Tear strength polyethylene

Antioxidants may be assessed in a variety of ways. For screening and for fundamental studies the induction period and rate of oxidation of petroleum fractions with and without antioxidants present provide useful model systems. Since the effect of oxidation differs from polymer to polymer it is important to evaluate the efficacy of the antioxidant with respect to some property seriously affected by oxidation. Thus for polyethylene it is common to study changes in flow properties and in power factor in polypropylene, flow properties and tendency to embrittlement in natural rubber vulcanisates, changes in tensile strength and tear strength. 

It is generally claimed that metallocene polyethylenes (often abbreviated to m-PE) exhibit superior mechanical and optical properties as well as better organoleptic properties (resulting from the lower residue levels). As an example m-LLDPE is particularly favoured as a stretch film for wrapping because of the good prestretchability, high puncture resistance and tear strength, all of which are claimed to be better than with conventional LLDPE. 

Rhoplex K-3 was also applied in combination with 1.2% polyethylene (Moropol 700, supplied by Mortex Chemical Products), a material that lubricates the surfaces of the yarns, gives the fabric more flexibility, and increases the tearing strength of resin-treated wash and wear fabrics (4). A second sample of Rhoplex K-3 with 1.2% polyethylene added was air dried instead of oven dried to assess the influence of different drying methods. 

Figure 2. The tearing strength of degraded cotton print cloth (50-Mrad dose) after application of various acrylic resins (A1-A4) and grafted monomers (M1-M4J U = untreated fabric, PE = polyethylene, AD = air dried. See text for identification of resins and monomers.

Prior to applying the acrylic resin, all fabric specimens except one replicate set were sprayed with a 2% emulsion of a polyethylene softening agent (Cyanalube TSI Special, 25% solids, from the American Cyanamid Company). This material lubricates the yams and thereby increases the tearing strength of the resin-treated fabrics. 

A polyethylene emulsion that improves sewing characteristics, tear strength, and abrasion resistance of textile fabrics. 

MYKON HD emulsion provides excellent sewing properties while imparting a soft hand to treated fabrics—unlike the waxy hand of other high density polyethylene products. MYKON HD softener also improves tear strength and abrasion resistance of treated fabric. 

As illustrated above, selection of cocatalyst is often predicated on cost. In some cases, however, use of an alternative cocatalyst may transcend the cost factor. This could be because the alternative cocatalyst provides enhanced polymer properties or improved process performance. For example, use of TMAL as cocatalyst in place of TEAL in a gas phase process has been shown to provide linear low density polyethylene with lower hexane extractables and superior film tear strength (14). Ultrahigh molecular weight polyethylene and polyethylene with broader molecular weight distribution can be produced using "isopre-nylaluminum" as cocatalyst (15-17). 

Composite Particles, Inc. developed two methods of surface modification of polymeric materials which are used for materials of different shapes and compositions. Here, only the spherical, non-rubber particles are discussed. Further information is included in the section on rubber particles below. One method of surface modification is based on exposing the polymeric powder to a chemically reactive gas atmosphere which oxidizes surface groups to form OH and COOH functionalities. These functionalities are then available for reaction with the components of the matrix into which modified particles are introduced. Vistamer HD and UH are manufactured by this method from polyethylenes of different molecular weights. Two factors can be regulated here the properties of the core particle and the type and density of functional groups on the surface of these particles. Polyethylene is a material, which without this modification, will not be compatible with most systems. The surface modification allows the incorporation of the material into resins. This improves abrasion resistance, tear strength, and moisture barrier properties and reduces the fiiction coefficient. 

Cyanalube Softener TSI Spec. [Am. Cyanamid] Polyethylene emulsion textile softener inqiroves tear strength of resin-treated cellulosic fibers. 

Dulceta. [IG Surf. UK] Pourable polyethylene emulsions inq oves sew-ability and tear strength of resin-treated fabrics. 

Ko and Odegaard (1997) and Tickner (2000) discuss alternative materials to plasticised PVC. mPE with a low crystallinity (density 900-905 kg m ) allows the downsizing of the bag gauge, since the biaxially oriented polyethylene film is stronger than plasticised PVC, and it has a higher tear strength (Fig. 15.10). The typical in-plane tensile strength of the mPE film is 29 MPa, compared with 16-24 MPa for plasticised PVC film. 

Setua and White (1991 a,b) used CM (chlorinated polyethylene) as a compatibilizer to improve the homogeneity of binary and ternary blends of CR, NBR, and EPR. NBR-EPM and CR-EPDM blends homogenize more rapidly when small amounts of CM are added. The presence of the compatibilizer leads to reductions in both the time needed for mixing, observed by flow visualization, and the domain size of the dispersed phase, observed by SEM. Arjunan et al. (1997) have used an ethylene acrylic acid copolymer and an EPR-g-acrylate as a compatibilizer for blends of EPDM-CR. The addition of the compatibilizer leads to the reduction in the phase size of the dispersed EPDM phase as well as increase in the tensile tear strength of the blend. 

A fairly recent development is the manufacture of cross-laminated unidirectionally oriented films which can be used for the manufacture of sacks. Rasmussen " invented this process in which films are spirally cut from unidirectionally stretched tubes and laminated by means of an adhesive. The orientation directions of both layers are perpendicular to each other and at an angle of approx. 45° to the longitudinal direction of the laminate. Sacks manufactured from cross-laminated high-density polyethylene film have very high strength, tear strength and puncture resistance and are sold under the trade name Valeron . 

Low-density polyethylene, LDPE, was blended with HDPE, PP, and EP block copolymer, to give films with good modulus, tear strength, and sagging... 

Chlorinated polyethylene has inherent oxygen and ozone resistance because of the saturated nature of the polymer. It also shows exceptionally high tear strength and heat aging characteristics and excellent oil and chemical resistance. To reduce cost, the base polymer can be heavily extended with processing oils and inert filler. 

The addition of a block copolymer of 10 phr epoxidized NR into NR/ chlorosulfonated polyethylene blends increased the tensile properties and tear strength of the blended system. The miscibility of the epoxidized NR was enhanced by an in situ grafting reaction of epoxidized NR onto the surface of the chlorosulfonated polyethylene particles. This graft copolymer reduced the interfacial tension between the chlorosulfonated polyethylene particles and the NR matrix, and the epoxidized NR acted as the load transferring agent between the NR and the chlorosulfonated polyethylene."... 

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