Low-temperature Plasma Pretreatment Research Articles

The effect of low-temperature plasma pretreatment on the biodegradability of polyethylene films

ABSTRACT With the increasing focus on environmental friendliness and sustainable development, extensive research has been conducted on the biodegradation of plastics. The non-hydrolyzable, highly hydrophobic, and high-molecular-weight properties of polyethylene (PE) pose challenges for cell interaction and biodegradation of PE substrates. To overcome these obstacles, PE films were treated with low-temperature plasma before biodegradation. The morphology, surface chemistry, molecular weight, and weight loss of PE films after plasma treatment and biodegradation were studied. The plasma treatment decreased the surface water contact angle, formed C–O and C = O groups, and decreased the molecular weight of PE films. With the increased pretreatment time, the biodegradation efficiency rose to 2.6% from 0.63% after 20 days of incubation. The mechanism was proposed that the surface oxygen-containing groups formed by plasma treatment can facilitate the bio-accessibility and be further decomposed and utilised by the microbes. This study provided an effective and rapid pretreatment strategy for improving biodegradation of PE.

Low-Temperature Plasma Pretreatment Enhanced Cholesterol Detection in Brain by Desorption Electrospray Ionization-Mass Spectrometry Imaging.

Cholesterol is a primary lipid molecule in the brain that contains one-fourth of the total body cholesterol. Abnormal cholesterol homeostasis is associated with neurodegenerative disorders. Mass spectrometry imaging (MSI) technique is a powerful tool for studying lipidomics and metabolomics. Among the MSI techniques, desorption electrospray ionization-MSI (DESI-MSI) has been used advantageously to study brain lipidomics due to its soft and ambient ionization nature. However, brain cholesterol is poorly ionized. To this end, we have developed a new method for detecting brain cholesterol by DESI-MSI using low-temperature plasma (LTP) pretreatment as an ionization enhancement. In this method, the brain sections were treated with LTP for 1 and 2 min prior to DESI-MSI analyses. Interestingly, the MS signal intensity of cholesterol (at m/z 369.35 [M + H - H2O]+) was more than 2-fold higher in the 1 min LTP-treated brain section compared to the untreated section. In addition, we detected cholesterol, more specifically excluding isomers by targeted-DESI-MSI in multiple reaction monitoring (MRM) mode and similar results were observed: the signal intensity of each cholesterol transition (m/z 369.4 → 95.1, 109.1, 135.1, 147.1, and 161.1) was increased by more than 2-fold due to 1 min LTP treatment. Cholesterol showed characteristic distributions in the fiber tract region, including the corpus callosum and anterior commissure, anterior part of the brain where LTP markedly (p < 0.001) enhanced the cholesterol intensity. In addition, the distributions of some unknown analytes were exclusively detected in the LTP-treated section. Our study revealed LTP pretreatment as a potential strategy to ionize molecules that show poor ionization efficiency in the MSI technique.

Effect of low temperature plasma pretreatment on drying process of vegetables with waxy layer

AbstractIn this study, low temperature plasma technology was used as an efficient pretreatment method of vegetables with waxy layer before drying. The effects of different low plasma pretreatment power (200, 300, 400, and 500 W), low plasma pretreatment time (30, 40, and 50 s) and drying temperature on the thin layer drying process of vegetables (peppers, lentils, and peas) were investigated. Peppers after plasma pretreatment were dried at 45, 50, and 55°C. Lentils and peas after plasma pretreatment were dried at 65, 70, and 75°C. Results showed that low temperature plasma can effectively improve the drying efficiency, promote the moisture diffusion and shorten the drying time. After pretreatment power of 500 W for 30 s at 55°C, drying time of peppers was shortened by 18.75%, the maximum effective moisture diffusivity is 5.843 × 10−10 m2·s−1, and lower activation energy (Ea) is 69.349 kJ·mol−1 in comparison with 71.118 kJ·mol−1 for the control group. After pretreatment power of 500 W for 30 s at 75°C, drying time of lentils and peas was shortened by 33.33 and 27.27%, respectively. The maximum effective moisture diffusivity of lentils is 2.526 × 10−9 m2·s−1, and lower activation energy (Ea) is 27.359 kJ·mol−1 in comparison with 33.366 kJ·mol−1 for the control group. The maximum effective moisture diffusivity of peas is 1.867 × 10−9 m2·s−1, and lower activation energy (Ea) is 23.583 kJ·mol−1 in comparison with 29.107 kJ·mol−1 for the control group. Results indicate that the higher plasma pretreatment power led to the higher drying efficiency but higher plasma pretreatment time cannot further shorten the drying time.Practical ApplicationsVegetable is important in daily life, but easy to dehydrate in a natural state. The transportation and storage are more convenient after drying. Low temperature plasma technology does not need high pressure and low energy consumption, which can maintain the color and nutrition of vegetables to a large extent. In industry, it can be applied to pretreat fruits, vegetables, and other foods before drying. It can effectively enhance the drying efficiency, and shorten the drying time.

