How To Measure Mv

Transcription

1 MVR as a Function of emperature and Relative Humidity Goal: o characterize the MVR properties of laminates under different conditions of temperature and relative humidity. est Procedure: he Water Intake test is a simple but yet very effective test method. First of all, small panels (~15cm x 12cmX5mm, Fiberglass and desiccant) were prepared, and held in a humidity oven at 4 C and 9%. he panels were weighed once a week along the test duration of 1-2 months. Mass gained during this period referred to water permeation only; theoretically, water permeation through metallized laminates is greater than gas permeation by factor of around 1. At the end of the test, the WVR of the panel (which depends on the envelope film only) was calculated by dividing the mass gain by test duration and the surface area of the envelope. (a) Small panel (~15cmx12cmX5mm) with glass fiber and desiccant (b) Panel weighed by accurate analytic balance Small ~15cm x 12cm VIP panels were prepared with different envelopes for MVR measurement by the Water Intake method, using the following laminates: i. V8621B - 3 metallized PE films with LDPE sealing layer. ii. V metallized PE films with LDPE sealing layer. iii. V metallized PE film with LDPE sealing layer. iv. V metallized (improved metallization) PE films with HDPE sealing layer. MVR as a Function of emperature and Relative Humidity Ed A, July 215

2 hree panels of each type of laminate were stored at different conditions: (a) 4 C/5, (b) 4 C/9, (c) 5 C/7 and (d) 7 C/8. he main advantage of the Water Intake test is the fact that the test is made at an application level. Moreover, the detection level of the test is about.2 gr /m 2 day, which is by factor of 5 lower than the detection level of the Mocon laboratory equipment available for testing. est results for standard Hanita 3 ply laminate V8621B at 4 C/9 are presented in Figure 1 below: S1 S2 S3 y = 7.187E-4x E+1 R 2 = 9.945E-1 Mass of panel [gr] y = 7.17E-4x E+1 R 2 = 9.945E-1 y = 6.228E-4x E+1 R 2 = 9.927E duration [days] Sample A [m 2 ] m [gr/day] MVR [gr/m 2 day] S S S Average.1733 Figure 1: Water Intake test for Hanita 3 ply laminate, 4 C/9 S1, S2 and S3 are different samples made from the same laminate, the results indicate that this is an accurate and repeatable test to determine MVR properties of laminate under given conditions (temperature and relative humidity). MVR as a Function of emperature and Relative Humidity Ed A, July 215

3 Results: he calculated MVR of each laminate under different condition is summarized in able 1 below: MVR [gr/m 2 day] Laminate 4 C/5 4 C/9 5 C/7 7 C/8 V8621B V Adhesive failure V V able 1: MVR measured under varying conditions for different laminates Saturation Pressure ( P ) of Water Vapor as a function of temperature is described by following equation, Eq 1: S 17.5 (1) PS ( ) = 6.11, PS [ mbar] and [ C] he general function that describes MVR as a function of temperature and relative humidity is shown below in Eq 2: Where: MVR, MVR - is the known MVR at a specific condition, = MVR f (2) ( ) and - is the reference relative humidity and the reference temperature at which the MVR value is known, - is the ratio between saturated water vapor pressure at the temperature under consideration and the saturated water vapor pressure at. f - is the temperature factor affecting the permeation rate. MVR as a Function of emperature and Relative Humidity Ed A, July 215

4 Most of the measurements were made at 4 C/9, so the MVR values at these conditions will be defined as MVR, so the general equation (2) can be rewritten as : (3) MVR(, ) = MVR4 C / 9 f = MVR4 C / f able 2 below presents the measured MVR and calculated MVR values without temperature factor (f =1), meaning that the general equation can be reduced to (4) MVR4 C / Measurement Condition V8621B Measured MVR [gr/m2 day] Calculated MVR [gr/m2 day] Ratio between measured and calculated 4 C/ C/ C/ C/ V C/ C/ C/ C/8 V6221 No data 4 C/ C/ C/ C/ V C/ C/ C/ C/ able 2: Measured MVR and calculated MVR without the effect of the temperature factor (f =1) % of difference ( / Measured ) MVR as a Function of emperature and Relative Humidity Ed A, July 215

5 Determination of f : able 3 below presents a summary of the "difference factor" between measured and calculated MVR: Difference Factor ( [ C] V8621B V7421 V6221 V8627 Average able 3: Difference factor between measured and calculated MVR f ) he following graph in Fig 2 below show the value of f as a function of temperature Average f y = -5E-5x x R 2 = Figure 2: f as a function of temperature o C [ C] Using the polynomial fit above, the general behavior of MVR is 9 4 C / (5) MVR(, ) = MVR 2.49 ( ), MVR as a Function of emperature and Relative Humidity Ed A, July 215

6 Conclusion: Based on the above work and formula (5), we can effectively predict the MVR level of PEME laminates at any given temperature and relative humidity. Eddie Shufer Materials Science and Engineering, MSc R&D Ultra High Barrier Laminates Hanita Coatings RCA Ltd MVR as a Function of emperature and Relative Humidity Ed A, July 215