PE graft copolymers

Table 4 summarizes the reaction conditions and the experimental results. Overall, the experimental results clearly show a new class of PE graft copolymers which can be conveniently prepared by the tranformation of metallocene catalysis to anionic graft-from polymerization. 

PE Graft Copolymers Prepared by Graft-from Reactions... 

The lithiated polyethylene copolymer was then suspended in hexane or THF solvent. The graft-from reactions were carried out in slurry solution by reacting the lithiated polyethylene copolymer with anionic polymerizable monomers, such as styrene and p-methylstyrene. After certain reaction time, 10 ml of isopropanol was added to terminate the graft-from reaction. The precipitated polymer was filtered and then subjected to fractionation. Good solvents for backbone and side chain polymers were used during the fractionization, using a Soxhlet apparatus under N2 for 24 hours. The soluble fractions were isolated by vacuum-removal of solvent. Usually, the total soluble fractions were less than 5 % of the product. The major insoluble fraction was PE graft copolymer, which was completely soluble in xylene or trichlorobenzene at elevated temperatures. 

With a polyethylene backbone, this grafting technique will not yield pure poly (ethylene-g-vinyl chloride)—"pure graft copolymer —but a mixture of this compound with PVC homopolymer and unmodified polyethylene. We call this raw graft polymerization product "VC/PE graft copolymer. Sometimes, we add its gross composition between parentheses—for example, VC/PE (50-50) graft copolymer. The same statement applies to the other backbone polymers. 

Graft Copolymers with High Backbone-Polymer Content. Work on VC/PE graft copolymers of this type led to a process (10) now being tested on pilot-plant scale. Its industrial application is being considered. The process is also applicable to other backbone polymers that are sufficiently swelled by this monomer. Most grades of ethylene-propylene... 

The backbone polymer is used in powdered form or as pellets or chips. The end product is generally of the VC/backbone (50-50) type. The process described here is for the VC/PE graft copolymers. 

To obtain a homogeneous VC/PE graft copolymer, all the liquid vinyl chloride must be absorbed in the polyethylene. This condition is realized when, at the polymerization temperature, the partial pressure... 

VC/PE Graft Copolymers. The most useful VC/PE graft copolymers are those with a high backbone-polymer content. 

The compatibilizing effect of poly(ethylene-g-vinyl chloride), the characteristic constituent of these VC/PE graft copolymers, may be shown by electron photomicrographs of films consisting of a PVC-PE/50-50 mixture on the one hand, and of a VC/PE (50-50) graft copolymer containing about 50 of poly(ethylene-g-vinyl chloride), 25 of polyethylene and 25 of polyvinyl chloride on the other hand (see Figure 8). The films were obtained from a solution in o-dichlorobenzene. In the first case, the polyvinyl chloride and polyethylene phases are clearly separated in the second case, they interpenetrate closely. 

Transparency. Alloys of PVC and VC/PE graft copolymer are more transparent than PVC-polyethylene mixtures having the same total polyethylene content. Graft copolymers based on high-density polyethylene give better transparency than do similar graft copolymers based on low-density polyethylene. Perfect transparency, however, cannot be obtained. 

Table III. Melt Viscosity of PVC-VC/PE Graft Copolymer Mixtures...

Figure 17. Notched Izod impact strength of PVC-VC/PE graft copolymer alloys and proportion of unbroken specimens hammer 10 ft-lb...

Figure 18. Influence of the gelling time on the Izod impact strength (notched) of a PVC/PE graft copolymer alloy (87% Solvic 239 + 13% VC/LD PE (50-50) graft copolymer) hammers 3 ft-lb, 10 ft-lb...

VC/PE Graft Copolymers. These applications have already been studied in some detail ... 

Use of Crosslinked VC/PE Graft Copolymers for Cable Insulation. At high temperatures, plasticized PVC cable insulations show a rather high flow. This should be improved by crosslinking of the thermoplastic insulation material. Unfortunately, PVC is not easily cross-linkable by chemical agents. The presence of about 503 of grafted or... 

Table VII. Crosslinking of Plasticized VC/PE Graft Copolymer Compositions...

Our work on vinyl chloride graft copolymers has led to the development of a graft polymerization process for the production of homogeneous VC/PE graft copolymers with high backbone-polymer content. This process is now being tested on a pilot-plant scale, and industrial applications are being considered. 

The brittleness of the VC/PE graft copolymers excludes their use without modification. Nevertheless, they should be useful PVC additives for improving impact strength and lowering melt viscosity. 

PE graft copolymers were synthesized from PE-OH by Inoue et al. using ATRP techniques, adopting similar techniques as mentioned above [74]. PE-g-PMMA and Polyclhylcnc-gra/f-poly( -bulyl acrylate) (PE-g-PnBA) were prepared through the combination of metallocene-catalyzed ethylene/10-undecen-l-ol copolymerization and conversion of the copolymer into P E-g-Br, as a macroinitiator, for ATRP. Well-defined graft copolymers, PE-g-PMMA and PE-g-PnBA, were confirmed by analyses of the detached side chains. Resulting PE-g-PMMA worked well as a compatibilizer. 

The preparation of PnBA-g-PE and PtBA-g-PE graft copolymers was reported using Fe-mediated olefin polymerization, chain shuttling with Zn and ATRP techniques [108]. Terminally hydroxyl PE was synthesized from Zn-terminated PE by oxidation and hydrolysis, as referred to above. It was converted to methacrylated PE, as PE macromonomer, using methacryloyl chloride. The resulting PE macromonomer was used for the copolymerization of nBA or tBA by ATRP using CuBr/tris((N,N-dimclhylamino)clhyl)aminc. The obtained graft copolymers were characterized by GPC, DSC, and JH NMR. 

Macroalkoxyamines were prepared by reacting brominated copolymer with hydroxylamine. PE graft copolymers (22.6 mol% of PSt) were obtained via NMRP of St initiated from the macroalkoxyamine. 

Preparation of Polyamide-PE graft copolymer by reactive melt blending process (from ref. 11). 

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