Viscoelastic Polyurethane Foams with Reduced Flammability and Cytotoxicity

Consistent and proper use of respiratory protective devices (RPD) is one of the essential actions that can be taken to reduce the risk of exposure to airborne hazards, i.e., biological and nonbiological aerosols, vapours, and gases. Proper fit of the facepiece and comfort properties of RPDs play a crucial role in effective protection and acceptance of RPDs by workers. The objective of the present paper was to develop viscoelastic polyurethane foams for use in RPD seals characterised by proper elasticity, allowing for the enhancement of the device fit to the face and the capability of removing moisture from the skin in order to improve the comfort of RPD use. Moreover, it was pivotal to ensure the non-flammability of the foams, as well as a simultaneous reduction in their cytotoxicity. The obtained foams were characterised using scanning electron microscopy, infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. Measurements also involved gel fraction, apparent density, compression set, rebound resilience, wettability, flammability, and cytotoxicity. The results are discussed in the context of the impact of modifications to the foam formulation (i.e., flame-retardant type and content) on the desired foam properties. The test results set directions for future works aimed to develop viscoelastic polyurethane foams that could be applied in the design of respiratory protective devices.

Influence of the length of the spacer group on the performance of the sulfate-based Gemini surfactants

PurposeA series of sulfate-based Gemini anionic surfactants were synthesized via etherification, ring opening and sulfation reactions using epichlorohydrin, fatty alcohol, ethylene glycol and chlorosulfonic acid as the main raw materials. Orthogonal experiments for 1,8-bisalkoxymethylene-3,6-dioxin-1,8-octane disulfate were performed on the sulfation reaction to determine the optimal reaction conditions.Design/methodology/approachA series of sulfate-based Gemini anionic surfactants were synthesized via etherification, ring opening and sulfation reactions using epichlorohydrin, fatty alcohol, ethylene glycol and chlorosulfonic acid as the main raw materials. Orthogonal experiments for 1,8-bisalkoxymethylene-3,6-dioxin-1,8-octane disulfate were performed on the sulfation reaction to determine the optimal reaction conditions. The structures of the intermediate and final products were characterized by FT-IR (Fourier transform infrared spectroscopy analysis), 1H-NMR (proton nuclear magnetic resonance spectroscopy) methods. The thermal performance of surfactants was analyzed using thermogravimetric analysis (TGA). The thermogravimetric results showed that the sulfate-based Gemini surfactants had good heat resistance (the thermal decomposition temperature of which was in the range of 140∼170?). The Krafft point, surface tension, foaming, Hydrophile–Lipophile Balance Number (HLB), emulsifying, wetting, and lime-soap dispersing performance were measured by visual observation, hanging drop method, aqueous surfactant solution method and Borghetti–Bergman method, respectively. The results have shown that all the sulfate-based Gemini surfactants had good water solubility and lime-soap dispersing ability. When spacer group was -(CH2)2-, with the increase of the carbon chain length from C12 to C14, the micellar concentration critical micelle concentration and surface tension (CMC) gradually increased from 8.25 × 10–4 mol/L to 8.75 × 10–4 mol/L and 27.5 mN/m to 30.9 mN/m, respectively. Also, the sulfate-based Gemini surfactants with the different length of the spacer group had a different effect on their performance on foaming properties and foam properties, HLB and emulsifying ability and wetting ability. FindingsIn view of the important role of the spacer group and the general use of anionic surfactants in oil fields, this article considers the preparation of a series of sulfate-based Gemini surfactants by changing the spacer group and the chain length of the hydrophobic group and evaluating their surface activity, and finally its Kraffi, on the foam properties, HLB value, emulsifying performance, lime soap dispersing ability etc.Originality/valueSulfate-based Gemini surfactants have broad application prospects in the fields of oil and gas exploitation, environmental protection, chemistry and daily chemical industry and so on.

