaCO3 as a nanofiller through various physical parameters for alternate biodegradable packaging. The films are fabricated by a solution casting method. Optical, morphological, structural and dielectric studies were made on the films. Improvements in mechanical and thermal properties were observed in the films because of CaCO3 loading. Biodegradability of the composite films was immensely thus replacing the present non-biodegradable packaging materials. Increase in biodegradability with time and wt% of CaCO3 was highlighted. The low dielectric constant combined with the biodegradable nature of the films might prove useful in microelectronic packaging and thin/foldable/wearable optoelectronics. The investigated properties of the films establish multifunctionality and merit applications in the designing of packaging materials. [ABSTRACT FROM AUTHOR]

This work was focused on the synthesis of polyurethane networks (PUNs) based on polycaprolactone (PCL) as soft segment (SS) and Boltorn® aliphatic hyperbranched polyester of the second pseudo generation and 4,4′-diphenylmethane diisocyanate (MDI) as the parts of the hard segments (HS), by a two-step solution polymerization. In order to find the best ratio between HS and SS to achieve good thermal and mechanical properties, suitable hydrophobicity and morphology of the PUNs, various experimental analyses were conducted. The obtained results revealed that features of the PUNs highly depend on the PCL content. The increase in the PCL content leads to the increase in thermal stability, hydrophobicity and appearance of the microphase separation, but on the other side, it also leads to the decrease in storage modulus in the rubbery plateau, crosslinking density and glass transition temperatures of PUNs. This work shows that features of PUNs can be easily adjusted for a specific application by careful selection of the SS and HS ratio. [ABSTRACT FROM AUTHOR]

This paper reports the study of the influence of the macrocyclic or linear topology of polylactide (PLA) on its resulting thermal and mechanical properties, when displaying identical molar masses. Even if both macrocyclic and linear PLAs crystallize in the same α phase, the results of the calorimetric study and of the tensile tests show some differences which are directly related to the topology of the polymer. The glass transition temperature of macrocyclic PLA was found to be slightly higher than that of the linear one (56 vs 53 °C) while its melting temperature is lower (165 vs 171 °C). Moreover, the crystallization rate of the macrocyclic PLA is slower than that of the linear PLA. Regarding the tensile tests, it has been observed that the macrocyclic PLA displays an earlier strain-hardening than the linear one when stretched in the rubbery state. These differences were attributed to the fact that the macrocyclic topology involves a more constrained entangled network than its linear analogous and/or that the disentanglement kinetics is faster in linear PLA than in macrocyclic PLA. [ABSTRACT FROM AUTHOR]

This study comes as a part of the recent efforts aimed to face the challenges of environmental pollution by non-degradable plastic. Thermoplastic starch is classified as one of those materials extensively investigated for its use as an alternative to fossil-based plastic for many applications. Since the starch is a natural material that could be extracted from different plant sources, the properties of produced thermoplastic starch vary according to the starch's biological origin. Herein, the rheological, structure, thermal and mechanical properties of thermoplastic starches prepared from two kinds of cereal starches (wheat and corn) that are mainly different in amylose content were studied. The same processing conditions were applied on both native starches to accomplish the phase transition from granules to molten thermoplastic state and the Torque, X-ray Diffraction (XRD), Thermogravimetric analysis (TGA) and Scanning Electron Microscopy (SEM) analysis were used to prove this transition. It was noticed by XRD and SEM that both thermoplastic starches contain remnants of granules and granules fragments and their ratio was higher in thermoplastic wheat starch. Besides that, Torque analysis showed that higher torque was required to reach steady-state during the plasticization process in wheat starch than in corn starch. This behavior can be attributed to the higher ratio of amylose in wheat starch than corn starch. The difference in the ability of each type of starch to form hydrogen bonds with plasticizers was studied by FT-IR and the outcome this analysis agreed with TGA analysis. The results showed that the wheat starch had a higher ability to form strong hydrogen bonds with plasticizers than corn starch. Finally, the mechanical properties were investigated and the results revealed a direct relation between these properties and amylose content. [ABSTRACT FROM AUTHOR]

