Thickener Type Research Articles

Grease-lubricated tribological contacts – Influence of graphite, graphene oxide and reduced graphene oxide as lubricating additives in lithium complex (LiX)- and polypropylene (PP)-thickened greases

Two types of thickener systems, lithium complex (LiX) and polypropylene (PP), were chosen to evaluate graphite, graphene oxide (GO) and reduced graphene oxide (rGO) as grease additives at a concentration of 0.1 wt%. To enhance the additive dispersibility, a mixture of polyalphaolefin oil (PAO) and oil soluble synthetic polyalkylene glycol (OSP-68) was used as base oil. The greases were evaluated in i) silver-coated copper contacts simulating high-load electrical contact applications subjected to fretting and ii) a steel/steel 4-ball wear test equipment. The additives showed no positive effect on friction and wear, neither in fretting nor in 4-ball tests. However, there is a statistically significant difference in wear scar diameter on the 4-ball steel contacts between the two thickener types, LiX and PP. Thus, the PP-grease lubricated steel contacts showed more wear and more tribofilms of iron oxide and grease constituents, indicating more metal-to-metal contact. Hence, the thickener type has a larger impact on the lubricating performance of the grease than do the graphite, GO and rGO additions. The results demonstrate that the addition of graphene-based materials to improve greases is not straightforward. Rather, the grease/graphene-based additive system is complex and many parameters influence the friction and wear results. Hence, more work is needed to obtain a better understanding and possibly better lubricating effects from the graphene-based additives.

Investigation of Tribological Behavior of Lubricating Greases Composed of Different Bio-Based Polymer Thickeners

One commonly used lubricant in rolling bearings is grease, which consists of base oil, thickener and small amounts of additives. Commercial greases are mostly produced from petrochemical base oil and thickener. Recently, the development of base oils from renewable resources have been significantly focused on in the lubricant industry. However, to produce an entirely bio-based grease, the thickener must also be produced from renewable materials. Therefore, this work presents the design and evaluation of three different bio-based polymer thickener systems. Tribological tests are performed to characterize lubrication properties of developed bio-based greases. The effect of thickener type on film thickness and friction behavior of the produced bio-based greases is evaluated on a ball-on-disc tribometer. Moreover, the results are compared to a commercial petrochemical grease chosen as benchmark.

Influence of temperature on wear performance of greases in rolling bearings

Purpose Rolling bearing operation under mixed and boundary lubrication conditions may lead to heavy adhesive or abrasive wear, which may lead to wear-induced rolling bearing failure. The purpose of this paper is to investigate the wear protection capabilities of different grease compositions at varying temperatures. It is considered that the temperature influences the lubrication conditions, the behaviour of grease components, namely, bleed oil and thickener, as well as the tribofilm formation due to tribo-chemical interactions between additives and surfaces. Design/methodology/approach In this study, four different greases were produced on the basis of a mineral base oil by varying the thickener and the addition of ZDDP. Various grease-lubricated rolling bearing experiments were conducted in a wide temperature range from 0°C to 120°C. Subsequently, the wear pattern, tribofilm formation and grease structures were analysed. Thereby, the influence of the different grease thickeners and the performance of ZDDP as a common antiwear and extreme pressure additive was evaluated. Findings The results show a strong temperature-dependency and allow a classification of temperature ranges concerning wear protection. At low temperatures, all greases provide a very good wear protection without the evidence of additive-based tribofilm formation. In the experiments at elevated temperatures, ZDDP tribofilms were formed. The formation depends on the thickener type: in comparison to lithium thickener, polyurea thickener favours more protective tribofilms at the same temperature. The experimental results show that medium temperatures in the range of 40°C–60°C are critical concerning wear due to the insufficient tribolayer formation and limited load carrying capacity of the grease. Originality/value Temperature is a key operating parameter for grease lubrication in roller bearings. The experimental work enables consideration of different impact pathways of temperature by combining roller bearing tests and microanalysis.

