Polymer Bubble Research Articles

Evaluating the performance of conventional DAF and PosiDAF processes for cyanobacteria separation at a pilot plant scale

Abstract In this work, a commercially available water treatment polymer poly(N,N-diallyl-N,N-dimethylammonium chloride) (PDADMAC) and a hydrophobically modified polymer (HMP) designed to adhere to bubble surfaces were applied for the first time in the novel Posi-dissolved air flotation process (PosiDAF) that uses polymer-modified bubbles, at pilot-scale for the treatment of waste stabilisation pond samples rich in algae. It was found that PDADMAC in PosiDAF gave comparable removal to that achieved using conventional DAF at >95% cell separation. Furthermore, the float layer was more uniform and thicker with up to 8% solid contents compared to conventional DAF, which comprised discrete floc clusters with an average solid concentration of ∼4.1%. In contrast to the use of PDADMAC, the application of the HMP did not achieve similarly good separation at pilot scale. It was hypothesised that this may be due to the micellisation of the HMP on the bubble surface, creating unstable bubbles that coalesced and prevented polymer–bubble–cell interactions, which are crucial for effective cell separation. On comparison of the costs of PosiDAF and conventional DAF, it was found that PosiDAF resulted in cost-savings of up to 74% due to low chemical consumption. In summary, PosiDAF reduced chemical cost and increased solid contents in the metal-free float.

Collection of polymer bubble as a nanoscale membrane

A critical hurdle in membrane fabrication is the threshold thickness, beyond which the artificial membrane becomes impossible. In contrast, biological membranes have a nanoscale thickness, enabling their excellent permeability and remarkably perfect selectivity. We address this challenge by designing a novel bubble spinning process that can produce nanoscale members instead of nanofibers from polymer bubbles. The process herein is to enlarge the bubble so that the thickness of the bubble wall is only a few tens of nanometers. The fragments of the broken bubbles are received on a mesh receptor, and an artificial membrane with nanoscale thickness is obtained. This process sheds a bright light on the biomimetic fabrication of nanoscale membranes. Moreover, although our work focuses on the mechanism, we anticipate that the bubble spinning can be used for large-scale fabrication of natural-inspired extremely thin membranes with good permeability and ideal selectivity, and other functions.

Jet speed in bubble rupture

When a polymer bubble is broken in the bubble electrospinning process, thousands of thousands jets are produced with almost same initial ejecting speed, which plays a very important role on the formation of the nanofiber. In this paper, the nanofiber membranes were prepared by the bubble spinning with different air temperatures. This paper also gives a simple mathematical model to predict the initial speed of jets, and it is as high as 300 m/s.

Sudden solvent evaporation in bubble electrospinning for fabrication of unsmooth nanofibers

Solvent fraction in a multiple solvent system plays a great important for controlling fiber morphology in the bubble electrospinning. The sudden release of air pressure when a polymer bubble is broken and an extremely high velocity of jets are two main factors for solvent evaporation, which can be used for fabrication of unsmooth fibers.

Hierarchical structure of nanofibers by bubbfil spinning

A polymer bubble is easy to be broken under a small external force, various different fragments are formed, which can be produced to different morphologies of products including nanofibers and plate-like strip. Polyvinyl-alcohol/honey solution is used in the experiment to show hierarchical structure by the bubbfil spinning.

Fabrication of Micro Yarn Composed of Nanofibers by Blown Bubble Spinning

Recent years, much attention has been paid to approaches for directly producing nanofibers along with a rising trend for their exploration and application in wide fields. Considering the melt blowing and bubble-electrospinning, a novel method called blown bubble-spinning was introduced by forcing airflow onto the polymer bubble. In this paper, a special hierarchical structure has demonstrated the ability to form micro yarn composed of nanofibers in this way. The resulting yarn is about 23 micrometers while the nanofibers 376 nanometers.

A Modified Bubble Electrospinning for Fabrication of Nanofibers

This paper suggests a new method for fabrication of nanofibers with polymer liquid membrane, which is produced by a metal ring rotating through the polymer solution. The thickness of the produced membrane is thin and suitable for nanomaterial fabrication. In this paper the membrane is to form a polymer bubble by blowing air under the presence of a high electronic field, and multiple jets eject when the bubble is ruptured. The effect of applied voltage on the fiber diameter is studied.

Oscillation of a Polymer Bubble Under Electrostatic Force

Oscillation of a Polymer Bubble Under Electrostatic Force

Investigation of Turbulent-Mixing-Layer Flow with Polymer Additives and Bubble Injection by Particle Image Velocimetry

Turbulent-mixing-layer flows in a vertical channel with polymer additives and bubble injection were experimentally studied by particle image velocimetry (PIV). The transparent test section was 1.0 m long with a 0.04 m × 0.11 m cross section, and the main stream was split into two substreams by a specially designed splitter. The velocities on the low- and high-speed sides are 0.36 m/s and 1.4 m/s, respectively. The Reynolds number based on the velocity difference between the two streams and the vorticity thickness δ at the trailing edge of the splitter was 13,500 for the pure water mixing-layer flow. Aquesous (200 ppm) Polyacrylamide (PAM) solutions and pure water were used as the liquid phase, and gas bubbles with a 0.5% void fraction were injected into the mixing-layer containing polymer additives, from the center of the splitter end, to check the influence of polymer additives and bubbles on the turbulent structure and properties. The distribution of the turbulence properties changed more significantly for the mixing-layer in the polymer additive case than in the pure water case. In the latter case, the Reynolds shear stress (RSS) peak was less than that for the pure water case at the same downstream cross section, but the vorticity peak in the polymer additive case was larger than that in the pure water case in the region the mixing-layer developed (x < 5δ). However, upon bubble injection, the effect of the polymer additives was diminished.