Nonylphenol Ethoxylate Surfactants Modified by Carboxyl Groups for Foam EOR at High-Salinity Conditions

High mineralization of water complicates the use of foam in reservoir conditions. Anionic–nonionic surfactants are one of the best candidates for these conditions since they have both high surface activity and salt tolerance. One of the ways to obtain anionic–nonionic surfactants is to modify nonionic surfactants by an anionic group. The type of the group and its chemical structure can strongly affect the properties of the surfactant. In this work, widely-produced nonionic surfactant nonylphenol (12) ethoxylate (NP12EO) was modified by new types of carboxylic groups through the implementation of maleic (NP12EO-MA) and succinic (NP12EO-SA) anhydrides with different saturation levels. The main objectives of this work were to compare synthesized surfactants with nonionic precursor and to reveal the influence of unsaturated bonds in the carboxyl group on the properties of the foam. NaCl concentration up to 20 wt% was used to simulate high mineralization conditions, as well as to assess the effect of unsaturated bonds on foam properties. Synthesized anionic–nonionic surfactants retained surfactant solubility and long-term stability in high-salinity water, but have better foaming ability, as well as higher apparent viscosity, in porous media. The presence of an unsaturated bond in NP12EO-MA surfactant lowers foaming ability at high mineralization.

Direct foam writing in microgravity

Herein we report 2D printing in microgravity of aqueous-based foams containing metal oxide nanoparticles. Such hierarchical foams have potential space applications, for example for in situ habitat repair work, or for UV shielding. Foam line patterns of a TiO2-containing foam have been printed onto glass substrates via Direct Foam Writing (DFW) under microgravity conditions through a parabolic aircraft flight. Initial characterization of the foam properties (printed foam line width, bubble size, etc.) are presented. It has been found that gravity plays a significant role in the process of direct foam writing. The foam spread less over the substrate when deposited in microgravity as compared to Earth gravity. This had a direct impact on the cross-sectional area and surface roughness of the printed lines. Additionally, the contact angle of deionized water on a film exposed to microgravity was higher than that of a film not exposed to microgravity, due to the increased surface roughness of films exposed to microgravity.

Myofibrillars and Sarcoplasmic Proteins Separated The Effect of Different Preservation and Cooking Methods on Functional Characteristics of From Common Carp and Silver Carp Prof.

The current study dealt with the use of methods of preserving (freezing and salting with drying), cooking methods (grilling and cooking in broth and frying) and studying their effect on functional characteristics (solubility, amount of water and oil absorbed, viscosity, emulsification, foaming, gel formation) of myofibrillars and sarcoplasmic proteins separated from carp meat, common and silver carp diagnosed with electrophoresis technique, the study was conducted during the period (10/2018-1/2020). The results were as follows: 1. Dried fibrous proteins and dried sarcoplasm proteins separated from fish meat have given a good functional properties compared to commercial cow's albumin. 2. It was found that the percentage of solubility and gelatinization of commercial cow's albumin protein was higher than in the myofibrillars and sarcoplasmic proteins separated from the two types of fish, whereas the amount of water absorbed by the commercial cow's albumin protein was less than of myofibrillars and sarcoplasmic proteins, while the amount of absorbed oil, viscosity, and emulsion composition. The commercial cow's albumin was comparable to the myofibrillars and sarcoplasmic proteins, and when comparing the foam properties of the myofibrillars and sarcoplasmic proteins of common carp and silver carp with the commercial cow's albumin at a concentration of 1% and at the normal pH=7, it was found that the foam size and persistence of sarcooplasmic proteins were close to the size and persistence of the foam for the commercial protein at the normal pH, while the volume and stability of the foam for myofibrillars proteins were slightly lower than in cow's albumin. 3. It was observed that the solubility values in the myofibrillars proteins and the sarcoplasmic proteins of the samples were close to each other when using preservation methods while the solubility of the myofibrillars proteins was lower than the solubility of the sarcoplasm proteins of the cooked samples. It was found that the amount of oil absorbed by the myofibrillars proteins was higher than the sarcoplasmic proteins, but that its viscosity and its ability to bind water and its ability to form gel were lower than it, and the capacity of emulsifiers of protein myofibrillars and their stability was higher than the capacity and the stability of emulsions of sarcoplasm proteins, as for the type of fish and the type of protein stability of emulsions, it was noted that there was a slight difference in the capacity of emulsions and the stability of emulsions for myofibrillars proteins as well as for sarcoplasm proteins. The emulsification values did not seem different between the two types of fish. 4. It was found that freezing contributed to reducing solubility and the amount of water absorbed while it had a role in increasing the amount of oil absorbed to fish proteins more than salting and drying. The freezing, as well as salting and drying were reduced the viscosity of proteins a little bit, also freezing reduced stability of emulsionsfor two type of fish proteins,but salting and drying was rised it, and the degree of influence of the measured foam property in myofibrillars and sarcoplasmic proteins of the fish species by means of preservation and cooking different methods was very small because the values were closely related, and we did not find a specific pattern that we could apply in terms of challenging degree of difference, freezing and salting with drying, grilling and frying and cooking in the broth sometimes susceptibility raises values formation of foam and other reduce it. 5. The solubility of proteins that measured on fish which cooked in broth was more than the solubility of grilled and fried samples. It was observed that the solubility values in myofibrillars proteins and sarcoplasm proteins for the cooked samples were close to each other, and the amount of water and absorbed oil, foam properties and viscosity of the measured proteins in cooked fish were not affected by the cooked methods whose used because the closely related of values. 6. Generally the results showed that the solubility and viscosity values in the samples of common carp were lower than in the silver carp which preserved and cooked by different ways, but the ability of common carp to bind the oil was higher than that of silver carp when using conservation methods while the values were close at the use of cooking methods, and we noted that there were no noticeable differences between myofibrillars proteins and sarcoplasmic proteins for the two fish species in their ability to bind water and their ability to form gel. It was also noted that there was a slight difference in the capacity of emulsions and their stability to myofibrillars proteins as well as to proteins sarcoplasm between the two types of fish. 7. The fish type, preservation methods, cooking methods, and di-interference had a significant effect at the probability level (P ≤ 0.05) on the percentage of solubility and the amount of water and oil absorbed by the myofibrillars and sarcoplasmic proteins separated from the meat of these fish, but did not significantly impact the viscosity of the protein.