Malignant peritoneal mesothelioma: correlation between CT imaging features and histologic subtypes

To identify correlation between CT imaging features and histologic subtypes of Malignant Peritoneal Mesothelioma (MPM). This was a retrospective single-center study of 51 consecutive patients with the diagnosis of Malignant Peritoneal Mesothelioma (MPM). The tumors were classified into pure epithelioid type and those with sarcomatoid component (pure sarcomatoid and biphasic type). Imaging features of these subtypes were compared for extent and type of peritoneal thickening, omental thickening, abdominal visceral infiltration, abdominal wall infiltration, and loco-regional and distant metastases. Fisher's Exact test was used to correlate the association of imaging features with histology types followed by multivariate analysis using logistic regression test. 32 males and 19 females with a median age of 63years (range 35-86years) were included in the study. 41/51 (80%) were epithelioid histology type and 10/51 (20%) had sarcomatoid component (3 pure sarcomatoid type, 7 biphasic type). Abdominal visceral infiltration was seen more commonly in cases of MPM with sarcomatoid component (p = 0.001). Sarcomatoid type also had a frequent association with metastases (p = 0.001) and discrete masses (p = 0.01). Epithelioid type was commonly associated with ascites (p = 0.04). On multivariate analysis, most significant correlation was identified between the sarcomatoid type and imaging features of metastases (p = 0.001) and visceral infiltration (p = 0.019). Sarcomatoid type of MPM showed significant correlation with more aggressive imaging features of metastases and visceral infiltration as compared to epithelioid type.

Advancements in Thickening Agents Used in Textile Printing

A thickening agent that is particularly suitable for printing pastes is, water-insoluble, water-swellable, or water-swollen polymer made by reverse phase polymerization of a blend of water-soluble. Where there are three basic types of thickeners: a) polysaccharide thickener, b) synthetic thickener, c) emulsion thickener, all of them can be used as a thickening agent alone or a mixture of them. Synthetic products, in particular, have come under severe criticism for their high environmental pollution at the manufacturing stages and applications. However, auxiliaries derived from natural resources, especially from plants are considered to be biodegradable, non-toxic as well as non-allergenic than their synthetic counterparts. The main goal of this review is to give an overview of academic study in the field of thickening agents based on thickener and the potential application in textile printing.

How Accurate Are the Consistency Labels Used in Hong Kong? An Objective Study of the Consistency of Thickened Liquids Using International Dysphagia Diet Standardisation Initiative and Consistometric Measurements

Objectives: The present study objectively examined the consistency (thickness) of labels that are used in Hong Kong for the population with dysphagia using an International Dysphagia Diet Standardisation Initiative (IDDSI) flow test and Bostwick consistometric measurements. Methods: Liquids were prepared by thickening water to achieve 4 consistency labels (slightly thick, mildly thick, medium thick, and extra thick) according to manufacturer’s instructions, employing 2 types of thickening products that are used in Hong Kong, i.e., starch based and gum based. For each consistency label prepared using each thickening product, the IDDSI flow test and consistometric measurements were obtained and compared. Results: The results showed that the actual thickness of liquids was highly dependent on the type of thickener (starch based vs. gum based) used. Thickened liquids prepared using the starch-based thickener were generally thinner than the actual value at a lower concentration. Conclusion: Though prepared strictly following the manufacturer’s instructions, the thickened liquids fail to faithfully correlate with the standardized norms established according to the IDDSI framework and the objective consistometric measurement using a Bostwick consistometer. Therefore, caution must be exercised when administering a thickened diet following the manufacturer’s instructions for patients with dysphagia.