Making Nano Technology Work in Foams using 1.5 Nanometer Titanate and Zirconate Coupling Agents - A Review

A review of data and references are provided to demonstrate the efficacy of titanates and zirconates in foamed unfilled and filled polymers with an emphasis on their recent application in nanocomposites. Titanates (and zirconates) are shown to catalyze a polymer - called Repolymerization by the author - to increase its stress-strain strength thereby creating finer cells and reducing open cell structure because the polymer bubble does not break while being foamed. Additives such as foaming agents, fillers and reinforcements are shown to be dispersed better reducing interfacial failure. The chemistry of the Six Functions of the titanate molecule are discussed along with selection, dosage, the physics of mixing, catalysis and rheology, mixing temperatures, compounding considerations such as initial boiling point, and the chemistry at the interface of nano particulates.

A Robust Experimental Methodology for Polymer Bubble Inflation

In thermoforming technique thermoplastic sheets are heated up well above their glass transition temperature and formed to the required shape by using an appropriate mold. Characterization of thermoplastic materials for thermoforming can be accomplished by employing polymer bubble inflation and rheology tests instead of undertaking expensive biaxial tensile testing. Polymer bubble inflation technique is very sensitive to process condition variations, so a robust experimental methodology is essential. Design and development of one such experimental system was undertaken by carrying out a variety of preliminary tests. This paper presents the experimental methodology developed for polymer bubble inflation. The developed experimental system demonstrates highly repeatable polymer bubble inflations. Bubble inflations were conducted at different temperatures and different diameter circular clamping using acrylonitrile butadiene styrene (ABS) thermoplastic. Polymer sheet initial sag due to heating and its influence on bubble inflation have been captured by using the experimental system.

A Simple Noncontact Displacement Measuring System for Online Bubble Height Measurement During Polymer Bubble Inflation at Elevated Temperature

In thermoforming process, thermoplastic materials are heated up well above their glass transition temperature and formed to the required shape by employing appropriate mold. Material is viscoelastic at that temperature, and its characterization for thermoforming applications are possible using a bubble inflation technique as well as rheology tests. Online bubble height measurement during the bubble inflation test is an important parameter for the material characterization. A simple noncontact displacement measuring system (NCDMS) has been developed and reduced to practice for online bubble height measurement during polymer sheet bubble inflation well above its glass transition temperature. The experimental design procedure and methodology is presented in this paper. The NCDMS measurements have been validated up to the displacement rate 100 mm/s. Bubble inflation has been undertaken at an elevated temperature with different inflation rates and the online bubble height captured using NCDMS. This experimental method is cost effective and shows good repeatability in measurements. This technique has been used for bubble inflation tests up to 90 1pm air flow rate that offered height growth rate of 75 mm/s.

Titanate and Zirconate Coupling Agents in Foamed Polymers

Ti or Zr coupling agents chemically bridge two dissimilar species such as an inorganic filler/particulate and organic polymer via proton coordination without the need of water of condensation. They may also act as in situ catalysts in the polymer melt at &gt;100°C independent of filler content by one or more distinct organometallic mechanisms of conventional catalysis, crosslinking, metallocene-like catalysis, repolymerization (US Patent 4,657,988), and copolymerization. For example, minor amounts of titanate in unfilled polymers will give 20% average faster polymer processing at 10% average lower temperatures while increasing mechanical properties. As a result of titanate (zirconate) coupling and catalysis – gaseous, endothermic and exothermic blowing agents are made significantly more efficient to produce lighter polymers with more uniform cell structure because at the elevated temperature where gas generation (blow) occurs polymer bubble stress (force/area) properties are maintained or increased while strain (elongation/unit length) properties are increased to as much as double or triple thus reducing open cell formation. For example, cell size variation is reduced from 6–48 micron to 9–15 micron in an exothermic azodicarbonamide-foamed PE. The density of an azodicarbonamide-foamed flexible PVC is decreased threefold from 0.408g/cc to 0.129g/cc. The amount of endothermic sodium bicarbonate needed to foam SBR (Styrene Butadiene Rubber) is reduced twenty-nine fold from 15 phr of NaHCO3 powder to 0.68 phr of a 75% active NaHCO3 paste masterbatch containing pyrophosphato titanate in the aromatic plasticizer phase.

Polymer shells by the droplet method

An acoustically modulated fluid jet (AMFJ) is used to generate a stream of identical droplets of a polymer solution by the breakup of a column of polymer solution resulting from Rayleigh jet instabilities. Selected droplets from this stream are then charged and deflected by an electric field into a vertical furnace. As the solvent evaporates, a polymer bubble is formed which hardens into a shell by the time it reaches the bottom of the furnace. By varying the polymer, solvent, temperature, and droplet size, we have been able to make polymer shells with a wide range of selected diameters and aspect ratios. Using an AMFJ, we have produced various polymer shells with narrow distributions of diameters.