Polymer Sealant Research Articles

Development and Characterization of CO2-Responsive Intelligent Polymer Sealant.

In this study, we present an innovative intelligent polymer sealant designed to mitigate CO2 leakage during underground geological storage (CCUS). This sealant is formulated by cross-linking CO2-responsive polymers, specifically acrylamide (AM) and N-[3-(dimethylamino) propyl] methacrylamide (DMAPMA), with polyethylenimine (PEI) serving as the cross-linking agent. The polymer sealant's characteristics were systematically investigated, varying the CO2-responsive polymer content (1.5 wt %) and PEI content (0.1-0.6 wt %). A comprehensive analysis encompassing the rheological properties, thermal behavior, conductivity, and microstructures was conducted. Experimental results indicate that the polymer sealant exhibits excellent injectability, rapid response kinetics, thermal stability, and robust mechanical strength. Upon encountering CO2, the polymer system undergoes a transition from sol to gel state, forming a surface-smooth, uniformly porous three-dimensional (3D) network skeleton structure. Remarkably, the gel's modulus remains relatively unaffected by the shear frequency. Core fluid displacement experiments demonstrated a substantial sealing efficiency of 73.6% for CO2 and an impressive subsequent injection water sealing rate of 96.2%, underscoring its superior sealing and migration performance. In conclusion, the proposed CO2-responsive gel sealant exhibits an exceptional potential for successful utilization in CCUS operations. This advancement introduces a novel avenue to enhance the effectiveness of CO2-responsive gel sealants, thereby contributing to the advancement of CO2 leakage mitigation strategies in geological storage scenarios.

Research on production of a composite coating system to control corrosion at pipe supports

The coating system which consists of 03 layers based on epoxy anti-corrosion primer containing graphene, MS polymer sealant, and glass fibre reinforced polyester has been studied for control of corrosion at pipe supports. Graphene is dispersed at a concentration of 100 ppm in epoxy to form a primer coating, which can improve the adhesion, mechanical properties, and corrosion resistance as compared to epoxy coating without graphene. Polyester reinforced with 20% glass fibre allows increased impact strength and enhances the economic efficiency of the pipelining. The silicone-based MS polymer layer with good elasticity and high adhesion helps increase the impact strength of the composite system and completely isolate the pipe from the environment, eliminating the crevite and galvanic corrosions at pipe supports.

Sprayable tissue adhesive with biodegradation tuned for prevention of postoperative abdominal adhesions.

Adhesions are dense, fibrous bridges that adjoin tissue surfaces due to uncontrolled inflammation following postoperative mesothelial injury. A widely used adhesion barrier material in Seprafilm often fails to prevent transverse scar tissue deposition because of its poor mechanical properties, rapid degradation profile, and difficulty in precise application. Solution blow spinning (SBS), a polymer fiber deposition technique, allows for the placement of in situ tissue-conforming and tissue-adherent scaffolds with exceptional mechanical properties. While biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA) have desirable strength, they exhibit bulk biodegradation rates and inflammatory profiles that limit their use as adhesion barriers and result in poor tissue adhesion. Here, viscoelastic poly(lactide-co-caprolactone) (PLCL) is used for its pertinent biodegradation mechanism. Because it degrades via surface erosion, spray deposited PLCL fibers can dissolve new connections formed by inflamed tissue, allowing them to function as an effective, durable, and easy-to-apply adhesion barrier. Degradation kinetics are tuned to match adhesion formation through the design of PLCL blends comprised of highly adhesive "low"-molecular weight (LMW) constituents in a mechanically robust "high"-molecular weight (HMW) matrix. In vitro studies demonstrate that blending LMW PLCL (30% w/v) with HMW PLCL (70% w/v) yields an anti-fibrotic yet tissue-adhesive polymer sealant with a 14-day erosion rate countering adhesion formation. PLCL blends additionally exhibit improved wet tissue adhesion strength (~10kPa) over a 14-day period versus previously explored biodegradable polymer compositions, such as PLGA. In a mouse cecal ligation model, select PLCL blends significantly reduce abdominal adhesions severity versus no treatment and Seprafilm-treated controls.

