Synthetic polymers:A review of applications in drilling fluids

With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,together with advances in SP-treatment methods aimed at reducing those impacts.Recommendations for required future research addressing SP property and performance gaps are provided.

DNA Separation by Capillary Electrophoresis with Ultraviolet Detection using Mixed Synthetic Polymers

The mixtures of two polymers, poly (N,N-dimethylacrylamide) (PDMA) and polyvinylpyrrolidone (PVP) were synthesized and used as the separation medium for double-stranded and single-stranded DNA fragments by capillary electrophoresis with UV detector. On optimal conditions, 2%w/v PDMA + 2%w/v PVP can be used to separate the doublet 123/124bp in pBR322/Hae III Markers.

Application of Pomegranate Rind Extract for Improvement of Functional Properties of Various Materials—A Critical Review

Pomegranate rind is abundantly available as a waste material. Pomegranate Rind Extract (PRE) can be applied to cotton fabrics for its natural colours, as a mordanting agent and also for imparting certain functional properties such as fire retardancy and antimicrobial properties. This paper reviews the feasibility of Pomegranate Rind Extract to improve the functional properties of cellulosic fabrics. Studies show that varying concentrations and higher temperatures that were used to apply the extract on the fabric, resulted in enhanced functional properties. At a particular concentration, the treated fabric showed a 15 times lower burning rate in comparison with the control fabric. Also, antimicrobial efficacy has been observed against Gram-positive and Gram-negative bacteria. Due to the natural colouring material, it can be used as a natural dye on cotton material. The fire retardancy of pomegranate rind extract was tested on jute material under varying alkalinity. Research has indicated that pomegranate rind extract could be used to dye polyamide as well. The rubbing and wash fastness of the finished fabrics is good. The light fastness was fair, and its antibacterial efficiency against tested bacteria was good.

Numerical study on polymer nanofibers with electrically charged jet of viscoelastic fluid in electrospinning process

Electrospinning is a useful and efficient technique to produce polymeric nanofibers. Nanofibers of polymers are electrospun by creating an electrically charged jet of polymer solution. Numerical study on non-Newtonian and viscoelastic jets of polymer nanofibers in electrospinning process is presented in this work. In particular, the effect of non-Newtonian rheology on the jet profile during the electrospinning process is examined. The governing equations of the problem are solved numerically using the Keller-Box method. The effects of yield stress and power-law index on the elongation, velocity, stress and total force are presented and discussed in detail. The results show that by increasing the values of yield stress, the fluid elongation is reduced significantly.

Synthetic biodegradable functional polymers for tissue engineering:a brief review

Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly(glycerol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, amino-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix(ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.

Engineered polymer nanoparticles incorporating L-amino acid groups as affinity reagents for fibrinogen

Synthetic polymer hydrogel nanoparticles(NPs)were developed to function as abiotic affinity reagents for fibrinogen.These NPs were made using both temperature-sensitive N-isopropyl acrylamide(NIPAm)and L-amino acid monomers.Five kinds of L-amino acids were acryloylated to obtain functional monomers:L-phenylalanine(Phe)and L-leucine(Leu)with hydrophobic side chains,L-glutamic acid(Glu)with negative charges,and L-lysine(Lys)and L-arginine(Arg)with positive charges.After incubating the NPs with fibrinogen,g-globulin,and human serum albumin(HSA)respectively,the NPs that incorporated Nacryloyl-Arg monomers(AArg@NPs)showed the strongest and most specific binding affinity to fibrinogen,when compared with g-globulin and HSA.Additionally,the fibrinogen-AArg binding model had the best docking scores,and this may be due to the interaction of positively charged AArg@NPs and the negatively charged fibrinogen D domain and the hydrophobic interaction between them.The specific adsorption of AArg@NPs to fibrinogen was also confirmed by the immunoprecipitation assay,as the AArg@NPs selectively trapped the fibrinogen from a human plasma protein mixture.AArg@NPs had a strong selectivity for,and specificity to,fibrinogen and may be developed as a potential human fibrinogen-specific affinity reagent.

