Gardner Impact Testing of Plastic

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ASTM D5420 – 16 Test for Impact Resistance of Flat, Rigid Plastic Specimen by Means of a Striker Impacted by a Falling Weight (Gardner Impact)

ASTM D4226 Test for Impact Resistance of Rigid Poly(Vinyl Chloride) (PVC) Building Products

Evaluate the impact strength or toughness of a plastic material. Evaluate the effect of factors on plastic impact properties.

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Description

ASTM D5420 – 16 Standard Test Method for Impact Resistance of Flat, Rigid Plastic Specimen by Means of a Striker Impacted by a Falling Weight (Gardner Impact)

Plastics are viscoelastic and it is possible that they are sensitive to changes in velocity of weights falling on their surfaces.

This test method covers the determination of the relative ranking of materials according to the energy required to crack or break flat, rigid plastic specimens under various specified conditions of impact of a striker impacted by a falling weight.

Specimen size
Ideally, 30 samples are tested.  The optimal size is a 100mm (4″) disk or plaque.

Data Provided
Mean Failure Height in cm (inches)
Mean Failure Energy in kg-cm (in-lb)

Significance and Use

5.1 Plastics are viscoelastic and it is possible that they are sensitive to changes in velocity of weights falling on their surfaces. However, the velocity of a free-falling object is a function of the square root of the drop height. A change of a factor of two in the drop height will cause a change of only 1.4 in velocity. Hagan, et al (2) found that the mean-failure energy of sheeting was constant at drop heights between 0.30 and 1.4 m. Different materials respond differently to changes in the velocity of impact.

5.3 The test conditions of Geometry GB are equivalent to the geometry used for the Gardner Variable Height Impact Test (3).

5.4 The test conditions of Geometry GC cause a punch-shear type of failure because the support-plate hole is close to the diameter of the striker.

5.5 The test conditions of Geometry GD are the same as those in Test Method D3763.

5.6 The test conditions of Geometry GE are the same as those in Test Method D4226, impactor head configuration H.25.

5.7 Because of the nature of impact testing, the selection of a test method and striker must be somewhat arbitrary. Consider the end use environment and requirements when choosing from the available striker geometries. The selection of any one of the striker geometries is permitted.

Scope

This test method covers the determination of the relative ranking of materials according to the energy required to crack or break flat, rigid plastic specimens under various specified conditions of impact of a striker impacted by a falling weight.

Referenced Documents

ASTM Standards

  • D618 Practice for Conditioning Plastics for Testing
  • D883 Terminology Relating to Plastics
  • D1600 Terminology for Abbreviated Terms Relating to Plastics
  • D2794 Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact)
  • D3763 Test Method for High Speed Puncture Properties of Plastics Using Load and Displacement Sensors
  • D4066 Classification System for Nylon Injection and Extrusion Materials (PA)
  • D4226 Test Methods for Impact Resistance of Rigid Poly(Vinyl Chloride) (PVC) Building Products
  • D5628 Test Method for Impact Resistance of Flat, Rigid Plastic Specimens by Means of a Falling Dart (Tup or Falling Mass)
  • D5947 Test Methods for Physical Dimensions of Solid Plastics Specimens
  • E171 Practice for Conditioning and Testing Flexible Barrier Packaging
  • E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

ICS Number Code 83.140.10 (Films and sheets)

UNSPSC Code 13100000 (Rubber and elastomers)

DOI: 10.1520/D5420-16

Citation

http://www.astm.org/cgi-bin/resolver.cgi?D5420-16

ASTM D5420-16, Standard Test Method for Impact Resistance of Flat, Rigid Plastic Specimen by Means of a Striker Impacted by a Falling Weight (Gardner Impact), ASTM International, West Conshohocken, PA, 2016, www.astm.org