In this study, preparation of polyfurfuryl alcohol (PFA) as a renewable binder resin with an origin in biomass conversion is reported for developing a heat-resistant coating. PFA resin was synthesized in the presence of maleic anhydride as a catalyst. Various techniques were used to characterize the synthesized PFA resin. In the second step, different coating samples were prepared using PFA resin. Flexibility, adhesion strength and thermal/curing behavior of the coating samples were investigated as a function of their compositions such as the resin, plasticizers and titanium dioxide (TiO2) contents. The coatings were cured optimally at 150 °C according to isothermal and non-isothermal DSC measurements. Leveling property of the coatings was significantly improved in the presence of TiO2 due to a corresponding increased viscosity of the compound. The adhesion strength of the coating was low due to the aromaticity of PFA chains, high cross-linking degree of the binder resin and the difference existing between thermal expansion coefficient of the coating and steel substrate. In the presence of dioctyl phthalate and long-oil alkyd resin as plasticizers, flexibility and adhesion strength of the coatings were significantly improved up to 15 mm and 2.7 MPa, respectively. High thermal stability of the coatings was supported by TGA findings but it was deteriorated in the presence of alkyd resin. Alkyd resin, a plasticizer, increased the extent of cross-linking due to the chain flexibility enhancement according to DSC and DMTA findings. Finally, a heat-resistant coating formulation containing 9.3 wt% long-oil alkyd resin and 9.3 wt% TiO2 was selected as a good candidate for heat-resistant coating development due to the highest thermal and mechanical properties shown. [ABSTRACT FROM AUTHOR]

The effect of acetoacetoxyethyl methacrylate (AAEM) comonomer was investigated on the adhesion and thermal and mechanical properties of methyl methacrylate (MMA) reactive adhesive. The free radical bulk copolymerization of AAEM-co-MMA at ambient temperature was carried out in the presence of redox couple of benzoyl peroxide (BPO) and N,N-dimethylaniline (DMA). The glass transition temperature (Tg) and Young's modulus of different AAEM comonomer compositions were investigated by dynamic mechanical thermal analysis (DMTA) and three-point bending test. The presence of AAEM comonomer resulted in a low Tg and high modulus adhesive. The results from tensile test and lap shear strength showed the usefulness of AAEM in MMA adhesive with an optimum AAEM contribution of 20 wt.%. The improvements in adhesive main properties and thermal stability may be well attributed to the formation of cross-linking bonds which is in agreement with the results of FTIR spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, epoxy nanocomposites were developed via polythiophene–carbon nanotube with different loadings of 0–1.0 wt%. Polythiophene–carbon nanotube (PTh–CNT) hybrids produced using in situ chemical polymerization method and the microstructures, morphology and properties of the PTh–CNT hybrids and epoxy nanocomposites were studied using Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), transition electron microscopy (TEM), mechanical (tensile and flexural properties), electrical, dynamic mechanical thermal analysis (DMTA) and thermogravimetric techniques (TGA). Mechanical analysis demonstrated that nanocomposites containing 0.5% PTh–CNT hybrids exhibited the highest properties among all nanocomposites and showed 78% and 51% increment of Young's modulus and strength. The fracture analysis of samples and extent of fillers dispersion were visualized by SEM and demonstrated that dispersion of hybrids within epoxy matrix related to the hybrid nature (PTh–CNT ratio) and its concentration that are the key factors affected final properties of nanocomposites. DMA thermograms represented higher modulus for all epoxy/PTh–CNT nanocomposites systems as compared to epoxy/CNT and the pristine epoxy. Electrical conductivity measurements showed that conductivity of epoxy filled nanocomposites increased up 10−1 S cm−1 for epoxy/PTh–CNT nanocomposites. In addition, epoxy/PTh–CNT nanocomposites were also compared to pure epoxy and epoxy/CNT nanocomposites and showed higher thermal stability. The PTh–CNT particles enhanced electrical, thermal and fracture toughness of nanocomposites, confirming the synergistic effect of PTh–CNT as multifunctional filler. [ABSTRACT FROM AUTHOR]

The influence of the interfacial area and the particle size of CaCO3 filler particles on the mechanical and thermal properties of high-density polyethylene (HDPE) was studied in this work. The HDPE-based nano- and microcomposites were manufactured by using an industrial compounder system. The tensile, impact, creep, flexural and hardness properties of the filled and unfilled HDPE samples were investigated. The experiment revealed that the addition of both micro- and nanoparticles increased the tensile and flexural modulus of unfilled HDPE. However, it was observed that the addition of these particles did not have a significant effect on the tensile and flexural strength of unfilled HDPE. On the other hand, the presence of these particles decreased the elongation of break of unfilled HDPE. The impact strength of filled HDPE composites decreased slightly with both micro- and nanoparticle contents. The nanoparticle at high stress level (16 MPa) is more effective on the creep behavior of unfilled HDPE than on microparticles. However, microparticles were found to be more effective at low stress levels (8 and 12 MPa). It was found that the particle size has a profound effect on the thermal and physical properties of unfilled HDPE, such as density, melt flow index and vicat softening temperature. The results showed that the size of filler particles has a significant effect on the mechanical and thermal properties of the unfilled HDPE. Therefore, the size selection of constituent materials of nano- and microcomposites is an important consideration because it directly affects the functional performance of particle-filled HDPE nano- and microcomposites. [ABSTRACT FROM AUTHOR]

