Rubber tear resistance test

ASTM D 624-86 Standard Test Method for Rubber Property — Tear Resistance, 5 pp (DOD Adopted) (FSC 9320) (MR) (Comm D-11)... 

The tear resistance (sometimes also called tear strength) is a more or less technological material parameter which should describe the resistance of the material against the growth of a sharp cut. Usually, tear tests are applied for rubber mixtures, mbber vulcanizates, thermoplastic films, leather or textiles. Different standards exist for the determination of the tear resistance for elastomers and thermoplastic films, for example ... 

The principal mechanism of reinforcement of tear resistance of vulcanized filled rubber is associated with the phenomenon of knotty tearing. In knotty tearing the tear deviates almost perpendicularly from the intended tear path and the knot looks approximately like a semi-circular arc on the torn test-piece (in the unstrained state) as shown in Figure 5.4. 

The advantages are that test pieces are relatively cheap and are easily prepared. A disadvantage is the tendency for cohesive failure, reflecting the tear resistance of the rubber. 

Instron tensile tester n. A high precision electronic test instrument designed for testing a variety of material under a broad range of test conditions. It is used to measure and chart the load-elongation properties of fibers, yarns, fabrics, webbings, plastics, films, rubber, leather, paper, etc. It may also be used to measure such properties as tear resistance and resistance to compression. 

Keywords surface-modification, polyurethane, rubber particles, composites, adhesion, filler, compatibility, coefficient of friction, peel tests, tear resistance. 

Tear Strength or Tear Resistance - Tear Strength or Tear Resistanee of rubber is defined as the maximum force required to tear a test speeimen in a direction normal to (perpendicular to) the direetion of the stress. Tear strength is expressed as foree per unit of speeimen thiekness - pounds force per inch (Ibl/in), kilograms force per eentimeter (kgl7cm), or kiloNewtons per meter (kN/m). 

Neoprene is the generic name for polychloroprene rubber. It has been produced commercially since 1931 and had rapid and wide acceptance because it is much superior to natural rubber for heat and oil resistance. Heat resistance is far better than NR, BR or SBR. but less than EPDM. When heated in the absence of air, neoprene withstands degradation better than other elastomers which are normally considered more heat resistant, and retains its properties fifteen times longer than in the presence of air. Compression set at higher temperature is better than natural rubber and 100°C is typically the test temperature rather than 70°C. Abrasion resistance is not as good as natural rubber but generally better than most heat resistant and oil resistant rubbers. This is also true for tear strength and flex resistance. 

The second class includes tests for ageing, oxygen and ozone attack, adhesion, resistance to wear and tear, fatigue, etc. This class also includes tests under simulated service conditions under laboratory environments and immersion in fluids. These two classes of tests are conducted on vulcanized rubber. 

This substance has extensive lipid solubility and is absorbed immediately by the skin. Additionally, DMM is able to penetrate many materials including plastic and rubber compounds such as latex, polyvinyl chloride, and neoprene in a matter of seconds. In permeability tests, a Silver Shield glove of a flexible, plastic-laminate, offered skin protection from DMM for 4h. This chemically resistant glove, when worn under an outer glove that is resistant to abrasion and tears, may provide limited protection for direct handling of DMM. 

The existing test standards on the resistance of these materials to crack propagation concentrate on determining the tear strength values. Some of these standards arc specific to plastics film and sheeting [202 208], fabrics coated with rubber or plastics [209-212]. non-woven textile fabrics [213-216], and woven textile fabrics [217-218]. 

The Lambda series of Medicaflex is a polyurethane-based TPE polymer that exhibits low modulus characteristics with high tear strength and abrasion resistance. Those listed in the tables have passed USP Class VI compatibility tests and have been used as replacements in some natural rubber latex and silicone rubber applications. The polymer has been applied to uses such as catheters, tubing and films where softness, low durometer hardness, low modulus or high elongation are needed (Tables 4.3, 4.12, and 4.13). 

D 1790 Test method for Brittleness Temperature of Plastic Film by Impact D 1938 Test method for Tear Propagation Resistance of Plastic Film and Thin Sheeting by a Single-Tear Method D 2240 Test Method for Rubber Property - Durometer Hardness D 2702 Standard Practice for Rubber Chemicals - Determination of Infrared Absorption Characteristics... 

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