Co2(CO)8 and unsaturated epoxides as unexpected partners in generating functionalized siloxane oils and cross-linked materials

Herein, we describe the unexpected ring opening of the epoxide group of allyl glycidyl ether and 4-vinylcyclohexene oxide in polymethylhydrosiloxane (PMHS) hydrosilylation reaction using 0.1 mol% of Co2(CO)8 as catalyst....

Interlaminar Toughening of Fiber-Reinforced Polymers by Synergistic Modification of Resin and Fiber

The synergistic effect of combining different modification methods was investigated in this study to improve the interlaminar toughness and delamination resistance of fiber reinforced polymers (FRP). Epoxy-compatible polysulfone (PSU) was end-capped with epoxide group through functionalization, and the fiber surface was chemically grafted with an amino functional group to form a micron-size rough surface. Consequently, the long chain of PSU entangles into cross-linked thermoset epoxy network, additionally, epoxide group on PSU further improves the bonding through chemical connection to the epoxy network and amino group on the fiber surface. The combined modification methods can generate both strong physical and chemical bonding. The feasibility of using this method in vacuum-assisted resin transfer molding was determined by rheometer. The impact of formed chemical bonds on the cross-linking density was examined through glass transition temperatures. The chemical modifications were characterized by Raman spectroscopy to determine the chemical structures. Synergistic effect of the modification was established by mode I and mode II fracture tests, which quantify the improvement on composites delamination resistance and toughness. The mechanism of synergy was explained based on the fracture mode and interaction between the modification methods. Finally, numerical simulation was used to compare samples with and without modifications. The experiment results showed that synergy is achieved at low concentration of modified PSU because the formed chemical bonds compensate the effect of low cross-linking density and interact with the modified fiber.

The Effects of Deoxynivalenol (DON) on the Gut Microbiota, Morphology and Immune System of Chicken – A Review

Feed contamination is a major cause of diseases outbreak in the poultry industry. There is a direct relationship between feeding, the intestinal microbiota and how the immune system responds to disease infestation. Cereals which form the bulk of poultry feed are mostly contaminated by mycotoxins of Fusarium origin. Adequate knowledge of mycotoxins and their effects on animals is necessary. Deoxynivalenol (DON) is a major contaminant of poultry feed. DON has the ability to bind with a large number of eukaryotic ribosomal subunits because of the presence of an epoxide group and these disrupt the activity of peptidyl transferase and the elongation or shortening of peptide chains. Deoxynivalenol has varying effect ranging from acute, overt diseases with high morbidity and death to chronic disease, decreased resistance to pathogens and reduced animal productivity. Deoxynivalenol also impairs the intestinal morphology, nutrient absorption, barrier function, and the innate immune response in chickens. This review highlights the impacts of deoxynivalenol on the immune system, intestinal microbiota composition and the morphology of chicken.

The Fate of Altertoxin II During Tomato Food Processing

The emerging <i>Alternaria </i>mycotoxin altertoxin II demonstrated substantial genotoxicity <i>in vitro</i>. Ubiquitous <i>Alternaria ssp</i>. frequently infest various agricultural crops, leading to economic losses and also potential food safety issues caused by associated mycotoxin contaminations. Due to the lack of commercially available reference standards, data on the general chemical behavior, the occurrence and the biological/toxicological effects of altertoxin II are scarce. Since tomatoes are particularly prone to <i>Alternaria </i>infestations, we simulated the storage and food processing of intact tomatoes and purees after altertoxin II-addition. We observed significant decrease in altertoxin II concentrations during storage at room temperature and particularly under thermal stress, by employing a validated LC-MS/MS method. Moreover, the reduction to the compound’s epoxide group to the alcohol, i.e. the formation of altertoxin I, was determined at considerable ratios in intact tomato fruits suggesting effective enzymatic xenobiotic metabolism.<br>

Curing of epoxy/alkyd blends in self-healing coating

Self-healing of polymeric material using microcapsules has been developed to repair microcracks within the materials. The self-healing character is reflected from the curing behavior of the material. In this work, curing study of alkyd/epoxy blend was carried out by replacing part of amine hardener with alkyd in the epoxy formulation. The inclusion of alkyd in the epoxy blend resulted in higher degree of curing and higher thermal stability compared to the alkyd-free blend, as evidenced from higher heat of reaction values of differential scanning calorimetry and maximum degradation temperature at 379°C, respectively. Self-healing reaction of epoxy coating as evaluated by Fourier-transform spectroscopy revealed that the 914 cm−1 peak attributed to C–O–C of epoxy has decreased, as the epoxide group was consumed in the reaction. Appearance of a new peak at 1631–1632 cm−1 in the cured coating confirmed that the epoxide has reacted with the carboxylic acid group of alkyd to form ester.

Interlaminar Toughening of Fiber Reinforced Polymers by Synergistic Modification of Resin and Fiber

The synergistic effect of combining different modification methods was investigated in this study to improve the interlaminar toughness and delamination resistance of fiber reinforced polymers (FRP). Epoxy-compatible polysulfone (PSU) was end-capped with epoxide group through functionalization, and the fiber surface was chemically grafted with amino functional group to form a micron-size rough surface. Consequently, the long chain of PSU entangles into crosslinked thermoset epoxy network, additionally, epoxide group on PSU further improves the bonding through chemical connection to the epoxy network and amino group on fiber surface. The combined modification methods can generate both strong physical and chemical bonding. The feasibility of using this method in vacuum assisted resin transfer molding was determined by rheometer. The impact of formed chemical bonds on the crosslinking density was examined through glass transition temperatures. The chemical modifications were characterized by Raman Spectroscopy to determine the chemical structures. Synergistic effect of the modification was established by Mode I and Mode II fracture tests which quantify the improvement on composites delamination resistance and toughness. The mechanism of synergy was explained based on the fracture mode and interaction between the modification methods. Finally, Numerical simulation was used to compare samples with and without modifications. The experiment results showed that synergy is achieved at low concentration of modified PSU because the formed chemical bonds compensate the effect of low crosslinking density and interact with the modified fiber.

Selective engineering of oxygen-containing functional groups using the alkyl ligand oleylamine for revealing the luminescence mechanism of graphene oxide quantum dots

The role of the epoxide group in light emission of GOQDs is demonstrated by selective passivation using the alkyl ligand oleylamine.

Synergetic effect of the epoxide functional groups in the photocatalyzed atom transfer radical copolymerization of glycidyl methacrylate

Methyl methacrylate (MMA) and glycidyl methacrylate (GMA) were copolymerized by photocatalyzed atom transfer radical polymerization under visible light irradiation. The polymerization was made faster by the epoxide group, which played the role of a reducing agent and thus favored the regeneration of the activator.