Adhesion Research Papers - Academia.edu (original) (raw)

Most industrially applied polymer resins and composites have low surface free energy and lack polar functional groups on their surface, resulting in inherently poor adhesion properties. A strong research momentum to understand polymer... more

Most industrially applied polymer resins and composites have low surface free energy and lack polar functional groups on their surface, resulting in inherently poor adhesion properties. A strong research momentum to understand polymer adhesion in the last decade has been motivated by the growing needs of the automotive and aerospace industries for better adhesion of components and surface coatings. This paper reviews the recent research efforts on polymer adhesion with a special focus on adhesion mechanisms. It starts with an introduction to adhesion with explanatory notes on adhesion phenomena. Recent research on the adhesion mechanisms of mechanical coupling, chemical bonding and thermodynamic adhesion is then discussed. The area of adhesion promoters is reviewed with the focus on plasma and chemical treatments, along with direct methods for adhesion measurement. The topics of polymer blends and reactive polymerization are considered and the interactions with adhesion mechanisms are reported. The concluding section provides recommendations regarding future research on the contentious aspects of currently accepted adhesion mechanisms and on strategies for enhancing polymer adhesion strength.

We investigate the adhesion of PBT on aluminum using density functional theory-based calculations. The geometric structure of the PBT monomer is first relaxed then an aluminum atom is connected to the monomer in different orientations. We... more

We investigate the adhesion of PBT on aluminum using density functional theory-based calculations. The geometric structure of the PBT monomer is first relaxed then an aluminum atom is connected to the monomer in different orientations. We calculate their total energies and determine the orientation that gives the strongest binding between the monomer and the aluminum atom. Binding is strongest when the Al connects linearly with the carbonyl oxygen in the ester group. We present binding mechanisms and total energy relationships for the different orientations.

Cellulose nanofibers with a size range of 5–100 nm have the potential to be a low cost renewable material that has application in a range of products. However, current chemical methods to produce crystalline nanofibers suffer from low... more

Cellulose nanofibers with a size range of 5–100 nm have the potential to be a low cost renewable material that has application in a range of products. However, current chemical methods to produce crystalline nanofibers suffer from low yields and high chemical costs, while mechanical methods require high energy costs. Methods to lower the energy costs of the mechanical methods have not been well documented in the literature. A bleached softwood kraft pulp was processed using a mechanical dispersion mill and a homogenizer to produce cellulose nanofibers. Two different commercial enzymes were used to pretreat the wood fibers before the mechanical treatments. The resulting nanofibers were characterized by light microscopy, atomic force microscopy, and inverse gas chromatography. Results indicate that the dispersion mill does not affect the overall pulp fiber fibrillation, but does help prepare the sample for the homogenizer. Most fibrillation occurs after three passes through the homogenizer. The enzyme pretreatment has little effect on the size of the fibers, but does allow for higher solids to pass through the homogenizer without clogging. The dispersion component of surface energy of the resulting nanofibrils is impacted by the type of enzyme used. The measurement of acid–base properties proved to be challenging using current IGC experimental protocols.

Biofilms have been of considerable interest in the context of food hygiene. Of special significance is the ability of microorganisms to attach and grow on food and food-contact surfaces under favourable conditions. Biofilm formation is a... more

Biofilms have been of considerable interest in the context of food hygiene. Of special significance is the ability of microorganisms to attach and grow on food and food-contact surfaces under favourable conditions. Biofilm formation is a dynamic process and different mechanisms are involved in their attachment and growth. Extracellular polymeric substances play an important role in the attachment and colonization of microorganisms to food-contact surfaces. Various techniques have been adopted for the proper study and understanding of biofilm attachment and control. If the microorganisms from food-contact surfaces are not completely removed, they may lead to biofilm formation and also increase the biotransfer potential. Therefore, various preventive and control strategies like hygienic plant lay-out and design of equipment, choice of materials, correct use and selection of detergents and disinfectants coupled with physical methods can be suitably applied for controlling biofilm formation on food-contact surfaces. In addition, bacteriocins and enzymes are gaining importance and have an unique potential in the food industry for the effective biocontrol and removal of biofilms. These newer biocontrol strategies are considered important for the maintenance of biofilm-free systems, for quality and safety of foods.

There is no consensus in the literature regarding the potential toxicity of universal dental adhesives (UDA). Being used in close proximity to the pulp, their biocompatibility should be an important factor in dental research. The aim of... more

There is no consensus in the literature regarding the potential toxicity of universal dental adhesives (UDA). Being used in close proximity to the pulp, their biocompatibility should be an important factor in dental research. The aim of the present study was to evaluate the biocompatibility of UDA in an in vitro model. The study was performed using a monocyte/macrophage peripheral blood SC cell line (ATCC CRL-9855) on four specific UDA, namely: All-Bond Universal (Bisco); CLEARFIL Universal Bond Quick (Kuraray); G-Premio BOND (GC); Single Bond Universal (3M ESPE). The cytotoxicity of the investigated UDA was measured using the XTT colorimetric assay. The genotoxicity of the analyzed compounds was evaluated using an alkaline version of the comet assay. Furthermore, flow cytometry (FC) apoptosis detection was performed using the FITC Annexin V Apoptosis Detection Kit I. FC cell-cycle arrest assessment was performed using propidium iodide staining. The study observed significant differ...

