Plasticisers phthalates

The application fields of plasticisers range from automobiles and construction to toys and medical products. Phthalate plasticisers such as dibutyl phthalate and di(2-ethylhexyl) phthalate are widely used due to the higher plasticising efficiency and lower volatility of these phthalate plasticisers. Phthalate plasticisers are still widely used in the processing of flexible PVC [29]. However, recently, the use of phthalate plasticisers has been questioned due to their debatable toxicity in consumer products made of PVC matrices, especially in blood supply and similar medical plastics, because the content of... 

Plasticisers Phthalate, trialkylphosphate, adipate esters Chlorinated paraffins High molecular weight polyesters Epoxy derivatives... 

The use of PVC feeding tubes is limited. PVC is firm but can be uncomfortable for the patient. The plasticisers in PVC dissolve when exposed to gastric juices. As a result, the feeding tube becomes hard and fragile and can therefore be used for a maximum of 10 days [2]. In practice the use is limited to 1 week. Lipophilic medicines easily adsorb to PVC. Lipophilic solvents, such as acetem (see Sect. 23.3.6) when administered through PVC feeding tubes may cause plasticisers (phthalates) to dissolve and the feeding tube to crumble. 

For over 20 years there has been a continued debate on the potentially negative environmental and health effects of phthalate based plasticisers. Phthalates are diesters of phthalic acid anhydride and alcohols. The most... 

A primary plasticiser for PVC is regarded as one which is fully compatible with the resin up to at least 100 parts per hundred parts resin (phr) and can be satisfactorily used for many applications as the sole plasticiser. Phthalate and phosphate esters and certain polyesters come into this category. A secondary plasticiser has limited compatibility with PVC, but is normally incorporated in a PVC compound as a partial replacement for a primary plasticiser to impart a specific desirable physical property. Low temperature plasticisers such as sebacates and adipates are typical of this category. Plasticiser extenders are plasticisers of limited efficiency and compatibility such as chlorinated paraffins and certain hydrocarbon oils, which are included in the composition to reduce costs. 

The majority (92% in 1988) of the butyraldehyde produced in the United States is converted into 1-butanol and 2-ethyIhexanol (2-EH). 2-EH is most widely used as the di(2-ethylhexyl) phthalate [117-81-7] ester for the plasticisation of flexible PVC. Other uses for 2-EH include production of intermediates for acryflc surface coatings, diesel fuel, and lube oil additives (24). 

However, not all EDs with a high log possess or require the ability to bioaccnmulate in order to be biologically active. For example, phthalate plasticisers, chlorophenols from Kraft mill effluents and natural or synthetic hormones can influence an organism s hormone profile and affect reproductive function and immune response without exhibiting bioaccnmiilation. ... 

From Table 5.7 it will be seen that plasticisers for PVC such as the octyl phthalates, tritolyl phosphate and dioctyl sebacate have solubility parameters within 1 cgs unit of that of the polymer. Dimethyl phthalate and the paraffinic oils which are not PVC plasticisers fall outside the range. It will be noted that tritolyl phosphate which gels the most rapidly with PVC has the closest solubility parameter to the polymer. The sebacates which gel more slowly but give products which are flexible at lower temperatures than corresponding formulations from tritolyl phosphate have a lower solubility parameter. It is, however, likely that any difference in the effects of phthalate, phosphate and sebacate plasticisers in... 

Comparison of Table 5.4 and 5.7 allows the prediction that aromatic oils will be plasticisers for natural rubber, that dibutyl phthalate will plasticise poly(methyl methacrylate), that tritolyl phosphate will plasticise nitrile rubbers, that dibenzyl ether will plasticise poly(vinylidene chloride) and that dimethyl phthalate will plasticise cellulose diacetate. These predictions are found to be correct. What is not predictable is that camphor should be an effective plasticiser for cellulose nitrate. It would seem that this crystalline material, which has to be dispersed into the polymer with the aid of liquids such as ethyl alcohol, is only compatible with the polymer because of some specific interaction between the carbonyl group present in the camphor with some group in the cellulose nitrate. 

In the rubber industry hydrocarbon oils are often used to reduce the softness and facilitate the processing of hydrocarbon rubbers. These appear to have a small interaction with the polymer but spacing effects predominate. Such materials are generally referred to as softeners. The rubber industry, like the plastics industry, commonly uses the term plasticisers to describe the phthalates, phosphates and sebacates which are more commonly used with the more polar rubbers. 

In volume terms the most important class of fire retardants are the phosphates. Tritolyl phosphate and trixylyl phosphate are widely used plasticisers which more or less maintain the fire-retarding characteristics of PVC (unlike the phthalates, which reduce the flame resistance of PVC products). Better results are, however, sometimes obtained using halophosphates such as tri(chloroethyl) phosphate, particularly when used in conjunction with antimony oxide, triphenyl stibine or antimony oxychloride. 

Benzenesulphonohydrazide (III) Hydrazide N2,H20 146 170-250 Blowing power affected by phthalate and phosphate plasticisers. 

