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Unsaturated chain structure of natural rubber makes it a poor defense against thermo-oxidative aging. Synthetic antioxidants are commonly used in rubber compound recipes to prevent/retard aging of the rubber material during its service life. However, synthetic antioxidants cause some negative effects on human and environmental health; they tend to be replaced by natural alternatives. In this study, the short- and long-term antioxidant effects of henna and its basic active components, lawsone and gallic acid, have been investigated individually for natural rubber cured with semi-efficient sulfur vulcanization system. The composition of henna was determined by gas chromatography-mass spectrometry (GC-MS) analysis. Qualitative and quantitative analysis were performed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) to highlight structural changes on aged vulcanizates. The authors attempted to correlate the suggested aging mechanism with rheological, mechanical, and morphological properties. Results showed that both lawsone and gallic acid were impressively successful regarding their anti-oxidation activity. In addition, henna, which contains a sufficient amount of lawsone and gallic acid, has been suggested as a competitive natural alternative to the common synthetic stabilization system for natural rubber, considering its sustainable commercial abundancy.

In the present work, various blend ratios of poly (lactic acid) (PLA), triallylisocyanurate (TAIC) and octavinyl-POSS (OvPOSS) were prepared by melt compounding in an Xplore microcompounder and molded by an Xplore microinjection molding device. POSS is a new generation organic/inorganic hybrid nanoparticle having possibility to improve the performance of polymers without sacrificing mechanical and thermal properties. TAIC and OvPOSS were used as crosslinking agents. After the compounding process, PLA, PLA/TAIC and PLA/OvPOSS composites were exposed to a gamma irradiation at various adsorbed doses ranging from 0 to 100 kGy. The properties of neat PLA, PLA/TAIC and PLA/OvPOSS composites were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and tensile testing. Results showed that both chain scission reactions and formation of network structure occurred simultaneously after gamma irradiation. The highest gel formation was obtained from PLA composites including 3 wt% OvPOSS at the dose of 100 kGy. DSC results indicated that a sharp decrease in the degree of crystallinity (Xc%) of PLA in the presence of TAIC and OvPOSS was obtained after gamma irradiation process. All irradiated composites exhibited lower elongation at break and higher E-Modulus values at any irradiation doses. TGA results showed that irradiated samples were more thermally stable than the unirradiated ones. Moreover, the heat deflection temperature (HDT) of PLA in the presence of TAIC and OvPOSS was found higher than that of neat PLA. Brittle surface morphology of composites after gamma irradiation process was obtained from SEM analysis.

In the present study, the effects of magnesia particles on thermal, dynamic mechanical, morphological, and surface properties of polystyrene resin are investigated. In general, the addition of magnesia particles in polystyrene matrix increases the thermal stability, storage modulus, and wettability, on other hand does not affect the molecular mobility. SEM results showed a limited distribution of magnesia particles in the polystyrene matrix at 15 wt.%.

In order to prepare an effective neutron shielding material, not only neutron but also gamma absorption must be taken into account. In this research, a polymer nanocomposite based novel type of multifunctional neutron shielding material is designed and fabricated. For this purpose, high density polyethylene (HDPE) was compounded with different amounts of hexagonal boron nitride (h-BN) and Gd 2 O 3 nanoparticles having average particle size of 100 nm using melt-compounding technique. The mechanical, thermal and morphological properties of nanocomposites were investigated. As filler content increased, the absorption of both neutron and gamma fluxes increased despite fluctuating neutron absorption curves. Adding h-BN and Gd 2 O 3 nano particles had a significant influence on both neutron and gamma attenuation properties (Σ, cm −1 and µ/ρ, cm −2 /g) of ternary shields and they show an enhancement of 200–280%, 14–52% for neutron and gamma radiations, respectively, in shielding performance.

Green composites of poly(lactic acid) (PLA) and waste cellulose fibers (WCF) were produced by using a facile technique comprising high-shear mixing within relatively short processing times that facilitates the ease of processing of such materials and ensures the homogeneous dispersion of such fibers in thermoplastics due to shear rates as high as 5200 rpm. Key parameters, such as optimal concentrations, homogeneous dispersion, direct and indirect mechanical contributions of the fibers, interfacial interactions, and crystallinity of the PLA matrix, were examined for the sustainable production of PLA/WCF green composites with enhanced stiffness, strength, toughness, and impact resistance. Briefly, around one-fold, 50%, and 20% increase in the elastic modulus, tensile strength, and impact strength of PLA, respectively, were achieved by the addition of 30 wt % WCF. In addition, an 87% increase in the impact strength of PLA was also achieved by the incorporation of 5 wt % WCF.

This chapter summarizes many of the recent technical accomplishments in the area of carbonaceous fillers such as carbon black, carbon nanotubes, and fullerene-filled/reinforced elastomer composites. Their characteristics, their impact, and their loading level on the thermal properties of rubbers such as natural rubber, styrene butadiene rubber, ethylene propylene diene monomer, and acrylonitrile butadiene rubber (NBR) are discussed by giving examples from the recently published literature. In addition to a literature survey, valuable information related to thermal techniques, differential scanning calorimetry, thermal gravimetric analysis, and thermomechanical analysis is given in this chapter.