Determination of dart drop impact resistance for HDPE and LLDPE film grades SL -M 513 Presenter by: Asaf Orujov

İNTRODUCTİON The dart drop Impact is a measure of the resistance to impact loading of on blown film of 15 μm ± 2 μm thickness for High Density Polyethylene (HDPE) or 38 ± 2 μm thickness for Linear Low Density Polyethylene (LLDPE) film at 23°C±1°C.

SUMMARY A standard adjustable weight dart with a hemispherical phenolic head of 38±1 mm diameter is dropped from a specified height on to a vacuum clamped film. The impact strength of the film is defined as the mass in grams of the dart which would be expected to break the specimen tested

SAFETY Safety glasses and goggles are the minimum personal protection needed when performing the test. Risk of cuts must be taken into account when using blades in order to prepare the film specimen. Be careful when the blown film extruder line is operated. During operation the film will get hot enough. Do not touch any hot parts or components without wearing heat-resistant gloves. The analyst must comply with the electrical safety regulations. Pay attention to the usual safety requirements for the connection of electric appliances.

APPARATUS Falling Dart Impact Tester Model FDA/230 (Fig. 10.1). Laboratory Blown Film Extruder Line type Collin BL 180/800 (Fig. 10.2). Micrometer (accuracy of mm).

Instrument setting  Dart of 70 g with a hemispherical head of 38 ± 0.1 mm of diameter  Dart head material: hard material like Phenolic  Different weights to be able to load the dart till 2000 g  Distance between the dart and the film: 660 mm

Calibration  Check the drop-height at regular periods of time  Check the vacuum pressure at regular periods of time  Check the weight of the dart and loading weights at regular intervals

Sample preparation The film specimens must be larger than the sample support of 127 mm of diameter and without imperfection. A dedicated room at 23°C ± 1°C and 50 % relative humidity or any equivalent oven able to maintain these conditions. The film must be conditioned minimum 40 hours at 23°C ± 1°C. Product Reference LLDPE - C 4 and C 6 Blown HDPE Blown Extrusion Line Name Die mm Die gap mm Screw diameter mm Screw length L/D Extrusion Conditions Temperature profile °C Output kg/h Bur Air temperature °C Frostline mm Neckeight mm Film Properties Thickness μm CMG to : KIEFEL to :

Scheme for typical blown film extruder line

Procedure  Take a 2 meters length conditioned flat film surface and separate it carefully without creasing the film. Measure the film thickness and record it.  Place the first area to be tested over the face of the holder with the inside film surface uppermost, ensuring that the entire test area is free from wrinkles and that there are no pinholes, folds or die lines.  Attach a dart, loaded to the expected film Impact Strength to the release mechanism.  Apply the clamping ring. The vacuum increases and the dart releases when the pressure equivalent to 22 inches of mercury obtained. Catch the dart when it is impacted once on the film.

CALCULATION DDI (Dart Drop Impact) is calculated with the following equation: Where,

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