Protective Colloid Research Articles

Influence of Protective Colloids on Calcium Tartrate Stability and the Astringency Perception in a Red Wine.

Calcium tartrate instability in wines has been a neglected topic for many years. However, it seems that this problem is gaining prominence, and the industry welcomes inputs to address this issue. Among the alternatives that winemakers use for tartrate salt stabilization, the addition of authorized protective colloids is one of the best choices because they are easy to apply and have a low energetic cost. In the present study, the same red wine was treated with five different commercially available protective colloids in triplicate. The effectiveness of such colloids on calcium tartrate potential instability was estimated, in addition to their side effects on the phenolic composition of the treated wines and their astringency perception, as assessed by sensory analyses of the treated wine. The results show that, under these trial conditions, carboxymethylcellulose is the best choice for reducing the risk of calcium tartrate precipitation in wine. Moreover, the application of protective colloids to the wines had little effect on their color, phenolic composition, or evolution during one year of bottle storage. Finally, the addition of protective colloids did not impact the astringency intensity, but it influenced the dynamic perception of astringency according to the temporal dominance of sensation analysis.

Preparation and systematic study of mechanical properties and suspension stability of polyurethane-polyurea double-shell perfume oil microcapsules

The perfume oil microcapsules are of considerable significance in personal care and household products due to their ability to control the targeted release of perfume oil under specific conditions, which enhances the longevity and overall performance of the product. In this study, double-shell perfume oil microcapsules were prepared using polyurea (PUA) and polyurethane (PU) as wall materials. The first PUA shell was formed at room temperature to encapsulate the perfume oil by adjusting the agitation speed, protective colloid concentration, and polymethylene polyphenyl isocyanate (PAPI) content. Subsequently, the second PU shell was formulated. Mechanical property analysis revealed that PU/PUA microcapsules exhibited superior characteristics, showing a threefold increase in mechanical strength compared to PUA microcapsules. Thermogravimetric analysis and dynamic release experiments in ethanol demonstrated that the PU/PUA microcapsules possessed higher thermal stability and greater compactness compared to the PUA microcapsules. Finally, by incorporating bacterial cellulose (BC) microgels and hydroxypropyl methylcellulose (HPMC) as stabilizing agents into the laundry detergent matrix (JJ), a stable suspension of PU/PUA microcapsules was achieved for over 180 days.

Preparation and performance assessment of high-strength polyurea microcapsules

Formulation of microcapsules with high mechanical strength holds great significance for their application in high-pressure scenarios. In this study, polyurea (PU) was employed as the shell material to encapsulate perfume oil through interfacial polymerization. Subsequently, a systematic assessment of mechanical strength was conducted. The results indicated that the protective colloid, triethylenediamine (TEDA) concentration, core/shell ratio (perfume oil to polymethylene polyphenyl isocyanate (PAPI)), and reaction temperature, significantly influenced the mechanical strength of PU microcapsules. Notably, employing a concentration of 1.5 wt% polyvinyl alcohol (PVA), 0.5 wt% TEDA, a core/shell ratio of 10:1, and a reaction temperature of 70 °C resulted in PU microcapsules boasting an average rupture force of 1.92 ± 0.22 mN and a Young's modulus of 0.0195 ± 0.0013 GPa. Impressively, when contrasted with melamine-formaldehyde microcapsules, those with PU shells exhibited markedly enhanced mechanical properties.

Explore the elimination of toxic dye using Bio-Synthesized cerium oxide nanoparticles derived from Morinda citrifolia leaf extracts

Due to their distinct physical characteristics, nanoparticles (NPs) with a mean size of 1 to 100 nm are of significant interest to numerous disciplines and industries. Because of improper disposal of pigments and effluents that enter watercourses, certain businesses are increasingly important contributors to hydrographic pollution. Due to its carcinogenic properties and low biocompatibility, dye degradation poses a severe risk to people, animals, and aquatic environments. This experiment used morinda citrifolia leaf extract as a reduction and protective colloid to break down pigments like methyl red and haematoxylin and make cerium nanoparticles. Cerium oxide nanoparticles demonstrated a surface plasmon maxima at 430 nm in the UV zone. The XRD examination demonstrated the synthesis of cerium nanocrystals. Cerium nanocrystal spheres were visible in the results of the photoluminescence study. All emission spectrum levels fall between 447 and 463 nm and are produced by various defects, including displacement, necessary for quick oxidative metabolism. CeO2 NPs emit the epiphenomenon at 487 nm due to the interfacial flaw. According to SEM data, mineral grains have an average crystallite size of 30 nm. The rate of dye elimination was measured using ultraviolet-visible spectroscopy between 200 and 600 nm. The peak value for haematoxylin was obtained between 420 and 500 nm, whereas the most excellent absorbance for methyl red was observed at 380 nm.

