Impact resistance determination methods

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). 

ISO 7765-1, Plastics film and sheeting - Determination of impact resistance by the free-falling dart method - Part 1 Staircase methods, 1988. 

ISO 2897-1 1997 Plastics - Impact-resistant polystyrene (PS-I) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 2897-2 2003 Plastics - Impact-resistant polystyrene (PS-I) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 14631 1999 Extruded sheets of impact-modified polystyrene (PS-I) - Requirements and test methods... 

Polypropylene (PP) is often blended with ethylene/propylene (BP) rubbers to improve the impact resistance. This so-called toughened PP (TPP) can be a mechanically blended PP/C2C3 rubber system or an in-situ polymerised PP/C2C3 rubber system. A number of rubber parameters (like concentration, particle size, particle size distribution, crystallinity, molecular weight etc.) determine the ultimate effect of the rubber addition on the impact resistance. DMA is one of the analytical techniques often used to investigate blends of polymers with an impact improver. The determination of the relation between the area of the rubber relaxation maximum as measured by DMA and the rubber concentration is usually a first step in such an investigation. The method to determine this area and the results measured on a series of PP/C2C3 rubber blends are reported below. 

BS 2782, Method 351 A, Determination of Charpy Impact Resistance of Rigid Plastics and Ebonite, London (1977). 

ASTM D256-05a Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics, p. 1-20, American Society for Testing and Materials, Philadelphia, 2005. 

ISO 7765-2 1994. Plastics Film and Sheeting - Determination of Impact Resistance by the Free-Falling Dart Method - Part 2 Instrumented Puncture Test. 

Test methods for determining the izod pendulum impact resistance of plastics. ASTM Standard ASTM D256-06a, ASTM International, West Con-shohocken, PA, 2007. 

ASTM D256 Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics. Used to determine the resistance of a plastic specimen to impact by a pendulum-type hammer. Specimens contain a milled notch and depending upon the test method, failure may be brittle or ductile. Test results are reported in terms of energy absorbed per unit of specimen width or per unit of cross-sectional area under the notch. 

ASTM D3420 Standard Test Method for Pendulum Impact Resistance of Plastic Film. Used to determine the resistance of film to impact-puncture penetration at ambient conditions. Also called Spencer Impact. 

Standard test methods for determining the Izod pendulum impact resistance of... 

During the process of dam-break evacuation, besides traffic capacity of motor vehicle, non-motor vehicle s traffic load also impacts on the travel time (or travel speed) (Wang Wei, Xu Jian, 1992), therefore, some scholars adopt half-theory and half-experience road resistance function method to calculate the travel time under the heavy mixed traffic situation (Zhang Xingxing, 2011). The major thought is as follows firstly determine the theoretical model of road resistance function based on the relationship of flow, speed and density. In such theoretical model, only consider the influence of traffic volume of motor vehicle, then correct non-motor vehicle s traffic volume, traffic lane number, traffic lane width and traffic disconnection (intersection) and calculation formula is shown below (Li Chaojie, 2007) (Wan Qing, Li Huiguo, 1995)... 

Rubber toughening is the most often used method of improving the impact resistance of polymers (Bucknall 1977). The impact modified materials are usually the blends of a rigid matrix polymer with an elastomer. The composition of the constituents, their miscibility, and the morphology influence the deformation and failure mechanism in the blend. Particle size of the elastomer, its dispersion, and its adhesion with matrix are also the important factors determining the toughness. 

Standard test methods for the determination of impact resistance (ASTM D 950-82, ISO 9653 1998 and BS 5350, Part C4) specify the specimen geometry shown in Fig. 1, see also Appendix. While providing a simple basis for comparisons between adhesives, a number of disadvantages are associated with this configuration for example, it does not reproduce the differential strain effects often present in real joints and it does not readily permit the evaluation of bonds to many important coated substrates. 

The RCP part of the mixture is designed to have ethylene contents on the order of 40-65% ethylene and is termed the rubber phase. The rubber phase can be mechanically blended into the ICP by mixing rubber and HPP in an extruder or it can be polymerized in situ in a two-reactor system. The HPP is made in the first reactor and the HPP with active catalyst still in it is conveyed into a second reactor where a mixture of ethylene and propylene monomer is polymerized in the voids and interstices of the HPP polymer powder particle. The amount of rubber phase that is blended into the HPP by mechanical or reactor methods is determined by the level of impact resistance needed. The impact resistance of the ICP product is determined not only by its rubber content but also by the size, shape, and distribution of the rubber particles throughout the ICP product. Reactor products usually give better impact resistance at a given rubber level for this reason. 

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