Polyethylene softeners

Polyethylene has low density when polymerized at pressures 9,000 - 45,000 psi and high density when made with special catalysts at 250 - 500 psi. Low-density polyethylene softens 68 F lower than high-density polyethylene, which is more crystalline and stiffer. The rigidity characteristics and surface of high-density polyethylene are comparable with polystyrene. It feels like nylon, has a bursting strength three times that of low-density polyethylene, and withstands repeated exposure to 250 F, hence, it can be sterilized. 

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. 

Most softeners consist of molecules with both a hydrophobic and a hydrophilic part. Therefore, they can be classified as surfactants (surface active agents) and are to be found concentrated at the fibre surfaces. Most softeners have a low water solubility. Therefore softening products are usually sold as oil in water emulsions containing 20-30 % solids. The softener molecules typically contain a long alkyl group, sometimes branched, of more than 16 and up to 22 carbon atoms, but most have 18 corresponding to the stearyl residue. Exceptions to this molecular structure are the special categories of silicones, paraffins and polyethylene softeners. About one-third of the softeners used in the textile industry are silicone based. 

Are the polyethylene softeners particularly effective and useful in the narrow fabric area. These products differing only in concentration, are excellent emulsions, compatible with most finishing baths and supply good softening. 

Nonionic polyethylene softeners and lubricants. Improve abrasion resistance while imparting excellent fabric softness and sewability. 

A novel high density polyethylene softener that greatly increases sewability of fabrics... 

Other characterization and identification techniques Polyolefin fibers can be characterized by numerous modem techniques ranging from thermal analysis and various spectroscopy techniques, to electron microscopy and nuclear magnetic resonance (NMR). Differential scanning calorimetry (DSC) is particularly important in determining the melting point of the fiber piece and quickly distinguishing between PE and PP. Polyethylene softens at 130 °C and melts around 140 °C, whereas polypropylene softens at 150 °C and melts around 160 °C. 

The irradiation of polyethylene and its copolymers has been the most commercially successful of all applications of radiation in the polymer field (Charlesby 1987). Upon warming, the unirradiated polyethylene softens between 70°C to 90°C and turns to a viscous liquid at 115°C-125°C. After irradiation with a dose of 20 kGy the polymer is form-stable to about 250° C. 

The fibers are unaffected by solvents at room temperature and are swollen by aromatic and chlorinated hydrocarbons oiUy at elevated temperatures. ThQ exhibit excellent heat and electric insulation characteristics and are extensively used in these applications. The fibers are heat sensitive. Polyethylene softens at 130 0 and melts at 150°C, while polypropylene softens at about 150 C and melts at about 170X . 

Ethylene. Under the influence of pressure and a catalyst, ethylene yields a white, tough but flexible waxy sohd, known as Polythene. Polyethylene possesses excellent electric insulation properties and high water resistance it has a low specific gravity and a low softening point (about 110°). The chemical inertness oi Polythene has found application in the manufacture of many items of apparatus for the laboratory. It is a useful lubricant for ground glass connexions, particularly at relatively high temperatures. 

Decopperized blast furnace bulHon is softened to reduce impurities below 2% before casting as anodes. The electrolyte is a solution of lead fluosUicate [25808-74-6] PhSiF, and free fluosUicic acid [16961 -83-4]. Cathode starting sheets are made from pure electrolytic lead. The concrete electrolytic ceUs are lined with asphalt or a plastic material such as polyethylene. 

Fabric Softeners, Surfactants and Bleach Activators. Mono- and bisamidoamines and their imidazoline counterparts are formed by the condensation reaction of one or two moles of a monobasic fatty acid (typically stearic or oleic) or their methyl esters with one mole of a polyamine. Imidazoline formation requires that the ethyleneamine have at least one segment in which a secondary amine group Hes adjacent to a primary amine group. These amidoamines and imidazolines form the basis for a wide range of fabric softeners, surfactants, and emulsifiers. Commonly used amines are DETA, TETA, and DMAPA, although most of the polyethylene and polypropane polyamines can be used. 

Most polymer properties depend on the average DP. Figure 22.2(b, c), for polyethylene, shows two the tensile strength, and the softening temperature. DPs of less than 300 give no strength because the short molecules slide apart too easily. The strength rises with DP, but so does the viscosity it is hard to mould polyethylene if... 

Whilst the Vicat test usually gives the higher values the differences are quite modest with many polymers (e.g. those of types A, B and C). For example, in the case of the polycarbonate of bis-phenol A (Chapter 20) the heat distortion temperatures are 135-140°C and 140-146°C for the high and low stress levels respectively and the Vicat softening point is about 165°C. In the case of an acetal homopolymer the temperatures are 100, 170 and 185°C respectively. With nylon 66 the two ASTM heat distortion tests give values as different as 75 and 200°C. A low-density polyethylene may have a Vicat temperature of 90°C but a heat distortion temperature below normal ambient temperatures. 

Polyethylene is a wax-like thermoplastic softening at about 80-130°C with a density less than that of water. It is tough but has moderate tensile strength, is an excellent electrical insulator and has very good chemical resistance. In the mass it is translucent or opaque but thin films may be transparent. 

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