The current study represents the modification of the side-chain functionality of kafirin to prepare amide and ester derivatives. To explore the effect of the pendant group on kafirin protein, the derivatives were subjected to film formation by compression molding. Mechanical and thermal behaviors of these films were investigated. FTIR and NMR confirmed the formation of amide and ester derivatives. Amide-derived films showed a reduction in the water absorption capacity as compared to the ester-derived films. The mechanical properties of amide-derived films were higher than that of unmodified kafirin films due to the high proportion of grafted pendant groups. Kafirin treated with benzoyl chloride system has the highest tensile modulus as compared to the other modification. These findings suggest that the kafirin has the potential to be used as a packaging material in various sectors. [ABSTRACT FROM AUTHOR]

In the present study, it was focused on developing mechanically stronger and thermally more stable polyvinyl chloride (PVC) composites by using green reduced graphene oxide (GRGO) filler to strengthen the negative features of PVC. For this purpose, GRGO reduced by vitamin C (ascorbic acid) with antibacterial properties was selected as filler. The PVC/GRGO composites were produced via colloidal blending method at different amounts of GRGO in PVC matrix (0.1, 0.3, 0.5 and 1% by weight), while pure PVC was also produced for comparison. The XRD and FTIR results showed that GRGO incorporated in the polymer matrix; this finding was also evident in SEM analysis. TGA and DSC analyses showed that the composite with 1% loading content of GRGO provided an important improvement on the thermal stability. The tensile strength and hardness of the composite having 0.1% GRGO increased by 42% and 98%, respectively. SEM image of PVC/GRGO-0.1 composite showed the galleries of GRGO filled with PVC. As a consequence, thermal and mechanical properties of PVC can be altered by changing loading content of GRGO. Moreover, the GRGO may be a good candidate for substitution of harmful fillers for PVC-based products. [ABSTRACT FROM AUTHOR]

Two types of rapeseed oil-based polyols in the content of 20 wt% and 50 wt% were used for synthesis of ureaurethane elastomers (EPUU) with isocyanate index 1.07. The bio-polyols were synthesized by epoxidation and opening of oxirane rings using isopropanol (RO) and diethylene glycol (MK). The aim of this work was to evaluate the impact of bio-polyols on the thermal and mechanical properties of the manufactured EPUUs, produced with poly(ethylene adipate) (PEA). Differences in the structure of used bio-polyols caused changes in the number of hydrogen bonds and degree of phase separation in EPUUs. As the content of bio-polyols increases, the number of hydrogen bonds connecting the rigid segments of these materials is reduced. The consequence of these changes is variation in the thermal characteristics of these materials. Cross-linking density calculated from dynamical mechanical thermal analysis increases for materials with 20% of both types of rapeseed oil-based polyols and is the highest for material 80PEA/20MK. An introduction of the MK polyol also resulted in an increase in the elongation at break of the modified elastomers. [ABSTRACT FROM AUTHOR]

Polystyrene (PS) has low impact strength and also shows poor strain hardening. In this work, poly(styrene–butadiene–styrene) triblock copolymer (SBS) was solution- and melt-blended with PS in the presence of a free-radical polymerization initiator, dicumyl peroxide (DCP), to enhance PS's thermal stability, mechanical properties, impact resistance, and strain hardening. The solution-blended PS/SBS containing 0.1% DCP annealed at 180 °C showed strong strain hardening, but the melt-blended PS/SBS annealed at the same temperature and time showed poor strain hardening. The change in the blending temperature, DCP concentration, and PS-to-SBS ratio had minimal effect on the strain hardening of melt-blended PS/SBS. The tensile strength increased with an increase in the concentration of DCP up to 0.1%, and beyond that level, the tensile strength started decreasing. The impact resistance considerably improved with an increase in the SBS loading in the PS matrix, and the enhancement was more than double of the impact resistance shown by the neat PS. [ABSTRACT FROM AUTHOR]

