Location of polyethylene utility pipes is improved by installing electromagnetic targets with the pipe. A new electromagnetic target could be created by impregnating polyethylene with conductive materials to impart it with electromagnetic properties necessary for use in utility location. Antennas created from this conductive polyethylene composite could be molded directly to the pipe during fabrication. The addition of high concentrations of conductive fillers into the material alters the mechanical performance of the material in addition to the electromagnetic properties, resulting in a material which displays brittle behavior, unlike neat polyethylene. Both electromagnetic and mechanical properties of the material are characterized to predict the behavior of the conductive polyethylene in service. In a layered composite with unmodified polyethylene and conductive polyethylene layers, the brittle behavior of the conductive polyethylene limits the strain to failure of the overall composite.
Conductive polymer composites can be customized through the addition of conductive fillers to the matrix. Fillers added to a conductive polymer composite modify the mechanical properties of the material as well as the electrical properties. Previous work with conductive polymer composites determined that conductive polymers with carbon‐based materials exhibit more brittle behavior when compared with unmodified polymers, reducing strains to failure of the material. A conductive polymer with self‐healing functionality could be healed to repair damage. This work demonstrates a conductive polyethylene composite, which can simultaneously restore electrical and mechanical performance when heated with induction. Because carbon‐based conductive composites cannot be sufficiently heated for healing, aluminum flake added to the composite served as the susceptor for induction heating. Conductive polyethylene specimens with 20% aluminum flake by volume demonstrated similar mechanical behavior both during the initial test and after healing.
Polyaniline (PANI) is a common electrically conducting polymer with numerous potential applications, including use in energy storage and electrochromic devices. In this communication, we describe the critical parameters for the deposition of PANI onto ITO-coated plastic, both under flat and curved conditions, and we explore the effects that the electrode curvature has on the electrochemical and electrochromic behavior of PANI. We found a simple water rinsing process after deposition was critical for good film adhesion and electrochemical activity. Additionally, PANI deposition and electrochemical performance was unaffected at a bending radius of 10 and 7.5 mm, but at 5 mm the electrochemical deposition was significantly impacted due to the strain on the underlying ITO.
Biofilms consist of bacterial cells surrounded by a matrix of extracellular polymeric substance (EPS), which protects the colony from many countermeasures, including antibiotic treatments. Biofilm EPS composition is affected by environmental factors. In the oral cavity, the presence of sucrose affects the growth of Streptococcus mutans that produce acids, eroding enamel and forming dental caries. Biofilm formation on dental implants commonly leads to severe infections and failure of the implant. This work determines the effect of sucrose concentration on biofilm EPS formation and adhesion of Streptococcus mutans, a common oral colonizer. Bacterial biofilms are grown with varying concentrations of sucrose on titanium substrates simulating dental implant material. Strategies for measuring adhesion for films such as peel tests are inadequate for biofilms, which have low cohesive strength and will fall apart when tensile loading is applied directly. The laser spallation technique is used to apply stress wave loading to the biofilm, causing the biofilm to delaminate at a critical tensile stress threshold. Biofilm formation and EPS structures are visualized at high magnification with scanning electron microscopy (SEM). Biofilm substrate coverage and adhesion strength of biofilms initially increase with increasing sucrose concentration, but then decrease as sucrose concentration continues to increase. For biofilms grown with non-zero concentrations of sucrose, S. mutans adhesion to the substrate is higher than the adhesion of osteoblast-like cells to the same substrates. These results suggest sucrose-mediated adhesion and formation on titanium of S. mutans biofilms may outcompete osteoblasts during osseointegration, which could explain higher rates of peri-implant disease associated with high sugar diets.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.