Microemulsion and microsuspension polymerization of methyl methacrylate in surfactant-free microemulsions (SFME)

HypothesisThis article presents a free-radical polymerization method in a mesostructured system – free of any surfactants, protective colloids, or other auxiliary agents. It is applicable for a large variety of industrially relevant vinylic monomers. The aim of this work is to study the impact of surfactant-free mesostructuring on the polymerization kinetics and the polymer derived. ExperimentsSo-called surfactant-free microemulsions (SFME) were investigated as reaction media with a simple composition comprising water, a hydrotrope (ethanol, n-propanol, isopropanol, tert-butyl alcohol), and the monomer as the reactive oil phase (methyl methacrylate). Polymerization reactions were performed using oil-soluble, thermal- and UV-active initiators (surfactant-free microsuspension polymerization) and water-soluble, redox-active initiators (surfactant-free microemulsion polymerization). Structural analysis of the SFMEs used and the polymerization kinetics were followed by dynamic light scattering (DLS). Dried polymers were analyzed with regard to their conversion yield by mass balance, the corresponding molar masses were determined using gel permeation chromatography (GPC), and the morphology was investigated by light microscopy. FindingsAll alcohols are suitable hydrotropes to form SFMEs, except for ethanol, which forms a molecularly disperse system. We observe significant differences in the polymerization kinetics and the molar masses of the polymers obtained. Ethanol leads to significantly higher molar masses. Within a system, higher concentrations of the other alcohols investigated give rise to less pronounced mesostructuring, lower conversions, and lower average molar masses. It could be demonstrated that the effective concentration of alcohol in the oil-rich pseudophases as well as the repulsive effect of the surfactant-free, alcohol-rich interphases constitute the relevant factors influencing polymerization. Concerning the morphology, the polymers derived range from powder-like polymers in the so-called “pre-Ouzo region” over porous-solid polymers in the bicontinuous region to dense, almost compacted, transparent polymers in unstructured regions, comparable to the findings for surfactant-based systems reported in the literature. Polymerizations in SFME comprise a new intermediate between well-known solution (i.e., molecularly dispersed) and microemulsion respectively microsuspension polymerization processes.

A thermal hazard risk evaluation of emulsion polymerisation and vinyl acetate monomers in the latex manufacturing process

Latex is extensively used in industrial products. However, completing some processes at scale leads to unacceptable levels of risk that need to be quantified and mitigated. Systemic risks must be eliminated wherever possible, and safety takes priority over efficiency and quality. To assess the process risks accurately, four raw materials were examined in this study: polyvinyl acetate (PVA), latex process-initiator-ammonium persulfate (APS) and hydrogen peroxide (H2O2), and vinyl acetate monomer (VAM). The physicochemical composition of the PVA latex process was determined via calorimeters, including differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2). The calorimetry results showed that the protective colloid was a critical component in the polymerisation reaction. In addition, when adding initiators to the system, it is vital to observe the normal ratio of materials and keep the stirring system operating. The scenario system also simulated the effects of shutting down various inhibitory programs, including the build-up of free radicals that could result in a runaway reaction when the initiator was added in excess. On the other hand, the result of the risk matrix displayed as a medium level, indicating that although the probability of an accident is low, the resulting severity is at disaster level. As a result, this study provides process safety engineers with a reliable frame of reference for assessing the potential dangers in the PVA latex manufacturing process.