In this study, the influence of nanosilica (SiO2 NPs) on the mechanical, thermal and barrier properties of poly(butylene adipate-co-terephthalate) (PBAT) nanocomposites was investigated. The PBAT/SiO2 composites were prepared by solution blending technique. PBAT/SiO2 composites were prepared with different percentages of nano-SiO2 loading (1, 3, 5, 7 and 10 wt%). The relations of SiO2 NPs with PBAT matrix were analyzed by Fourier transform infrared spectroscopy. The mechanical properties such as tensile strength, % of elongation at break, tensile modulus and thickness were determined. The thermal properties such as thermo-gravimetric analysis were analyzed for the nanocomposites. The PBAT/SiO2 composites exhibit high mechanical and thermal performance than the pure PBAT. The nanocomposites were also investigated through scanning electron microscope (SEM) and transmission electron microscope micrographs to examine the morphology between PBAT and SiO2 NPs. In addition, the results of SEM acquired are in SiO2 agreement with the data resulting from FTIR and tensile strength of the nanocomposites. The nanocomposite shows improvement in mechanical and thermal stability than that of pure PBAT. [ABSTRACT FROM AUTHOR]

This research was conducted to investigate the effect of montmorillonite (MMT) content on the flame retardancy, physico-mechanical properties of electron beam irradiated polycarbonate (PC)/acrylonitrile butadiene styrene (ABS) blends. Based on this research, it is revealed that the increase in MMT loading level has gradually increased the flame retardancy and thermal stability of the flame retarded PC/ABS blends, which is due to the induction of char residues formed by the presence of MMT particles as measured in TGA analysis. Besides, the introduction of electron beam irradiation has gradually improved the flame retardancy (LOI) by forming crosslinking networks in PC/ABS blends (as evident by the increment in gel content) which restricts the permeability of volatile and air through the polymer matrix. The addition of low MMT amount (2 phr) has reduced the elongation at break which is attributed to the intercalation of polymer matrix into the interlayer galleries of MMT particles as evident by increment in d spacing. However, the higher amount of MMT particles tended to form agglomeration and thus reduced the tensile strength of flame retarded PC/ABS blends. The increase in irradiation dosages has gradually induced the Young's modulus of flame retarded PC/ABS blends by forming crosslinking networks. [ABSTRACT FROM AUTHOR]

The surface of sol-gel-synthesized nano-alumina (Al2O3) was modified by three types of silane coupling agents with different specific functionalities, namely 3-aminopropyltriethoxysilane (APTES), triethoxy(octyl)silane (OCTEOS) and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT). The aim of the present study was to explore the effect of both unmodified and surface-modified nano-Al2O3 on the cure characteristics, mechanical properties, cross-link density and thermal stability of natural rubber (NR) nanocomposites. Results revealed that silane coupling agents were very effective to enhance maximum rheometric torque (R∞) and mechanical properties like modulus and tensile strength of nano-Al2O3-based NR nanocomposites. APTES offered higher value of cure rate index for NR compounds as compared to two other silane coupling agents. Among three silane coupling agents, TESPT provided highest improvement in the mechanical properties of NR/nano-Al2O3 composites. This might be explained by considering excellent improvement in the cross-link density of NR compounds in the presence of TESPT-treated nano-Al2O3. The incorporation of both TESPT- and OCTEOS-modified nano-Al2O3 into the NR matrix markedly improved the thermal stability of NR composites. Moreover, bi-functional silane TESPT not only increased the hydrophobicity of nano-Al2O3, but also improved the probability of sulfur cross-linking during cure process of NR compounds. [ABSTRACT FROM AUTHOR]

