Journal of Applied Research in Chemical-Polymer Engineering

Abstract Research subject: Poly (vinyl chloride) (PVC) is non-biodegradable, and the widespread use of conventional plasticizers, particularly phthalates, in its formulation poses significant risks to human health and the environment. In this research, various blends of PVC and poly (lactic acid) (PLA) with different ratios were prepared in an internal mixer. The effect of PLA content, as well as the influence of various plasticizers including dioctyl phthalate (DOP), dioctyl adipate (DOA), epoxidized soybean oil (ESO), and chlorinated paraffin wax, on the mechanical and biodegradability properties was investigated. Furthermore, the role of a compatibilizer in improving the distribution of the PLA phase and increasing the compatibility between the polymers was evaluated.
Research approach: Tensile testing and dynamic mechanical analysis (DMTA) were performed to study the mechanical behavior. Scanning electron microscopy (SEM) imaging was used to examine the morphology and the distribution of the PLA phase. In addition, a biodegradability test was carried out to analyze the degradation behavior of samples in the environment.
Main results: The results indicated that the PVC/PLA(90/10)-DOP blend exhibited a suitable distribution of the PLA phase within the PVC matrix, whereas a poor distribution of PLA in PVC was observed in the PVC/PLA(80/20)-DOP blend. The addition of a compatibilizer to the PVC/PLA(80/20)-DOP sample led to increased uniformity in the PLA phase distribution and improved tensile strength. Samples with higher PLA content showed greater biodegradability behavior, suggesting the role of PLA as a degradability-enhancing agent. The comparison of different plasticizers indicated that several of the ones used in this research exhibit properties comparable to DOP and may be considered as effective substitutes for it. The findings suggest that the simultaneous use of PLA and appropriate plasticizers such as ESO, along with the application of a compatibilizer, is an effective method for producing PVC samples with enhanced mechanical and biodegradability properties.

Abstract Abstract
Research Subject: In recent years, the use of graphene nanoplatelets (GnPs) in polymer nanocomposites has attracted considerable attention. Dispersion state of GnPs in the polymer matrix has a great importance which can affect microstructure and final properties of nanocomposite. Therefore, in the present work, the effect of compatibilizer on the dispersion state of GnPs and also on internal structure, orientation, and tensile properties of polypropylene (PP)/GnPs nanocomposite fibers are investigated.
Research Approach: PP/GnPs nanocomposite fibers containing 0.1% and 0.5% GnPs with and without maleic anhydride-grafted polypropylene (PP-g-MA) were melt spun. Dispersion state and location of GnPs in the nanocomposite fibers were investigated by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). Fiber orientation and crystallinity were studied by polarized Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC), respectively. Moreover, fracture behaviour of PP/GnPs nanocomposite fibers was investigated by cross-sectional scanning electron microscopy (SEM) images of tensile fractured samples. Using Halpin-Tsai model, experimental tensile moduli of fibers were compared with the predicted values.
Main Results: TEM images show that in the compatibilized PP/MA/GnPs nanocomposite fibers, GnPs aggregates decrease and their size also reduces, suggesting that GnPs dispersion improved. An increase in L_p of the compatibilized sample recorded from SAXS analysis indicates that the more GnPs are located in the intrafibrillar region. Based on polarized FTIR and DSC results, orientation and crystallinity of PP/G0.5 nanocomposite fiber are found to significantly increase after inclusion of PP-g-MA. Moreover, reinforcing effect of GnPs in PP/MA/GnPs nanocomposite fibers could be explained by better GnPs dispersion and changes in internal structure of fiber. Furthermore, the tensile fracture behavior of PP/GnPs nanocomposite fiber changes from ductile to brittle in the presence of PP-g-MA.

Abstract Oil resistant o-rings on the basis of acrylonitrile butadiene rubber (NBR) reinforced by nanoclay were produced via a traditional industrial method in accordance with aviation standard, AMS 7272. The production of nanocomposites comprised the compounding of nanocomposite with optimum mechanical properties and minimum contents of used carbon black and nanoclay, design and manufacturing of the required mold and finally compression molding of the oring. Mechanical and morphological properties of NBR/nanoclay compounds were optimized by introduction of proper contents of a compatibilizer containing a mixture of resorcinol and hexamethylene tetramine through using a master batch production method. The prepared nanocomposites were characterized using X-ray diffraction (XRD) analysis, curing measurements and tensile test analysis. The XRD analysis showed that the compatibilizer facilitates the intercalation of nanoclay silicate layers with the rubber chains which leads to the increase of their basal spacing. The cure characteristics of the nanocomposites showed a decrease of scorch time and increase the cure rate index with the nanoclay loadings. Furthermore, the minimum scorch time and maximum cure rate index could be achieved through using the appropriate content of compatibilizer. The results exhibit that the nanocomposites containing the compatibilizer have higher mechanical properties especially at higher deformations compared to the corresponding uncompatibilized nanocomposites