Application and Properties of Hydroxypropylmethylcellulose HMPC

Plaster is a substrate treatment for the inside of walls, render refers ro the substrate for the outside of walls, it is sometimes also referred to as putty, though in British English putty also refers to a linseed paste that is used in the installation of traditional wooden windows. Plaster or Render is often applied in a maleable putty like format, which helps to achieve to a sealed and smooth finish, prior to final coating. The main function is to fill in defects in the base wall and to microfine the base surface.

edit]<p class=""mw-headline"" id=""What_is_Hydroxypropyl_Methylcellulose_.28HPMC.29.3F""> What is Hydroxypropyl Methylcellulose (HPMC)?

Hydroxypropyl methylcellulose (HPMC) is a non-ionic cellulose ether. It is an odourless and tasteless white powder. It is produced from purified cotton or wood pulp by a series of etherification reactions.

edit]Properties of HPMC

Hydroxypropylmethylcellulose (HPMC) has thermal gelation properties, as its aqueous solution precipitates and gels, and dissolves when cooled. The gelation temperature varies depending on the specification, and its solubility varies with viscosity, the lower the viscosity, the higher the solubility. HPMC is essentially methane-epoxide-modified methyl cellulose and therefore has similar properties to methyl cellulose, being readily soluble in cold water and insoluble in hot water. The solution does not contain an ionic charge and therefore will not react with metal salts or ionic compounds.

HPMC has good dispersability, emulsification, thickening, adhesion, water retention, and glue retention properties and is therefore widely used in pharmaceuticals, petrochemicals, construction, ceramics, textiles, food, daily chemicals, synthetic resins, coatings and other fields, as well as electronic products.

edit]

Application of HPMC in putty powder

Depending on the application, hydroxypropyl methyl cellulose (HPMC) can be classified as construction grade, food grade and medical grade. In construction, HPMC is mainly used in laster (also called putty powder), with varying percentages used in the gypsum mix.

HPMC powder is mainly used as a thickener, water retention agent and lubricant.

• Thickeners: HPMC is added to putty powder to thicken it, enhance its suspension, resist sagging and keep it in a homogeneous solution.

• Water Retainer: HPMC is added to putty powder to keep it moist and to allow the auxiliary grey calcium to act as an underwater agent.

• Lubricant: Hydroxypropyl methylcellulose has a lubricating effect. The use of HPMC in putty powder gives the putty powder a good compatibility, keeps it flat during construction and saves labour.

Hydroxypropylmethylcellulose (HPMC) does not chemically react, except as an auxiliary molecule. Though adding water to the powder causes a chemical reaction, during which a new substance (calcium carbonate) is formed. Because of the formation of this new substance (calcium carbonate) it can't be reused in the same way twice.The main components of grey calcium powder are:Ca(OH)2, CaO and a small amount of CaCO3 mixture.CaO+H2O=Ca(OH)2 - Ca(OH)2+CO2=CaCO3↓+H2O gray calcium in water and air under the action of CO2, the formation of calcium carbonate, and HPMC only water, auxiliary gray calcium better reaction, its own did not participate in any reaction.

The formulation of the putty can vary from one size to another. As a result, the viscosity and dosage of hydroxypropyl methylcellulose (HPMC) vary. In practice, it is recommended to use a lower viscosity HPMC product in winter, which is more conducive to construction. Otherwise, when the temperature is low, the viscosity will increase and this may cause problems for further applications.

--Yichenghpmc

edit]Buildings

Related articles on Designing

The antimicrobial efficacy test is used to assess the efficacy of preservation systems in the final product. The antimicrobial efficacy test was initially designed to assess the performance of antimicrobials added to inhibit the growth of microorganisms that may be introduced into the product during or after the manufacturing process [97]. Several tests have been recommended by different laboratories, but the challenge test (described next) remains the method adopted by the international regulations. These methods are described in the European, American, and Japanese pharmacopoeia, as well as other organizations, such as PCPC (Personal Care Products Council) (from CTFA-M1 to CTFA-M7), ASEAN (Association for Southeast Asian Nations), ASTM (American Society for Testing and Materials), and International Organization for Standardization (ISO 11930 standard), among others.

Challenge Test

The challenge test is used during product development to determine the efficacy and stability of the preservative system over time. The test involves inoculating a measured amount of product with known amounts of microorganisms (bacteria, yeasts, and molds) [98]. Whenever possible the original packaging is used for the test. The containers are protected from light and incubated at room temperature for 28 days. The mortality rate is measured over this period in relation to the acceptance criteria set out in the official regulations documents [97,99].

Challenge test assessment is related to the stability of a formulation during manufacture, storage, and its use by the consumer. It is recommended that all these aspects be duly taken into account when performing such tests by carrying out the following parameters: (1) validation of the preservation efficacy when freshly prepared in laboratorial conditions; (2) validation of the preservation efficacy after the end of storage in the container, to show possible interference with the packaging materials; and (3) validation of preservation efficacy in the first production batch, just prior to packaging, thus revealing all possible influences occurring throughout the manufacturing process [100]. To evaluate the microbiological quality of a product, results of the efficacy test of a cosmetic product preservatives are collected and a prognosis is achieved [99]. The recommendations of the challenge test are inspired by the European, American, and Japanese pharmacopoeia. A comparison between these three pharmacopoeias is summarized in  .

a. Test organisms

The specific strains recommended to be used in these tests can be obtained from official cell culture collections, such as the American Type Culture Collection (ATCC). The most common test strains are potentially pathogenic representatives of Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), molds (Aspergillus niger), and yeast (Candida albicans) [17].