Construction of consumer-friendly essential oil microcapsules with viscous cores to provide extra long-lasting release

Essential oil microcapsules with viscous cores were formulated by encapsulating oil droplets with intermediate non-crosslinked polymer shells and crosslinked polymer outer shells, followed by dissolution of the intermediate shells with essential oil to form viscous cores. The study found that when the core/shell ratios of the intermediate shell = 3:2, the rotational speed = 500 rpm, the concentration of the protective colloid = 1.0 wt%, the concentration of the crosslinking agent = 20 wt% and the core/shell ratio of the outer shell = 10:1 by using three times' addition method, caprylic/capric triglyceride (GTCC) microcapsules with viscous cores were obtained. The release profile, mechanical strength and adsorption performance of GTCC microcapsules were evaluated in comparison with melamine-formaldehyde microcapsules. It was found that the viscous cores microcapsules had better heat resistance, extreme long-lasting release property, viscoelasticity and been more adhesive to cotton fabrics, which were more consumer-friendly compared with that of melamine-formaldehyde microcapsules. • Construction of essential oil (GTCC) microcapsule with the viscous core structure. • Polystyrene (PS) was used as wall material, which is safe and consumer-friendly. • MF (Melamine-formaldehyde)-GTCC and PS-GTCC microcapsules were compared. • The release, viscoelasticity and adsorption property of microcapsule was enhanced.

Synthesis and evaluation of grafted xanthan gum as a drug carrier in developing lornoxicam gel formulations

Background: In the medical and pharmaceutical fields, man has successfully used natural-origin things for millennia. Polymers obtained from plant sources have flashed much consideration in current eras owing to their various pharmaceutical properties, such as gelling agents in gels. Also incorporated in cosmo products, fabrics, dyes, and paper manufacture as binders, diluents, disintegrating agents, thickeners in oral fluids, protective colloids in suspensions, and bases in a suppository. Objectives: Natural polymers are chosen over semisynthetic and synthetic excipients due to their lack of toxicity, low cost, availability, soothing action, and nonirritant nature, as well as their ability to undergo a variety of chemical modifications. However, they have some drawbacks, including microbial contamination, lot to lot variation, reduced viscosity throughout storage, inappropriate mechanical properties, low storage, and an uninhibited rate of hydration. Current research work aims to chemically modify xanthan gum and study its impact on the formulation of topical gels. Materials and Methods: Chemical modification of xanthan gum is conceded by using a thiol-esterification reaction with thioglycolic acid (TGA) in the presence of hydrochloric acid. Microwave irradiated thiolated xanthan gum was also willing by further irradiation of thiolated xanthan gum by microwave using 750 W frequency. Topical drug delivery of lornoxicam release applications of thiolated and microwave irradiated xanthan gum are comparatively evaluated with pure xanthan gum polymer by formulating gel incorporated lornoxicam as a drug. Results: The physical properties of gel-like physical evaluation and viscosity results are within official limits. Formation of gel with idyllic properties. Determination of drug content, spreadability, and extrudability of modified xanthan gum was high compared with native xanthan gum. In vitro drug release study showed that prepared gel sustains the drug release for 24 h. Conclusion: Thiolation and irradiated xanthan gum sustain the release of lornoxicam over a prolonged period and might be a promising lornoxicam carrier in topical drug delivery to enhance antinociceptive and anti-inflammatory efficiency.

High-performance process fluids used for vibration finishing of parts with granular media made of natural material “Baykalit”

The results of studies of the technological capabilities of granular media made of natural material “Baykalit” in the conditions of vibration technological systems are presented. Baikalit is a siliceous rock-fine-grained quartzite (microquartzite) - with an aggregate structure of quartz grains measuring 1.5-3 microns with sharp boundaries between these very grains. The granules obtained as a result of crushing the mineral rock Baikalit have a sufficiently high hardness (at least 6.0 - 7.0 on the Mohs scale). The presence of many wedge-shaped vertices along the perimeter of the granules and the arbitrariness of the shape allows us to consider them as a universal cutting tool that has access to various surfaces of complexity. It is shown that vibration treatment with granular media made of natural material “Baykalit” reduces the height of the initial surface micrprofile by 0.2-0.3 microns and is an effective way to remove burrs when processing parts with a surface microprofile height of more than 0.63 microns. The use of process fluids, which include increasing the wetting capacity of both Baikalit and processed workpieces, reduces the technological time of vibration processing by 1.5 times. The presence of components in the process fluid, such as protective colloids (Na CMC), prevents the sludge from sticking to the galtovochnye bodies, that is, prevents the “salting” of their profile, reduces the rigidity of the layer on the surface of the galtovochnyh bodies and workpieces, which contributes to productivity growth.