Fabrication and properties of PEI/APP layer‐by‐layer coated ramie fabric combined with low‐temperature plasma treatment

SummaryThe present work demonstrates a surface pretreatment of reducing assembly layers for flame retardant modification of ramie fabric used by layer‐by‐layer (LbL) assembly. In order to achieve this goal, low‐temperature plasma (LTP) pretreatment was chosen. Attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR) and scanning electron microscope (SEM) were used to confirm the effect of LTP pretreatment on polyethylenimine/ammonium polyphosphate (PEI/APP) flame retardant coating constructed on the surface of ramie fabric using LbL assembly. The thermal property and flame retardancy of PEI/APP coated ramie fabrics were analyzed by TG, LOI, UL94 vertical burning, and cone calorimeter tests. The results indicated that the decomposition rate of ramie fabrics was reduced and the char forming ability at high temperature was improved by PEI/APP coating on the ramie surface. Its LOI increased markedly to 30.6% and ramie fabric achieved self‐extinguishing effect. Meanwhile, LTP‐O2‐(PEI/APP)20 ramie fabric exhibited the low flammability and high fire safety. It was proved that LTP pretreatment under oxygen atmosphere could endow ramie fabric with better flame retardancy due to more PEI/APP adsorbed on its surface. These findings have significant implications for the application of LTP pretreatment to flame retardant modification of ramie fabric by LbL assembly.

Low temperature plasma pretreatment enhances hot‐air drying kinetics of corn kernels

AbstractIn this study, an efficient method for hot‐air drying of corn kernels was developed through a pretreatment of low temperature plasma. Corn kernels after plasma pretreatment were dried at 37.5, 45, and 52.5°C. It was found that the dried samples with plasma pretreatment presented shorter drying time and higher drying rate. After pretreatment power of 500 W for 30 s at 37.5°C, drying time was shortened by a maximum of 21.52%, and the drying rate was increased by 8.15%. The effective moisture diffusivity is in the range of 1.6107 – 1.9962, 2.8454 – 3.3600, 4.3237 – 4.7171 × 10−11m2s−1at drying temperature of 37.5, 45, and 52.5°C. Plasma pretreatment enhances the drying kinetics more effectively with lower activation energy 47.79 kJ mol−1in comparison with 54.82 kJ mol−1for the control group. Atomic force microscopy showed the plasma pretreatment can change the surface topography with some microholes, which explain how the plasma pretreatment can improve the drying process.Practical ApplicationThe low temperature plasma pretreatment can improve the efficiency of corn kernels drying. Furthermore, it has potential application for reducing energy consumption in drying. The low temperature plasma pretreatment can be potentially applied in commercial drying.

Effect of NTP Pretreatment on Thermal Resistance and Fouling Components of Oilfield Wastewater

In order to prevent scaling in the process of oilfield wastewater evaporation, low temperature plasma is used for pretreatment of heavy oil wastewater. It reacts with the ions and radicals produced by the low-temperature plasma and then is send into the evaporator. The changes of various indexes of the distilled water and the distribution of fouling in the evaporation process of heavy oil wastewater after plasma pretreatment were studied. The results showed that the content and hardness of silica in wastewater were decreased after plasma pretreatment, which was more suitable for evaporation treatment. At the same time, the content of salt and oil in distilled water is reduced, and the quality is improved. In addition, when the steam concentration was 30∼40 times, the suspended solids in the concentrated solution of the wastewater increased significantly after the plasma treatment. Correspondingly, the fouling at the bottom of evaporator is greatly reduced. Comparing the various indexes of distilled water and the feed water index of gas injection boiler, it can be seen that the excessive oil content in distilled water is the biggest obstacle to the recovery of distilled water to boiler feed water. Low temperature plasma pretreatment can provide a quick and new way to solve the scaling problems and water quality problems in the recovery of distilled water from a large number of heavy oil wastewater.

