Antioxidant for polyethylene

The dithiocarbamates have the pentacoordinate binuclear structure (44). The diamyl- and diethyl-dithiocarbamate complexes have been found to inhibit the hardening of asphalt, but the effect appears too weak to be useful.127 The latter complex is an effective antioxidant for polyethylene,128 polypropylene,129 polystyrene,130 poly(methyl methacrylate)130 and an isoprene-styrene copolymer.131 The di-n-butyldithiocarbamate complex is important in the vulcanization and injection moulding of rubber,132 as a stabilizer against photolytic and thermal degradation. 

British Standard - Listed as an antioxidant for polyethylene and polypropylene compositions used in contact with foodstuffs or water intended for human consumption (max permitted in final compound 0.5%). 

Gelbin ME, et al. Liquid antioxidants for polyethylene. International Polyolefins Conference, conference proceedings. Society of Plastics Engineers 2008. 

However, the new free radical cannot react because it is hindered from doing so by the very bulky t-butyl groups. Hindered phenols of this type are frequently used as antioxidants for polyethylene and polypropylene to which they are added in quantities of about 1%. 

SantonOX." Trademark for antioxidant for polyethylene. Light gray tc light tan... 

BNX 1035 is a particularly effective antioxidant for polyethylene, styrenic polymers, polypropylene and elastomers such as EPDM and SBR and for carboxylated SBR latex, polybutadiene rubber and polyisoprene rubber. 

Pasanphan, W Buettner, GR Chirachanchai, S (2008). Chitosan conjugated with deoxycholic acid and gallic acid A novel biopolymer-based additive antioxidant for polyethylene Journal of Applied Polymer Science, 109 (1), 2008, 38-46. 

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. 

Acid-treated clay catalyst Engelhard F-24 was found to be very effective for the alkylation of diphenylamine (DPA) with an olefin such as a-methyl styrene (AMS) to obtain a mixture of mono and dialkylated diphenylamines (Chitnis and Sharma, 1995). For example, alkylation of DPA with AMS produced a mixture of 4-(a,a-dimethyl benzyl) diphenylamine, i.e. monocumyl-diphenylamine (MCDPA) and 4,4 -bis(a,a-dimethylbenzyl) diphenylamine, i.e. dicumyldiphenylamine (DCDPA) (Eqn.(l 1)). The dialkylated diphenylamine, i.e. DCDPA, is indu.strially important as an antioxidant and heat stabilizer. DCDPA is reported to be an ideal antioxidant for many materials like polyethylene, polypropylene, polyether polyol, polyacetals, nylon 6, synthetic lubricants, hot melt adhesives, etc. 

A reliable procedure for determination of molecular parameters number, weight and z-averages of the molecular weight (Mj, i = n, w and z respectively) for polyethylenes, PE, by means of Size Exclusion Chromatography, SEC, has been developed. The Waters Sci. Ltd. GPC/LC Model 150C was used at 135 C with trichlorobenzene, TCB, as a solvent. The standard samples as well as commercial stabilized and not stabilized PE-resins were evaluated. The effects of sampling, method of solution preparation, addition of antioxidant(s), thermal and shear degradation were studied. The adopted procedure allows reproducible determination of and M , with a random error of 4% and M2, with 9%, within 2 to 72 hrs from the initial moment of preparation of solutions. 

Uses. Stabilizer/antioxidant for vinyl plastics and polyethylene, polypropylene, styrene copolymers, and rubber... 

Among the most important antioxidants are hindered phenols, which account for more than 50% of the total market for antioxidants sold into the global plastics industry as shown in Figure 8.1. Phosphite esters are second in importance as antioxidants for the global plastics industry. Polyethylene and polypropylene account for approximately of the total market for antioxidants, as shown in Figure 8.2. 

A high-temperature cyclic peroxyketal peroxide cross-linking agent for polyethylene has been found to function as a blowing agent as well. This is another example of dual-function additives. Activated by thiodipropionate antioxidants, it evolves COj and should be useful in making crosslinked polyethylene foams. 

ZDEC is used in the following applications as a fast primary or secondary vulcanization accelerator in NR, SBR, IIR, EPDM and for natural and synthetic latex a stabilizer in butyl, butadiene, and urethane rubbers an antioxidant in rubber-based adhesive systems a stabilizer in cement a heat stabilizer for polyethylene. 

Non-discoloring, sulfur containing phenolic antioxidant and stabilizer that provides long-term heat stability by preventing thermo-oxidative degradation. Used for the process stabilization of polyethylene wire and cable resins for polyethylene during extruder compounding. Can also be applied in styrenic polymers, polypropylene, elastomers such as EPDM and SBR and for carboxylated SBR latex, polybutadiene rubber and polyisopropene rubber. 

Use Antioxidant for polypropylene, high-density polyethylene, spandex fibers, polyamides and specialty rubbers. 

Vitamin E, as an antioxidant choice for Polyethylene Medical Packaging, Anthony O Driskoll, Ciba speciality Chemical Inc. Basel, Switzerland. 

Polyethylene shows a relatively high resistance to oxidation compared to other polyolehns (polypropylene among them, see below), hence, requires lesser amount of antioxidants for processing and for the following service outdoors. 

Sumilizer BBM-S SWP SWP (antioxidant) Yoshinox BB, Antioxidant for polypropylene, polyethylene, nylon molding powders, and other polymer resins. DuPont Great Lakes Fine Chem. Monsanto Co. 

In this simple model description of antioxidant fimction, it can be seen, that a combination of primary and secondary antioxidants ensures a particularly effective stabilisation. Synergies resulting from mixing different antioxidants are still the subject of scientific investigation. Specific packages of stabilisers have been used as accepted standards in practice for a considerable time. A typical stabiliser package for polyethylene and polypropylene contains a phosphite and a phenolic antioxidant. (Zweifel 2001) reports on developments in antioxidants offered. 

In selecting stabilizers for practical application, an important factor is a knowledge of the effectiveness of compounds of various classes. Unfortunately, there are no data on series of antioxidants in the published literature as applied to concrete examples. Comparative data on the effectiveness of a limited number of antioxidants and their mixtures for polyethylene and polypropylene are cited only in [29, 41, 63, 64, 79, 80], However, even in these works the researchers limited themselves to a measurement of the induction period of the oxidation process, without investigating widely the change in properties of the polymer. 

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