Comparative anatomy of five species of Campyloneurum (Polypodiaceae) from South America

Anatomical characters of the sporophyte of five Campyloneurum species are presented: C. aglaolepis, C. angustifolium, C. angustipaletum, C. lorentzii, and C. tucumanense, to evaluate anatomical characters with a taxonomic value. Histological sections of the root, rhizome, and petiole were made in three sections (basal, middle, and distal) and lamina, using specimens of herbarium and material collected for this purpose. Observations were made with a light microscope and a scanning electron microscope. The anatomical characters, such as the type of helical thickening in parenchymal cells in outer cortex and the number of layers in the inner cortex of the root; diameter, presence of prurine, number of meristeles and sclereid nests in the rhizome; adaxial groove and the number of vascular bundles in the petiole; and mesophyll, stomata and hairs types in the lamina, shows a highly significant in taxonomic value for the separation between the five studied species. For the first time, hydathodes, nectaries, diacytic stomatal types and homogeneous mesophyll are described in Campyloneurum, and the anatomy of C. tucumanense is presented.

Thermal oxidation stability of lubricating greases

This review article deals with a particular property of lubricating greases – resistance to oxidation. This property, also referred to as oxidative or thermal oxidation stability, has a decisive influence on the quality and duration of lubricating greases service life in friction nodes, bearings and lubrication systems. Lubricating greases are colloidal systems in which the thickener creates an elastic three-dimensional network, maintaining the liquid phase. The structure of lubricating greases, division of greases into types, depending on the thickener used, is presented. The basic additives in lubricating greases are described, and the group of used antioxidant additives is discussed in detail. Under operating conditions, the grease is subject to factors that cause its destruction – shear stress, pressure, loads, changing operating conditions, especially temperature changes. The types of lubricating greases degradation are presented, as well as methods and techniques of aging processes evaluation. During operation, the grease fulfilling its basic functions in the lubrication system is primarily exposed to high temperatures. The predominant aging process which directly affects the service life of the grease is oxidation. The oxidation process is discussed, with the specification of its four stages: initiation, propagation, chain branching and termination. One of the methods of preventing the oxidation process is the selection of appropriate improvers. Thermal oxidation stability of greases can be modified by introducing appropriate antioxidants, the selection of which depends on the type of grease thickener and the operating temperature of the grease. The published literature review from over the last ten years shows how diverse are the ways of modifying thermal oxidation stability of greases and the methods of assessing this property.

Oral behavior of emulsified systems with different particle size and thickening agents under simulated conditions

Food behavior during oral processing plays an essential role in the perception of texture. It depends on different factors, including food structure and composition, as well as its behavior when interacting with saliva. This study aimed to investigate the effect of particle size and thickener type of emulsified systems on physical, rheological, tribological, and oral oily coating properties under oral conditions. Six matrices based on oil-in-water emulsions with different particle sizes (NE-nanoemulsion and CE-conventional emulsions) were prepared using a mixture of emulsifiers (10% w/w) and sunflower oil (10% w/w). Thickened agents were added to the matrices (NE and CE) at different concentrations (3–4.5% w/w of starch-ST or 0.4–0.8% w/w xanthan gum-XG) to obtain equi-viscous samples (NE-EV) with their CE-based counterpart. Results showed a decrease in apparent viscosity values under oral conditions (saliva and shearing at 10 s−1) during the shear time, but this behavior was more evident in starch-based matrices. The lubrication properties of the different matrices depended mainly on the thickener concentration since equi-viscous samples (NE-ST-EV and NE-XG-EV) showed higher coefficient of friction (CoF) values. Finally, oral oily coating was more related to the oil droplets size than to the type of thickener since all NE-based matrices showed a higher amount of coating retained compared to the CE-based ones. Therefore, NE-based matrices could be used as an alternative to increase mouthfeel sensations in food emulsions.

Assessment of tomato-based thick fluid diet for patients with dysphagia using a simple and cheap test.

