Application of the hottest glass atmospheric dryer

2022-08-23
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Application skills of glass atmospheric dryer in the testing of polymer cement waterproof coating

application skills of glass atmospheric dryer in the testing of polymer cement waterproof coating

November 30, 2018

there is a lot of discussion on the standard GB 23445-2009 polymer cement waterproof coating. This paper mainly discusses the application of glass atmospheric dryer in the performance testing of polymer cement waterproof coating (hereinafter referred to as JS coating). GB 23445-2009 standard stipulates the use of the dryer as follows: after the sample is formed, it is allowed to stand for 96 hours under standard conditions, and then the film is removed. The reverse side of the sample after film removal is upward and treated in a (40 ± 2) ℃ drying oven for 48 hours. After taking out, the sample is placed in the dryer and cooled to room temperature. There are many kinds of dryers. The most common glass dryers in the laboratory are atmospheric dryers and vacuum dryers, two kinds of Chinese coatings. In the GB 23445-2009 standard, it is not required to use a vacuum dryer to cool the sample after the completion of the activity, so the atmospheric dryer is generally used in the test. Its specification is expressed in the diameter of the upper mouth of the seat body, and the common specification is Φ 100 ~ 400 mm. The comprehensive practicability is CPU damage and price. Generally, most laboratories choose specifications of Φ 240 mm and Φ 300 mm colorless transparent glass dryer

gb 23445-2009 standard stipulates that the molding size of the sample is 320mm × 350 mm. According to this size, the diameter of the upper opening of the dryer should be greater than 475mm to ensure the smooth placement of the sample. However, there is no glass dryer of this specification at present. The condition of the whole piece of the sample after being put into the dryer is shown in Figure 1. It will be difficult to restore the flatness of the sample after drying, and will affect the accuracy of the test. If the front faces of the samples are stacked together after being divided in advance (Fig. 2), the bending amplitude of the samples below will be large, and it will be difficult to flatten after being taken out, and the samples are easy to stick together, and it will be difficult to separate completely after cooling to room temperature, which will also affect the accuracy of the test. In order to ensure the accuracy of the test, it is necessary to discuss the use skills of the dryer

1 experimental part

1.1 preparation of instruments, equipment and samples

multifunctional stepless speed regulating agitator: d-8401 type, Tianjin Huaxing scientific instrument factory, paddle mixing rod; Constant temperature and humidity incubator: hws-250, Shanghai senxin Experimental Instrument Co., Ltd; Layered frame: self made. JS coating products from 10 different domestic manufacturers were used in the test, which were prepared according to the ratio of powder and liquid required by each manufacturer (Table 1). On the basis of GB 23445-2009 standard, add the following conditions []: the sample preparation is coated twice, with an interval of 24 hours, at the same time, the same coating size, mixing container, mixing speed, mixing time, the same molding process, the total mass of lotion powder added each time is the same, the same person applies it, and the same scraper is used

1.2 application of layered segmentation method

1.2.1 layered placement of JS coating sample in glass dryer

take JS coating sample in specification as Φ Take the placement in a 240 mm glass dryer as an example. In a dryer with a diameter of 240 mm, the maximum area is a square with a diagonal diameter, and its side length is about 170mm. See Figure 3, so the size of the sample placed cannot exceed 170 mm × 170 mm。 JS coating sample to be formed (320 mm × 350mm) cut into 8 pieces as shown by the dotted line in Figure 4 to obtain 4 145 mm × 160mm and 4 30mm × The 160 mm sample is put into the (40 ± 2) ℃ drying oven for 48 hours according to the requirements of GB 23445-2009 standard, and then the sample is dried and cooled to room temperature in a glass dryer by using a layered frame (Fig. 5 and Fig. 6). The dimension of the layered frame is subject to the dryer: the specification is Φ In the 240 mm glass dryer, the size of the layering frame is selected Φ 220mm is enough. Figure 5 shows four 145 mm shelves in four layers × 160 mm specimen, another 4 pieces of 30 mm × A 160 mm specimen can be placed on the support with an additional layer. Considering the height of the dryer and the permeability between layers, it is recommended that the layered frame should not exceed 6 layers at most

1.2.2 segmentation of JS coating samples

JS coating samples dried and cooled to room temperature are divided according to the solid line in Figure 4, and 32 test pieces can be obtained, which can meet the requirements of tensile properties and low temperature flexibility test pieces in GB 23445-2009 standard

1.3 mechanical property test

refer to GB 23445-2009 standard to determine the tensile strength and fracture elongation of JS coating samples

2 results and discussion

js coating products from 10 manufacturers were exposed and cooled at room temperature and placed in a dryer with the "segmentation and layering method" respectively, and their tensile strength and fracture elongation without treatment for 2 and 5 hours were tested. The test results are shown in Figure 7-8

it can be seen from Figure 7 and figure 8 that when other conditions are consistent, JS coating samples are cooled by dryer for 2 hours and 5 hours, and their tensile strength and fracture elongation change little. Among them, the change rate of tensile strength of 50% of the samples is less than 3.0%, and the change rate of sample 1 is the smallest, only 1.44%; The change rate of tensile strength of 30% samples is between 3% and 5%; The change rate of No. 9 sample with the largest change rate of tensile strength is only 9.94%. The largest change rate of fracture elongation is sample 8, reaching 9.77%; The smallest change rate of fracture elongation is sample 9, only 3.08%; The change rate of fracture elongation of 50% of the samples is between 5% and 7%

this shows that the cooling time of JS coating sample in the dryer has little effect on the performance test results, and the test data obtained by this method is stable. JS coating samples exposed and cooled at room temperature. 2. The tensile strength and fracture elongation change greatly when the indenter or anvil is replaced. The change rate of tensile strength of only one sample is less than 20%, which is 14.66%. The change rate of tensile strength of the other nine samples is more than 20%, of which the change rate of tensile strength of three samples is more than 40%, and the change rate of tensile strength of sample 9 is 45.71%. The change rate of fracture elongation of 80% samples is between 26% and 30%, and that of 40% samples is between 30% and 40%; No. 10 sample with the smallest change in fracture elongation has a change rate of 26.32%; The largest change in fracture elongation is also sample 9, with a change rate of 49.0%

the test results change greatly when exposed and cooled because the tested 10 JS coatings produced before the selection fixture are all made of acrylic lotion. The acrylic lotion is a thermoplastic polymer. Different temperature and humidity will change the intermolecular force. When the room temperature is exposed and cooled, the temperature and humidity change greatly, resulting in unstable test results. Due to the different varieties of acrylic lotion used by different manufacturers, its sensitivity to temperature and humidity is also different, resulting in different product test results

3 conclusion

cooling JS coating samples with a dryer can well maintain the stability of JS coating product performance test results. The "layered segmentation method" can make full use of the glass atmospheric dryer in the performance test of JS coating, which is of great significance to maintain the flatness of the sample and ensure the accuracy of the test results

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