Froth flotation improvement by plasma pretreatment of sulfide minerals

By implementing a low-temperature plasma pretreatment step in the processing procedure for separating different sulfide mineral mixtures, it has been possible to improve the efficiency of froth flotation. Two powder mixtures consisting of pyrite/chalcopyrite and chalcopyrite/molybdenite were selectively oxidized in an Ar/O2 microwave plasma. The oxide/sulfur mixture obtained was separated by using an oxide collector. The recovery of each mixture component was measured and the results were compared with the untreated material. For separating the pyrite/chalcopyrite mixture, high selectivity could be achieved after plasma pretreatment using the oxide collector Flotinor FS-2. One hundred percent of chalcopyrite could be recovered whilst the recovery rate of pyrite remained below eight percent. Additionally, major improvements could be achieved in the efficiency of separating the chalcopyrite/molybdenite mixtures. In all cases, it was possible to avoid the use of activating and depressant reagents, which successfully demonstrates that the surface oxidation selectivity of the plasma pretreatment ensures high flotation efficiencies by using an oxide collector to separate the sulfide mixture. Additional XPS measurements have been carried out to investigate the oxidation of the sulfide surface.

Color management for enhancing the performance of superfine nylon ink jet printing with reactive dyes inks

AbstractThe challenge for the inkjet printing textiles is that the colors reproduction quality of printed output is an accurate match to the original artwork. Actual evidence from art workers with digital print facilities reveals that they regularly encounter problems in this area. This article concerns the initial stages of an investigation into color accuracy in digitally printed superfine nylon under low temperature plasma pretreatment in order to get a accuracy and color‐increased superfine nylon digital prints. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 346–351, 2017

A method to modify PVDF microfiltration membrane via ATRP with low-temperature plasma pretreatment

The hydrophilic modification of a polyvinylidene fluoride (PVDF) microfiltration membrane via pretreatment with argon plasma and direct surface-initiated atom transfer radical polymerization (ATRP) was studied. Both modified and unmodified PVDF membranes were characterized by Fourier transform infrared spectroscopy (FTIR), water contact angle, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and pore size distribution measurements. FTIR and XPS spectra confirmed that sulfobetaine methacrylate (SBMA) had been grafted onto the membrane surface. The initial contact angle decreased from 87.0° to 29.8° and a water drop penetrated into the modified membrane completely in 8s. The pore size distribution of the modified membrane exhibited a smaller mean value than that of the original membrane. The antifouling properties of the modified PVDF membrane were evaluated by a filtration test using bovine serum albumin (BSA) solution. The results showed that the initial flux of the modified membrane increased from 2140.1L/m2 h to 2812.7L/m2 h and the equilibrium flux of BSA solution increased from 31L/m2 h to 53L/m2 h.

Modification of wool by air plasma and enzymes as a cleaner and environmentally friendly process

Abstract A big disadvantage of the traditional anti-felting modification of wool is the problem of environmental pollution. Low temperature plasma (LTP) and enzyme process are the two important cleaner technologies which have potential use in the textile industry. In this paper, transglutaminase, a protein crosslinking enzyme, combined with air low temperature plasma and protease was used to modify wool fiber. The influences of the combination treatment on wool knitgoods performances were discussed. It was shown that air low temperature plasma pretreatment, instead of conventional chemical pretreatment, improved wettability significantly and made enzyme molecule more accessible to protein chains of the wool. Protease treatment following air plasma impacted a significant reduction in fabric shrinkage and the loss of strength was under control. Transglutaminase remediated wool damage, resulting in an increase in bursting strength. The machine washable wool knitgoods are obtained and the damage to the wool fiber can be controlled by using the combination treatment of air plasma, protease and transglutaminase. TGase was demonstrated to catalyze cross-linking reaction in wool protein by analyzing the thermal behavior of wool.

