Izod impact strength test

About: Izod impact strength test is a research topic. Over the lifetime, 4965 publications have been published within this topic receiving 96592 citations.

Nylon 6 nanocomposites: the effect of matrix molecular weight

Abstract: Organoclay nanocomposites based on three different molecular weight grades of nylon 6 were prepared by melt processing using a twin screw extruder. Mechanical properties, transmission electron microscopy, wide-angle X-ray diffraction, and rheological measurements were used to characterize the three types of composites. Tensile modulus and yield strength were found to increase with increasing concentration of clay, while elongation at break decreased. Izod impact strength was relatively independent of clay content for the higher molecular weight composites, but slightly decreased with increasing clay content for the lowest molecular weight polyamide. In general, nanocomposites based on the higher molecular weight polyamides yielded superior composite properties, having higher degrees of clay exfoliation, higher stiffness and yield strength values, and marginal loss of ductility as compared to nanocomposites based on the low molecular weight polyamide. Differences in properties between the three types of composites were attributed to differences in melt rheology. Capillary and dynamic parallel plate data revealed sizeable differences in the levels of shear stress between each nanocomposites system. A mechanism for exfoliation during melt mixing is outlined.

Review of low-velocity impact properties of composite materials

Abstract: This paper is a review of low-velocity impact responses of composite materials. First the term ‘low-velocity impact’ is defined and major impact-induced damage modes are described from onset of damage through to final failure. Then, the effects of the composite's constituents on impact properties are discussed and post-impact performance is assessed in terms of residual strength.

Toughening of polypropylene with calcium carbonate particles

Abstract: Polypropylene–CaCO3 composites were prepared on a twin screw extruder with a particle content of 0–32 vol%. The influence of particle size (0.07–1.9 μm) and surface treatment of the particles (with and without stearic acid) on the toughening properties were studied. The matrix molecular weight of the polypropylene was also varied (MFI 0.3–24 dg/min). The experiments included tensile tests, notched Izod impact tests, differential scanning calorimetry (DSC), scanning electron microscopy and rheology experiments. The modulus of the composites increased, while the yield stress was lowered with filler content. This lowering of yield stress was connected to the debonding of the particles from the polypropylene matrix. From DSC experiments it was shown that the particle content had no influence on the melting temperature or crystallinity of the PP phase, also particle size showed no effect on the thermal properties. The impact resistance showed large improvement with particle content. The brittle-to-ductile transition was lowered from 90 to 40 °C with the addition of CaCO3 particles. Notched Izod fracture energy was increased from 2 up to 40–50 kJ/m2. The stearic acid coating on the particle surface showed a large positive effect on the impact strength. This was mainly due to the improved dispersion of the CaCO3 particles. Aggregates of particles clearly had a detrimental effect on the impact behaviour of the composites. The smaller particle sizes ( 20 vol%), however, still problems seem to occur with dispersion, lowering the toughening efficiency. Of all particle types used in this study the stearic acid treated particles of 0.7 μm were found to give the best combination of properties. From the study of the micro-toughening mechanism it was shown that at low strain the particles remain attached to the matrix polymer. At higher strain the particles debond and this leads to a change in stress state at the particle size level. This prevents crazing of the matrix polymer and allows extensive plastic deformation, resulting in large quantities of fracture energy.

Effect of molecular weight and crystallinity on poly(lactic acid) mechanical properties

Abstract: Several samples of poly(lactic acid) with different molecular weights and tacticity have been prepared, and some PLLA injection moulded specimens have been annealed to promote their crystallization. From the characterization data, poly(L-lactide) showed more interesting mechanical properties than poly(D, L-lactide), and its behavior significantly improves with crystallization. In fact, annealed specimens possess higher values of tensional and flexural modulus of elasticity, Izod impact strength, and heat resistance. The plateau region of flexural strength as a function of molecular weights appears around Mv = 35,000 for PDLLA and amorphous PLLA and at higher molecular weight, around Mv = 55,000, for crystalline PLLA. The study of temperature effect shows that at 56°C only crystalline PLLA still exhibits useful mechanical properties. © 1996 John Wiley & Sons, Inc.

Some mechanical properties of untreated jute fabric-reinforced polyester composites

Abstract: This research work is concerned with the evaluation of the mechanical properties—modulus, Poisson's ratio and strength—of woven jute fabric-reinforced composites. The specimens are prepared using hand lay-up techniques as per the ASTM standard. This is the first report by any single group of researchers in which tensile strength, compressive strength, flexural strength, impact strength, inplane shear strength, interlaminar shear strength and hardness are given. This work being an experimental study on untreated (`as received' jute fabric) woven jute fabric-reinforced polyester composites, demonstrates the potential of this renewable source of natural fibre for use in a number of consumable goods.