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test methods

Test methods

Plastic Additives


To evaluate the performance of our polymer additives and to enable the development of new additives we have several tests methods available in our lab. 


The test methods are either dedicated to measure and evaluate the bulk or surface properties of compounds or to analyze the quality of pigment dispersions in polymers.

For the preparation of masterbatches & compounds we run a three roll mill as well as two double screw extruders. For the preparation of different test plates (e.g. plain, grained) or melt flow spirals we make use of a moulding machine. 

Besides our analytical department we operate a state of the art Plastics Technology Center.

test scratch and mar resistance

We have all standard methods for the evaluation of scratch and mar resistance in house available.
For grained surfaces such as pp/talc in automotive applications we use the Erichson equipment that generates a pattern of crossed lines on test plate. Thereby, the scratching force as well as the diameter of the scratching head can be adjsuted. The difference in color before and after the scratching is measured (D L) and taken as indicator for the scratch resistance. Secondly, we use the five finger scratcher to evaluate the scratch resistance of grained surfaces. It is a fast method to evaluate the scratch resistance at different forces in one single test.

For plain or glossy surfaces made from PMMA, PC/ABS or PA we use in addition to the above described methods the crockmaster which is suitable to measure the mar resistance. For the test a defined textile material is moved several times on the surface and the decrease of gloss is measured. Materials which are evaluated by the crock master method are typically used for the production of flat tv frames or other housing applications in the electronic industry. Damages of these surfaces can occur mainly if the materials are cleaned and therefore the crockmaster is the appropriate test method.

 
Crockmaster

The crockmaster was developed to determine the colour fastness to wet and dry rubbing of textiles. Nowadays it is also well accepted in the plastic industry to evaluate the scratch and abrasion resistance of plastic surfaces.

On a round shaped cylinder with a diameter of 16 mm, a crocking cloth is fixed. This cylinder with a loading weight of 6 N, will apply a defined number of strokes on the surface of the specimen. The number of strokes can vary dependent on the plastic article which has to be evaluated. In general 10, 50, 100, 500, 1000 and / or 2000 strokes are usual.

This method comply with EN ISO X12, AATCC 8 and M&S C8 and can be is applied to soft and hard material.

 
Meltflow

According to ASTM D-1238 

The calculation of Melt Flow Index (MFI) is a variation of the capillary viscometer method with a standard diameter and length of capillary. 

The heating procedure is well defined and determined by the polymer under investigation. After equilibration for a specified time the polymer is forced by a piston of a specified weight through the capillary.

The MFI is obtained by cutting off lengths of extrudate which are forced out of the orifice in a standard time period.The MFI is measured in grams per 10 minutes at a defined temperature.

 
Impact test

The impact test is a measure of stress in form of a stroke by a pendulum applied to a standardized test specimen. 

Two different methods are known. According to Izod impact strength a defined stroke is applied by a pendulum which leads to breakage of the test piece.

From the height of the pendulum´s swing the forced needed to lead to breakage can be calculated.

Flexural impact test according to Charpy is applied to test specimen with high deformability which hardly would break by Izod.

A notched panel is stressed by a force applied from the top. The force counteracted by the panel is measured.

 
Tensile strength

The tensile strength (E-modulus, [N/mm²]) is defined as the maximum stress that a material can withstand before failure in tension. Unless indicated otherwise, values were determined by an extension test.

 
hardness test

The hardness testing of plastics measures the resistance of the plastic toward indentation. 

It provide an empirical hardness value that doesn't correlate to other properties or fundamental characteristics. During the hardness test (e.g. shore hardness) a standardized body penetration is applied with a standardized force to the surface of the test specimen. The penetration depth is measured.

 
Pressure filter test

The pressure index (PI) is a measure of the fineness of dispersion of pigments in a masterbatch 

  • It is carried out in a single screw extruder

  • 400 mesh screen pack

  • Temperature of 200 °C

  • Masterbatch is let down to 10 % pigment concentration in HDPE resin

  • Period of 60 minutes

The pressure rise across the screen pack is measured. 

PI is expressed as bar x cm2 x g-1 (Pressure rise per unit area of screen pack per gram of pigment).  

Low pressure index values (PI) stand for high dispersion quality. They are a measure of processing properties of color masterbatches especially on polypropylene fiber spinning.

Pressure filter test can be evaluated after test method DIN EN 13900-5.

 
Speck evaluation

Pigment agglomerates result in many disadvantages. They affect printability and sealability as well as optical appearance through speck formation. Speck free processing plays a crucial role in coloring of films and thin walled injection molded parts.  

Masterbatch is diluted to 1 % pigment content 

Plates (150 µ) and films (50 µ) are injected or blow molded 

Speck evaluation by confocal laser scanning microscope

Samples evaluation by confocal laser scanning microscopy in a fluorescent mode. Pigment particles (30% Pigment Red 57:1 - MB) are visible as bright spots in front of the darker polymer matrix. Even 10% less additive mean better dispersion with TEGOMER® P 121.

 
test color masterbatches

To determine the color strength,

  • Pigment concentration of the masterbatch is reduced to 0.2 % by diluting it in HDPE

  • It is carried out with 10 parts of titanium dioxide at 1 part of pigment in the formulation

  • The blend is compounded with minimum shear on a two-roll mill or using a single screw extruder

  • Color strength is measured at plates of 2 mm thickness

  • For color measurements Datacolor or Macbeth spectrophotometer is used.

    Injection Molded Plates for Color Strength Determination