Flame Retardant Properties of Plasma Pretreated/Metallic Salt Loaded Cotton Fabric Before and After Direct Dyeing

In this research work, cotton fabrics were pretreated with low temperature plasma (LTP) and then inoculated in various metallic salts and flame retardancy of cotton fabric was investigated. More polar functional groups were present on the substrate surface after LTP pretreatment. Titanium dioxide (TiO2), zinc sulfate (ZnSO4), lead (II) acetate [Pb(C2H3O2)2], aluminium sulfate [Al2(SO4)3] and silver nitrate (AgNo3) were used as metallic salts. The flame retardancy of the samples was characterized by limiting oxygen index (LOI) and char yield. Good flame retardant activity for Al2(SO4)3 and AgNo3 treated fabrics were achieved, however, the effect of TiO2 and ZnSO4 on flame retardany of cotton fabrics was moderate. It was concluded that, nitrogen plasma pretreatment, improve the flame retardant properties of cotton samples. The plasma treated and Aluminium sulfate loaded cotton fabric sample has a LOI value of 23.3. It shows that, nitrogen plasma pretreatment has synergistic effect on metallic salts for improving the flame retardant properties of cotton samples. In this research work, the dyeability of samples after loading with metallic salts was investigated. Also effect of dyeing on flame retardant properties was studied. The cotton fabrics treated with metallic salts demonstrate an excellent dyeability property. Color intensities of the dyed fabrics were measured by using a UV VIS–NIR Reflective Spectrophotometer, over the range of 200–800 nm. The results showed that, by using silver nitrate as mordant before dying, the relative color strength (K/S values) of the dyed fabrics has been increased. Water drop test and wash fastness determination (ISO 105-C01) were conducted. Also Electronic Crock meter/Rubbing Fastness Tester AATCC 8 was used to determine the color fastness of textiles. We also concluded that dyeing the plasma treated and inoculated cotton fabrics do not have any negative effect on flame retardancy of cotton fabric.

Hydrophobic sol-gel finishing for textiles: Improvement by plasma pre-treatment

The surface of cotton (COT) and polyester (PET) fabrics was modified to create a water-repellent finishing by depositing a modified silica-based film using the sol-gel technique. TEOS (tetraethoxysilane)-based physically modified sols with 2% and 11% on weight fabric (o.w.f.) of hydrophobic additives were tested. N-propyltrimethoxysilane (C3), hexadecyltrimethoxysilane (C16) and 1H,1H,2H,2H-fluorooctyltriethoxysilane (FOS) were investigated as additives. Furthermore, a low-temperature plasma pre-treatment was used to activate the COT and PET fabric surface to improve the sol-gel coating adhesion, resistance to abrasion and fastness to washing stresses. A complete chemical/morphological (Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscopy) and physical characterization (abrasion and air permeability test) of treated samples was carried out. High values of θ (around 140°) on PET and COT samples were obtained with all additives used (C3, C16 and FOS) even at a low concentration (2%). Due to plasma pre-treatment, interesting water-repellent properties were achieved for PET (θ = 148°) treated with TEOS/FOS molar ratio 0.63 and for COT (θ = 140°) with TEOS/C16 molar ratio 0.63. The enhanced coating adhesion, due to plasma surface activation, was confirmed by abrasion and washing tests.

KES-F Characterization and Hand Evaluation of Oxygen Plasma-Treated Wool Fabrics Dyed at Temperature Below the Boil

In our previous works, we investigated the possibility of reducing the dyeing temperature of wool fabrics with oxygen low-temperature plasma pre-treatment. Fabrics were dyed replicating an industrial process on a laboratory-scale machine, and it was found that pre-treated fabrics could be dyed at 85°C with no worsening of their dyeing performances compared with fabrics conventionally dyed at the boil. In this work, the physical, low-stress mechanical and surface properties of untreated fabrics, untreated fabrics conventionally dyed at 98°C, and plasma-treated fabrics dyed at 85°C, were measured using Kawabata’s Evaluation System for Fabrics. In particular, there were significant increases in bending and shearing characteristic values for plasma-treated fabrics dyed below the boil (85°C). Moreover, subjective hand tests highlighted that these fabrics were stiffer and crisper than the other two types of fabric, thus confirming the results of objective measurements.

