The effect of ageing in water solution containing iron sulfate on the mechanical properties of epoxy adhesives

This study investigates the effect of operating factors such as seasoning in water solution containing iron (II) sulfate—FeSO4 (5 different water solution variants were tested) on the mechanical properties of an adhesive compound made of epoxy resin and amine curing agent, in a ratio of 100 g resin to 12 g curing agent. Strength tests of cured adhesive compound samples were performed on the Zwick/Roell Z150 testing machine in compliance with the EN ISO 604 standard. During the tests, compression modulus, compressive strength and compressive strain were measured. Obtained results served as a basis for analyzing the effect of a water environment containing iron sulfate on a given adhesive compound. It has been found that too high iron sulfate content in water has a negative effect on the mechanical properties of adhesive compound samples

Thermal/electrical properties and texture of carbon black pc polymer composites near the electrical percolation threshold

Polycarbonate (PC), a thermoplastic polymer with excellent properties, is used in many advanced technological applications. When PC is blended with other polymers or additives, new properties, such as electrical properties, can be available. In this study, carbon black (CB) was melt-compounded with PC to produce polymer compounds with compositions (10–16 wt.% of CB), which are close to or above the electrical percolation threshold (13.5–14 wt.% of CB). Effects due to nanofiller dispersion/aggregation in the polymer matrix, together with phase composition, glass transition temperature, morphology and textural properties, were studied by using thermal analysis methods (thermogravimetry and differential scanning calorimetry) and scanning electron microscopy. The DC electrical properties of these materials were also investigated by means of electrical conductivity measurements and correlated with the “structure” of the CB, to better explain the behaviour of the composites close to the percolation threshold

Debonding of adhesive joints by means of microwave and induction heating processes

In this work, an innovative technique for adhesive joint separation that combines the use of a hybrid-modified adhesive with microwave (MW) or induction heating (IH) [1-3] processes is presented. Graphene nanoplatelets (GnPs) and iron oxide particles were used to modify a thermoplastic adhesive, polyolefin hot-melt adhesive by mean of a twin-screw extruder. This thermoplastic adhesive, already used for bonding automotive applications, was modified with both iron oxide and GnPs in order to enhance the electrical properties and the sensitivity to MW and IH. The mechanical and electrical properties together with the sensitivity of the modified adhesives to microwave or induction heating processes are investigated. Single Lap Joint (SLJ) specimens were used to evaluate the mechanical properties of the pristine and the modified adhesive. The mechanical tests illustrate that the maximum loads of modified adhesives decrease slightly. Tests conducted with microwave and induction heating processes showed that these two systems are able to melt the modified adhesive. Thus, the separation of bonded joints is possible with both systems. The temperature increase of the induction heating system is found to be more rapid than the microwaves but the latter system is energetically more efficient. Scanning Electron Microscope (SEM) was used to measure the particle distribution and to evaluate the differences between the manual mixed mode and the tween extruder system as preliminary analysis

On the interactions of melatonin/β-cyclodextrin inclusion complex: A novel approach combining efficient semiempirical extended tight-binding (xtb) results with ab initio methods

Melatonin (MT) is a molecule of paramount importance in all living organisms, due to its presence in many biological activities, such as circadian (sleep–wake cycle) and seasonal rhythms (reproduction, fattening, molting, etc.). Unfortunately, it suffers from poor solubility and, to be used as a drug, an appropriate transport vehicle has to be developed, in order to optimize its release in the human tissues. As a possible drug-delivery system, β-cyclodextrin (βCD) represents a promising scaffold which can encapsulate the melatonin, releasing when needed. In this work, we present a computational study supported by experimental IR spectra on inclusion MT/βCD complexes. The aim is to provide a robust, accurate and, at the same time, low-cost methodology to investigate these inclusion complexes both with static and dynamic simulations, in order to study the main actors that drive the interactions of melatonin with β-cyclodextrin and, therefore, to understand its release mechanism

On the interactions of melatonin/β-cyclodextrin inclusion complex: A novel approach combining efficient semiempirical extended tight-binding (xtb) results with ab initio methods

Melatonin (MT) is a molecule of paramount importance in all living organisms, due to its presence in many biological activities, such as circadian (sleep–wake cycle) and seasonal rhythms (reproduction, fattening, molting, etc.). Unfortunately, it suffers from poor solubility and, to be used as a drug, an appropriate transport vehicle has to be developed, in order to optimize its release in the human tissues. As a possible drug-delivery system, β-cyclodextrin (βCD) represents a promising scaffold which can encapsulate the melatonin, releasing when needed. In this work, we present a computational study supported by experimental IR spectra on inclusion MT/βCD complexes. The aim is to provide a robust, accurate and, at the same time, low-cost methodology to investigate these inclusion complexes both with static and dynamic simulations, in order to study the main actors that drive the interactions of melatonin with β-cyclodextrin and, therefore, to understand its release mechanism