To improve the thermal stability and mechanical properties of poly(lactic acid) (PLA), bis(tert-butyl dioxy isopropyl) benzene (BIBP) (0-0.4 wt%) as cross-linking agent was introduced into the PLA. The PLA/BIBPx samples were characterized by Fourier transform infrared spectrometry. The gel fraction and degree of swelling of PLA/BIBPx were studied. The thermal and degradation properties of samples were also investigated by means of differential scanning calorimetry and thermogravimetric analysis; the thermal stability of the samples was improved by the addition of BIBP. The complex viscosity (η*), storage modulus (G′), and loss modulus (G′′) were increased with the increase in BIBP content from rheological measurement. The mechanical properties of the PLA/BIBPx blends and PLA/BIBPx films were tested by tensile tests, and the blends' tensile strength was enhanced due to the cross-linking effect of BIBP. The 0.2 wt% BIBP gave the PLA/BIBPx blends the best mechanical properties, while the 0.1% BIBP made PLA/BIBPx films an optimal mechanical property. The morphology of the tear-fractured surface of the films was also studied, and PLA/BIBP0.1 film revealed more clearly layered structure than PLA. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) were fabricated from sulfuric hydrolysis of cotton. The CNCs were modified with TEMPO/NaBr/NaClO oxidization and quaternary ammonium salts adsorption. Polystyrene-CNC composite films were prepared with solution casting method. The results of characterization revealed that the thermal properties of CNCs and the compatibility of CNCs with polystyrene were improved, while the morphology and the crystalline structure of the modified CNCs were seldom broken. The contact angle of the modified CNCs was increased from 35.8° of the pure CNCs to 54.6° of CNCs modified with stearyltrimethylammonium chloride, and SEM revealed that the modified CNCs dispersed evenly in the polymeric matrix. In addition, the breaking strength and elongation at break of PS/CNC composites were increased. The study shows that the combination of TEMPO-mediated oxidization and quaternary ammonium’s adsorption is an effective method for improving the thermostability and compatibility of CNCs in organic matrix. [ABSTRACT FROM AUTHOR]

In this study, two different pre-polymers were obtained first through efficient hydrosilylation reaction by changing reaction time and catalyst dosage in the presence of polyoxyethylene epoxy resin (DEG-501) and hydrogen silicone oil with phenyl (UC-233), named EH-F and EH-L. And the chemical structure of pre-polymers was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance (1H-NMR). Then the pre-polymers were incorporated into phenyl-containing silicone rubber at different mass fractions. Scanning electron microscopy observations demonstrated that a “sea-island” phase separation occurred obviously in the cured composites. Thermogravimetric analysis evaluation revealed that thermal stability of silicone rubber composites improved markedly after modification, the residual yield at 800 °C achieved 32.69% in the air atmosphere when 20 phr EH-F were introduced. And a degradation mechanism was discussed through elemental analysis and electronic images of char of silicone rubber systems. The mechanical properties results showed that tensile strength and shear strength of composites increased gradually with increasing EH pre-polymers. All of these results provide very valuable information for understanding hydrosilylation reaction and effects of molecular structures on performance of silicone rubber systems. [ABSTRACT FROM AUTHOR]

In this work, cellulose nanoparticles (CNP) reinforcement on synthetic rubber (SR)/polylactic acid (PLA) blend was investigated. Initially, SR/PLA blend was prepared by varying SR from 5 to 20 wt%. Later, a fixed amount (3 wt%) of CNP was added and resulting effect on mechanical, thermal, and dynamic properties was studied. The results show the addition of CNP in SR/PLA blend resulted in ~147 and ~196% improvement in tensile strength and storage modulus, respectively. In addition, impact strength of SR/PLA blend was almost doubled after CNP incorporation. An improvement of ~4.5% in the thermal stability of SR/PLA was also observed. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS), a 2D layered material has been recognised as a new paradigm in the area of materials science due to its graphene like structure. Herein, we prepared functionalized MoS nanosheets through one-pot hydrothermal technique using cationic surfactant, cetyltrimethylammonium bromide (CTAB). The surfactant functionalized MoS (CTAB-MoS) was subsequently dispersed in epoxy matrix at the loading level of 0.1-0.5 wt% to investigate the reinforcing competence of MoS on the mechanical and thermal properties of the composites. Fourier transform infrared spectroscopy, X-ray diffraction and field emission scanning electron microscopy (FE-SEM) were used to characterize the microstructure and morphology of the hydrothermally prepared pristine MoS and CTAB-MoS. Dynamic mechanical and tensile properties were studied to comprehend the effect of functionalized MoS on the mechanical properties of the composites. At 0.2 wt% loading, the tensile strength and Young's modulus was improved by ~23 and 26.7%, respectively, while ~83% improvement in storage modulus was recorded. Thermal stability of all the studied specimens were compared by selecting the temperatures at 10 and 50% weight losses which showed small decrease in onset degradation temperature. [ABSTRACT FROM AUTHOR]

