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Atom ash, also known as putty, is a raw material used for filling and repairing holes in many construction projects such as home decoration and automotive work. However, what effect does hydroxypropyl methylcellulose (HPMC) have in atom ash? In simple terms, it has three main functions: thickening, water retention, and aiding in construction. The specific explanations are as follows:

  1. Thickening: Cellulose can thicken the mixture, suspending particles and ensuring uniformity, preventing sagging.

  2. Water retention: It slows down the drying of atom ash, assisting lime in reacting with water.

  3. Construction: Cellulose acts as a lubricant, improving the workability of atom ash.

HPMC does not undergo any chemical reactions; it only plays a supportive role. When water is added to atom ash and applied to the wall, a chemical reaction occurs. If the atom ash is removed from the wall, ground into powder, and reused, it is not suitable because a new substance (calcium carbonate) has formed. HPMC, on the other hand, only retains water and assists lime in reacting more effectively, without undergoing any chemical reactions itself.

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The difference between hydroxypropyl methyl cellulose and hydroxyethyl cellulose:

  1. Characteristics:

    • Hydroxypropyl methyl cellulose: White or white fiber-like powder or granules, belonging to various non-ionic types in cellulose mixtures. It is a semi-synthetic product, classified as a non-reactive viscoelastic polymer.
    • Hydroxyethyl cellulose: A white or yellow, odorless, non-toxic fiber or solid powder, primarily derived from alkaline cellulose and epichlorohydrin etherification. It is a non-ionic soluble cellulose ether.

  2. Uses:

    • In the coating industry, hydroxypropyl methyl cellulose has good solubility as a thickener, dispersant, and stabilizer in water or organic solvents. Polyvinyl chloride, used as a paint remover for suspension polymerization of polyvinyl chloride, is widely applied in industries such as leather, paper, fruit and vegetable preservation, textiles, etc.
    • Hydroxyethyl cellulose: It is almost insoluble in anhydrous ethanol, ether, and acetone; it dissolves in cold water to form a transparent or slightly turbid colloidal solution. It finds extensive applications in industries such as coatings, inks, fibers, dyeing, papermaking, cosmetics, pesticides, mineral processing, petroleum recovery, and pharmaceuticals.

  3. Solubility:

    • Hydroxypropyl methyl cellulose: Almost insoluble in anhydrous ethanol, ether, and acetone; soluble in cold water to form a transparent or slightly turbid colloidal solution.