Process Characterization of Polyvinyl Acetate Emulsions Applying Inline Photon Density Wave Spectroscopy at High Solid Contents.

The high solids semicontinuous emulsion polymerization of polyvinyl acetate using poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated by optical spectroscopy. The suitability of Photon Density Wave (PDW) spectroscopy as inline Process Analytical Technology (PAT) for emulsion polymerization processes at high solid contents (>40% (w/w)) is studied and evaluated. Inline data on absorption and scattering in the dispersion is obtained in real-time. The radical polymerization of vinyl acetate to polyvinyl acetate using ascorbic acid and sodium persulfate as redox initiator system and poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated. Starved–feed radical emulsion polymerization yielded particle sizes in the nanometer size regime. PDW spectroscopy is used to monitor the progress of polymerization by studying the absorption and scattering properties during the synthesis of dispersions with increasing monomer amount and correspondingly decreasing feed rate of protective colloid. Results are compared to particle sizes determined with offline dynamic light scattering (DLS) and static light scattering (SLS) during the synthesis.

Preparation and Characterization of Japanese Ink-Inspired Aqueous Dispersions of Carbon Materials with the Help of Glue as Colloid Chemistry Teaching Aid

Aqueous dispersions of soot and other carbon materials, prepared in a manner similar to that used for preparing traditional Japanese ink, were developed as teaching materials for colloid chemistry. The protective colloid formed by the addition of glue is an interesting teaching material that allows visual understanding of various colloidal phenomena. In addition, such dispersions can be prepared using glue and various carbon materials (e.g., pencil lead, barbecue charcoal, C60 fullerene, graphene, and carbon nanotubes), following an extremely simple and environmentally friendly method. The carbon materials are insoluble in water without the glue, highlighting the need for glue to act as a protective colloid in ink preparation. Herein, we describe convenient colloid chemistry experiments that are adaptable to a wide range of educational settings.

Cellulose Stabilized Polyvinyl Acetate Emulsion: Review

The global energy crisis and overconsumption of non-renewable resources have depleted natural resources, climatic changes with global warming, and rise in sea level. The research on alternate sources and chemicals has resulted in the usage of green materials. These biomaterials are sustainable sources, biodegradable, and are abundant in nature. The replacement of petrochemicals with biopolymers has gained much importance in this aspect. Conventionally, polyvinyl alcohol is employed as a protective colloid in polyvinyl acetate adhesive. Polyvinyl alcohol has the limitation of petroleum origin, is replaced by biopolymers. Starch being a biopolymer, has gained interest in replacing polyvinyl alcohol as a stabilizer. Cellulose has a low cost, and the most abundant biomaterial finds application as a reinforcing agent in conventional adhesives. Exploring cellulose as a stabilizer for polyvinyl acetate emulsion polymerization with reinforcement has created potential applicability of cellulose in adhesives. Surface hydroxyl groups in cellulose act as sites for functionalization, making it material for the adhesive sector. This review paper aims to showcase biomaterials, namely starch, and cellulose, in the adhesive field. A detailed review of cellulose as functional filler for polyvinyl acetate emulsion adhesives has been explained.

Renewable sources: applications in personal care formulations.

A global tendency for products considered environmentally sustainable, and ecologically obtained led the industry related to personal care formulations to fund the research and the development of personal care/cosmetics containing ingredients from natural resources. Furthermore, consumers are aware of environmental and sustainability issueans, thus not harming the environment represents a key consideration when developing a new cosmetic ingredient. In this study we review some examples of active ingredients or raw materials used in cosmetics/personal care/biomedical products that are coming from either through biotechnological systems, or as byproducts of several industries. A skin formulation containing biosynthetic actives, prepared by us and the study regarding its dermocosmetic properties are also described. The need for the standardization processes, the safety assessment tools, the improvement of the exploitation methods of these renewable sources in order the production to be ecologically and economically better are also discussed.