A comprehensive review of biodegradable synthetic polymer-ceramic composites and their manufacture for biomedical applications

The application of various materials in biomedical procedures has recently experienced rapid growth.One area that is currently receiving significant attention from the scientific community is the treatment of a number of different types of bone-related diseases and disorders by using biodegradable polymer-ceramic composites.Biomaterials,the most common materials used to repair or replace damaged parts of the human body,can be categorized into three major groups:metals,ceramics,and polymers.Composites can be manufactured by combining two or more materials to achieve enhanced biocompatibility and biomechanical properties for specific applications.Biomaterials must display suitable properties for their applications,about strength,durability,and biological influence.Metals and their alloys such as titanium,stainless steel,and cobalt-based alloys have been widely investigated for implant-device applications because of their excellent mechanical properties.However,these materials may also manifest biological issues such as toxicity,poor tissue adhesion and stress shielding effect due to their high elastic modulus.To mitigate these issues,hydroxyapatite(HA)coatings have been used on metals because their chemical composition is similar to that of bone and teeth.Recently,a wide range of synthetic polymers such as poly(L-lactic acid)and poly(L-lactide-co-glycolide)have been studied for different biomedical applications,owing to their promising biocompatibility and biodegradability.This article gives an overview of synthetic polymer-ceramic composites with a particular emphasis on calcium phosphate group and their potential applications in tissue engineering.It is hoped that synthetic polymer-ceramic composites such as PLLA/HA and PCL/HA will provide advantages such as eliminating the stress shielding effect and the consequent need for revision surgery.

Segmental long bone regeneration guided by degradable synthetic polymeric scaffolds

Recent developments in synthetic bone grafting materials and adjuvant therapeutic agents have opened the door to the regenerative reconstruction of critical-size long bone segmental defects resulting from trauma,osteoporotic fractures or tumour resections.Polymeric scaffolds with controlled macroporosities,degradability,useful surgical handling characteristics,and the ability to deliver biotherapeutics to promote new bone ingrowth have been developed for this challenging orthopaedic application.This review highlights major classes of degradable synthetic polymers and their biomineral composites,including conventional and amphiphilic polyesters,polyanhydrides,polycarbonates,and polyethylene glycol-based hydrogels,that have been explored for the regenerative reconstruction of critical-size long bone segmental defects over the past two decades.The pros and cons of these synthetic scaffold materials are presented in the context of enabling or impeding the functional(mechanical and radiographic)repair of a long bone segmental defect,with the long bone regeneration outcomes compared with healthy long bone controls or results achieved with current grafting standards.

Biomaterials for refractive correction:corneal onlays and inlays

Corneal inlays and onlays represent a means of providing patients with permanent refractive error correction. As an alternative to conventional spectacles and contact lens, these techniques are less invasive compared with laser-based refractive surgery and are reversible. In this review, we provide a brief overview of the anatomic microstructure of the human cornea, indicating the primary physiological function for each component. Next, the wide range of biomaterials used as corneal inlays and onlays are considered, from synthetic polymers to biological components derived from the extracellular matrix. The limitations and challenges associated with the most common materials are discussed as is the need to improve their properties to achieve long-term, complication-free intraocular implantation. Finally, the prospect of applying tissue engineering strategies is noted for its potential to generate autologous corneal tissue that could be implanted as the optimal inlay or onlay materials.

New insights into hydraulic fracturing fluids used for hightemperature wells

Current interest in deep,low-permeability formations(<10 md)demands accelerated development of high-temperature hydraulic fracturing technologies.Conventional guar systems break down above 300°F and require higher polymer loadings to maintain thermal stability.However,higher polymer loadings generate more residue and damage to the proppant pack and the formation.To resolve these problems,a variety of high-temperature stabilizers are added to enhance the thermal stability of these fracturing fluids at temperatures above 300F.The focus of this work is to:(1)identify those additives that best enhance temperature stability of fracturing fluids and(2)study the rheological influence of incorporating these additives on the fracturing fluid systems.The experimental fracturing-fluid solutions were prepared at a total polymer concentration of 30 and 40 lb/1000 gal.Additives such as synthetic polymer,oxygen scavengers,crosslinkers,crosslinker delay additives,and pH buffers were examined in this work.Hydrated polymer solutions were crosslinked with a metallic crosslinker between 200 and 400°F.Viscosity measurements were carried out in a highpressure/high-temperature(HP/HT)rheometer to evaluate rheology and thermal stability.Results show that adding a synthetic polymer and a crosslinker with the slowest reaction rate improves the fracturing fluid thermal stability.Of the three other additives tested,oxygen scavengers showed the greatest enhancement to thermal stability while pH buffers showed the least.Through the addition of high-temperature stabilizing additives,the fracturing fluid in this work was able to maintain a stable performance at temperatures up to 400°F.Maintaining the thermal stability of fracturing fluids at a lower polymer loading remains a challenge in the industry.This work proposes techniques that can be used to enhance the thermal stability of fracturing fluids.Deeper knowledge about these different techniques will allow for better additive development and application in the field.