Gardner impact resistance

Methods employed to determine the impact resistance of plastics include pendulum methods (Izod, Charpy, tensile impact, falling dart, Gardner, Dynatup, etc.) and instrumented techniques. In the case of the Izod test, what is measured is the energy required to break a test specimen transversely struck (the test can be done either with the specimen notched or unnotched). The tensile impact test has a bar loaded in tension and the striking force tends to elongate the bar (Chapter 5, Impact Strength). 

The impact resistance of the pseudo-IPN coatings was measured on a Gardner-SPI modified Variable Height Impact Tester using both the direct and the indirect techniques. 

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.

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... 

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

Impact resistance Particularly relevant for PO packaging are Gardner (falling dart) impact, drop Impact strength for containers, and tear strength for films. 

Uses Epoxy-a lic in photo resists, solder masks, conformal coatings, overprint varnishes, paper coalings in clear coatings-type applies. Features Enhanced impact resist., flexibility, and resist, to thermal shock Properties Gardner 7-8 color m.w. 1500 vise. 5800 cps (65 C) acid no. 2.4 tens. str. 2700 psi tens, elong. 38%... 

Uses Epoxy for supported and nonsupported adhesives, chem. corrosion resist, coatings, laminating, container, coil, and powd. coatings Features Good flexibility and impact resist. fast dry in sol n. coatings Properties Gardner 3 solid sp.gr. 1.19 dens. 9.9 Ib/gal EEW 1825 100% solids... 

Uses Lubricant corrosion inhibitor polymer building block modifier (increases flexibility, impact resist., toughness, hydrolytic stability) for industrial coatings (automotive, coil, textile, leather, wood lacquers) Properties Gardner 5 max. liq. sp.gr. 0.93 vise. 7100 mPa s acid no. 194-198 sapon. no. 197-201 flash pt. (COC) 285 C fire pt. 320 C 93-98% dimer, 2-4% trimer Pripol 1015 [Uniqema UniqemaAm.]... 

Milliken HPN-600ei is used to improve aesthetics, Gardner (falling weight) impact resistance, flexural modulus, and top-load strength of thermoformed PP parts (e.g., cups and lids). ... 

Impact strength, Izod, notched, unnotched, Charpy Impact resistance, free-falling dart (Gardner impact)... 

D5420 Falling dart impact resistance (Gardner impact) see also D4226, D5628 —... 

ASTM D5420, Standard Test Method for Impact Resistance of Flat, Rigid Plastic Specimen by Means of a Striker Impacted by a Falling Weight (Gardner Impact), 2004. 

Lavach [50] discussed the factors that affect results obtained by the Gardner impact test. This test is used by plastics producers to approximate the mean failnre energy for many plastics. The test is inexpensive and easy to operate. The test eqnipment can be placed close to the manufacturing equipment, permitting fast and nearly online determination of the impact resistance of an article. The test is useful for finding the mean failure energy for brittle thermoplastics such as acrylic and high-impact polystyrene with standard deviations between 8% and 10%. 

The glass mat at the core of the STX sheet was shown to impart some very unusual impact properties to the material. The testing performed in the laboratory (Gardner drop test) and the field results from production components have shown that, in contrast to glass reinforced plastics, the failure mode is elastic rather than brittle. The resultant damage is a hole with little or no crack propagation around the impact area whereas the other reinforced materials will shatter under similar conditions. The STX failure mode applies not only at room temperature, but is equally valid at -40°F. STX impact resistance increases with the thickness of the material, i.e., V4 in. thick plate will resist much higher impact loads than Vs in. thick plate. 

Gardner Impact Test (falling-weight test) A test for the impact resistance of rigid plastic sheets or parts. ASTM... 

One of the most important properties—impact resistance—has been tested in various conditions of acceleration of the impact weight (acceleration being recorded on an oscilloscope). In this way, the falling rate, impact strength, and kinetic energy transmitted to the film can be calculated by the Gardner test [41, 42],... 

Feati es Low vise. high functionality good abrasion resist., adhesion, chem. resist., flexibilily, hardness, heat resist., impact str, water resist. low shrinkage prods, are fast curing, strong Properties Gardner 1 dear liq. dens. 9.5 Ib/gal vise. 330 cps tens. str. 700 psi elong. 80%... 

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