The colloidal stabilization of young red wine by Acacia senegal gum: The involvement of the protein backbone from the protein-rich arabinogalactan-proteins

The arabinogalactan-proteins (AGPs) from Acacia senegal gum are used as protective colloid in young red wines to prevent the precipitation of the coloring matter. Usually, Acacia senegal gum is chosen based on its efficiency to stabilize iron hexacyanoferrate salts in hydro-alcoholic solution. In this study, the protective activity of Acacia senegal gum and its macromolecular fractions (HIC–F1, HIC–F2 and HIC–F3), separated according to their hydrophobicity, towards the precipitation of iron hexacyanoferrate salts and polyphenols in hydro-alcoholic solutions are reported. AGPs prevent the colloidal instability of both iron hexacyanoferrate salts and polyphenols in “model” hydro-alcoholic solutions and young red wine with a good correlation between results obtained on both systems. This result strengthens the use of iron hexacyanoferrate salts (hydro-alcoholic – mineral test) for the evaluation of the protective activity of A. senegal gum in young red wine. The precipitation of iron hexacyanoferrate salts is avoided by the electrostatic binding of Ca2+, the driver of the instability, with the negatively charged carried by amino-acids from the protein backbone or both by amino acids and uronic acid monosaccharides localized close to the protein backbone of AGPs. The protective activity closely depends on the protein content of AGPs in both iron hexacyanoferrate salts and polyphenols hydro-alcoholic solutions: the more they are rich in proteins, the more their colloidal stabilizing efficiency is (HIC–F3>HIC–F2>HIC–F1). The differences observed in the protective activity between AGPs from the three HIC fractions are relied not only to their protein content but also to their related rate of glycosylation that modulates the protein accessibility to its environment, then their physicochemical properties as their hydrophobic behavior.

The THERAPEUTIC IMPORTANCE OF GUMS IN FOLK MEDICINE FROM EASTERN GHATS, ANDHRA PRADESH

Objective: The objective of the present study is to collect ethnobotanical information of gums of medicinal plants from Eastern Ghats of Andhra Pradesh.
 Methods: Intensive ethnobotanical field trips were conducted in the forests of Eastern Ghats to collect firsthand information on therapeutic importance of gums used in folk medicine.
 Results: The present report deals with the therapeutic importance of gums in folk medicine used by local tribes inhabiting in and around the forests of Eastern Ghats of Andhra Pradesh. The results of the present study revealed that 21 crude drugs belong to 19 genera and 14 families of higher plants. The critical review of literature on crude drugs with reference to that of Eastern Ghats revealed that 13 crude drugs are hitherto not known to the science. 24 herbal formulations are commonly prepared by the local people to cure 14 human ailments. Out of 21 crude drugs reported in the present study, 10 crude drugs have pharmaceutical importance, namely drug delivery agents (Acacia), disintegrate in tablets (Sterculia), thickeners in oral liquids (Acacia and Mangifera), dilutents, binders, gelling agents in gels (Butea, Neem, and Moringa), and protective colloids in suspensions (Anogeissus) and bases in suppository.
 Conclusion: Natural gums of plant origin have multifarious pharmaceutical applications. In view of the potential crude drugs with promising therapeutic properties used by the tribal people, there is a need to take up the phytochemical and pharmacological investigations.

Effect of different ions present in fresh water on performance of polyvinylamine based ASA emulsion

Alkenyl succinic anhydride (ASA) is an alkaline sizing chemical used during papermaking. ASA emulsified in conventionally used cationic starch (CS) solution, has low shelf life i.e. 20–25 minutes and forms stickies/deposits as a result of hydrolyzed ASA on paper machine wire. Anionic polyvinylamine (APVAm) dilution in de-ionized water as a substitute to CS for ASA emulsification is a protective colloid, which seems to provide a protective shield to the ASA molecules, thereby reducing hydrolysis. In that case, the ASA emulsion was found to be stable up to four hours. In our knowledge no reliable studies have been done on study of different ions present in fresh water used for the preparation of APVAm stabilized ASA emulsion for commercial utilization. The present communication relates to the study on effect of different ions viz. Ca2+, Mg2+, Cl−, SO42− & HCO3− present in fresh water on the performance of ASA emulsion prepared by using APVAm as protective colloid. The permissible limit of each ion was measured. It was observed that the concentration of calcium ions was higher than the maximum permissible limit which may be responsible for the poor emululsification of ASA. The concentrations of Mg2+ ions and other counter ions were less than that of the maximum allowable limit. It was also observed that chloride ions adversely affected while bicarbonate ions assisted the ASA emulsification.

