Resistance to impact

Its key properties are its excellent transparency, rigidity, and chemical resistance, plus its resistance to impact and to high temperatures. It withstands repeated autoclaving, even at 150°C. 

A number of amorphous thermoplastics are presently employed as matrices in long fiber composites, including polyethersulfone (PES), polysulfone (PSU), and polyetherimide (PEI). AH offer superior resistance to impact loading and higher interlaminar fracture toughnesses than do most epoxies. However, the amorphous nature of such polymers results in a lower solvent resistance, clearly a limitation if composites based on such polymers are to be used in aggressive environments. 

Mechanical Properties Mechanical properties of wide interest include creep, rupture, short-time strengths, and various forms of ductihty, as well as resistance to impact and fatigue stresses. Creep strength and stress rupture are usually of greatest interest to designers of stationary equipment such as vessels and furnaces. 

Gray iron has outstanding damping properties—that is, ability to absorb vibration—as well as wear resistance. However, gray iron is brittle, with poor resistance to impact and shock. Machinability is excellent. 

There is another interesting difference between the two irons. Ni-Hard (nominally 1 A Cr, 4 A Ni, 3C) has a matrix of the iron carbide that suiTounds the areas of the steel constituent. This brittle matrix provides a continuous path if a crack should start thus the alloy is vulnerable to impact and is weak in tension. In contrast, HC 250 (nominally 25 Cr, 2 AC) has the steel portion as the matrix that contains island crystals of chromium carbide. As the matrix is tougher. HC 250 has more resistance to impact and the tensile strength is about twice as high as that of Ni-Hard. jMoreover, by a suitable annealing treatment the... 

For many applications the resistance to impact is the most important property of a plastics material. It is also notoriously one of the most difficult to assess. 

Acetal resins find a number of applications in gears, where they come into competition with the nylons. Acetal gears are superior to those made from nylon in fatigue resistance, dimensional stability and stiffness, whereas nylon gears in conditions of average humidity have greater resistance to impact fatigue and abrasion. 

This has a very high resistance to impact damage, even at subzero temperatures. It has good creep strength in dry conditions up to 115°C but degrades by continuous exposures to water hotter than 65°C. It is resistant to aqueous solutions of acids, aliphatic hydrocarbons, paraffins, alcohols (except methanol), animal and vegetable fats and oils, but is attacked by alkalis, ammonia, aromatic and chlorinated hydrocarbons. 

Low-boy trailers are used for truck movement of ISO containers. Low center of gravity trailers are also available for tanks. The lower center of gravity reduces the risk of a turnover. Baffles can be used in large containers to improve stability. Nonbrittle containers can be used to improve resistance to impact or shock damage. 

Thermoplastic polyurethane (TPU) is a type of synthetic polymer that has properties between the characteristics of plastics and rubber. It belongs to the thermoplastic elastomer group. The typical procedure of vulcanization in rubber processing generally is not needed for TPU instead, the processing procedure for normal plastics is used. With a similar hardness to other elastomers, TPU has better elasticity, resistance to oil, and resistance to impact at low temperatures. TPU is a rapidly developing polymeric material. 

Fibrous materials such as nylon are added to increase strength, in particular, resistance to impact loads. 

All these alloys are characterised by high hardness values and low resistance to impact. In this they are probably more similar to stoneware than to other metals but they are superior to stoneware in thermal conductivity and in their resistance to thermal shock, which, however, is poor compared with that of other metals. Moreover, it is usually easier to make castings of silicon iron than to fabricate required parts from stoneware. 

Resistance to impact. The coating must be able to resist impacts without cracking. 

All polyethylenes are soft, flexible and resistant to acids and alkalis up to 60°C. They retain this flexibility down to —40°C. Hence they have good resistance to impact even at low temperatures. However, unless correctly formulated they can suffer from environmental stress cracking (ESC), poor adhesion and UV degradation. ESC is the phenomenon which occurs when a thermoplastic is put under stress, e.g. bent, in a particular environment and prematurely cracks or crazes. Alcohol and detergent are examples of agents that can cause ESC in polyethylenes. 

This is another property for which it is very difficult to obtain a reliable figure. In general, ceramic materials are not very resistant to impact and should be guarded to prevent breakage by accidental blows. 

The term impact implies a very high speed of the acting force, whereas toughness is not related to any specific speed. Since the two terms are used in conjunction with each other in describing resistance to impact, it appears desirable to correlate those readily obtainable properties that would reflect on speed of impact and toughness. 

Zytel Polyamine Stable to temperatures up to about 325°F (163°C) resistant to impact, deformation, and fatigue Fuel rails filter housings... 

To help ensure resistance to impact and internal pressure increases, plastic tank wall thickness is greater than steel tank thickness. Plastic tanks are typically >4 mm in thickness, whereas steel tanks are somewhat less than 1 mm in thickness. Plastic tanks, however, are considerably lighter in weight. 

Although some polymers may be satisfactory when used under the stress of static loads, they may fail when subjected to impact. The impact resistance, or resistance to brittle fracture, is a function of the molecular weight of a polymer. Thus uhmwpe is much more resistant to impact failure than general purpose high-density polyethylene (hdpe). The impact resistance of brittle polymers is also increased by the addition of plasticizers. Thus polyvinyl chloride (PVC), plasticized by relatively large amounts of dioctyl phthalate, is much less brittle than unplasticized rigid PVC. 

The most widely used acrylic plastics are PMMA (Lucite) or copolymers of methyl methacrylate with small amounts (2 to 18%) of methyl or ethyl acrylate (Plexiglas). These commercial products, which are available as sheets and as molding powders, have a specific gravity of about 1.2, a heat deflection temperature of about 95 C, a refractive index of about 1.5, and a water absorption of 0.2%. PMMA is more resistant to impact than PS or glass, but its scratch resistance is inferior to that of glass,... 

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