The kelch motif was discovered as a sixfold tandem element in the sequence of the Drosophila kelch ORF1 protein. The repeated kelch motifs predict a conserved tertiary structure, a β-propeller. This module appears in many different... more

The kelch motif was discovered as a sixfold tandem element in the sequence of the Drosophila kelch ORF1 protein. The repeated kelch motifs predict a conserved tertiary structure, a β-propeller. This module appears in many different polypeptide contexts and contains multiple potential protein–protein contact sites. Members of this growing superfamily are present throughout the cell and extracellularly and have diverse activities. In this review, we discuss current information concerning the structural organization of kelch repeat proteins, their biological roles and the molecular basis of their action.

Background: Common measures of adherence to prescribed medications derived from administrative databases reflect both patients’ and physicians’ behavior, even if the measures are often interpreted as reflecting only the patient's... more

Background: Common measures of adherence to prescribed medications derived from administrative databases reflect both patients’ and physicians’ behavior, even if the measures are often interpreted as reflecting only the patient's adherence. Adherence to inhaled corticosteroids (ICSs) has been shown to be low among patients with asthma. Objective: To develop a new measure of patients’ adherence adjusted for prescription patterns and to evaluate the extent to which the low use of ICSs in asthma is due to patients’ nonadherent or suboptimal prescribing practices. Methods: The new measure of adherence, called the proportion of prescribed days covered (PPDC), is defined as the ratio of the total days’ supply dispensed to the total days’ supply prescribed during the study period. The PPDC is a modification of an existing adherence measure, the proportion of days covered (PDC). The PPDC and PDC for ICSs, therapy that should be prescribed for chronic daily use to patients with persisten...

Glass polyalkenoate cements (GPCs) have been used in dentistry for over 40 years. These novel bioactive materials are the result of a reaction between a finely ground glass (base) and a polymer (acid), usually poly(acrylic acid) (PAA), in... more

Glass polyalkenoate cements (GPCs) have been used in dentistry for over 40 years. These novel bioactive materials are the result of a reaction between a finely ground glass (base) and a polymer (acid), usually poly(acrylic acid) (PAA), in the presence of water. This article reviews the types of PAA used as reagents (including how they vary by molar mass, molecular weight, concentration, polydispersity and content) and the way that they control the properties of the conventional GPCs (CGPCs) formulated from them. The article also considers the effect of PAA on the clinical performance of CGPCs, including biocompatibility, rheological and mechanical properties, adhesion, ion release, acid erosion and clinical durability. The review has critically evaluated the literature and clarified the role that the polyacid component of CGPCs plays in setting and maturation. This review will lead to an improved understanding of the chemistry and properties of the PAA phase which will lead to further innovation in the glass-based cements field.

This study aims to investigate the adhesion phenomena between glass and composite materials, which-if they work in synergy-can increase the performance of glass structures, as regard both structural elements and the manufacture of joints.... more

This study aims to investigate the adhesion phenomena between glass and composite materials, which-if they work in synergy-can increase the performance of glass structures, as regard both structural elements and the manufacture of joints. The experimental programme consisted of shear traction tests on all samples: glass-glass singlelap shear adhesion, glass-GFRP double-lap shear adhesion and glass-SRP shear adhesion. Different types of adhesive and various interface geometries were also tested to evaluate the ultimate force and identify fracture patterns with different bonding lengths. It was possible to identify the effective bonding length for each type of resin used to prepare test samples, by taking fracture load and average peel stress into account. Bonding length variations were also recorded. This enabled the values of bonding length to be verified analytically. Based on experimental results, a formula for the evaluation of delamination resistance and the optimal bonding length is proposed.

Eggs of 23 Characiformes and eight Siluriformes, belonging to nine families with diverse reproductive behaviour, were ultrastructurally analysed. The migratory species exhibited non-adhesive eggs, whereas, most of the sedentary species... more

Eggs of 23 Characiformes and eight Siluriformes, belonging to nine families with diverse reproductive behaviour, were ultrastructurally analysed. The migratory species exhibited non-adhesive eggs, whereas, most of the sedentary species presented some degree of egg adhesiveness. Among the Characiformes, non-adhesive eggs showed zona radiata with pore-canals or a fibrillar net at the surface; weakly adhesive eggs presented only zona radiata with pore-canals while adhesive eggs exhibited zona radiata with apparatus like globules, filaments, villi or honeycomb-like pores depending on the systematic group. The ‘jelly’ coat is strongly related to the Siluriformes eggs apparently without relationship with adhesiveness. A micropylar disc was present in adhesive eggs of a few species of both Characiformes and Siluriformes. Some patterns were characteristic of the animal pole, others of the vegetal pole, and others were common to both poles. The radial ridges converging to the micropyle in Astyanax bimaculatus lacustris appear to be related to fertilization. In general, egg surface structures in the Characiformes varied according to the genus, whereas all Siluriformes showed a similar egg surface pattern, regardless of the group analysed. Multivariate analysis allowed the identification of eight clusters among the Characiformes and three among the Siluriformes showing relationships between reproductive style and egg characteristics. It is suggested that egg surface and adhesiveness may be related to reproductive patterns and to phylogenesis.