Structural properties of cellulose nanofibril foam depending on wet foaming conditions in Pickering stabilization

Porous cellulose nanofibril (CNF) foam was prepared by stabilizing bubbles with CNF and a surfactant and then drying the stabilized wet foam in a convection oven. The consistency of carboxymethylated CNF (CMCNF) and the addition amount of the surfactant were controlled and the effects of these factors on the CNF wet foam and dry foam properties were investigated. An adequate amount of the surfactant (0.02–0.04 wt%) with CMCNF consistency higher than 0.5 wt% yielded wet foams with excellent stability. When the wet foam was dried at 60 °C in an oven, dry CNF foam with over 97% porosity was generated. The stable wet foams resulted in dry CNF foam with a sphere-like pore structure and low levels of shrinkage during drying. In contrast, unstable wet foams generated dry foam with severe shrinkage and large cavities. The pore size and the porosity of the dried foam were determined by the shape of bubbles in the wet foam and the degree of shrinkage during drying, which, in turn, affected the mechanical strength. In addition, the compressive strength of the oven-dried foam was 83% higher than that of the freeze-dried foam. Therefore, the preparation of a stable wet porous CMCNF foam by controlling the CMCNF consistency and the amount of surfactant was essential for obtaining a porous CMCNF foam with a uniform pore structure and good mechanical strength by oven drying. Graphic abstract

A study on fabrication of nanocomposite polyethylene foam through extrusion foaming procedure

Foaming a polymer not only turns it into a lightweight material but also gives some special properties to it. However, the most important issue is controlling the foaming process to achieve a desirable structure with high cell density and low relative density. In the present study, the extrusion foaming process of polyethylene was studied through stepwise amendments. An innovative extrusion system was designed and implemented to produce extrusion foams under different material and process conditions using N2 as blowing agent. In the first step, the final cooling condition was investigated. The air-cooling condition led to a higher cell density/lower cell size compared to the water-cooling condition although a higher relative density was obtained. In the second step, the effects of the addition of talc and the synergetic effect of talc/nanoclay at different contents were investigated in detail. The hybrid of talc/nanoclay had a noticeably improving effect on the cellular structure. In the third step, the effects of processing parameters including the die temperature and screw speed were studied on the foam properties. Finally, up to 49.4% decrease in the relative density of samples was observed, also cell densities up to 2.5 × 104 cell/cm3 and cell sizes as small as 280 µm were achieved.