Toughness tear resistance

A new approach to modification of thermosetting epoxy or polyurethane systems (Plastics Technology, p. 14 (April 1994)) involves surface modified rubber or UHMW-PE particles. These particles after reaction with Cl, 0 or F allows for improved properties (toughness, tear resistance, abrasion resistance, modified coefficient of friction) in the noted thermosets. 

General Description Dow Chemicals Affinity resins, homogenous ethylene alpha-olefin copolymers, contain up to 20% octene comonomer. Affinity polyolefin plastomers (POPs) can be used in any of the extrusion technologies as a sealant, to deliver an unparalleled combination of low seal-initiation temperature, hot-tack strength, toughness, tear resistance, and transparency.f ... 

Shore hardness can be as soft as 70 A and as hard as 74 D, depending on the hard/soft segment ratio. Specific gravity, modulus, compressive stress, load-bearing strength, and tear strength are also hard/soft ratio dependent. TPU thermoplastic elastomers are tough, tear resistant, abrasion resistant, and exhibit low-temperature properties. ... 

Polyisobutylene has been added to HDPE and LDPE to improve toughness, tear resistance and environmental stress rupture resistance. Commercial systems include Allied Chemical s ET polymers and BASF s Lupolen . Polypropylene/poly(butene-l) blends have been shown to exhibit miscibility and utility in films has been noted with some commercial activity [43, 44].Increased crystallization rate of poly( 1 -butene) with PP addition offers a blend approach as a nucleation additive [45]. Poly(l-butene)/LDPE blends have been employed as peelable films in packaging applications [46]. 

The crystallization kinetics of commercial polyolefins is to a large extent determined by the chain microstructure [58-60]. The kinetics and the regime [60] of the crystallization process determine not only the crystalline content, but also the structure of the interfaces of the polymer crystals (see also Chapter 7). This has a direct bearing on the mechanical properties like the modulus, toughness, and other end use properties of the polymer in fabricated items such as impact resistance and tear resistance. Such structure-property relationships are particularly important for polymers with high commercial importance in terms of the shear tonnage of polymer produced globally, like polyethylene and polyethylene-based copolymers. It is seen that in the case of LLDPE, which is... 

Ecoflex F was designed to be a strong and flexible material with mechanical properties similar to PE. The films are tear-resistant and flexible, as well as resistant to fluctuations in water and humidity. Ecoflex F is a thermoplastic and can be melt-processed on standard polyolefin equipment (see Sect. 5). It is mainly used in film applications. The very high toughness and failure energy represent product characteristics of Ecoflex F that significantly exceed the respective properties of PE films. 

Polymers having broad MW distributions not only exhibit improved polymer molding, but the MW breadth can also increase some of the polymer physical characteristics, including impact and tear resistance, toughness, creep and hoop stress resistance in pipe, and especially resistance to chemical attack, or stress crack (ESCR). These improved properties result because a broad MW distribution usually contains more of the long chains that can act as tie molecules to connect the crystalline lamellae (Figure 42). 

Oriented LDPE is the most widely used of the shrink wrap materials. It has good strength, toughness and tear resistance. It also has good low-temperature resistance, hence is suitable for parts of the world with well below zero conditions. LDPE is a reasonable moisture barrier but is a relatively poor oxygen and carbon dioxide barrier. 

Blends of polyolefins (e.g., HPDE/LDPE, LDPE/ ethylene copolymers, PP/EPDM, PP/HDPE/EPDM, HDPE/butyl rubber) have been commercial since the late 1960 s and early 1970 s. Specific film formulations were commonly based on polyolefin blends to achieve the proper balance of processing, environmental stress crack resistance, modulus, toughness, cling, transparency, filler acceptance, printability, tear resistance, shrinkage characteristics, and permeability. Ethylene-propylene mbber (EPR, EPDM) was commonly incorporated into polypropylene as an impact modifier at moderate levels and as a flexibilizer at high levels. One of... 

The essential ingredients of a free-radical adhesive formulation are an acrylate-terminated prepolymer and a photoinitiator. A wide range of prepolymers can be acrylated, including epoxies, urethanes, polyesters, polyethers, and rubbers. Those most commonly used in adhesive formulations are epoxy and urethane acrylates. Epoxy acrylates have properties similar to those of the parent epoxy resin, with excellent adhesion, chemical resistance, and toughness. Urethane acrylates, on the other hand, are noted for their high reactivity, good adhesion, flexibility, and tear resistance. 

Dow Chemical Company Dowlex LLDPE resins offer toughness, puncture resistance, and good tear resistance. " ... 

Pax-Plus 3205. A rubber-modified film resin. Its major use is in films that require good WVTR and excellent tear resistance. It offers a good combination of toughness, flexibility, and processing into blown film. 

Elvanol 71-30 forms tough, abrasion-resistant, tear-resistant films. The strength, flexibility, and hardness of films vary with the plasticizer content and relative humidity. ... 

Features Moderately fast setting imparts rubber-like elastomeric and tear resist, props, with epoxy toughness and adhesive qualities at and below freezing... 

Synonyms PEEK Polyarylene ether ether ketone Definition Partially cryst. thermoplastic with exc. chem./heat/flame/tear resist. compds. feature exc. flex, and tens. str. and elec, props, at high temps., toughness and abrasion resist. 

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