Intercalated nanocomposites comprised of poly(propylene carbonate) (PPC) and organo-montmorillonite (OMMT) were prepared via a direct melt blending method. The morphological, thermal, rheological, mechanical, and gas barrier properties of composites were carried out in detail. Results of XRD, TEM, and SEM revealed that OMMT dispersed homogeneously in the polymer matrix, and were intercalated by PPC macromolecules. Compared with neat PPC, the PPC/OMMT nanocomposites showed an enhancement in the 5 wt% weight loss temperature ( T ) by near 20 °C with 3 phr OMMT concentration. With the percolation threshold formed, the rheological properties of composites translated from a liquid-like behavior to a solid-like one. Interestingly, PPC/OMMT nanocomposites revealed a concurrent improvement in the modulus, yield strength, and toughness with the addition of homogeneously dispersed clay. The oxygen permeability of well-dispersed PPC/OMMT nanocomposites reduced significantly compared with that of neat PPC. Consequently, this convenient and effective method, which facilitates to prepare PPC/OMMT nanocomposites with superior mechanical properties and excellent gas barrier performances, can be considered to broaden the application of PPC. [ABSTRACT FROM AUTHOR]

The aim of this work is to obtain and evaluate the mechanical and thermal properties of low Density Polyethylene (LDPE) composites reinforced with fibers from Australian King Palm fibers. Raw fibers were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy. The chemical composition of the fibers was also evaluated. After characterizing the fibers were mixed into the LDPE, in proportions of 5, 10, 15 and 20% (wt/wt) using a thermokinetic mixer model MH-50H. Furthermore tensile, flexural and impact specimens were prepared for evaluation of mechanical properties. The composites were analyzed through SEM micrographs of fractured surfaces and thermal analysis. The results indicate that the reinforcement decreases the thermal stability of the composites, but caused an increase the mechanical properties of the composites. The composites reinforced with of raw fibers 20% (wt/wt) showed significant increase in the tensile strength, flexural and impact. [ABSTRACT FROM AUTHOR]

In this work, poly(lactic acid) (PLA) was melt blended with liquid natural rubber (LNR) and linear low-density polyethylene (LLDPE) to fabricate a PLA-LNR-LLDPE ternary blend. The torque rheology demonstrates the melt mixing behavior of PLA-LLDPE binary and PLA-LNR-LLDPE ternary blends. Mechanical properties of ternary blend illustrate the highest toughness as compared to neat PLA and PLA-LLDPE binary blend. Fracture morphology reveals the plastic deformation behavior in the ternary blend which is illustrated in TEM micrograph. The cold crystallization temperature of the ternary blend appears at a lower temperature as compared to the binary blend. The thermal stability of PLA is improved due to blending with LLDPE and LNR. The ternary blend exhibits greater storage modulus in the glassy state as well as in the rubbery state as compared to neat PLA and binary blend. Finally, LNR performed as an effective compatibilizer between PLA and LLDPE. [ABSTRACT FROM AUTHOR]

In this study, MWCNT/epoxy composites were fabricated via combination of ultrasonication with two post-processing techniques namely, casting and hot-pressing, respectively. The effect of these two post processing techniques and MWCNT loading ranging from 0 to 1.0 vol% on the mechanical, electrical and thermal properties of MWCNT/epoxy composites were investigated. The addition of MWCNT in epoxy reduced the tensile strength and tensile modulus of the MWCNT/epoxy composites compared to unfilled epoxy. However, the MWCNT/epoxy composites prepared by hot-pressing technique improved the tensile strength and tensile modulus at 0.4 vol% MWCNT loading as confirmed by morphological analysis. The DMA properties of MWCNT/epoxy composites prepared by both post-processing techniques showed no significant change in storage modulus and T values. The increment of MWCNT loading slightly increased the electrical and thermal properties of MWCNT/epoxy composites via the hot-pressing technique. These findings indicate that different post-processing techniques and filler loading govern the properties of MWCNT/epoxy composites. [ABSTRACT FROM AUTHOR]

As multifunctional high-performance materials, polylactic acid/carbon nanotube (PLA/CNT) composites are currently of great interest for using in an extensive range of medical and industrial applications. The main focus of the present work, accordingly, is to review the recent developments on PLA/CNT composites. In addition, the dependence of thermal, mechanical, electrical, and rheological properties on the type, aspect ratio, loading, dispersion state, and alignment of CNTs within PLA matrix was reviewed. The discussion of the different properties revealed that the CNTs additive could be an effective method to improve the performance of PLA materials for medical and industrial applications. [ABSTRACT FROM AUTHOR]

