Polyvinylidenechloride

Packaging film from plasticized PVCD has improved thermal stability and reduced stickiness to metal surfaces when only 2 wt% of epoxidized soybean oil is added as a plasticizer. In addition, the metal soaps of ricinoleie acid are added. They also act as plasticiz-ers. The addition of 1 to 4 wt% tetraethylene glycol di-(2-ethylhexoate) is expected to reduce oxygen transmission rates and to improve extrudability of film.  

Vasiliy V. Tereshatov, Valery Yu. Senichev, Elsa N. Tereshatova, Marina A. Makarova Institute of Technical Chemistry, Ural Branch of Russian Academy of Sciences, Perm, Russia 

Plasticizers are blended with polyurethanes, PU, to regulate their rheological, thermal, and mechanical properties. Plasticizers are used in PU synthesis to lower viscosity of reaction medium and to dissolve reaction components (e.g., aromatic diamines).  

This section includes the following mechanism of the specific actions of plasticizers on the PU, the analysis of material properties affected by plasticizers, description of chemically inert liqttids applied as PU plasticizers, and discussion of selection principles of plasticizers for the segmerrled polyrrrethanes. 

The special attention is given to the mechanism of plasticizers action in segmented polyrrrethanes and perspectives of plasticizers application for regulating properties of polyrrrethane compositions. 

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The pore structure in molecular sieving carbon is typically ascribed to arise from at least three different mechanisms. In the first the structure of the carbon is derived from the precursor, but in shrunken form. In this way the structure of wood charcoal is similar to the cellular structure of the wood (2). Another type of porosity arises in the fissures and cracks left behind in the carbon matrix. These faults relieve the thermally-induced, mechanical stresses brought on by pyrolysis. Ultramicroporosity can also originate from the volatilization of small molecules. These molecules are formed during pyrolysis, and leave molecularly-sized channels in the solidifying carbon matrix (3-6). Pyrolysis of polyfurfuryl alcohol, polyvinylidenechloride, and polyacrylonitrile lead to the formation of formaldehyde and water, hydrogen chloride, and hydrogen cyanide, respectively. 

Factors of 1/100 and more were observed in the adsorption rates for bulky molecules like 3,3-diethylpentane compared to linear and planar molecules. The rate differences were attributed to steric limitations on the adsorption of the bulkier molecules. Separation of n-butane from isobutane was accomplished both on Saran- and other polyvinylidenechloride-derived carbons (9-11). 

Polyvinylidenechloride, PVDC, was discovered in 1838 by Regnault but commercialized 100 years later as Saran . The commercial PVDC is modified by the incorporation of either 15-20 wt% vinyl chloride, or 13 wt% vinyl chloride and 2 wt% acrylonitrile. PVDC blends are summarized in Table 1.32. 

Figure 9-33. Selectivity of different polymer membranes to He-N2 separation as a function of nitrogen permeability (n, incm /(cm x atm x s)) (1) polyvinylidenechloride (2,4)polyethylene terephthalafe (3) polyvinylfluoride (5) polyvinylchloride (6) polyamide (7) plasfified polyvinylidene chloride (8) cellulose nitrate (9) polypropylene (lO)fluoroplast (26) (ll)co-polymer of isoprene (74%) and acryl-nitryl (26%) (12, 18, 20) different co-polymers of butadiene and acryl-rritryl (13) polyacrylate (14) polycarbonate (15) polyisobutylene (16) bulyl latex (17) co-polymer of vinyl chloride and vinyl acetate (19, 37) butyl acetate of cellulose (21) polyethylene vinyl acetate (22) polybutadiene (23) special polymer SKI-3 (24) natural latex (25) nitryl silicon latex (26) dimethyl silicon latex (27) special polymer SKS-30 (28) special polymer SKMS-50 (29) special polymer SKMS-30 (30, 34, 35) high-density, medium-densily, and low-density polyethylene (31) polyethylene with 5% soot (32) co-polymer of ethylene (90%) and propylene (10%) (33) co-polymer of ethylene (96.5%) and vinyl acetate (3.5%) (36) triacetate of cellulose (38) acetate cellulose (39) polystyrene.

Polyvinylidenechloride (Saran ) Polyolefins Polyethylene Good Good Resistant Resistant except NH4OH Resistant Resistant Unstable Resistant... 

Polyvinylidenechloride is another chlorine containing plastic that can be produced in both sheet and fibre forms, though it is not made in anything like the same tonnage as PVC. It has more or less the same property of chemical inertness leading to bonding problems unless the correct adhesive is chosen. 

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