Field evaluation of a polymer sealant for canal seepage reduction

A large amount of the water diverted for irrigated agriculture seeps from earthen canals during its conveyance to fields. Besides a shortfall in water availability, a variety of environmental and economic damages are caused by canal seepage. Polymer sealants provide an economical alternative to permanent liners for reducing seepage from earthen canals temporarily. Field studies of the polymer sealant linear anionic polyacrylamide (LAPAM) conducted on two canals in Colorado, USA, and on a canal in Sindh, Pakistan, reveal the potential usefulness of LAPAM to substantially lower seepage losses. LAPAM application rates for the three experiments on the canals in Colorado were 14.2, 18.3, and 12.1 kg per ha of canal wetted perimeter area, and was 12.4 kg/ha for the canal in Pakistan. Flowing water balance tests show a decline of 69–100% in seepage rates for a period of up to three months after LAPAM application. Uncertainty analysis of the pre- and post-application tests on the Colorado canals indicates an 85% likelihood that seepage reduction of some magnitude occurred. Guidelines are presented for conducting further studies of LAPAM and other polymer sealants to systematically determine the impact of several factors that influence seepage control effectiveness.

Pilot Test of pH Triggered Polymer Sealant for CO2 Storage

Wellbore integrity is a critical subject in oil and gas production and CO2 storage. Successful subsurface deposition of various fluids, such as CO2, depends on the integrity of the storage site. In a storage site, injection wells and pre-existing wells might leak due to over-pressurization, mechanical/chemical degradation, and/or a poor cement job, thus reducing the sealing capacity of the site. Wells that leak due to microannuli or cement fractures on the order of microns are difficult to seal with typical workover techniques. We tested a novel polymer gelant, originally developed for near borehole isolation, in a pilot experiment at Mont Terri, Switzerland to evaluate its performance in the aforementioned scenario. The polymer gel sealant was injected to seal a leaky wellbore drilled in the Opalinus Clay as a pilot test. The success of the pH-triggered polymer gel (sealant) in sealing cement fractures was previously demonstrated in laboratory coreflood experiments [1-3]. pH-sensitive microgels viscosify upon neutralization in contact with alkaline cement to become highly swollen gels with substantial yield stress that can block fluid flow. The leaky wellbore setup was prepared by heating-cooling cycles to induce leakage pathways in the cased and cemented wellbore. The leakage pathways are a combination of fractures in the cement and microannuli at the cement-formation interface. The exact nature of these leakage pathways can be determined by over-coring at the end of the experiment life. We used polyacrylic acid polymer (sealant) to seal these intervals. The process comprises of three stages: (1) injection of a chelating agent as the preflush to ensure a favorable environment for the polymer gel, (2) injection of polymer solution, and (3) shut-in for the polymer gelation. Then, we evaluated the short-/long-term performance of the sealant in withholding the injected fluids (formation brine and CO2 gas). The novel sealant was successfully deployed to seal the small aperture pathways of the borehole at the pilot test. We conducted performance tests using formation brine and CO2 gas to put differential pressure on the polymer gel seal. Pressure and flow rate at the specific interval were monitored during and after injection of brine and CO2. Results of performance tests after polymer injection were compared against those in the absence of the sealant. Several short-term (4 min) constant-pressure tests at different pressure levels were performed using formation brine, and no significant injection flow rate (rates were below 0.3 ml/min) was observed. The result shows more than a ten-fold drop in the injection rate compared to the case without the sealant. The polymer gel showed compressible behavior at the beginning of the short-term performance tests. Our long-term (1-week) test shows even less injectivity (~ 0.15 ml/min) after polymer gelation. The CO2 performance test shows only 3 bar pressure dissipation overnight after injection compared to an abrupt loss of CO2 pressure in the absence of polymer gel. Sealant shows good performance even in the presence of CO2 gas with high diffusivity and acidity. Pilot test of our novel sealant proves its competency to mitigate wellbore leakage through fractured cement or debonded microannuli, where other remedy techniques are seldom effective. The effectiveness of the sealing process was successfully tested in the high-alkaline wellbore environment of formation brine in contact with cement. The results to date are encouraging and will be further analyzed once over-coring of the wellbore containing the cemented annulus occurs. The results are useful to understand the complexities of the cement/wellbore interface and adjust the sealant/process to sustain the dynamic geochemical environment of the wellbore.

