2D-COS–FTIR was used to locate the crystallization-sensitive bands of ion-irradiated poly(ether ether ketone). The band at 1310 cm−1 was the most sensitive band, and the area under this band changed linearly with the degree of crystallization which was obtained from differential scanning calorimetry. The deviation between experimentally determined and calculated degree of crystallization progressively increased at irradiation doses above 20 MGy for proton and helium-irradiated PEEK. This was attributed to different cross-linking mechanism on irradiation with the two different ions. 2D-COS–FTIR spectroscopy is a powerful tool for polymer characterization and helps in the quantitative analysis.
Mn3O4/MnSnO3 nanocomposites have been successfully synthesized via solvothermal method by using the mixed solution consisting of manganese chloride and tin chloride salt dissolved in the mixture of ethanol and deionized water in 50:50 ratio at the processing temperature of 180 °C by adapting different capping agents such as PVP, PVA and ethylene glycol. The synthesized Mn3O4/MnSnO3 nanocomposites were characterized by employing X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, photoluminescence spectra and scanning electron microscopy (SEM) studies. The obtained XRD spectra confirmed the formations of Mn3O4/MnSnO3 nanocomposite illustrated by the sharp predominant diffraction peak observed at 34.2° corresponding to the (021) lattice planes of Mn3O4. The SEM images supply the information about the morphology of synthesized Mn3O4/MnSnO3 nanocomposites. The sharp peaks observed at 483 cm−1 further characterize the presence of Mn–O stretching vibration bond in Mn3O4/MnSnO3 nanocomposite by employing Raman spectra. The PL result revealed the emissive nature of the sample. FTIR spectra observed at 625 cm−1 attributed to the characteristic peaks of Mn3O4/MnSnO3 nanocomposite. The Mn3O4/MnSnO3 nanocomposite synthesized by the assistance of PVP surfactant exhibits the high specific capacitance of 178.2 F g−1 at 0.5 Ag−1 current density which can be considered as potential candidate and excellent electrode for pseudocapacitors applications.
In this research, mechanical, thermal, and water uptake behaviour of surface-modified sea urchin spike biofiller and kenaf woven fibre mat-reinforced neem oil blended epoxy resin composite has been studied. The principal aim of this research was fabrication of eco-friendly hybrid composite and explicitness of the importance of surface modification on reinforcements. Neem oil was blended with epoxy resin to reduce extreme brittleness of epoxy, making the composite as an eco-friendly one. Sea urchin biofiller was prepared using high energy ball mill. Both filler and fibre were surface-treated by amino silane. The results revealed that additions of surface-treated sea urchin particle and kenaf fibre increased the mechanical properties of composite. Similarly thermal results exposed that addition of sea urchin bioceramic filler greatly increased the thermal stability of neem-epoxy biocomposite. SEM fractographs showed uniform dispersion of sea urchin filler and improved adhesion of kenaf fibre with epoxy matrix.
There is a global acceleration in the employment of inorganic fiber-reinforced wood–plastic composites in various fields. The durability of composites is challenged by hot and humid environments, where their service life is greatly shortened compared to that in normal environments. Therefore, it is rare to adding basalt fibers (BF) for wood plastic composites, to extend the actual applications; how to better improve the service life is important issue. So, the physical, mechanical, and thermal properties of composites are deeply investigated for durability. In this study, BF, which is a relatively stable fiber, is selected as the research object. The results indicate that the physical, mechanical, and thermal properties of composites improved by BF. The mechanical properties of composites are optimal when the content of BF reached 10%. Water resistance of the impregnated composites improves more than that of non-impregnated composites. The physical and mechanical properties of composites were observed by scanning electron microcopy. Good interfacial adhesion limits the mobility of polymer chains lead to good performance. Additionally, the thermal properties are enhanced owing to the addition of BF, especially the low linear coefficient of thermal expansion and the high thermal decomposition temperature. BF has a positive effect in reinforced composites.
Red brick dust (RBD) is the waste or leftover powder, or the powder formed from deformed bricks in the process of their manufacturing. Bricks can be deformed while handling and the deformed bricks cannot be used for construction purposes; hence, they are dumped as waste. This article describes on erosion wear response of a new class of hybrid composites consisting of epoxy reinforced with glass fiber and filled with RBD particulates. Different compositions of composites are prepared by simple hand lay-up technique. Erosion characteristics are studied with the help of an air jet type erosion test rig employing the design-of-experiments approach based on Taguchi’s orthogonal arrays. An artificial neural network approach is also applied to predict the wear rate of the composites. The morphology of worn surfaces is then examined by scanning electron microscopy, and possible wear mechanisms are discussed. This study reveals that addition of red brick dust improves the erosion resistance of glass–epoxy composites significantly and thus, makes them suitable for tribological applications.
