Styrene to polypropylene film

Figure 3. Effect of divinylbenzene on grafting of styrene to polypropylene film in methanol at dose rate of 4.1 X 10 rad/h to 2.4 X 10 rad. Key A, styrene-methanol , styrene-methanol-divinylbenzene (1% v/v).

Fig. 2. Effect of miscellaneous solvents on radiation grafting of styrene to polypropylene film at dose rate of 4.0 x 10 rad/hr to total dose of 0.2 X 10 rad except dioxan (4.5 x 10 and 0.3 X 10 ).

Fig. 1. Acid effect in radiation grafting of styrene to polypropylene film (isotactic, doubly oriented, 0.06 mm) in methanol and ethanol at dose rate of 4.5 x 10" rad/hr to...

Figure 1. Role of dose rate in the synergistic effect of divinyl-benzene and sulfuric acid on grafting of styrene on polypropylene film in methanol dose rate of 4.1 x 104rad/hr to total dose of 2.4 x lO rad (A) styrene-methanol, (o) styrene-sulfuric acid (0.2M). ( ) styrene-methanol-divinylbenzene (1% v/v), and (o) styrene-methanol -di vinyl benzene (1% v/v)-sulfuric acid (0.2M). dose...

Styrene in methanol radiation grafted to polypropylene film (0.06 mm) at 4.1x10 rad/hr to dose of 2.4x10 rad in air. 

Table 1. Effect of Sulfuric Acid (0.02 M) on Radiation Grafting of Styrene in Low Molecular Weight Alcohols to Polypropylene Film ...

The optimum in the copolymerisation process occurs at 50% monomer concentration with both additives. The behaviour of sulfuric acid in these reactions is representative of the most reactive of the mineral acids (12). A comparison of TMPTA with H SO (0.2 M) also indicates that similar trends in enhancement in radiation grafting to polyethylene film are observed with both additives (Table III). Again, when polypropylene film is used as backbone polymer (Table IV), acid and DVB show similar increases in grafting yield with styrene in methanol, however in this system, it is interesting to note that the concentration of monomer at the position of the Trommsdorff peak does not vary for neutral and acidified grafting solutions but changes from 30% to 35% when DVB is additive. 

Monomers which have also been demonstrated to have been grafted to polyethylene and polypropylene film by this process include styrene and various acrylated esters, mixtures of acrylated esters, and acrylonitrile. The application of this technology to improving the barrier properties of films is discussed. Some initial data on the O2 barrier, fragrance/aroma, and haze performance of these graft modified films indicate substantial Improvement and place them in the high barrier range where dry Oo permeabilities of less than 1 cc/100 ln /24 hrs. are ootained. 

One can also make combined acrylic/urethane (hybrid) aqueous dispersions (33). Acrylic monomers are emulsion polymerized in the presence of an aqueous dispersion of a hydroxy-terminated polyurethane. The polyurethane stabilizes the aqueous dispersion, minimizing need for surfactant. Coalescence requires balance of the Tg of both the urethane and acrylic parts of the system. Compositions based on an IPDl/polypropylene glycol/DMPA urethane with styrene/methyl methacry-late/butyl acrylate are reported to form films at low temperatures. 

Although considerable work has been reported using preirradiation grafting, the present treatment will be confined to the mutual or simultaneous procedure since by this latter technique, much lower doses are needed to accomplish a particular percentage graft The simultaneous method is also amenable to the use of additives to accelerate copolymerization. The additives to be discussed in this paper include solvent, mineral acid and polyfunctional monomers for the grafting of styrene monomer to polyethylene and polypropylene films in the presence of gamma radiation ... 

Blends of butadiene-styrene block polymers with polyolefins, particularly polypropylene are mentioned in literature to improve the impact strength of the latter. Since similar improvements can be realized from the use of polyolefin block polymers, the blends have not gained much recognition. However, butadiene-styrene radial teleblock polymers are blended into polyethylene film, to increase the tear resistance and tensile impact. ... 

Photochemical grafting of monomers/molecules onto substrates continues to show interest in terms of improving property requirements. Dyes have been effectively photografted onto polypropylene and nylon 6 films using 1,2-diphenyl-2,2-dimethoxyethanone while methacrylic acid and acrylamide have been successfully photografted onto polypropylene sheets using benzophenone as a sensitiser in order to modify the surface of the polymer from a hydrophobic to a hydrophilic one. A styrene-2,2,6,6-tetramethyl-4-piperidinyl... 

In preliminary work (19), divinylbenzene (DVB) has been reported to be a useful additive for enhancing the above grafting reactions. These early data (19) indicate that there are possible common mechanistic pathways between the acid effect and the DVB process. More detailed DVB studies are discussed in this paper for enhancing the radiation grafting yields of styrene in methanol to films of polyethylene and polypropylene. The work has been extended to include the use of other polyfunctional monomers such as tri-methylol propane triacrylate (TMPTA) as additives. The possibility of being able to use these additives for copolymerisation of monomers to naturally occurring trunk polymers such as cellulose will also be considered. 

The properties of bitumen paints (Section 2.14.2) can be favorably modified and adjusted to suit practical requirements by combination with other film-forming substances. For example, the thermoplasticity can be reduced and/or mechanical properties (e.g., hardness, extensibility) can be improved by adding polymers such as polyethylene, polypropylene, polyisobutene, and styrene-butadiene copolymers. The chemical resistance can also be improved high-quality corrosion protection coatings can be obtained by combination with alkyd resins. 

It is important to see that a similar trend has been observed for the grafting of styrene into all three (PTFE, FEP, and PFA) films under identical conditions [75,78,86]. The DG increased dramatically with the increase in styrene concentration until it reached a maximum, and then decreased sharply as the concentration was increased further [74]. The authors emphasized that the DG of styrene in PTFE depends on both the number of radicals formed and the diffusion of styrene through the polymer matrix, and on its concentration in the grafting layers. Therefore, the increase in the DG in this system may be attributed to the increase in styrene diffusion and its concentration in the grafting layers. At very high concentrations of styrene, homopolymer formation was enhanced and the diffusion of styrene across the viscous medium was hindered. These studies are also supported by Cardona et al. [12] who observed that with increasing monomer concentration the DG reached a maximum and then decreased for styrene grafting into PFA and polypropylene. 

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