Response surface design of a thiol-ene polymer sealant to model adhesive strength

Commercial aircraft fuel tanks require sealants applied at contact points to prevent leakage or moisture contamination, but cure times for conventional sealants range from hours to days. Thiol-ene ultraviolet (UV) curable sealants have been a proposed material for these applications. However, selecting proper monomers and optimizing synthesis conditions for a figure of merit is an arduous process. Therefore, modeling the adhesive strength of a thiol-ene sealant was performed using a response surface design of experiment (DoE). Two separate crosslinking alkenes were separately combined with a thiol monomer, and a 6 mm thick polymer was synthesized at different cure temperatures, cure times, and with various solid filler material on an aluminum substrate according to a response surface design. The samples were then peeled off the substrate at a 180° angle, and peel strength was measured. The DoE utilized the peel data to derive a multivariable numeric function for the peel strength. Resulting contour data shows the system has not been fully optimized, but trends in the data show that future experiments should lean toward higher cure times and temperatures to maximize peel strength. Additionally, the resulting model equation can predict adhesive strengths near the studied conditions.

The occurrence and sources of polychlorinated biphenyls (PCBs) in agricultural soils across China with an emphasis on unintentionally produced PCBs.

In addition to being historically intentionally manufactured as commercial products, polychlorinated biphenyls (PCBs) can be unintentionally released as by-products from industrial processes. Recent studies have emphasized the importance of unintentionally produced PCBs (UP-PCBs) and have even identified them as major contributors to atmospheric PCBs. However, little is known about contributions of UP-PCBs in current soils. In this study, all 209 PCB congeners were analyzed in agricultural soils on a national scale to investigate the influence of unintentional sources on Chinese soil. The concentration of Σ209PCBs in soils across China was in the range of 64.3-4358pg/g. Four non-Aroclor congeners, i.e., PCB11, PCB44+47+65, PCB68, and PCB209, were dominant among all PCBs, averagely accounting for 26.3%, 8.83%, 3.03%, and 2.80% of total PCBs, respectively. PCB11 and PCB209 were found to be higher in East China, while PCB44+47+65 and PCB68 were higher in South China. Their spatial distributions were largely dependent on local sources. The results of source apportionment indicated that the legacy of historically produced and used commercial PCB mixtures was the dominant contributor to seven indicator PCBs in Chinese agricultural soils, especially high-chlorinated congeners. However, unintentional sources (i.e., pigment/paint, combustion-related sources, and polymer sealant), which contributed 57.4% of the total PCBs, are controlling PCB burdens in agricultural soils across China.

Facile fabrication of versatile superhydrophobic coating for efficient oil/water separation

Nowadays, finding an efficient way to treatment oil spill and oily wastewater emission has attracted much attention all over the world. In this work, we fabricated a superhydrophobic coating (humic acid grafted by octadecylamine) with a simple method, and sprayed this coating on different structures which apply for self-cleaning, collect oil, and filter oil/water mixtures. In addition, silane-modified polymer sealant was used to strengthen the adhesive attraction between coating and structures. The coated mesh exhibited excellent superhydrophobicity (water contact angle of 153.14°) and superolephilicity (oil contact angle near 0°). Moreover, the coated mesh displayed outstanding performance in oil/water separation with huge oil flux about 16633.9 L h−1 m−2, high separating efficiency more than 95%, and good reusability (more than 10 cycles). Furthermore, the pore size of the coated mesh could regulate by changing the cycle of coated process, and the micro pore size of mesh could realize water-in-oil emulsions separation. To sum up, these merits of the superhydrophobic humic acid grafted by octadecylamine coating displayed great potential for effective oil/water separation.

Influence of Sealing Treatment on the Corrosion Resistance of PEO Coated Al-Zn-Mg-Cu Alloy in Various Environments

In the present work, a coating was prepared on an Al alloy substrate by plasma electrolytic oxidation (PEO). To seal the micro defects in the oxide scale, a siloxane layer was prepared on the PEO coating by sol gel method. The polymer sealant was synthesized from Tetraethoxy silane (TEOS) and methacryloxy propyl trimethoxyl silane (MPTES). The chemical structure of the polymer was studied by Fourier transform infrared spectroscopy (FTIR). The morphologies and microstructure of the PEO coating and siloxane coating were investigated by scanning electron microscopy (SEM). The results showed that siloxane formed a continuous layer on the surface and effectively sealed the micro defects. The corrosion behavior of the coatings in three different corrosion solutions (NaCl, HCl, and NaOH) was examined by electrochemical impedance spectroscopy and potentiodynamic polarization. The corrosion resistance of the sealed coatings was superior to that of the PEO coating because it prevented the penetration of corrosive solutions. The corrosion resistance of the sealed coatings was found to decrease with increasing electrolyte concentration. The work demonstrated that siloxane sealing may greatly enhance the corrosion resistance of Al-based PEO coating in acidic, neutral, and alkaline environments.

