Water retention test method of hydroxypropylmethylcellulose

Shandong chuangyao Biotechnology Co., Ltd. has been engaged in the production and operation of hydroxypropylmethylcellulose for many years, and has its own patent research in the mortar field. Hydroxypropyl methylcellulose is the most commonly used additive in powder building materials such as dry powder mortar, putty powder and ceramic tile glue. Hydroxypropyl methylcellulose plays an important role in dry powder mortar. After the hydroxypropyl methylcellulose in mortar and putty is dissolved in water, the effective and uniform distribution of cementitious materials in the system is guaranteed due to the surface activity, while hydroxypropyl methylcellulose As a kind of protective colloid, element "covers" solid particles and forms a lubricating film on its outer surface, which makes the mortar system more stable and improves the fluidity of mortar in the mixing process and the smoothness of construction.

Shandong chuangyao Biotechnology Co., Ltd., a manufacturer of hydroxypropyl methylcellulose, analyzes that the water in the mortar is not easy to lose due to the molecular structure characteristics of hydroxypropyl methylcellulose solution, which is gradually released in a long period of time, giving the mortar good water retention and workability. Water retention of HPMC is the most important and basic index. Water retention refers to the amount of water retained by the newly mixed mortar after capillary action on the absorbent substrate. Shandong chuangyao Biotechnology Co., Ltd. analyzes the test method of water retention rate of HPMC according to the specific situation of customers, hoping to help users!

One filter method

Filter paper method is to evaluate the water retention of HPMC by the water absorption of filter paper. It is composed of a certain height of metal ring test mold, filter paper and glass supporting plate. Under the test mold are six layers of filter paper, the first layer is fast filter paper, and the other five layers are slow filter paper. First weigh the pallet and 5 layers of slow filtering filter paper with a precision balance. After mixing, pour the mortar into the test mold and scrape it flat. After 15min, weigh the pallet and 5 layers of slow filtering filter paper. Calculate according to the following formula:

M=（m1-m2）/S

M --- water loss, g / mm2

M1 --- weight of tray + 5 layers of slow filtering paper; G

M2 --- weight of 15 min back tray + 5 layers of slow filtering paper; G

S --- area of test mold mm2

It can also directly observe the water absorption degree of filter paper. The lower the water absorption of filter paper, the better the water retention. This test method is easy to operate, and general enterprises can meet the test conditions.

Two vacuumizing method

Water content in slurry after suction filtration

Water content in slurry before suction filtration

During the test, fill the mortar mixed with water into the Buchner funnel, place it on the suction filter bottle, start the vacuum pump, and filter it for 20min under the negative pressure of (400 ± 5) mm Hg. Then, according to the water quantity in the slurry before and after suction filtration, calculate the water retention rate as follows.

Water retention rate (%) = (water content in slurry after suction filtration / content in slurry before suction filtration) × 100

The method of vacuum pumping is more accurate and less error, but it needs special equipment and large investment.

(III) test method for surface drying time:

This method can refer to gb1728 method for determination of drying time of paint film and putty film. The mixed mortar can be scraped and coated on the asbestos cement board with a thickness of 3mm.

Method 1. Cotton ball method

A degreasing cotton ball shall be lightly prevented on the mortar surface, and the distance between the nozzle and the cotton ball shall be 10-15cm at regular intervals, and the cotton ball shall be blown gently along the horizontal direction. If it can be blown away and there is no cotton wire flowing on the mortar surface, the surface shall be considered dry. The longer the time interval, the better the water retention.

Method 2. Finger touch

Lightly touch the mortar surface with clean fingers every certain time. If you feel some sticky, but there is no mortar on the fingers, the surface can be considered dry. The longer the time interval, the better the water retention.

Shandong chuangyao Biotechnology Co., Ltd. summarized the above methods, filter paper method and finger touch method are more commonly used and simple. Through the above methods, users can preliminarily evaluate the water retention of HPMC with different viscosity. For more information about HPMC products, please pay attention to HPMC manufacturer Shandong chuangyao Biotechnology Co., Ltd.