Epoxy composites with biphenyl liquid crystalline polyester (BLCP)-grafted graphene oxides (GO) as inclusions were prepared successfully. The thermal and texture analyses of BLCP were characterized by DSC and POM. The results show that the texture structure of BLCP turned into fan texture from woven texture with increasing temperature and present double texture structure. More importantly, the thermal and mechanical properties of epoxy composites could be improved by incorporating BLCP-grafted GO (BLCP-GO). The epoxy composite with only 0.5 wt% BLCP-GO produced an increase in the initial decomposition temperature ( T ) by 28 °C and glass transition temperature ( T ) by 17.2 °C when compared with the neat epoxy. Moreover, for the mechanical properties tests, the composites with 1.0 wt% BLCP-GO exhibit an increase in impact strength, tensile strength, flexural strength and flexural modulus by 103, 52, 66, and 56 %, respectively, compared with the neat epoxy resin. These excellent performances of the graphene-epoxy composites have a great potential for applications in aerospace and other electrical devices. [ABSTRACT FROM AUTHOR]

In this study, modified wollastonite nanorods (MWNRs) as core and polystyrene (PS) as a shell [Core-shell nanorods (CSNRs)] was synthesized using atomized microemulsion technique. CSNRs were compounded with styrene butadiene rubber (SBR) on a two-roll mill and compressed into sheet form using compression moulding machine. The encapsulation of MWNRs into PS was confirmed by field emission scanning electron microscope (FE-SEM), transmission electron microscope, X-ray diffraction spectrophotometer (XRD) and Fourier transform infrared spectroscopy. CSNRs/SBR nanocomposites were also characterized by XRD, FE-SEM, differential scanning calorimetry, thermogravimetric analysis, universal testing machine and Mooney viscometer. Incorporation of CSNRs resulted in improvement in rheological, thermal and mechanical properties of the nanocomposites. FE-SEM images showed a perfect dispersion of the CSNRs in SBR matrix at <1 wt% loading. Thermal stability of CSNRs/SBR nanocomposites was also increased significantly by the addition of CSNRs. Graphical abstract: [ABSTRACT FROM AUTHOR]

The purpose of the present article is to modify the surface of nano-titanium dioxide (TiO) and to investigate the reinforcing effect of both unmodified and surface-modified nano-titanium dioxide (TiO) on the mechanical properties and thermal stability of natural rubber (NR) nanocomposites. Surface of nano-TiO is modified by polyethylene glycol (PEG) and polypropylene glycol (PPG). The effective surface modification of nano-TiO is evaluated by Fourier transform infrared (FTIR) spectra and field emission scanning electron microscopy (FESEM). The result notifies that the final properties of NR nanocomposites are dramatically improved in the presence of surface-modified nano-TiO in comparison to unmodified nano-TiO. The excellent reinforcing capability of surface-modified nano-TiO is due to its better hydrophobicity and uniform dispersion within the NR matrix, as confirmed from morphological analysis. Furthermore, due to its small size PEG is better surface modifier for nano-TiO than PPG. [ABSTRACT FROM AUTHOR]

Blends of cis-polyisoprene (CPI) and nitrile butadiene rubber (NBR) in different volume ratio were prepared to see the effect of composition on different properties. Structure characterization has been done through X-ray diffraction and scanning electron microscope. Scanning electron micrographs confirm homogeneous nature of all the blends. The dynamic mechanical analyzer was used to measure damping, storage modulus, glass transition temperature and mechanical properties (Young's modulus and tensile strength) of these blends. Activation energy and fragility were determined for the non-Arrhenius (fragile) behavior of viscosity using Vogel-Fulchuer-Tammann (VFT) equation. Thermal conductivity has been analyzed through thermal constant analyzer. Results indicate that all the measured properties are dependent on blend composition and crosslink density. [ABSTRACT FROM AUTHOR]

Crosslinking of polyamide 6 (PA) and filled one with glass fibres (PA/GF) was initiated via macroradical formation by gamma irradiation either in air or in inert argon atmosphere. The crosslinked portion was found to start at absorbed dose around 300 kGy and achieved about 60 and 40 wt% for PA and PA/GF, respectively, if irradiation proceeded in inert, while in air molecular weight increase was only observed without crosslinked gel formation. DSC indicated that irradiation leads to a decrease in crystallinity as well as lamellae thickness. Besides crosslinking, scission of polymer chains also occurs. Modest increase of impact strength was found for PA while small decrease for PA/GF was observed. The dependence of Young's modulus values on the irradiation dose indicates a minimum around gel point being more pronounced for PA compared to the composite. Irradiation resulted in minor changes in tensile strength and elongation at break while a substantial increase in the elongation at yield was found for PA if irradiated in inert atmosphere. Generally, the application of an optimal dose of gamma irradiation in air results in an increase of toughness of PA without changing other mechanical properties. [ABSTRACT FROM AUTHOR]