High Abundance of Unintentionally Produced Tetrachlorobiphenyls (PCB47/48/75, 51, and 68) in the Atmosphere at a Regional Background Site in East China.

Although polychlorinated biphenyls (PCBs) have been banned for several decades, they are still detected with elevated levels due to their unintentional production from combustion and industrial thermal processes (UP-PCBs). To investigate the composition and current levels of UP-PCBs and understand which sources are controlling PCB burdens in ambient atmosphere, air samples were collected from August 2012 to August 2015 at a background site in east China. An unexpected high abundance of PCB47+48+75 was observed to be the predominant congener with an average concentration of 786 ± 637 pg/m3. It accounted for 48 ± 16% of ΣPCBs, followed by PCB51 (10 ± 4%), PCB11 (8 ± 6%), and PCB68 (7 ± 3%). Seasonal variations with high levels in summer and lowest levels in winter were observed for PCB47+48+75, 51, and 68. These tetrachlorobiphenyl congeners were strongly correlated with temperature ( r2 > 0.7), suggesting the control of temperature-dependent volatilization processes from contaminated surfaces. The decreased occurrence of PCB47+48+75, 51, and 68 in commercial products and their negative correlations (| r| < 0.35) with polycyclic aromatic hydrocarbon (PAHs) and weak correlation with other PCB congeners suggested unique unintentional sources that differ from combustion and industrial thermal processes or pigment, such as the use of polymer sealant, for PCB47+48+75, 51, and 68 in the ambient air.

Refill friction stir spot welding of 7075-T6 aluminium alloy single-lap joints with polymer sealant interlayer

With the addition of a sealant interlayer, 7075-T6 aluminium alloy sheets were refill friction stir spot welded (RFSSW). Two sealants were used in the investigations: phenol-formaldehyde resin-based adhesive and epoxy resin-based tape. Single-lap RFSSW joints were made in 0.8- and 1.6-mm-thick sheets, which corresponds to the actual thicknesses of welded stringer of aircraft skin. The welding of the sheets with polymeric interlayer lowered the tensile pure/shear load capacity of the joint from approximately 9% to 28%, according to the variant of sealant application. However, the polymer interlayer increases considerably the protection of the weld against the corrosion environment. Considering that the main indicator of joint quality is a tight interlayer of sealant between the faces of joined sheets and simultaneously a minimum degree of imperfection induced in the joint microstructure by sealant material, it can be concluded that the most advantageous joint variant is that with a single interlayer of epoxy-based tape.

Emissions of Tetrachlorobiphenyls (PCBs 47, 51, and 68) from Polymer Resin on Kitchen Cabinets as a Non-Aroclor Source to Residential Air.

Both Aroclor and non-Aroclor sources of airborne polychlorinated biphenyls (PCBs) were found in residential homes. We deployed passive air samplers at 16 residences and found PCB-47, PCB-51, and PCB-68 to account for up to 50% of measured indoor ΣPCBs (2700 pg m-3). Although PCB-47 and PCB-51 are neurotoxins present in Aroclor mixtures (<2.5 and <0.3 wt %, respectively), we found them at much higher levels than expected for any Aroclor source. PCB-68 is not present in Aroclor mixtures. Another non-Aroclor congener, PCB-11, a byproduct of pigment manufacturing, was found inside and outside of every household and was frequently the predominate congener. We conducted direct measurements of surface emissions and identified finished cabinetry to be a major source of PCB-47, PCB-51, and PCB-68. We hypothesize that these congeners are inadvertent byproducts of polymer sealant manufacturing and produced from the decomposition of 2,4-dichlorobenzoyl peroxide used as an initiator in free-radical polymerization of polyester resins. The presence of these three compounds in polymer products, such as silicone, has been widely noted, but to our knowledge they have never been shown to be a significant environmental source of PCBs.