Staphylococcus aureus represents Gram-positive cocci in many tests. It is a part of normal nasal and cutaneous microflora. Although rare, its presence in cosmetic products may be indicative of human contamination. Pseudomonas aeruginosa is a Gram-negative bacilli. It is a well-known and highly pathogenic ubiquitous bacteria. It also shows high resistance against many preservatives. Escherichia coli is a Gram-negative bacilli of the family Enterobacteriaceae. It is considered as an indicator of fecal contamination. Like most coliform bacteria, it can easily develop resistance to preservatives. Candida albicans is present in human mucous and ubiquitous in the environment. It is the representative of yeasts being an example of yeast resistance to presents to preserved systems. Aspergillus niger is a major cause of product decomposition and contamination by filamentous fungi [6,17,101].

The conservation of strains is an important factor. For example, most bacteria and the yeast Candida remain viable for one month under refrigerated conditions, while Pseudomonas aeruginosa cannot be useful after two weeks (depending on specific conditions). An effective way to keep mold spores is to store them at room temperature on slanted agar. Weekly or periodic transplanting may be done to ensure the viability of microorganisms, but this practice increases the risk of resistance loss. Alternatively, the cultures can also be frozen or lyophilized, in order to maintain the stability of the microorganism and avoid the need of frequent subcultures. The main advantage of these storage media is the prevention of genetic resistance factors loss [28,102].

b. Inoculum

Strain maintenance is an important component of any standard protocol, and involves standardization of strain storage, culture conditions (time and temperature), and selected nutrient medium [103]. The growth and preparation of a test organism determines its physiological state and have a direct influence on the results of the preservative efficacy analysis [104,105]. It is essential to maintain cultures of microorganisms that are transplanted on suitable supports, to ensure viability and resistance [103].

A medium such as tryptic soy agar (soybean-casein digest agar) supports vigorous growth and is recommended for the initial culture of the bacteria. Sabouraud dextrose agar is a non-selective medium used for the cultivation and conservation of pathogenic and non-pathogenic fungi [106].

Pharmacopoeia use saline solutions to wash test strains before inoculation instead of nutrient broth. The latter decreases the inactivation rate of the test organisms comparatively with the saline solution prepared for the strains grown on the agar [107].

According to all the three pharmacopoeia, the strains are cultured for the same period of time, ensuring that the cells are viable and growing in the log phase, thereby normalizing the response to antimicrobial agents [38,108,109].

c. Inoculation of samples

After adjusting the number of starting cells, the inoculum is then used to inoculate test samples. For some organizations (such as CTFA), samples of cosmetic products can be inoculated as bacterial or fungal “cocktails”. Nevertheless, the use of bacterial or fungal mixtures offers considerable savings in time and cost. However, the three pharmacopoeias recommend inoculation by a single strain separately. The volume of the inoculum should not exceed 1% of the product sample, in order to avoid the modification of its physical and chemical properties [38,108,109].

The inoculated test samples are incubated during 28 days, varying the conditions between room and high temperature, depending on the objective, since higher temperatures are used to simulate specific environmental conditions. Temperatures between 20–25 °C support the growth of microorganisms and their possible reaction with preservative active ingredients [98].

d. Assessment of the microbial level for cosmetic products

To estimate the level of microorganisms inoculated in a sample of a cosmetic product, it is required to select the appropriate conditions of each culture (culture medium, dilution, temperature and period of incubation). These conditions must provide an unlimited growth of microorganisms, resulting in the inactivation of the preservative system present in the sample [102].

The number of viable microorganisms’ existent in the inoculums suspension is determined by the plate count method, through which the initial concentration of CFU/mL in the test product is determined. The inoculated vessels are examined 7, 14, 21, and 28 days after inoculation and the number of microorganisms (CFU/mL) is determined at each time interval, being the percentage of microorganisms estimated relative to the initial concentration [28].

The preservative inactivation is considered successful when the number of the microorganisms inoculated at zero time deviates by no more than 1 log10 from the one theoretically predicted. The survival rate can be either qualitatively or quantitatively evaluated [110]. Several independent researchers have applied other microorganism counting methods in the efficacy test of preservatives, including impedance, direct epifluorescence (DEF), and ATP bioluminescence (ATP-B).