Molecular and morphological properties of poly(vinyl chloride) (PVC) grains produced by suspension polymerization of VCM in the presence of a mixture of fast, mild and slow initiators (named as Cok process) was experimentally investigated in a pilot-scale reactor. In contrast to nonisothermal and fast initiator dosage process, using initiators mixture has the smallest influence on molecular weight and polydispersity index compared to the control process. It is found that Cok-PVC grains have the lowest cold plasticizer absorption and porosity among productivity-enhancing processes. Scanning electron microscopy showed that the particles produced by Cok process are more regularly shaped, with a smoother surface compared with the control resin. All three productivity-enhancing techniques lead to an apparent quality enhancement, higher flowability and greater bulk density of final grains when compared with control resin grains. While both nonisothermal and fast initiator dosage polymerization process broaden the particle size distribution (PID) of final PVC grains, applying Cok process produces particles with the same PID as a control process. In comparison with nonisothermal trajectory and continuous fast initiator dosage system, the Cok polymerization process leads to the most delay of motionless conversions, fusion time and the formation of a three-dimensional skeleton of primary particles as well.
The effects of thermo-mechanical recycling through repeated extrusion cycles on morphology and properties of neat ethylene vinyl acetate copolymer (EVA) and EVA/olive husk flour (OHF) composites (70/30 w/w) with and without ethylene–butyl acrylate–glycidyl methacrylate (EBAGMA) compatibilizer were investigated in a single screw extruder machine up to five repeated cycles. The study showed that no significant modifications in the properties of the virgin EVA/OHF composite were observed along the recycling and this stability was further enhanced in the presence of EBAGMA. Indeed after five repeated extrusion cycles, the chemical structure and properties of both uncompatibilized and compatibilized composites remained unchanged compared to the neat polymer, which was subjected likely to cross-linking, in the fifth cycle. Furthermore, SEM analysis showed a better dispersion of OHF particles in EVA matrix and a good filler–polymer interfacial adhesion, being, however, more pronounced for the compatibilized composite.
Pineapple leaf fiber (PALF) is one of the abundantly available agro-waste materials in Bangladesh. PALF-reinforced low-density polyethylene (LDPE)-based composites were fabricated by compression molding with randomly oriented fiber loading varying 10–60 wt%. In this study the influence of the fiber loading on the mechanical properties such as tensile, flexural and Izod impact was investigated. Water absorption tests of the composites were also carried out for determining water resistance properties of composites. Thermal properties of PALF were analyzed by thermogravimetry and derivative thermogravimetry. Scanning electronic microscopic studies were performed to understand the fiber–matrix adhesion and fiber breakage. To improve the compatibility between fiber and matrix, 50/50 PALF/LDPE composites were irradiated with gamma rays (Co-60) of doses where composites irradiated with 7.5 kGy dose showed the best results. Tensile properties of the composites were found to be improved significantly after gamma irradiation.
The logical outline and assembly of structural–functional materials are a progressive tendency of materials knowledge. Graphene (Gr) spread in LDPE considerably increases thermal/mechanical properties of LDPE/Gr composites. DMA and strength testing machine were used to study mechanical properties. The high specific surface areas and superior properties of Gr improved thermal strength, conductivity, storage modulus, and mechanical properties of composites. The electrical conductivity upgraded owing to the great thermal strength of Grs in LDPE matrix. In terms of rheology, the addition of Grs augmented viscosity of LDPE matrix. Outstanding distribution of Grs was accomplished. LDPE/Gr composites were characterized by SEM, TEM, Raman spectra, XRD, TGA and DSC to study distribution morphology and thermal strength. Results display that presence of filler does not create an alteration in microscopic structure of polymers. However, on a macroscopic scale, Gr constrains mobility of polymer chains, causing a growth in stiffness and strength of composite.
The thermal decomposition and flame-retardant physical characteristics of specimens are explained via the limiting oxygen index (LOI), cone calorimeter, smoke density, and thermogravimetry analysis (TGA) tests. The outcomes of TGA, smoke emission, and LOI tests showed that thermal strength and flame-retardant characteristics of the specimens containing magnesium hydroxide (MH) have superior thermal strength compared with the similar specimens containing alumina trihydrate (ATH). The flame-retardant characteristics and thermal strength of specimens were boosted upon radiation and the development of cross-linking bonds in the polymer structure. The smoke density tester results present that MH specimens generate the least smoke density associated with the pristine low-density polyethylene and the similar ATH specimens. This study proved that the inclusion of MH and radiation of specimens generated greater thermal strength and flame-retardant characteristics compared with the inclusion of ATH to radiated specimens. These successes are right and proper for cable companies to deliver halogen-free flame-retardant cable materials.