Swallowing difficulty, also known as dysphagia, is a health condition that can be managed by different approaches, such as changing the viscosity of fluid foods with thickener agents. Tomato-based beverages such as "gazpacho" and "salmorejo" are common foods much appreciated by the populations that adopt a Mediterranean diet, mainly in Spain. These beverages usually present a low viscosity, challenging to include in diets for dysphagia patients. Thus, this work aimed at evaluating the flow properties of tomato-based beverages with or without the addition of thickener agents (based on maltodextrin or gum) using a simple and cheap method proposed by the International Dysphagia Diet Standardization Initiative (IDDSI) to verify the suitability of using those products in a diet of patients with dysphagia. The study also evaluated the differences in using BD-type syringes on the test. Results indicated that the type of thickener significantly (p< .05) affects the samples' flow properties, enhancing their rheological behavior. The type of syringe can also affect the results, as they present different Luer slip tips. The results revealed that tomato-based beverages may have their properties improved simply by using low amounts of thickener agents (1.2-3.0g 200 ml-1 ) and that the IDDSI test can be an alternative, cheap and straightforward method for evaluating these types of foods in hospital environments. Including tomato-based beverages in the diet of patients with dysphagia may present many benefits as these products have a rich nutritional composition (fiber) in addition to biocompounds such as lycopene and phenolic compounds.

Milk Flow Rates From Bottle Nipples: What We Know and Why It Matters

Feeding difficulties are common in infants hospitalized in the NICU and can be a challenge to manage. The purpose of this article is to explain how and why the flow rate from the bottle nipple affects physiologic stability in infants and to describe the current evidence available on the flow rates of nipples used in the hospital and after discharge. Study results have indicated that flow rate varies widely among different types of nipples. Within the same type of nipple, there can be significant variability in flow from one nipple to another. Other factors, such as type of infant formula and thickening, also affect flow. Altering the flow rate of the bottle nipple is a relatively simple intervention that may support safe oral feeding.

Influence of the Periapical Status of the Posterior Maxillary Teeth on the Width of the Schneiderian Membrane of the Maxillary Sinus Mucosa

Background: Various parameters are known to affect the amount and type of mucosal thickening. The aim of this retrospective study was to investigate these effects through a survey of cone-beam computed tomography (CBCT) images. CBCT scans of 150 patients, which included the area of the MS and maxillary teeth (canine, first premolar, second premolar, first molar, second molar, and third molar), were evaluated retrospectively for the presence of sinus mucosal thickening. The parameters evaluated as possible causes of mucosal thickening were age, sex, tooth type, proximity to the maxillary sinus, endodontic treatment, and periapical lesion. Descriptive statistics and multiple logistic regression were used to analyze the data. A total of 28% of the teeth presented with mucosal thickening, which was associated with periapical lesions in 57.1% of 77 cases. The size of the lesion was the only parameter that was found to be significantly connected to the presence of mucosal thickness. More than 50% of teeth with periapical lesions in the posterior maxilla exhibited mucosal thickening. Other parameters such as age, sex, and the position of the root tips in relation to the MS floor did not influence the probability of developing mucosal thickening.

Influence of thickening agents on rheological properties and sensory attributes of dysphagic diet.

Dysphagia is the difficulty during the progression of the bolus from the mouth to the stomach. Modifying the texture of the food is a fundamental factor for safe swallowing in patients with dysphagia since inadequate consistency can result in complications. To personalize and develop diets for dysphagia, understanding, and controlling the rheological and sensory properties of thickeners is useful. This review examines the different types of thickeners used to modify the texture of foods, as well as their influence on rheological properties and sensory attributes to efficiently manage the diet in dysphagia. The study discusses characteristics such as: hardness, viscosity, viscoelasticity, as well as sensory attributes related to rheology. The thickeners xanthan gum, methylcellulose, carboxymethylcellulose, guar gum, linseed, and chia, carboxymethylated curdlan, and konjac glucomannan were reviewed in this work. Sensory evaluations of different foods have already been carried out on some products such as: meats, carrots, soups, pates, and timbales with their modified textures. The sensory attributes measured among hydrocolloids are strongly correlated with rheological parameters. Dysphagic diets should have less hardness and adherence, but with adequate cohesiveness to facilitate chewing, swallowing to protect from aspiration and reduction of residues in the oropharynx. The use of a single type of thickener may not be ideal, their mixtures and synergistic effect can improve the viscous and elastic characteristics of foods, to obtain safe food to swallow and to improve the sensory interest of dysphagic patients. Personalized recommendations with follow-up on swallowing approaches, respecting patient's individuality, explaining thickening agents' differences would be pertinent.

