Polyvinyl chloride sebacates

Fig. 4. Transport selectivity Kjj and potentiometric selectivity Kj j of a Na+-selective neutral carrier membrane using ligand 11. Experimental coefficients fCNaM obtained with (2) and (11) respectively given for different cations M. Membrane composition 32wt.% polyvinyl chloride, 65 wt.% dibutyl sebacate, 3wt.% carrier //. Thickness of membrane = 100 p.m. Current density approx. 0.1 p.Amm 2.

The selectivity factors determined in potentiometric studies (K[,ot) should therefore be identical to the ones (Kjj) determined in transport experiments. In Fig. 4 selectivities obtained potentiometrically on a membrane containing ligand 11 (3 wt.% carrier 11, 65 wt.% dibutyl sebacate 32 wt.% polyvinyl chloride, thickness =100 /xm) are compared with those obtained in electrodialytic transport experiments.55 Although widely different methods have been used to determine the ion selectivity, the agreement between the two sets of data is evident and corroborates the model presented. The deviation for CsH may possibly be due to kinetic limitations suggesting a loss in transport selectivity (see Section IV.D). 

Arcites are rocket propellants developed recently in the US by Atlantic Research Corp, Alexandria, Virginia. They usually contain oxidizers(sueh as AN or NH4C104), binders (such as polyvinyl chlorides) and plastici-zers(such as dibutyl sebacate)... 

The external plasticizing method is applied most frequently to polyvinyl chloride (PVC). The distance between the macromolecules of the plastics is increased by incorporation of plasticizer molecules [aromatic plasticizers, e.g., tricresyl phosphate (TCP) and aliphatic plasticizers, e.g., dioctyl phthalate (DOP) or dioctyl sebacate (DOS)]. This reduces the secondary bonding forces and increases chain segment mobility. Solvents (including water in polyamides) may also act by inward diffusion in a manner similar to plasticizers [11]. 

Several electrodes are used for the direct determination of pharmaceuticals. For example, an electrode is prepared using a polyvinyl chloride (PVC) membrane and bis(2-ethylhexyl)sebacate has been applied to tetracyclines in pharmaceutical formulations. The system has also been used to obtain the dissolution profile of some tetracycline formulations. A membrane for the determination of dopamine was synthesized using a CuS04-poly(ethylene-co-vinyl acetate) mixture in tetrahydrofuran, and the resulting solution was dropped into a tubular graphite-epoxy electrode. The drug was oxidized by Cu(II) immobilized on the membrane. 

The irritancy of polyvinyl resins is due to the plasticizers and stabilizers, dibutyl thiomaleate, dibutyl sebacate or dioctyl phthalate (Di Lernia et al. 1989 Kanerva et al. 1996). PVC powder may irritate in a special environment. An outbreak of acneform eruptions occurring in a PVC-manufacturing factory has been reported (Goh and Ho 1988). The cause was probably the combination of heat, high humidity and the irritation caused by the PVC powder. Toxic polyvinyl chloride disease from the manufacturing of PVC, consisting of Raynaud s phenomenon, lytic disease of bone, and scleroderma, has been reported. 

Plasticizers, which are added to improve the flexibility, softness and processibility of plastics, constitute a broad range of chemically and thermally stable products of a variety of chemical classes. Their principal use is in thermoplastic resins, and 80-85% of the world s production of plasticizers are used in polyvinyl chloride (PVC) manufacturing. Approximately 450 plasticizers are commercially available. Many are esters of carboxylic acids (e.g. phthalic, isophthalic, adipic, benzoic, abietic, trimellitic, oleic, sebacic acids) or phosphoric acid. Other plasticizers are chlorinated paraffins, epoxidized vegetable oils and adipate polymers. 

On the other hand, GC, because of the physical separation it effects, furnishes both a qualitative and a quantitative analysis of polymer-plasticiser mixtures with almost the same ease as the analysis of plasticisers alone, and this is discussed further in Chapter 5.1. It suffices to submit the sample, prepared as for the pyrolysis of plastics, to a controlled pyrolysis in order to disengage the vaporised plasticisers. The polymer is partially degraded, but its pyrolysis products were in all the cases studied by Guiochon and Hennicker [82] much lighter than the plasticisers and in no way prevented their separation and identification. Figure 4.18 shows the separation obtained of four plasticisers (a) dibutyl succinate, (b) tributyl phosphate, (c) dimethyl sebacate and (d) diethyl phthalate and the pyrolysis products of polyvinyl chloride. The latter are eluted during the first minute of operation. 

Mainly used in polyvinyl chloride, chloroethylene copolymer, nitrocellulose, ethyl cellulose, and synthetic rubber. It is especially suitable material for making cold-resistant cables, leatherette, thin film, and sheet materials. Dioctyl sebacate is often used in combinatirai with acetate o-phthalate plasticizer and can also be used as a plasticizing agent in producing many kinds of S5fnthetic rubbers. 

Among the additives used to modify the properties of polymeric packaging materials, plasticisers have raised much concern from the hygienic point of view. Butyl stearate, acetyltributyl citrate, alkyl sebacates and adipates are important because they are types of plasticisers that typically have low toxicities. Materials such as epoxidised soybean oil are widely used in polyvinyl chloride, polyvinylidene chloride and polystyrene as thermal stabilisers and lubricants at a level of 0.1-27%. Toxicity of epoxidised soybean oil is affected by the presence of oxirane, also known as ethylene oxide, which was upgraded to Group 1 as a carcinogenic agent to humans, based on mechanistic and other relevant data. 

An excsllent low tea erature plasticizer for a wide range of polynere, particularly nitrile rubber, chloroprene rubber and polyvinyl chloride. It is essentially the ester of triethylene glycol with linear acids, average carbon nuaber C9 and gives superior low teagierature performance to the adipates end the sebacates. 

Exchange between product and pack can occur in both directions, e.g. certain labelling materials such as heat sensitive and self-adhesive labels when in contact with plastic materials. Both the plastic and the adhesives may contain plasticisers or migratory constituents. Most cellulosics use phthalate, sebacate, phosphate-type plasticisers (e.g. methyl phthalate (DMP) may be used in cellulose acetate). Plasticisers may also be found in poly vinyl chloride/acetate copolymers, polyvinyl acetate and polyvinyl alcohol formulations, polymethyl methacrylate, nylon and certain thermosetting resins. 

Dibutyl sebacate (DBS) n. (CH2)s (COO C4H9)2. a plasticizer, one of the most effective of the sebacate family. It has good low-temperature properties, low volatility, and is compatible with vinyl chloride polymers and copolymers, polyvinyl butyral, and ethyl cellulose. It is non-toxic, suitable for uses in food wrappings. 

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