Polydimethylsiloxane belongs to a polymeric organosilicon compounds that is widely used as silicon-based organic polymer. Polydimethylsiloxane is a basically optically clear, inert, nontoxic and inflammable material which is widely used in medical devices, as an elastomer, antifoaming agent, heat-resistant lubricants, fire retardants, in cosmetics and for other valuable domestic applications. This comprehensive review of polydimethylsiloxane describes synthesis, characterization, surface modifications and formation of vital biodegradable films/membranes that can facilitate improvements in modern research. Polydimethylsiloxane is viscoelastic, hydrophobic, cytocompatible and herbicidal penetrant that provides water-repellent coatings in textile industry. In this study, copolymers of polydimethylsiloxane were thoroughly studied based on polyimides, carboxyesters, hydroxyethyleneoxide, degradation with polystyrene, cross-linking with block copolymers, phosphorus-based, gelatin-based and polyurethanes, which can be used for modern manufacturing purposes in all kinds of industrial world. Graphic abstract
Aiming to achieve different characteristics with polypropylene copolymer, especially in relation to transparency similar to glass packaging, the effect of the addition of a clarifying agent derived from sorbitol to the polypropylene copolymer was studied. A specific cup shape packaging used for Brazilian cream cheese was applied. The samples were produced with different amounts of clarifying agent and were injected in industrial equipment. Further, the samples were characterized in regard to optical, mechanical and thermal properties. The results confirmed that the addition of clarifying agent, besides improving the transparency of the polypropylene copolymer, also increases the tensile strength. Moreover, from the view of applicability, the clarifying agent was demonstrated to be advantageous for the polypropylene copolymer production of Brazilian cream cheese packaging.
Microencapsulation is a widely used method for making healing agents used in self-healing composites. In this study, a novel two-stage process was used to make double-walled microcapsules. Dicyclopentadiene–urea formaldehyde (DCPD–UF) microcapsules were synthesized by in situ polymerization of oil-in-water emulsion followed by siloxane coating through ‘sol–gel process’ (DCPD–UF–siloxane microcapsules). Average diameter of microcapsules, UF shell thickness and siloxane coating thickness were found to be 300, 1.4 and 16 µm, respectively. The effect of addition of microcapsules on rheological properties of epoxy was studied. Breaking pattern of single-walled and double-walled microcapsules immersed in epoxy was analyzed by continuous monitoring of the deformation behavior through a rheometer–microscope arrangement, confirming improved mechanical properties of the double-walled microcapsules. In this study, epoxy resin cast specimens with and without microcapsules were prepared and the effect of microcapsules on mechanical properties was examined. Epoxy specimens with double-walled microcapsules were found to be having improved mechanical properties compared to those with single-walled microcapsules. Finally, healing efficiency of DCPD–UF–siloxane microcapsules in epoxy was observed to be marginally higher, and therefore, this double-walled microcapsule system is shown to be a promising candidate for further self-healing composite investigations.
Composites of polyurethane (PU)/multi-walled carbon nanotubes (MWCNTs) have been successfully prepared by using Solvent Mixing approach followed by injection molding. Field emission scanning electron microscopy has been performed and indicated reasonable dispersion of MWCNTs into PU matrix. Mechanical characterization shows that tensile modulus and stiffness of PU/MWCNT composites have been greatly improved by 23 times and 15 times, respectively, for 7 wt% in comparison with pure PU. Torsion and three-point bend tests revealed that torque and flexural modulus of PU composite with 7 wt% of MWCNTs have also been improved in comparison with pure PU. Excellent load transfer property of MWCNTs and their interaction with polymer matrix due to even dispersion are the suggested reasons for the improvement in mechanical properties. This significant improvement in mechanical properties of PU/MWCNT composite opens up several new avenues of mechanical applications like fabrication of shoes, gloves, helmet and other materials for armed force personnel.
Polyamide 6 (PA6)/polyvinyl alcohol (PVOH) blends of different compositions (90/10, 80/20, 70/30, 60/40) were prepared using Haake rheomixer. The selected blend compositions (80/20 and 60/40) were modified with peroxides (dicumyl peroxide—DCP and tertiary butyl cumyl peroxide—TBCP). The thermal and mechanical properties of the blends were studied. The thermal stability of blends is found to be intermediate to that of PA6 and PVOH. There is no significant change in thermal stability with the addition of peroxides. The FTIR studies proved good interaction between the components in blend systems. The DSC measurements showed reduction in crystallinity of PA6 with the addition of PVOH. The crystallinity further reduced with the addition of peroxides to the blends, due to the formation of crosslink network. The MFI values decreased with the addition of PVOH and peroxides. The PA6/PVOH blends showed poor mechanical properties, whereas the properties were improved with the addition of peroxides to PA6/PVOH blends.
