CENTRAL PHILIPPINE UNIVERSITY COLLEGE OF ENGINEERING Jaro, Iloilo City, Philippines
Group No. 1
Name: Carla Joy Ember C. Berezo
ChE 4203 Chemical Engineering Laboratory 1
Experiment. No. 7
Water Absorptiveness Test
I. Objectives: To determine the quantity of water absorbed b y corrugated fiberboard in a specified time under standardized conditions. II. Theory: Hygroscopy is the phenomenon of attracting and holding water holding water molecules molecules from the surrounding environment, surrounding environment, which is usually at normal or room temperature. This is achieved through either absorption absorption or adsorption adsorption with the absorbing or adsorbing substance becoming physically changed somewhat. Water absorbency is a measure of the amount of water absorbed by the wetted surface of paper and board materials. There are a number of different methods available namely namel y Cobb Test, Klemm Method and Cage Method. Klemm Method is used for unsized papers such as blotting papers and other papers having relatively high water absorbency the Klemm method for determining water absorbency is used. Test pieces are immersed to a set depth in water and the height of the water rise is measure after a set time. Cage Method is used to determine the water absorbency time and water absorbance capacity of tissue paper and tissue products in accordance with DD ENV 12625-8. The Cobb test determines the amount of water absorbed into the surface by a sized (non bibulous) paper, paperboard, and corrugated fibreboard paper or paperboard sample in a set period of time, usually 60 or 180 seconds (Cobb60 or Cobb180). Cobb18 0). Water absorbency is quoted in g/m2. The water absorbency of a material can have strong influence on printability and the setting rate of water based adhesives.
Date Performed: 01/07/17
Submitted to: ENGR. SHARON ROSE DUMAM-AG
Page 2 of 6
Water absorbency rate determines the liquid sorption rate of bibulous paper, paperboard, and paper products using gravimetric principles. A set volume of water is dropped onto the paper surface and the time for the drop to be absorbed is measured. The water absorbency rate is used as a measure of the acceptability of tissue, towelling and blotter papers in sorptive tasks. Other test liquids such as ink, oil and milk are used to assess the comparative performance of papers for specific applications.
Fig. 1 Set – up of the Cobb Test III. Materials and Apparatuses:
Corrugated Fiber Board Cobb Tester Mettler Lab Balance Stopwatch Water Cutter Paper Ruler
Date Performed: 01/07/17
Submitted to: ENGR. SHARON ROSE DUMAM-AG
Page 2 of 6
IV. Procedures: To start the experiment, we cut 4 pieces of 12.5 x 12.5 cm square corrugated fiberboard material. Two samples were tested for their outer side and the other two for their inner side. We weighed each sample using a Mettler lab balance and recorded the readings. After weighing the samples, we prepared the set-up of the Cobb test. We wiped the metal plate and metal ring until they were completely dry. We laid the sample on the metal plate and placed the metal ring upon it. We fastened it with a crossbar to prevent any leakage between the ring and the sample. We poured 100 mL of water into the ring as rapidly as possible and started the stopwatch. The test ran for 2 minutes. At around 10 seconds before the time stopped, we poured the water quickly from the ring while carefully ensuring that no water was dropped on the dry side of the sample. After 2 minutes, we carefully removed the sample from the ring. We immediately reweighed the sample and recorded the readings. We did the same test for all the samples and on each side. V. Diagram: See attached page at the back VI. Data and Results Final Weight (g)
1 2 3
Initial Weight (g) 7.91 7.92 8.06
%Absorption
17.34 14.42 9.95
Weight of Water (g/m2) 943 650 189
4
7.81
9.69
188
24.07
119.22 82.07 23.45
VII. Computations Weight of water = (Final weight – Initial weight) x 100 %Absorption Date Performed: 01/07/17
Initial Weight−Final Weight =
Initial Weight
100
Submitted to: ENGR. SHARON ROSE DUMAM-AG
Page 2 of 6
Corrugated Board 1: Weight of water = (17.34 – 7.91) x 100 = 943 g/m2 %Absorption
7.9−7.34 =
7.9
100
=
119.22%
Corrugated Board 2: Weight of water = (14.42 – 7.92) x 100 = 650 g/m2 %Absorption
7.92−4.42 =
7.92
100
=
82.07%
Corrugated Board 3: Weight of water = (9.95-8.06) x 100 = 189 g/ m2 %Absorption
8.6−9.95 =
8.6
100
=
23.45%
Corrugated Board 4: Weight of water = (9.69-7.81) x 100 = 188 g/ m2 %Absorption
7.8−9.69 =
7.8
100
=
24.07%
VIII. Observations and Discussion of Results: In this experiment, we have observed that water absorptiveness test specifically the Cobb test was really important. It had a vital role in measuring the water absorbency of corrugated board which was usually used as a packaging material for different products. In this experiment, we have observed that when we poured the water on the sample, the two samples that were tested for the inner side of the corrugated board was the ones who absorbed the water faster compared to the two samples that were tested for the outer side. Based on our computed results, the one with the higher absorbency rates were the two corrugated boards tested for the inner side which were 119.22% and 82.07%, respectively. Also, corrugated boards tested for the inner side had a higher value for the weight of the water which were = 943 g/m2 and 650 g/m2. Date Performed: 01/07/17
Submitted to: ENGR. SHARON ROSE DUMAM-AG
Page 2 of 6
We compared the results obtained from the two inner sides tested with the other two outer sides which had a great difference. The discrepancies that may have occurred during the experiment was that we nay have not tightened the clamping force in the set-up that caused the leakage of water in just a short span of time. IX. Conclusion and Recommendations Therefore, Cobb test was an efficient method in determining the water absorbency of corrugated fiberboard. From the results obtained in the experiment, we could say that the inner side of the corrugated fiberboard was the one who absorbed more water. The outer side of the corrugated board absorbed only minimal water co mpared to its inner side. In this experiment, changing the time to 60 seconds would be more appropriate since the type of corrugated fiberboard used absorbed water faster than other type of corrugated board to test. After using the specified condition, it may be compared to the ones obtained in this experiment. Also, to avoid errors during the experiment, make sure that the clamping force was tightened to avoid sudden leakage. X. References:
http://www.tappi.org/content/tag/sarg/t441.pdf http://www.smitherspira.com/services/materials-testing/paper-other-properties/waterabsorbency http://olympic-construction.co.uk/salt-dampness/
Date Performed: 01/07/17
Submitted to: ENGR. SHARON ROSE DUMAM-AG
Page 2 of 6
X. Documentations:
Date Performed: 01/07/17
Submitted to: ENGR. SHARON ROSE DUMAM-AG
Page 2 of 6