All PVC plasticisers have a solubility parameter similar to that of PVC. It appears that differences between liquids in their plasticising behaviour is due to differences in the degree of interaction between polymer and plasticiser. Thus such phosphates as tritolyl phosphate, which have a high degree of interaction, gel rapidly with polymer, are more difficult to extract with solvents and give compounds with the highest brittle point. Liquids such as dioctyl adipate, with the lowest interaction with polymer, have the converse effect whilst the phthalates, which are intermediate in their degree of interaction, are the best allround materials. 

Developments in the USA have led to the availability of terephthalate plasticisers, for example dioctyl terephthalate (DOTP). Whilst these materials are very similar to the corresponding o-phthalate esters they are generally less volatile and are best compared with d-phthalates with one or more carbon atom in the alkyl chain. As with the linear dialkyl phthalates the terephthalates show good fogging resistance. This is a phenomenon in which new cars on storage fields awaiting delivery develop misting on the windows due, apparently, to the volatility of additives in PVC compounds used with the car. 

Figure 12.24. Effect of plasticiser (diaphanyl phthalate) on initial paste viscosity with two...

Plasticisers are sometimes added to the polymer, dibutyl phthalate being commonly employed in quantities of the order of 5%. Use in moulding powders will enhance the melt flow but somewhat reduce the mechanical properties of the finished product. 

Although many plasticisers have been suggested for cellulose acetate very few have been used in practice. The most important of these are dimethyl phthalate (8 = 21.4), triacetin (8 = 20.3) and triphenyl phosphate (8 = 20.0), each of which have a solubility parameter within one unit of that of cellulose diacetate (-22.0). (All in units ofMPa. )... 

Triphenyl phosphate is a crystalline solid which has less compatibility with the polymer. This may be expected from solubility parameter data. It is often used in conjunction with dimethyl phthalate and has the added virtues of imparting flame resistance and improved water resistance. It is more permanent than DMP. Triacetin is less important now than at one time since, although it is compatible, it is also highly volatile and lowers the water resistance of the compound. Today it is essential to prepare low-cost compounds to allow cellulose acetate to compete with the synthetic polymers, and plasticisers such as ethyl phthalyl ethyl glycollate, which are superior in some respects, are now rarely used. 

Table 22.4 Influence of amount of plasticiser (dimethyl phthalate) on some physical properties of cellulose acetate compositions...

In some moulding compositions other special purpose ingredients may be incorporated. For example, naphthalene, furfural and dibutyl phthalate are occasionally used as plasticisers or more strictly as flow promoters. They are particularly useful where powders with a low moulding shrinkage are required. In such formulations a highly condensed resin is used so that there will be less reaction, and hence less shrinkage, during cure. The plasticiser is incorporated to... 

In order to increase the flexibility, and usually, in consequence, the toughness of the resins, plasticisers and flexibilisers may be added. Non-reactive plasticisers such as the conventional phthalates and phosphates have proved unsuccessful. Monofunctional materials, which in some cases also act as reactive diluents, have been used but are not of great importance. 

The hydrohalide is liable to dehydrochlorination, particularly when moist acid is used in its preparation, so that hydrochloric acid acceptors such as lead carbonate are useful stabilisers. Dibutyl phthalate and tritolyl phosphate are effective plasticisers. Rubber hydrochloride is used as a packaging film (Pliofilm) and as a rubber-to-metal bonding agent (e.g. Typly). 

Plasticised amorphous thermoplastics Certain plastics may be mixed with high-boiling low-volatility liquids to give products of lower T. The most important example occurs with p.v.c. which is often mixed with liquids such as di-iso-octyl phthalate, tritolyl phosphate or other diesters to bring the below room temperature. The resultant plasticised p.v.c. is flexible and to some degree quite rubbery. Other commonly plasticised materials are cellulose acetate and cellulose nitrate. 

Being slightly crystalline, there are few good solvents, the best known of which are nitrobenzene, cyclohexanone and tetrahydrofuran. When mixed with certain non-volatile solvents such as some phthalates, adipates and phosphates, flexible materials are obtained and which are referred to as plasticised p. v.c. 

Brandt [200] has extracted tri(nonylphenyl) phosphite (TNPP) from a styrene-butadiene polymer using iso-octane. Brown [211] has reported US extraction of acrylic acid monomer from polyacrylates. Ultrasonication was also shown to be a fast and efficient extraction method for organophosphate ester flame retardants and plasticisers [212]. Greenpeace [213] has recently reported the concentration of phthalate esters in 72 toys (mostly made in China) using shaking and sonication extraction methods. Extraction and analytical procedures were carefully quality controlled. QC procedures and acceptance criteria were based on USEPA method 606 for the analysis of phthalates in water samples [214]. Extraction efficiency was tested by spiking blank matrix and by standard addition to phthalate-containing samples. For removal of fatty acids from the surface of EVA pellets a lmin ultrasonic bath treatment in isopropanol is sufficient [215]. It has been noticed that the experimental ultrasonic extraction conditions are often ill defined and do not allow independent verification. 

MAE has also been used for the extraction of adipate plasticisers from PVC [464]. The efficiency of MAE depends on the kind of solvent, the temperature achieved and the heating time. The final temperature reached depends on the microwave power, number of vessels and irradiation time. Higher recovery values than SEE were reported for both phthalate and adipate. Other reports on microwave-assisted solvent extraction have appeared [465-467]. 

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