An Absorbable Hydrogel Spray Reduces Postoperative Mediastinal Adhesions After Congenital Heart Surgery

Adhesions encountered during reoperative cardiac surgery can prolong operative time and increase operative risk. The purpose of this clinical study was to investigate the antiadhesion property of a synthetic bioabsorbable polymer spray after cardiac reoperations in infants. A prospective randomized double-blinded study was designed. Forty infants requiring staged cardiac operations were randomly allocated to a study group (n=20) or a control group (n= 20). The appropriate volume of the polymer was sprayed onto the mediastinal surfaces before chest closure after the first surgical procedure in the study group. At reoperation, adhesions were evaluated by a blinded investigator following a 5-grade scoring system. Five predetermined anatomic areas were scored. Incision to extracorporeal circulation time was also analyzed. In all, 40 subjects were enrolled into the study. Four babies died before the second operation. Three others were missed for reevaluation. The control group (n= 16) had longer incision to extracorporeal circulation time (38 ± 10 minutes) than the study group (n= 17; 23 ± 6 minutes; p < 0.001). The control subjects had significantly more severe adhesions than the study group at all five mediastinal areas: (1) retrosternal (p < 0.001); (2) base of the heart (large vessels [p < 0.05]); (3) right side (p < 0.01); (4) left side (p < 0.02); and (5) diaphragmatic side of the mediastinum (p < 0.001). The use of synthetic bioabsorbable polymer sealant spray at the end of primary pediatric cardiac surgery reduces the intensity of mediastinal adhesions and the reentry time in infants undergoing repeat median sternotomy.

Self-healing polymer sealant for encapsulating flexible solar cells

Herein we demonstrate the utility of polyisobutylene (PIB) as a fully printable self-healing sealant for protecting organic photovoltaic devices from degradation under ambient conditions. These sealants can be applied on flexible substrates using drop casting, spin coating or blade coating. PIB-based crosslinked sealants show excellent device stability, especially the low molecular weight PIB.

Compressive and lap shear tests on traditional putty and polymer sealants

In the 19th century, iron-and-glass roofs were built using linseed oil based putty as sealant to fix the glass plates in the iron glazing bars. Since then, two evolutions influenced the construction details of roofs drastically. First, new sealants with better mechanical properties and higher durability displaced the use of traditional putty. Second, as the insights in the properties and behaviour of glass improved, glass plates can today play a structural role in the global stability of an iron-and-glass structure.This article examines the mechanical properties of the traditional linseed oil based putty to assess the structural integrity of existing iron-and-glass roofs. Single-lap shear and compressive tests are carried out on a traditional linseed oil putty sealant. Next, to determine the impact of a renovation campaign, a modern MS polymer sealant with comparable viscosity and texture but higher durability, is subjected to single-lap shear experiments.The experiments demonstrate that the linseed oil putty can have significant compressive stiffness. However, the shear strength is negligible. The modern polymer sealant has higher shear stiffness and strength as well as a cohesive failure in shear.

Photoinduced smart, self-healing polymer sealant for photovoltaics.

Polyisobutylene (PIB)-based polymer networks potentially useful as smart coatings for photovoltaic devices have been developed. Low molecular weight coumarin functional triarm star PIB was synthesized via a single step SN2 reaction of bromoallyl functional triarm star PIB with 4-methylumbelliferone or umbelliferone in the presence of sodium hydride. Quantitative end functionality was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. UVA (λmax = 365 nm) induced reversible photodimerization of the coumarin moieties resulted in cross-linked elastomeric films exhibiting self-healing behavior. The extent of photodimerization/photoscission was monitored by UV-vis spectroscopy. The low oxygen (1.9 × 10(-16) mol m m(-2) s(-1) Pa(-1)) and moisture (46 × 10(-16) mol m m(-2) s(-1) Pa(-1)) permeability of the cross-linked polymer films suggest excellent barrier properties of the cross-linked polymer films. The self-healing process was studied by atomic force microscopy (AFM). For this, mechanical cuts were introduced in the cross-linked PIB films through micromachining with an AFM tip and the rate of healing induced by UV, sunlight, or both was followed by taking AFM images of the film at different time intervals during the repair process.

