Gardner impact

Gardner impact, 243 Gas chromatography/mass spectrometry (GC/MS) analysis, 304 Gaymans, Reinoud J., 135 Gel coats, 30... 

B. Gardner Impact strength of Pseudo-IPNs with and without Opposite Charge Groups... 

Mechanical Properties of Cast Resins. The toughness of the cross-linked polymers was determined by the area under the stress-strain curve and by the energy required to fracture. The fracture or impact energy, expressed in inch-pounds, was measured by a simple but reliable test— the Gardner impact—which consists of striking cured specimens with a 2-lb round-nose rod, %-inch in diameter, from various distances the test specimens were discs 0.1 inch thick by 2.0 inches in diameter. 

Table II. Gardner Impact of ERL-4221/HHPA Modified with Carboxyl Terminated Elastomer (CTBN)...

The strength properties more often specified for plastics materials are (1) tensile strength and elongation, (2) flexural strength, (3) Izod and Gardner impact, and (4) heat deflection temperature under load. Our purpose here is not to describe each test in detail but to point out some of the known effects that colorants and other formulation ingredients can have on these properties. Table 22.1 lists the ISO and ASTM test methods for most of the physical properties, and ref. 1 (pp. 7-112) describes each of the methods in detail. Table 22.2 lists typical values of the above cite four properties for selected thermoplastics. 

Table IV shows test results of samples with various levels of piperidine and a constant amount of Hycar CTBN. The data on fracture energy in the table show conclusively an increase in crack resistance with increasing amounts of piperidine, but there is no corresponding increase in the Gardner impact. This system shows a rate sensitivity. The slow rate cleavage test for fracture energy improves although a fast rate impact test does not. Also there is a greater deterioration of mechanical properties when the additional piperidine is used.

Nelson investigated the relationship between density and physical properties, e.g., flexural modulus, Gardner impact, heat distortion, ten-sile/flexural strength, coefficient of linear thermal expansion, dynamic mechanical testing, and creep testing. The specific gravity of the SRIM obtained was changed from about 0.3 to 1.2. 

The authors are grateful to Himont, Inc. for a fellowship to H.K.A., support from 3M Co. for hardware and software development, and to Mr. George Turner of Turner Designs, Inc., for loan of a Luminometer. The assistance of Mr. Burt Blanch with the Gardner impact tests is gratefully acknowledged. 

Gardner impact very low very low medium high high very high very high... 

Impact strength vs. time was determined on solidified samples of the formulation that had been allowed to react from 30 min to 70 days at 135 °C. The impact strengths were measured with a Gardner impact tester on 1/2 in. thick samples. Impact strength values for all samples stabilized in the range 7-9 in.-lb. Hardness of the solidified samples was about 75 Shore D after 1 hr and increased to a maximum of about 80... 

The crystallinity of isotactic polypropylene homopolymer, PP, however, leads to its well known brittle behavior at low temperatures or when impacted under conditions of stress concentration, i.e., in the presence of sharp notches. For example, the low temperature drop weight (Gardner) impact strength of unmodified PP is... 

At lesser rubber levels, heavy duty solventless coatings models based on dlethylenetrlamlne or fatty polyamide cures, showed elastomer-modification (10 phr rubber level) to advantage in Gardner impact, mandrel bend and corrosion-resistance testing (41). Impact testing (direct and reverse) gave 110 and 60 in-lbs, respectively for the rubber-modified fatty polyamide cured epoxy coating (14 days at R.T.), whereas a control formulation tested 10 in-lbs in each mode. 

Impact resistance of epoxy coatings, as determined by a reverse Gardner impact test, is enhanced by liquid polymer addition independent of functional type. Again, these results are consistent with both unpigmented and pigmented model coatings. Although... 

The method detailed in ASTM D.S420 [87] is somewhat unusual compared to other impact standards in that the test piece, which is placed on a support plate having a circular hole of given size, has a striker resting upon it. and the striker is then impacted by the falling weight. This is the so-called Gardner impact test, and a number of variations in... 

ASTM D5420. Impact resistance of flat, rigid plastic specimens by means of a striker impacted by a falling weight (Gardner impact), 1993. 

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