1. Raw material of cellulose ether
Cellulose ether for construction is a non-ionic water-soluble polymer whose source is:
Cellulose (wood pulp or cotton linter), halogenated hydrocarbons (methane chloride, ethyl chloride or other long-chain halides), epoxy compounds (ethylene oxide, propylene oxide, etc.)
HPMC-Hydroxypropyl Methyl Cellulose Ether
HEC-Hydroxyethyl Cellulose Ether
HEMC-Hydroxyethyl Methyl Cellulose Ether
EHEC-Ethyl Hydroxyethyl Cellulose Ether
MC-methyl cellulose ether
2. Properties of cellulose ether
The properties of cellulose ethers depend on:
Polymerization degree DP The number of glucose units—viscosity
Substituents and their degree of substitution, degree of uniformity of substitution —- determine the application field
Particle Size—-Solubility
Surface treatment (i.e. delayed dissolution)—-viscosity time is related to the pH value of the system
Modification degree—-Improve the sag resistance and workability of cellulose ether.
3. The role of cellulose ether – water retention
Cellulose ether is a polymer chain compound composed of β-D-glucose units. The hydroxyl group in the molecule and the oxygen atom on the ether bond form a hydrogen bond with the water molecule, which adsorbs the water molecule on the surface of the polymer chain and entangles the molecules. In the chain, it delays the evaporation of water and is absorbed by the base layer.
Benefits provided by the water retention properties of cellulose ethers:
No need to wet the base layer, saving process
good construction
sufficient strength
4. The role of cellulose ether – thickening effect
Cellulose ether can increase the cohesion between the components of gypsum-based mortar, which is reflected in the increase of the consistency of the mortar.
The main benefits provided by the thickening of cellulose ethers are:
Reduce ground ash
Increase adhesion to base
Reduce the sagging of mortar
keep the mortar even
5. The role of cellulose ether – surface activity
Cellulose ether contains hydrophilic groups (hydroxyl groups, ether bonds) and hydrophobic groups (methyl groups, ethyl groups, glucose rings) and is a surfactant.
(The surface tension of water is 72mN/m, surfactant is 30mN/m, and cellulose ether is HPC 42, HPMC 50, MC 56, HEC 69, CMC 71mN/m)
The main benefits provided by the surface activity of cellulose ethers are:
Air-entraining effect (smooth scraping, low wet density, low elastic modulus, freeze-thaw resistance)
Wetting (increases adhesion to substrate)
6. Requirements of light plastering gypsum for cellulose ether
(1). Good water retention
(2). Good workability, no caking
(3). Batch scraping smooth
(4). Strong anti-sagging
(5). The gel temperature is higher than 75°C
(6). Fast dissolution rate
(7). It is best to have the ability to entrain air and stabilize the air bubbles in the mortar
11. How to determine the dosage of cellulose ether
For plastering plasters, it is necessary to retain sufficient water in the mortar over a long period of time in order to have good workability and to avoid surface cracks. At the same time, cellulose ether retains an appropriate amount of water for a long time to make the mortar have a stable coagulation process.
The amount of cellulose ether depends on:
Viscosity of cellulose ether
The production process of cellulose ether
Substituent Content and Distribution of Cellulose Ether
Particle Size Distribution of Cellulose Ether
Types and composition of gypsum-based mortar
The water absorption capacity of the base layer
Water Consumption for Standard Diffusion of Gypsum-Based Mortar
Setting time of gypsum-based mortar
Construction thickness and construction performance
Construction conditions (such as temperature, wind speed, etc.)
Construction method (manual scraping, mechanical spraying)
Post time: Jan-18-2023