Halloysite modified by melamine cyanurate and its compositions based on PA6

The results of the investigation on the synthesis and applications of halogen-free hybrid flame retardants (HFR) are presented. HFR were obtained by in situ modification of halloysite (HNT) with melamine cyanurate (MC). The reactions were conducted with and without the presence of poly(vinyl alcohol) (PVA) as a protective colloid. The modification of HNT was confirmed by using infrared spectroscopy (IR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) and transmission electron microscopy (TEM) analyses. The thermal properties of flame retardants were investigated as well. The obtained HFR were introduced into polyamide 6 (PA6). The relationship between a type of HFR and its effectiveness in reducing the flammability as well as in improvement of mechanical properties of polymer composites was investigated. It was found, that depending on the type of applied HFR, the value of the oxygen index (OI) of the obtained composites was within 29–34.5 %. In turn, the use of PVA in the synthesis of HFR increased the flexibility of the compositions containing this type of HFR.

The use of phytotherapy in the treatment of small kidney stones

The properties of the drug Nokamen in the treatment of kidney stones up to 1 cm are studied. Lycokinetic, bactericidal, anti-inflammatory properties of the drug are shown. The lack of litolytic properties in the drug Nokamen may be due to the fact that its application does not take into account factors such as the composition of stone, pH of urine, the properties of protective colloids, preservation of obstruction of the urinary tract, etc. The impact of Nokamen on the content of uric acid, calcium in blood and urine can help prevent the formation of stones.

Grafting in polymeric dispersions stabilized with Alkali-Soluble Resins: Towards the production of leaching-free waterborne coatings

Alkali-soluble resins (ASRs) are a type of polymeric surfactants that can beneficially improve the properties of waterborne dispersed polymers, thus attracting great attention from the industrial point of view. When used as protective colloids in emulsion polymerization systems, grafting reactions between the surfactants molecules and the particles may occur. These grafting reactions can prevent the release to the environment of the surfactant when the dispersion is employed in formulations for coating. Two different mechanisms lie behind grafting reactions, i.e. hydrogen abstraction by reactive radicals from acrylic moieties, followed by propagation of the newly-formed active center, and the incorporation through polymerizable double bonds present on the backbone of the ASR. In this work, quantification of grafting using three different model ASRs revealed appreciable amounts of linking in different experimental conditions. Moreover, the discrimination of the two different contributions to grafting indicated that incorporation of reactive double bonds is the predominant pathway leading to extended linking. These findings may help the design of the new generation of leaching-free waterborne coatings with reduced environmental impact.

Unique alkyl ketene dimer Pickering‐based dispersions: Preparation and application to paper sizing

ABSTRACTHerein, particle‐stabilized alkyl ketene dimer (AKD) dispersions were prepared using dodecyl trimethyl ammonium chloride (DTAC)‐modified laponite as the stabilizer, and sodium alginate (SA) as the protective colloid. The modification of laponite particles with DTAC, which was characterized by transmission electron microscopy, infrared spectroscopy, and X‐ray diffraction technique, moderately decreases the negative zeta potential and causes the dehydration of laponite particles. Consequently, the modification of laponite promotes the absorption of laponite particles on AKD droplets/spherical particle surfaces, leading to formation of AKD dispersions with reduced particle size and enhanced uniformity when DTAC‐to‐laponite mass ratio is <1%. Meanwhile, SA significantly increases the stability of the AKD dispersions and provides stable AKD dispersions with smaller particles when SA‐to‐AKD mass ratio is <0.08%. By means of confocal laser scanning microscopy, scanning electron microscope imaging and energy dispersive spectroscopy (EDS)/EDS mapping, the function of DTAC‐modified laponite particles in stabilization of AKD dispersions was found to include both formation of a particle barrier around AKD particles and an increase in the moving resistance of AKD particles by laponite particles with SA. AKD dispersions at a DTAC‐to‐laponite mass ratio 1.0% and SA‐to‐AKD mass ratio 0.054% provide the smallest droplet size and best sizing performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45730.