Wpływ rodzaju bazy olejowej na właściwości reologiczne ekologicznych smarów plastycznych

The article presents the results of research on the influence the type of base oil in lubricating compositions has on the rheological parameters of selected lubricants. Vegetable, mineral, and synthetic dispersion phases were used to produce lubricating greases. The modified amorphous silica was used as the dispersed phase. However, as a modifying additive was used a substance containing the antioxidants, corrosion inhibitors, and EP/AW additives. The experiments on rheological properties were carried out using a Physica MCR 101 rotational rheometer (manufactured by Anton Paar), equipped with a diffusion air bearing and connected to a pneumatic supply – an oil-free Jun-Air compressor and air drying block. The device is equipped with a Peltier system for temperature control in the range of –20°C to 200°C and an external thermostatic VISCOTHERM V2 system, working in the temperature range of –20°C to 200°C. The rheometer control and measurement data analysis were performed using Rheoplus software. The tests were carried out using a cone-plate measuring system with a shear rate range of 0.01–100 s-1 at 20°C for lubricating compositions prepared on various oil bases. To evaluate the value of rheological parameters, the results of tests of the dependence between shear stress and shear rate (flow curves) were used. For the theoretical determined on the flow curves, the following rheological models were used: Bingham, Herschel–Bulkley, Casson, and Tscheuschner. The values of the shear stress (yield point) in depending on the type of dispersion phase has changed. This proves that the use of a base oil with the appropriate functional properties does not weaken, but reinforces the spatial structure of a lubricating grease. It has an important meaning when selecting construction parameters when designing a central lubrication system with grease made from a vegetable oil base (Abyssinian oil). The rheological properties of the lubricating grease are influenced by the type of base oil and thickener, any additives in the grease, the production technology of the grease, and the conditions in which it is used. The tests revealed an important influence of the base oil on the rheological parameters that describe the behaviour of lubricating compositions subjected to stresses and strains in a lubricating system.

Inkjet printing of silk: factors influencing ink penetration and ink spreading

PurposePretreatment of fabric with a number of chemicals and auxiliaries is a prerequisite for inkjet printing. Owing to the rapidly increasing use of inkjet printing for textile fabrics, the study of the effects of process variables on various characteristics of the resulting print has drawn considerable interest recently. The purpose of this paper is to study the effects of different variables associated with the inkjet printing process on the quality of the resulting print. Specifically, the effects of chemicals and auxiliaries used in the pretreatment of the fabric prior to printing and factors such as steaming time were studies.Design/methodology/approachIn the present study, which forms a part of a larger study by the authors, the influence of the nature of thickener, the amounts of thickener, urea and alkali, pH of the pretreatment liquor and the duration of steaming on ink penetration into the printed fabrics and the ink spreading across the fabrics was studied. The nature of ink penetration and ink spreading are known to have pronounced effects on the quality and, in turn, the overall appearance of the resulting print. A set of experiments based on a blocked 25–1 fractional factorial design with four centre points were conducted to evaluate the role of the aforementioned five variables. Ink penetration was quantified on the basis of the principles of Kebulka-Munk theory while ink spreading was analysed by image analysis.FindingsDetailed statistical analyses of the experimental data obtained show that different thickeners perform differently and can have a marked influence on ink penetration and ink spreading. In the case of polyacrylic acid-based thickener, changing the levels of the factors has a marked effect on ink penetration and in-turn on ink spreading. In the case of polyacrylamide (PAM)-based thickener, on the other hand, the effect of changing the levels of various factors on the ink penetration and ink spreading is considerably less pronounced. In addition, PAM treated samples exhibited better performance in terms of ink penetration and spreading.Originality/valueThis study provides useful information for textile printers and highlights the importance of selecting the right type of thickener to make the printing process and the quality of the resulting print more predictable and controllable.

