Mechanical and tribological properties of nylon 6 and nylon 6/h-BN composites were investigated in this paper. Tensile, hardness, and impact tests were carried out for mechanical properties, while wear tests on pin-on-disc were carried out for tribological properties identification. Abrasion resistance tests were carried out on the TABER apparatus to analyze the abrasive wear of materials. SEM, XRD, and TGA were used to characterize the materials and to understand the distinctive features of nylon 6 and nylon 6/h-BN composites. Experimental results show that the mechanical properties and tribological behavior of nylon 6 got enhanced by the h-BN fillers. Tensile strength and modulus of elasticity were enhanced by 15.2% and 64.5%, respectively, while hardness and impact strength were enhanced by 3.45% and 6%, respectively. COF and wear rate of composites decreased up to 4 wt% filler reinforcement due to smooth transfer film formation. Coefficient of friction (COF) and wear resistance were improved by 10–15% and 8–10%, respectively, at various testing conditions. h-BN reinforcement in the matrix resulted in more weight loss due to abrasion and it reduced the abrasion resistance of nylon 6 by 5.5 times. Thermal stability was slightly increased, and crystallinity was little affected by the h-BN fillers.

Nylon composites are of evolving interest due to their good strength, toughness, and low coefficient of friction. Various fillers like micro- and nanoparticulates of metals and metal compounds were used to enhance the mechanical and tribological properties of nylons for many years by researchers. In this paper, an overall understanding of composites, filler materials, especially particulate filler materials, application areas of polymer composites, wear of polymers, and the effect of various fillers on tribo-mechanical properties of nylons have been discussed. The detailed review is limited to micro- and nanoparticulate fillers and their influence on the mechanical and tribological properties of various nylon matrices.

Summary A new, environmentally safe water-based polymer system has been developed for drilling applications with temperatures up to 232°C (450°F) and high pressures. The system components are newly developed synthetic polymers that do not contain chromium or other environmentally harmful materials. These new synthetic polymers are designed to perform specific functions at high temperatures and the innovative designs of these thermally stable polymers allow for the use of a minimum number of products in the formulation of high-temperature fluids. The new system consists of two basic polymeric components for rheology and filtration control at high temperatures. High-temperature fluid formulations are greatly simplified utilizing this new system, with only the two polymeric components being required, along with a pH control additive, weight material, and small amounts of clay for filter cake quality. This simplicity is a significant advantage over "traditional" high-temperature systems, which normally require the use of a large number of additives to control or limit the effects of thermal degradation. The new system may be formulated with fresh water or sea water, providing flexibility for a variety of drilling environments. Excellent resistance to common contaminants, such as calcium and magnesium hardness and solids accumulation, is another important characteristic of this new system. This paper will review the previous state of the art with respect to high-temperature, water-based muds and will generically discuss the unique chemistry of the newly developed polymer system components. System formulation and application will be discussed. Introduction The application of high-temperature, water-based fluids is traditionally based on concerns associated with the use of oil-based fluids, such as environmental compliance, logistical problems in remote locations, gas solubility in the fluids, and anticipated lost circulation zones. Although during the past several decades high-temperature, water-based fluids composed of modified natural products have been proven to exhibit effective and predictable performance,1 today's environmental and drilling performance requirements have mandated an alternative to these materials.2 For over 20 years sulfonated polyacrylic chemistries have been available for fluid loss control additives and fluid deflocculants. Since their inception, most of these polymers contain one, two, or three starting materials selected from a relatively small group of common monomers. High-temperature, water-based drilling fluids prepared with these materials often require supplemental treatment with modified natural products to achieve their necessary performance properties. The utilization of new and economically feasible monomers, along with a different approach to polymerization, allows for the preparation of new materials for use in high-temperature, water-based drilling fluids. In turn, these new fluids do not require traditional products to obtain good rheological and fluid loss control properties. The New High-Temperature Polymers Control of the Fluid Loss Properties of Drilling Fluids. Advances in high-temperature, high pressure (HTHP) fluid loss control have been realized with a new cross-linked copolymer prepared from acrylamide (monomer A), a sulfonated monomer (monomer S), and a cross-linking monomer (monomer X). The amount of cross-linking in the polymer's structure plays an important role in its solubility,3 which is related to the property of fluid loss control. Too much cross-linking will result in a polymer that is very rigid in physical structure and difficult to hydrate in water-based fluids. Too little cross-linking produces polymers having properties similar to those of the commonly used acrylamide copolymers, whose long and linear structures are known to have limited tolerances to contamination and shear. The new cross-linked polymer is compact and globular in morphological structure, as Fig. 1 shows. It retains a somewhat compact spherical shape in aqueous solution when compared to the expanded form of non-cross-linked linear chain polymers. When comparing the properties of this polymer to traditional linear molecules having the same molecular weight, the cross-linked polymer has a much smaller hydrodynamic volume in aqueous solution. The unique structure of the cross-linked polymer results in it being sterically hindered, increasing its intrinsic hydrolytic stability. Also, cross-linking makes it less sensitive to solids and more resistant to shear. Consequently, both rheological and filtration control properties of water-based drilling fluids are improved and preserved with the use of this unique polymer.

To investigate the influence of boric anhydride (B 2 O 3 ) on mechanical properties of nylon 6, tensile, hardness and impact test were carried out. Average tensile strength along with percentage elongation and modulus of elasticity has been calculated and plotted in this paper. Rockwell hardness and Izod impact tests were carried out to identify the hardness and toughness of materials. Boric anhydride used in this research was limited to less than 10 wt% of nylon 6 matrix material and was 2 wt%, 4 wt% and 8 wt%. Abrasion resistance of pure nylon 6 and composites was measured as weight loss due to abrasion. For the characterization of nylon 6 and its composites, Thermo-gravimetric analysis (TGA) and x-ray diffraction (XRD) were carried out. In results, it was found that the boric anhydride reinforcement increased the tensile strength and abrasion resistance when used up to 2 wt% in the nylon 6 matrix. Hardness found to be continually increased as the boric anhydride reinforcement percentage increased. The crystallinity of nylon 6 was little affected due to fillers and was found minimum for the 4 wt% boric anhydride reinforced nylon 6 composites. It was also found that the elastic modulus, Rockwell hardness and tensile strength, abrasion resistance show good correlations which are discussed in the discussion section.

Purpose This paper aims to investigate the mechanical and thermal behavior, i.e. tensile strength, hardness, impact strength and glass transition temperatures of water-treated polyamide6/boric oxide (PA) composites. Design/methodology/approach The PA6 and PA6/boric oxide composites were exposed to an open environment and immersed in water for 15 days to analyze the effect of environmental humidity and frequent water immersion conditions on the composite’s mechanical and thermal properties. The tensile strength, elastic modulus, hardness and impact strength of materials were measured to identify the mechanical properties. The scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) characterizations were used to see the effect of humidity/water absorption on microstructure, crystallinity and glass transition temperatures. Findings The testing results revealed the loss in strength, elastic modulus and hardness, while the impact resistance was improved after exposure of materials to humidity/water. SEM images clearly show the formation of voids and XRD graphs revealed the loss in crystallinity after water immersion. The DSC plots of water immersed materials revealed the loss of glass transition temperatures up to 15°C. Originality/value The mechanical and thermal behavior of PA composites varies according to the surrounding atmosphere. Experiments were performed to investigate the influence of water treatment on the PA6/B2O3 composite’s mechanical and thermal properties. Water treatment resulted in the bonding between PA and water molecules, which generated voids in the materials. These voids generations are found the main reason for the low strength and hardness of water-treated materials.