Use of a cyanoacrylate skin adhesive to reduce external ventricular drain infection rates

OBJECT.: Ventriculitis related to external ventricular drain (EVD) placement is a significant source of morbidity in neurological intensive care patients. Current rates of EVD-related infections range from 2% to 45% in the literature. The authors sought to determine if a 2-octyl cyanoacrylate adhesive would result in lower infection rate than standard semiocclusive dressings. The authors tracked ventriculitis rates via CSF cultures among 259 patients whose EVD sites were dressed with sterile semiocclusive dressings and underwent routine sterile dressing exchanges every 48 hours. They analyzed data obtained in an additional 113 patients whose EVD sites were dressed one time with a surgical adhesive, 2-octyl cyanoacrylate. Ventriculitis rate in patients with standard bioocclusive dressings and wound care was 15.1%, whereas that in patients with a 2-octyl cyanoacrylate dressing was 3.54% (p = 0.002). Staphylococcus genus accounted for 79.5% of instances of ventriculitis among patients with bioocclusive dressings and routine wound care, whereas it accounted for 25.0% of the instances of ventriculitis among patients with a liquid polymer sealant dressing. A 90% reduction in Staphylococcus infection completely accounts for the observed effect (p = 0.04). The one-time application of 2-octyl cyanoacrylate to EVD wounds and exit sites provided superior protection against EVD-related ventriculitis compared to conventional EVD-site wound care. Likely this protection results from a barrier to the entry of gram-positive skin flora along the EVD exit tract. The results should be validated in a randomized trial.

Briefing: Microscopic study into biodeterioration of joint sealant

This research presents an exploratory study into the biodeterioration of joint sealants used in concrete coastal structures. Monocular, inverted-light microscopy and scanning electron microscopy with an energy dispersive X-ray analyser were used to observe colonisation of site specimens, enabling the further understanding of this interaction. Algal filaments have been observed growing within the matrix of a polymer sealant. Growth has been observed tunnelling within and adhered to the surface of the sealant. This degradation mechanism will weaken the material bond as a direct result of the physical activity of an organism, resulting from its growth. Loss of material, either through biodeterioration or through other mechanical means, such as tidal action, is not the primary cause of degradation, but it should be considered with associated environmental conditions, to exacerbate the condition.

Effect of fissure integrity on lung volume reduction using a polymer sealant* in advanced emphysema

RationaleInterlobar fissure integrity has previously correlated with responsiveness to endobronchial lung volume reduction therapy in patients with advanced emphysema.ObjectiveThis report summarises the effect of interlobar fissure integrity on responses to...

Design and fabrication of a laminated thermoforming tool with enhanced features

Thermoforming is a popular manufacturing process for creating useful shapes out of heated thermoplastic sheets using a porous tool under differential pressure. For large, heavy-gauge parts, thermoforming tools are typically made by CNC machining a billet of material or sand casting from an inexpensive master pattern. Although these tooling methods are well established, it is difficult to incorporate enhanced tool functionality such as conformal cooling channels, embedded sensors, unimpeded vacuum channel placement, and customized thermal mass. Profiled Edge Laminas (PEL), a rapid tooling method based on profiling, assembling, and clamping an array of thick layers, is ideally suited for tools used for thermoforming large, heavy-gauge parts and requiring enhanced features. This paper describes how the PEL tooling method can be applied to the design and fabrication of a thermoforming tool and demonstrates the entire process through a case study. Tooling design guidelines and analytical models for predicting conformal channel and vacuum line performance are included. The ease with which multiple-zone conformal cooling/heating channels, vacuum lines, and temperature sensors are incorporated into the tool is also highlighted. Specifically, a 46-layer aluminum PEL tool clamped together with bolts is successfully designed, fabricated, and demonstrated for thermoforming a 0.3×0.4×0.4 m part made from a PVC/Acrylic blend based on the outlined method. The tool incorporates three independent cooling zones sealed by a polymer sealant, three embedded temperature sensors, and an elaborate matrix of vacuum channels. All tool features and the basic geometry were machined into each individual lamina in the same set-up by 2D abrasive waterjet machining, and the final tool surface was CNC-machined. The PEL tooling method is successfully applied to the manufacture of a large, heavy-gauge thermoformed part intended for production.