Film Flexibility

Poly(vinyhdene chloride) (PVDC) film has exceUent barrier properties, among the best of the common films (see Barrier polymers). It is formulated and processed into a flexible film with cling and tacky properties that make it a useful wrap for leftovers and other household uses. As a component in coatings or laminates it provides barrier properties to other film stmctures. The vinyUdene chloride is copolymerized with vinyl chloride, alkyl acrylates, and acrylonitrile to get the optimum processibUity and end use properties (see Vinylidene chloride monomer and polymers). 

Polypyrroles. Highly stable, flexible films of polypyrrole ate obtained by electrolytic oxidation of the appropriate pyrrole monomers (46). The films are not affected by air and can be heated to 250°C with Htde effect. It is beheved that the pyrrole units remain intact and that linking is by the a-carbons. Copolymerization of pyrrole with /V-methy1pyrro1e yields compositions of varying electrical conductivity, depending on the monomer ratio. Conductivities as high as 10 /(n-m) have been reported (47) (see Electrically conductive polymers). 

Copolymers wet and adhere well to nonporous surfaces, such as plastics and metals. They form soft, flexible films, in contrast to the tough, horny films formed by homopolymers, and are more water-resistant. As the ratio of comonomer to vinyl acetate increases, the variety of plastics to which the copolymer adheres also increases. Comonomers containing functional groups often adhere to specific surfaces for example, carboxyl containing polymers adhere well to metals. 

Process of molding or laminating in wliich fluid pressure is applied, usually by means of water, steam, air or vacuum, to a flexible film or bag that transmits the pressure to the material being molded. 

Phenoxaphosphine ring-containing poly (1,3,4-oxa-diazoles) were synthesized by cyclodehydration of poly-hydrazides obtained from (BCPO) and aliphatic and aromatic dihydrazines [152]. All these polymers are soluble in formic acid, w-cresol and concentrated H2SO4. The polyhydrazides yield transparent and flexible films when cast from DMSO solution under reduced pressure at 80-100°C. The polyhydrazides exhibit reduced viscosities of 0.24-0.40 dl/g in DMAC. Phenoxaphosphine ring-containing oxadiazole polymers showed little degradation below 400°C. 

Polyoxamides Phenolphthalein polymers Some melting points above 400°C (752°F) give clear, flexible films. Melting points of 300°C (572°F) to over 400°C (752°F) formable into fiber and film. 

Polyhydroxybenzoic acids Films melt at 380-450° C (716-842°F) stable to oxidation but not to hydrolysis tough, flexible films good thermal stability. 

The flexible film products used in these experiments were all constructed for heat seal closure. Packets were made by heat sealing three sides of two 2% inch squares of the subject film together face to face. The heat seal was XA inch wide along each edge. 

The most effective antiozonants are the substituted PPDs. Their mechanism of protection against ozone is based on the scavenger-protective film mechanism [68-70]. The reaction of ozone with the antiozonant is much faster than the reaction with the C=C bond of the rubber on the rubber surface [56]. The rubber is protected from the ozone attack tUl the surface antiozonant is depleted. As the antiozonant is continuously consumed through its reaction with ozone at the mbber surface, diffusion of the antiozonant from the inner parts to the surface replenishes the surface concentration to provide the continuous protection against ozone. A thin flexible film developed from the antiozonant/ozone reaction products on the mbber surface also offers protection. 

Table I serves to illustrate how the nature and size of the substituent attached to the P-N backbone can influence the properties of the poly(organophosphazenes). The glass transition temperatures range from -84 °C for (NP CH-CH ) to around 100 °C for the poly(anilinophosphazenes). Polymers range from elastomers to flexible film forming thermoplastics or glasses at room temperature.

These waxes have branched structures of higher molecular weight (40-70 carbon atoms) than paraffin waxes and form a quite different crystalline structure on the surface of the rubber when emerging from solution from within the vulcanised rubber. Microcrystalline waxes form smaller crystals, which pack tighter together to form a more coherent, much more flexible film on the rubber surface which is more resistant to ozone penetration. 

Variation of Maleate to Vinyl Ether Ratio. Variation of the stoichiometric ratio of vinyl ether double bond to maleate double bond should produce more flexible films due to plasticization by dangling end groups but also may reduce cure speed and mechanical properties. The curing of unsaturated polyester F with DVE-3 using 4% Darocur 1173... 

Six novel fluorinated poly(aryl ether)s containing 1,4-naphthalene moieties were synthesized in high yield using 2,2-bis[4-( 1 -naphthoxy)phenyl]hexafluoro-propane (1). Oxidative coupling ofl yielded a polymer with high 7, low moisture absorption, and low dielectric constant that could be cast into flexible films. The low dielectric constant and low moisture absorption of 6FNE may make it useful as a dielectric insulator in microelectronics applications. 

The solubility is generally improved by the introduction of fluorine atoms into aromatic condensation polymers. Poly(carbonate)s containing hexafluoroisopropylidene units are much more soluble than Bisphenol A poly(carbonate) (3). All of the hexafluoroisopropylidene-unit-containing poly(carbonate)s become soluble in acetone, ethyl acetate, chloroform, and dimethyl sulfoxide (DMSO) in addition to the solvents of Bisphenol A poly(carbonate) (3). Colorless, transparent, and flexible films are prepared from hexafluoroisopropylidene-unit-containing poly(carbonate)s by casting or pressing. 

Because flexible films have excellent strength and good electrical and thermal properties, have low permeability to gases, water, oil, odour and could be sterilised so they are used in capacitors, cables, magnetic recording tapes, typewriter ribbons, food packaging, tracing film, book covers, etc. The film is coated with aluminium by vacuum disposition and used for decoration and in textiles. 

Al(acac) flexible film Mn(acac)3 very brittle film... 

Fe(acac)3 brittle film NiCl2-6H20 flexible film... 

Lithium containing films were unusual in that the film after curing was damp on the surface with what appeared to be the solvent, DMAC. No other films exhibited this property. The AgNO containing film had the appearance of a silver mirror but the film was exceedingly brittle and "flaky-like". Only two truly flexible films were produced from BTDA + m,m -DABP. These contained Al(acac)3 and NiCl2 6H2O respectively. 

Stretch wrap is a strong, flexible film that can be stretched to take the shape of the contained goods. It is used at home to over-wrap fresh meat and other leftovers or industrially to secure shipping cartons to pallets. It is usually made of LLDPE, LDPE or PVC. 

Fluorinated poly(imide-ether-amide)s are readily soluble in organic solvents like dimethylformamide (DMF), N-methylpyrrolidone (NMP), pyridine or tetrahydrofu-ran (THF) and give flexible films by casting of such solutions. These polymers exhibit decomposition temperatures above 360°C, and glass transition temperatures in the 221-246° C range. The polymer films have a low dielectric constant and tough mechanical properties. 

The authors reported that tough, flexible films were obtained by solution casting from dimethyl sulfoxide (DMSO), which would indicate little or no backbone chain degradation occurred during phos-phonation and dealkylation. 

We have observed both dark and photo-induced one-dimensional currents along DNA strands aligned in the flexible film. The DNA-lipid film, in which aligned rod-like strands with hairy alkyl side chains occur, shows thermotropic liquid crystal properties. 

The aligned-DNA, transparent, self-standing, and flexible film is of interest as a new naturally-occurring functional material, as well as an anisotropic conductive film. For example, the DNA-lipid film is effective as an adsorption filter of carcinogens such as acridine orange and ethidium bromide. The aligned-DNA film also shows polarization of light. 

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