The impedance method is based on a calibration between CFU and the impedance detection time (DT) establishment. In this method, the electrochemical changes in a microbiological culture due to microorganisms’ metabolism is measured [111]. In a culture medium, the impedance variation occurs due to the chemical composition modification caused by the growth of microorganisms and metabolic activity. The density of the population of microorganisms is correlated with the DT of the impedance. The DT is referred to as the time required to produce a detectable acceleration in the impedance curve [112]. The results obtained indicated that this method is applicable to the entire range of test strains (bacterial and fungal), having a detection sensitivity equivalent colony counting method, representing a satisfactory alternative to this one [113,114]. In 2014, Ferreira et al. [115] used lyophilized inoculum of solid powders in order to enable the microorganisms’ homogenization in the sample. They also verified the applicability of the impedance method for these lyophilized inoculum.

The direct epifluorescence (DEF) method is based on the observation that viable microbial cells, which mainly contain RNA, are stained in red with orange acridine, while non-viable cells, which mainly contain DNA, are stained in green. The DEF, as a quick method, has two major advantages: first, it gives an immediate result (between 1 to 4 h); and second, it presents the potential for high detection sensitivity which is determined by the maximum sample volume that can be concentrated on the filter. However, in practice, there are problems associated with the interference of cellular debris with viable cells (red stain), as well as interference of dead clumped cells with microcolonies (green fluorescence). The clumping of bacterial cells by some preservatives (chlorhexidine) is another problem which overestimates the viability. Thus, this technique is not applicable to Aspergillus and it is not suitable for processing complex formulations that cause problems in filtration of samples [116].

In the ATP bioluminescence method (ATP-B), the bioluminescence mechanism involves the enzyme luciferase in the presence of luciferin, oxygen (O2), magnesium and ATP. This reaction leads to the emission of photons and the intensity of the light produced is directly proportional to the rate of ATP [117]. However, this method is not applicable to the genus Aspergillus, and to creams or suspensions, since these latest could interfere with the detection of light emission [116].

e. Interpretation of results

The acceptance criteria, in terms of the logarithmic reduction of the viable microorganism’s number relatively to the value obtained for the inoculums, vary for the different categories of preparations, according to the international organizations [118]. The criteria of the three pharmacopoeias for the evaluation of antimicrobial activity are given in  . The log reduction is calculated by the following equation: log reduction = log of initial CFU/mL-log of product challenge results CFU/mL [98].

What Is Hydroxyethyl Cellulose. Applications and Properties

Hydroxyethyl Cellulose

Hydroxyethyl Cellulose is a white, free-flowing granular powder, prepared from the alkali cellulose and ethylene oxide (or ethylene chlorohydrin) by etherification, and belongs to non-ionic soluble cellulose ethers, both soluble in hot and cold water. Owing to good thickening, suspending, dispersing, emulsifying, film-forming, water-protecting and providing protective colloid properties, Hydroxyethyl Cellulose has been widely used in oil exploitation, coating, building, medicine, food, textile, papermaking, polymerization and other fields.

In the daily chemical industry such as toothpaste, soap, lotion and cosmetics, and ointment, Hydroxyethyl Cellulose acts as a thickener, dispersing agent, binder and stabilizer to increase the density, lubrication, and mercerized appearance of products. SidleyCel™ Hydroxyethyl Cellulose products are applicable to personal care and cosmetics, with purity over 95%. The reliable quality and high stability have been recognized by customers.

Hydroxyethyl Cellulose has wide applications: In the paint industry, Hydroxyethyl Cellulose can provide the latex paint especially high PVA paints with excellent coating performance. When the paint is thick paste, no flocculation will occur. Hydroxyethyl Cellulose has higher thickening effects. It can reduce the dosage, improve the cost-effectiveness of formulation, and enhance the washing resistance of paints. Hydroxyethyl Cellulose is all treated by the delayed dissolution, and in the case of adding dry powder, can effectively prevent caking and make sure hydration starts after the adequate dispersion of Hydroxyethyl Cellulose powder.

Hydroxyethyl Cellulose of daily-chemical grade has good mildew-resistant performance, system thickening and rheology modifying functions, as well as good water retention and film formation, and gives the final product full visual effects and all necessary application performance. The surface-treated Hydroxyethyl Cellulose has cold water solubility, and dry powder can be used and directly added into water. Good dispersion of the product in water can avoid clumping of product, and the occurrence of uneven dissolution. The final aqueous solution is uniform, continuous and full.

Hydroxyethyl Cellulose can be used as a thickener and cementing agent of workover fluid for oil wells. It helps to provide with the clear solution with a low fixed content, thus greatly reducing the damage to the structure of oil wells.  The liquid with Hydroxyethyl Cellulose used for thickening gets easily decomposed by the acid, enzyme or oxidizing agent, and greatly enhances the ability of hydrocarbon recovery. In the oil well fluid, hydroxyethyl cellulose is used as the carrier of proppant. These fluids can be easily decomposed by the the processes described above.

Applications

Description/Benefits

Coating ,Painting  Industrial

Applications in Oil Well Cementing and Drilling

Application Guide for Daily Chemical Industry

Mix viscous HydroxyEthylCellulose solutions, using the NovAseptic HS mixer, at small & large scales

This mixing demonstration illustrates when pilot scale mixing evaluations are developed beforehand it simplifies larger scale mixing trials and improves the likelihood of an efficient mixing process. more

 Also learn more about Hydroxypropyl Methylcellulose