Polyethylene in the presence

Chlorination of natural rubber, involving both addition and substitution (with some cyclization), yields a product with improved chemical and corrosion resistance. Chlorination of polyethylene in the presence of sulfur dioxide results in substituting both chloride and sulfonyl chloride groups into the polymer. A commercially useful material is one which contains about 12 chlorides and one sulfonyl chloride per 40-45 repeating units. This extensive substitution converts the polyethylene, a plastic, into an elastomer by destroying crystallinity. 

Figure 2. Grafting of styrene in DMF to polyethylene in the presence of HtSOt at various concentrations total dose 0.5 X 10s rad at dose rate 0.080 X 10s rad/hr...

Figure 1. Plot of Gf vs. dose in the irradiation of various polyethylenes in the presence of CTFE (( ) HDPE (O) LDPE ((D) BG-LDPE-1 (C) BG-LDPE-2 (9) BG-LDPE-3 (Q) IG-LDPE) and in vacuum ((A) LDPE (A) HDPE)...

Figure 2. Plot of Dg vs. dose in the irradiation of various polyethylenes in the presence of CTFE (symbols are the same as in Figure 1)...

These results lead to the consideration that the cross-linking of polyethylene in the presence of CTFE is not... 

Radiation-induced cross-linking of various polyethylenes in the presence of CTFE... 

Figure 5 shows the relationship between the gel fraction and the total consumption of the unsaturated groups (—A[U] expressed by equation (4)) in the irradiation of butadiene-and isoprene-grafted polyethylenes in the presence of CTFE. 

Radiation-Induced Cross-Linking in the Presence of CTFE/Butadiene Mixture. On the basis of the results mentioned in the previous section, it is concluded that in the irradiation of polyethylenes in the presence of CTFE the polyethylenes are mainly cross-linked through the addition reaction of the unsaturated groups contained in the main and the side chains of the polymers to the propagating graft chain radical of CTFE. Therefore, the radiation-induced cross-linking of polyethylene is expected to be accelerated by the presence of the mixture of CTFE and a diene monomer effectively than the presence of pure CTFE. 

The radiation-induced cross-linking of polyethylenes in the presence of CTFE/butadiene mixture with various compositions are shown in Figure 6. The overall degree of co-grafting decreased gradually with the increase in the mole fraction of butadiene in the mixture, while the gel fraction of the polymer was increased rapidly by the addition of a small amount of butadiene to CTFE and then decreased with the increase in butadiene mole fraction in the mixture. The maximum of the gel fraction was found at about 0.1-0.2 of butadiene mole fraction in the mixture. 

N. G. Gaylord and R. Mehta, Peroxide-catalyzed Grafting of Maleic Anhydride onto Molten Polyethylene in the Presence of Polar Organic Compounds, J. Polym. Sci. Part A Polym. Chem., 26, 1189-1198 (1988). 

M. Sentmanat and S. G. Hatzikiriakos, Mechanism of Gross Melt Fracture Elimination in the Extrusion of Polyethylenes in the Presence of Boron Nitride, Rheol. Acta, 43,624—633 (2004). 

H. Nanbu, Y. Ishihara, H. Homna, T. Takesue, and T. Ikemura, Synthesis of Branched Polyethylene by Catalytic Degradation-Isomerization of High Density Polyethylene in the Presence of Silica-Alumina Catalyst, Chem. Soc. Jpn., 765-770 (1987). 

M. Blazso, B. Zelei, andE. Jakab, Thermal decomposition of low-density polyethylene in the presence of chlorine containing polymers, J. Anal. Appl Pyrol, 35, 221-235 (1995). 

Anbarasan, R. Babot, O. Maillard, B. Cross-linking of high-density polyethylene in the presence of organic peroxides. J. Appl. Polym. Sci. 2004, 93, 75-81. 

Uniaxial creep experiments were carried out on two types of commercial polyethylene In the presence of various environments. One polymer, which will be designated hereafter as sample D, was a linear polyethylene having a weight-average molecular weight (My) of 99,000 and a nominal density of 0.966 g/cm. ... 

Irradiation of solid polyethylene in the presence of air leads to a reduction in the concentrations of branches, an increase in the concentrations of hydroperoxide and carbonyl groups and a decrease in molecular weight. 

Apparently, this can explain an unusually steep temperature dependence of the OIT of polyethylene degradation, described in Application News T95 of Shimadzu DSC, entitled Measurement of Oxidizing Induction Time of PE by DSC. The authors have obtained the following data for the oxidation of polyethylene in the presence of an antioxidant ... 

Polyethylene - A large number of studies has been carried out reacting polyethylene in the presence of HZSM-5 is a... 

The decomposition of polyethylene in the presence of zeolite Y has also been extensively studied using a variety of catalyst-polymer contacting patterns.Zeolite Y is a component of commercial fluidized catalytic cracking catalysts that is very stable under hydrothermal conditions and has relatively large pores (7.8 A pores and 11.8 A supercages). Since the pores are... 

Figure 7 Proposed mechanism for decomposition of polyethylene in the presence of acid catalysts via carbenium ion chemistry...

Low chlorination of polyethylene, causing random substitution, reduces chain order and thereby also the crystallinity. The low chlorine products (22-26% chlorine) of polyethylene are softer, more rubber-like, and more compatible and soluble than the original polyethylene. However, much of the market of such materials has been taken up by chlorosulfonated polyethylene (Hypalon, Du Pont), produced by chlorination of polyethylene in the presence of sulfur dioxide, which introduces chlorosulfonyl groups in the chain. 

Very recently, siloxane-crosslinked wood plastic composites based on the use of spruce and pine wood fibres and high density polyethylene in the presence of varying amounts of vinyltrimethoxysilane (XIV) have been reported [43]. 

Gaylord, N. G. and Mishra, M. K. 1983. Nondegradative reaction of maleic anhydride and molten polypropylene in the presence of peroxides. Journal of Polymer Science Letters 21 23-30. Gaylord, N. G. and Mehta, R. 1988. Peroxide-catalyzed grafting of maleic anhydride onto molten polyethylene in the presence of polar organic compounds. Journal of Polymer Science, Part A Polymer Chemistry 26 1189-1198. 

Semikolenova, N. V., Nesterov, G. A., and Zakharov, V. A. 1986. Preparation of polymerization-filled polyethylene in the presence of catalysts based on organic and hydride compounds of Ti, Zr, Cr. Polymer Science USSR 28 186-192. 

Fiiardo, G., Dispenza, C., Silvestri, G. and Sparado, G. (1998) Irradiation of low and high density polyethylenes in the presence of carbon dioxide insubcritical an supercritical condition, y. Supercritc Fluids, 12, 177-184. 

Hakim, S. MobaUegh, L., Tailoring MWD of Bimodal Polyethylene in the Presence of Zeigler-Natta Catalyst. Macromol. Symp. 2011, 302,191-197. 

It is characteristic that the practical absence of autocatalysis during oxidation is observed for a number of sulfur-containing compounds in conjunction with carbon black. For example, at 140°C the induction period of the oxidation of polyethylene in the presence of 0.1% 2-thionaphthol was equal to 10 hr, while in the presence of 3% channel black it was 30 hr. In the case of the joint action of these antioxidants, slow oxidation began after 1000 hr autocatalysis was not observed even after 2000 hr. An analogous picture is observed for combinations of carbon black with thiurams [90]. 

When heated with polyethylene, in the presence of radical initiators, poly(maleic anhydride) becomes grated to the polyolefin, with a grafting degree of 4.4% (see Sec. 11.1). The properties of this type material are more appropriately discussed in Chapter 11. 

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