The effects of filler content and chemical treatment on mechanical and thermal properties of polypropylene-chitosan composites were investigated. Filler chemical treatment was carried out by reacting chitosan with organosolv lignin/sodium dodecyl sulphate binary modifying agents under mild condition. Filler-matrix interfacial adhesion enhanced considerably in presence of the binary agent that effectively modified the chitosan surface, leading to increased tensile and impact strength of the composites. Even though the chemical treatments did not change the thermal degradation mechanism of the composites, the obtained results exhibited that the treated composites had better thermal properties than the untreated composites. These finding implies that organosolv lignin-containing binary modifying agents could be a potential reagent to replace synthetic modifying agents. [ABSTRACT FROM AUTHOR]

4-Aminophenyl propargyl ether (APPE) containing alkynyl group and diazide monomers were synthesized for the click reaction. 1, 2, 3-triazole-containing diamine monomers were synthesized by the 1, 3-dipolar cycloaddition reaction in the presence of Cu (I) catalyst by click reaction which was used to prepare a novel polyimide containing 1, 2, 3-triazole ring (polytriazoleimide) by polycondensation reaction with aromatic dianhydride. The chemical structure of the monomers and polymers was confirmed by FT-IR, H-NMR and C-NMR spectral techniques. Polytriazoleimides exhibit low dielectric constant of 2.74-3.12 at 1 MHz, high thermal stability, the temperature corresponding to a 5 % weight loss from (441-473 °C) and good flame retardancy (LOI value 35.6-38.8). Glass transition temperature was observed to be between 218 and 248 °C and storage modulus between 2.61 and 3.54 GPa. These polymers are readily soluble in highly polar organic solvents. Furthermore, the incorporation of 1, 2, 3-triazole significantly improves the glass transition temperature, thermal stability and storage modulus of the polymer. Hence the click coupling is an effective approach to develop the structural and functional polyimides. [ABSTRACT FROM AUTHOR]

Nanostructured zinc oxide (ZnO) and magnesium oxide (MgO) are synthesized by sol-gel method and characterized by X-ray diffraction and field-emission scanning electron microscopy. The curing characteristics, mechanical, thermal and aging resistance properties of polychloroprene rubber (CR) composites in presence of both nanostructured and conventional cure activators in different combinations are determined. The CR composite containing 2 phr (parts per hundred parts of rubber) nano-ZnO along with 2 phr nano-MgO shows an excellent improvement in the curing characteristics as well as in the values of modulus and tensile strength in comparison to CR composite containing conventional cure activator system, i.e., 5 phr conventional ZnO along with 4 phr conventional MgO. Morphological analysis confirms the uniform distribution of nanosized cure activators within the CR matrix in comparison to conventional cure activators. Thermogravimetric analysis reveals that rapid degradation region for CR composite starts at higher temperature in presence of nanostructured cure activator system in comparison to conventional cure activator system. This study reveals that only 2 phr nano-ZnO in combination with 2 phr nano-MgO can successfully replace conventional cure activator system containing 5 phr conventional ZnO along with 4 phr conventional MgO with the enhancement of cure, mechanical and thermal properties of CR composites. [ABSTRACT FROM AUTHOR]

This research aimed to employ inorganic filler such as talc to promote crystallization in poly(lactic acid) (PLA). Three different talc particle sizes, namely 1, 5 and 30 µm, were used as nucleating agents; each was compounded with PLA at various contents from 0 to 10 wt%. The crystallization temperature ( T) reduced most rapidly from 128 to 107 °C with the presence of 1 wt% talc. Beyond this concentration, the T still decreased but only minutely. Compared to other sizes, finer talc particles were found to promote a slightly higher degree of crystallinity. X-ray diffraction peaks indicated that the α-crystal was formed in all PLA/talc compositions. The heat distortion temperature values suggested that the modified PLA could resist the thermal deformation from 58 °C to a maximum value of 139 °C when 1 µm talc was added at 10 wt%. With the presence of talc, the composites were more brittle and both tensile elongation at break and impact strength were decreased. [ABSTRACT FROM AUTHOR]