EFFECT OF SURFACE TREATMENT ON THE ENZYMATIC TREATMENT OF CELLULOSIC FIBER

Fiber modifications by environmentally friendly processing are essential in order to simplify the preparation and finishing processes, in addition to minimizing the chemical waste and associated disposal problem. In this regard, enzymes have been used extensively because it can remove the small fiber ends from yarn surface to create a smooth fabric surface appearance and introduce a degree of softness without using traditional chemical treatment. However, a significant strength reduction and slow reaction rate of the enzymatic reaction limit its industrial application. In this paper, the potential of using low-temperature plasma (LTP) as a surface pre-treatment prior to enzyme treatment on flax fiber has been studied. By means of the LTP pre-treatment, the effectiveness of enzyme treatment can be enhanced.

Influence of low‐temperature plasma on the ink‐jet‐printed cotton fabric

AbstractThis article studies the effect of low‐temperature plasma (LTP) on an ink‐jet‐printed cotton fabric. Owing to the specific printing and conductivity requirements for ink‐jet printing, none of the conventional printing chemicals used for cotton fabric can be directly incorporated into the ink formulation. As a result, the cotton fabric requires pretreatment with the printing chemicals prior to the stage of ink‐jet printing. The aim of this article is to study the possibility and effectiveness of applying LTP treatment to enhance the performance of pretreatment paste containing sodium alginate so as to improve the properties of the ink‐jet‐printed cotton fabric. Scanning electron microscopic pictures show that LTP treatment may cause cracks on the fiber surface and hence more dyes could approach the fiber surface during the ink‐jet printing process, leading to a higher dye uptake subsequently. In addition, not only the dye uptake is increased after the LTP treatment but the color‐fastness properties and the definition of the final print marks are also improved. Therefore, LTP pretreatment in couple with the ink‐jet printing technique could improve the final printed properties of cotton fabric. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

The use of plasma pre-treatment for enhancing the performance of textile ink-jet printing

In this study the effect of low temperature plasma (LTP) treatment of cotton fabric for ink-jet printing was investigated. Owing to the specific printing and conductivity requirements for ink-jet printing, none of the conventional printing chemicals used for cotton fabric can be directly incorporated into the ink formulation. As a result, the cotton fabric requires treatment with the printing chemicals prior to the stage of ink-jet printing. The printing chemicals as a treatment to cotton fabric are applied by the coating method. The aim of this study was to investigate the possibility and effectiveness of applying LTP pre-treatment to enhance the performance of treatment paste containing sodium alginate, to improve the properties of the ink-jet printed cotton fabric. Experimental results revealed that the LTP pre-treatment in conjunction with the ink-jet printing technique could improve the final properties of printed cotton fabric.

Improvement of dye adsorption on synthetic polyester fibers by low temperature plasma pre-treatment

Adsorption of the dyes on the surface of the natural and synthetic polymer fibers, or weaved fabrics is created due to the effect of the intermolecular forces between fiber surface and the dye. Such forces are causing relatively strong bonding interaction between dye dipoles and the stained matrix. In the case of polymer and biopolymer materials the number of the dipoles is directly proportional to the number of polar groups in macromolecular side chains. The latter number of present dipoles is possible to be increased by several physico-chemical methods, e.g. fire treatment, chemical etching by strong acids, UV irradiation, corona discharge or low-temperature plasma treatments etc. In this communication the effect of low-temperature plasma treatment of polyester (PES) weaved fabric on dye adsorption to the surface of the studied substrate is discussed. Obtained increased dye selectivity to the stained matrix results in improved tinctorial strength, better economical effectiveness as well as to the improved ecology of the process.

Effect of Low-temperature Plasma Pre-treatment on the Chemical Silver-plated Polyester Fabrics

Low-temperature plasma (LTP) has been increasingly employed for polymer surface modifications. In this paper, plasma gases of oxygen and argon were used for pre-treating polyester fabrics before conducting chemical silver plating, aiming to increase the amount of metal content and improve the performance of the polyester fabrics. After LTP pre-treatment, there was a thin plasma layer generation on the fabric surface which was in good contact with the fibre. Based on the observation of micro-structure using scanning electron microscopy (SEM), it was found that there was an increase in the amount of silver particles deposited on the fibre surface after the LTP pre-treatment. The surface observation implies that the LTP pre-treatment could enhance the hydrophilicity of fibre surface and help facilitate the absorption of silver particle layer to reach the necessary level of uniformity and adhesive strength.