In this work, the mechanical response of fused deposition modeling (FDM) specimens made of polylactic acid (PLA) and polylactic acid nanocomposite with graphene (PLA GnP) filler is experimentally determined. A wide variety of standard tests was performed. Test results were assessed to depict quantitatively the mechanical properties of the materials tested. Comprehensive comparison of the mechanical strength between FDM-printed PLA and PLA GnP polymers was carried out to illustrate the filler’s impact. Effect of the FDM process in these materials’ properties arises by comparing them to the ones of the bulk or injection molded specimens, in quantitative and qualitative terms. Comparison demonstrates that both polymers exhibit similar behavior in every case, with slight domination of the PLA to the PLA GnP composite. Test results were correlated with the patterns of the specimens’ fractured surfaces, obtained through scanning electron microscopy. Effect of graphene in the dielectrics of the material is also evaluated, with the measurements showing a significant increase in the dielectric values, with the addition of this specific nanocomposite in the material.
A novel superabsorbent polymer composite based on mung bean starch was prepared via emulsion polymerization technique of partially neutralized acrylic acid grafted onto waste polystyrene chain using ammonium persulfate and N,N′-methylenebisacrylamide as initiator and crosslinker, respectively. Fourier transform infrared confirmed the presence of mung bean starch in the grafting of polyacrylic acid and waste polystyrene. The introduction of starch in superabsorbent polymer greatly enhanced the swelling capacity with the optimum absorbency recorded at 59.3 g/g for 20% of starch loading. Meanwhile, thermogravimetric analysis showed enhance in thermal stability upon incorporation of mung bean starch.
Surface damage in machining of fiber-reinforced polymer-based composites is almost unavoidable during manufacturing. Most often, machining operation—drilling causes delamination of composite surface that leads to the loss of quality of product. As a consequence, reasonably accurate prediction of delamination factor (Fd) of drilled hole emerges as a prerequisite during the product development stage and freezing the design before final production. However, stochastic nature of the response and heterogeneous material properties make the modeling difficult. In this article, one of the most advanced generalized learning-based technologies, support vector machine (SVM) which could read the underlying unseen effect of input factors on response, is applied for regression model developing of drilling response—Fd on glass fiber-reinforced polyester composite. Gaussian radial basis function and ε -insensitive loss function are used as kernel functions and loss function, respectively. Particle swarm optimization (PSO) is modified, and modified PSO is employed to search the optimal combination of internal parameters of SVM for modeling of Fd. Model, thus developed, is validated with follow-up testing data sets. Based on estimated model, optimum input parameters for minimum Fd is further investigated using the procedure of modified particle swarm optimization.
The present work was focused on studying the effects of different CB loadings on the rheological, thermal, tensile, dynamic mechanical, and electrical properties of polyvinylidene fluoride and FKM composites. To these ends, dynamic mechanical thermal analysis (DMTA) was conducted, and the CB grade and method chosen for compound preparation were CB (N330) by melt mixing with different shear effects were examined, respectively. The composites were melt-blended with CB at 190 °C in an internal mixer, after which the properties of filled and unfilled composites were compared. The DMTA analysis revealed that the area under the loss tangent (tanδ) peak decreased and that the tanδ temperature of the rubber phase increased with CB loading. The presence of CB improved the mechanical properties, such as the Young’s modulus and tensile strength, of the composites and increased thermal stability given the high thermal stability of CB and the interaction between the CB particles and the polymer matrices. The increase in the electrical conductivities of the composites under different CB loadings was also examined with different shear effects because of the different dispersion states of CB. The percolation threshold of conductive thermoplastic vulcanizate composite based on conductive CB was observed and the experimental data could be well fitted to the general equation model.
A new type of co-polymer between anthranilic acid cinnamoyl ester and monoethyleneglycol dimethacrylate was synthesized via aza-Michael addition polymerization reaction by bulk polymerization method without adding any catalyst. The polymerization reaction was carried out at 100 °C for 2 h under N2 atmosphere with mild stirring. The co-polymer was synthesized at various monomer ratios. The above-synthesized co-polymer was characterized by Fourier transform infrared (FTIR) spectroscopy, UV–visible reflectance spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy, etc. The FTIR data confirmed the 0.032 order of reaction with respect to [M1/M2]. The amorphous nature of the above-synthesized polymer was confirmed by XRD. The non-isothermal degradation kinetics was followed at five different heating rates with five different models. The goal of the present work is to compare the results from TGA data and select the best approach for the synthesized polymer. The activation energy (Ea) values were also determined by model-free methods. The experimental results were carefully analysed and compared with the literature values.
