Atch 1b. SOW Appendix C.pdf

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Pummel adhesion test

Significance

Pummel adhesion is a measure of the bond strength between the interlayer and the glass. The laminate bond strength must be controlled to avoid potential problems of delamination at low adhesion and impact failures at high adhesion.

Safety Required

• Face shield or goggles

• Heavy cotton or leather gloves

• Hearing protection

• Particle/dust mask

• Lab coat or apron

Equipment and materials needed

• Freezer or cold air cabinet set at –18°C (0°F)

• Pummel box—a hard metal flat surface, preferably at a

45° angle to allow the pulverized glass to slide away from the sample.

• 0.45 kg (16-oz) ball-peen hammer

• Cardboard squares

• Pummel adhesion standards

Procedure

1. Laminate samples should be prepared or cut to size according to normal procedures.

2. Place laminates in a –18°C (0°F) freezer and allow sufficient time for them to reach temperature equilibrium. Depending on the type of freezer cabinet and space between the laminates for air circulation, this typically takes between

1 and 6 hours.

3. After the samples have been conditioned, quickly remove one sample with a gloved hand and close the door to the cabinet. Using the ball-peen hammer, start pummeling within seconds of removal from the freezer to obtain accurate results. The sample is held at about a 5° angle to the plane of the pummel plate so that only the edge of the unbroken glass contacts the plate.

4. The laminate is then struck progressively in about 12-mm

(0.5-in.) increments along the bottom 18 mm (0.75 in.) of the laminate. When the bottom edge has been completely pulverized, the next 18 mm (0.75 in.) is pulverized in the same manner (see Figure 1). This is repeated until at least

7–10 cm (3–4 in.) of the laminate has been pummeled. Turn the laminate over and pummel the opposite side to ensure all smooth glass is pulverized.

5. The pummeled sample can then be brushed against the striking plate to remove excess chips and dust before being placed on a black background.

6. The pummeled laminates are allowed to come to room temperature, and the condensed moisture is allowed to evaporate before they are rated. Assuring no condensation is present is important for accurate rating.

7. Pick up the pummeled laminate and remove any loose glass dust by lightly brushing it or tapping it against the edge of a basket. Place the laminate on a piece of cardboard slightly larger than the laminate itself.

Figure 3. Pummeling

5° a ng le h am m er

Sequence of hammer blows

1 2 3 4 5 6 7

½-in.

steel plate

Etc.

8. Carefully, compare the sample to the pummel adhesion standards to find the standard that the sample most closely matches. Tilt the laminate and the standard together to see the reflection of the plastic, not the glass. Repeat this comparison with other standards until a good match is found. If the match is deemed to be between two standards, it is given a half rating (e.g., if it is between 6 and 7, it is rated as 6.5).

9. Turn the laminate over and repeat rating the other side in the same manner. Record the rating of each side. For example, 6/7 where 6 = the inner pane and 7 = the outer pane.

10. Recommended range depends on the interlayer product and intended use. For Saflex Clear, Acoustic and Solar, interlayer pummel adhesion between 4–7 is typical for laminated safety glass. For Saflex Structural and Storm, pummels tend to be higher. However, for glass > 4 mm, pummel is not the appropriate test method. Consult your

Eastman interlayers representative for specific ranges recommended for various applications.

Reporting

1. Report each individual rating inner/outer.

2. Average each side of similar material. All inner = avg.

All outer = avg.

3. Average all ratings to give overall pummel rating of similar material.

4. Report range of pummel of similar material.

Precision

Pummel ratings are not continuous variables and, technically, normal distribution statistics do not apply. Nevertheless, using these statistics indicates the standard deviation of a single rating to be about 0.5 for a mean value in the 4–8 adhesion range. A single rating is defined as the observed adhesion level at one of the PVB-glass interfaces in a laminate.

(Note that if a pummel laminate has been rated on both sides, then two observations have been made.)

Laminate moisture content by spectrophotometer

Significance

The moisture content of the interlayer influences critical laminate performance attributes such as adhesion and impact strength and must be carefully controlled to avoid significant deviations.

Safety

Normal precautions for handling cut samples of laminated glass

Equipment and materials needed

• Spectrophotometer capable of scanning between

1600 nm and 2000 nm

• Saflex interlayer moisture standards with appropriate glass configuration