Acceptance of different types of thickeners, with and without flavoring, in hospitalized patients with dysphagia - A pilot study.

Introduction: the goal of this work was to evaluate the acceptance of various types of thickeners, specifically modified starch thickener and gum thickener, both with and without flavoring. Patients and methods: a randomized sample of 40 hospitalized patients with oropharyngeal dysphagia was recruited. The taste, smell, and appearance of each type of thickener were evaluated, as well as the volume of liquid ingested by the patients taking each type of thickener (modified starch thickener vs. gum thickener, both with and without flavoring). Results: the overall acceptance of gum thickener was significantly higher than that of modified starch thickener (7.45 (1.57) vs. 5.10 (2.43), respectively; p = 0.001). When a food flavor was added to the thickened water, the overall rating of the product was higher than when no flavor was added (7.70 (1.53) vs. 4.85 (2.16); p < 0.001). The difference between the daily volume of water consumed by the patients who received gum thickeners (928.33 (331.27) mL) and those who received starch thickeners (670.00 (288.35) mL) was statistically significant (p = 0.012). Patient consumption was also higher when flavoring was added as compared to when it was not (943.33 (302.45) mL) vs. (655.00 (304.60) mL; p = 0.005). Conclusion: the acceptances of the thickener and of water intake by patients with dysphagia were both significantly higher when using gum thickeners compared to starch thickeners, and when adding flavoring.

Berry fillers based on local plant raw materials

When developing a diet for citizens with diseases of the gastrointestinal tract or obesity, it is necessary to adhere to a therapeutic diet in which bakery products and dairy products with berry fillers can be wholesome ingredients. In order to increase the range of berry fillers based on local plant raw materials, the physicochemical quality indicators were studied and the organoleptic evaluation of fillers with various types of thickeners was given.

Automated batch settling column with vibrated rods and evaluation protocol for living waters mud thickening

Gravity solid-liquid phase separation is applied in minerals industries, waste water treatment, filtration, sewage, drinking water, ocean (water) engineering, dredging, environment and biotechnology. The healthy nation of freshwaters like Lake Balaton and River Bodrog can be maintained by regular mud dredging. The on-water pure mechanical mud thickening would be a really beneficial technology. A new automated batch settling column with vibrated rods had been developed and fundamental tests had been carried out with model materials (glass sand) and muds (Siofok, Tihany, Tokaj). A numerical evaluation protocol with spline interpolation and derivation had been developed by with simple key parameters were determined. Results can be used for the design of a new type of thickener called the rod-lamella thickener.

Acceptance of different types of thickeners, with and without flavouring, in hospitalized patients with dysphagia. A pilot study.

Rationale: Dysphagia may affect both nutritional and hydration status, as well as the prognosis of patients. Thickeners have been developed to adapt the viscosity of liquids, allowing safe and effective swallowing, reducing the risk of aspiration, and ensuring a [GM1] proper state of hydration. The objective of this work was to evaluate the acceptance of different types of thickeners, with and without flavouring.

A mixed EHL model of grease lubrication considering surface roughness and the study of friction behavior

Grease lubrication is widely used in rolling element bearing because of its special rheological characteristics. Available studies are mainly based on experiments, while the relevant numerical studies of grease are quite limited. The purpose of this article is to establish a mixed elastohydrodynamic lubrication (EHL) model in point contact based on the rheological model of grease, which can calculate film thickness distribution applied to smooth and roughness surface. The obtained result is compared with that of it operated only in base oil. Besides, the impacts of load, surface roughness and rheological parameters on the grease film thickness have been investigated. In addition, the Stribeck curves of four greases covering different base oil viscosity and thickener types were measured on a ball-on-disc device, which can ensure that the contact area was in full film lubrication. From the study, it is concluded that the obtained grease friction behavior agrees well with the variation of grease film thickness calculated by the present mixed EHL model.