REACTIVE PLASTICISER

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. 

Triallyl cyanurate(TAC) was used as a reactive plasticiser to promote the high-temp, creep resistance of PVC plastisols. The resultant crosslinked structure was characterised using gel content and swell ratio measurements as well as FTIR spectroscopy. The crosslinking reaction was initiated using peroxide. The effect on the network structure of using a free radical scavenger in the formulation was also studied. The gel yield and crosslink density in the gel increased with increasing TAC concentration in the plastisol, while the... 

Often non reactive plasticisers, such as saturated polyester adipates or epoxidised soya bean oils, are added in small quantities to thermosetting acrylics to improve the flexibility or drawing properties of the coating. 

Louisville, Ky., 8th-l 1th Oct.1996, Paper 17, pp.37. 012 STABLE CROSSLINK SYSTEMS AND A REACTIVE PLASTICISER FOR IMPROVED WEAR RESISTANCE OF TRUCK TREADS... 

The chloride ion is the most frequent cause of contact corrosion, since chlorine is present in the many chlorinated plastics, and is also frequently retained in residual amounts from reactive intermediates used in manufacture. Thus epoxides usually contain chloride derived from the epichlor-hydin used as the precursor of the epoxide. In addition to the contaminants referred to in Table 18.18, various metal and ammonium cations, inorganic anions and long-chain fatty acids (present as stabilisers, release agents or derived from plasticisers) may corrode metals on contact. 

Various additives show considerable extraction resistance, such as impact modifiers (polyacrylates and polyblends PVC/EVA, PVC/ABS, etc.), highpolymeric processing aids (PMMA-based), elastomers as high-MW plasticisers, reactive flame retardants (e.g. tetrabromobisphenol-A, tetrabromophthalic anhydride, tetrabromophthalate diol, dibromostyrene). Direct measurement of additives by UV and IR spectroscopy of moulded films is particularly useful in analysing for additives that are difficult to extract, although in such cases the calibration of standards may present a problem and interferences from other additives are possible. 

Many common polymers, polymeric additives and lubricants oxidise so rapidly after impact in liquid oxygen that they are hazardous. Of those tested, only acrylonitrile-butadiene, poly(cyanoethylsiloxane), poly(dimethylsiloxane) and polystyrene exploded after impact of 6.8-95 J intensity (5-70 ft.lbf). All plasticisers (except dibutyl sebacate) and antioxidants examined were very reactive. A theoretical treatment of rates of energy absorption and transfer is included [1], Previously, many resins and lubricants had been examined similarly, and 35 were found acceptable in liquid oxygen systems [2],... 

They may also act as reactive super plasticisers to increase rubber flow while increasing the mechanical properties of the rubber. Viscosity reduction or polymer solvation and higher filler loading can be accomplished with less plasticiser. Flow is achieved through molecular rearrangement and not average molecular weight reduction of the rubber. 

In summary, there are at least four ways in which residual moisture in the amorphous state can impact on chemical reactivity. First, as a direct interaction with the drug, for example, in various hydrolytic reactions. Second, water can influence reactivity as a by-product of the reaction, by inhibiting the rate of the forward reaction, for example, in various condensation reactions, such as the Maillard reaction. Third, water acting locally as a solvent or medium facilitating a reaction, without direct participation. Finally, by virtue of its high free volume and low Tg, water can act as a plasticiser, reducing viscosity and enhancing diffusivity [28]. 

The DnPont photopolymeric system consists of polymeric binder resins, e.g. PVA, PMMA, cellnlose acetates and styrene-acrylates, reactive acrylic monomers, e.g. aryloxy or alkoxy acrylates, a dye sensitiser and a radical or charge transfer photoinitiator, e.g. DEAW and HABI respectively (see Chapter 4, section 4.5.2), and plasticisers. The process for producing the refractive index structures is as follows ... 

The first is metakaolin. This is a partially calcined product that forms above about 500 °C. Only about 10% of the original hydroxyl groups of the kaohnite are retained and much of the crystalline nature of the structure is destroyed. Metakaolin is considerably more reactive than the original kaolin and appears to have an especially reactive surface. It is generally used uncoated and finds most use in plasticised PVC cable insulation, where it is reported as giving uniquely useful electrical properties [86]. 

The interaction of blood with PVC-P based on a phthalate and trimellitate plasticiser has shown that there is a higher reactivity for the trimellitate, which correlated with the plasticiser distribution at the polymer surface (316). Another important aspect is for the medical packaging to be suitable for sterilisation of the contents. Details are available of improving the gamma irradiation stability of PVC-P in order to retain colour (447). In addition to unacceptable colour formation, excessive shifts in pH and extractables can occur in inappropriately stabilised PVC-P (301). An additive system, based on materials approved for medical use, has been developed to give low extractables and low blush with good colour and processability (239). The effects of different plasticisers... 

A study has been carried out on the interactions of blood with plasticised poly(vinyl chloride) biomaterials in a tubular form. The influence of different factors such as the biomaterial, antithrombotic agent, blood condition and the nature of the application is represented when considering the blood response in the clinical utilisation of the plasticised PVC. The PVC was plasticised with di-(2-ethylhexyl)phthalate (DEHP) and tri-(2-ethylhexyl)trimellitate (TEHTM)and in-vitro and ex-vivo procedures used to study the biomaterial with respect to the selection of the plasticiser. The blood response was measured in terms of the measurement of fibrinogen adsorption capacity, thrombin-antithrombin III complex and the complement component C3a. X-ray photoelectron spectroscopy was used for surface characterisation of the polymers and the data obtained indicated that in comparison with DEHP-PVC, there is a higher reactivity... 

The industrial manufacturing process for cyanoacrylate monomers is designed to generate pure organic compounds free of metals. The prepared monomer is functionally very reactive and is polymerised by several mechanisms of which the most common is by anionic methods. In most applications the initiation is usually carried out by the nucleophilic contaminant (water or moisture) found on most surfaces. These adhesives differ from other adhesives in that they are monofunctional and can homopolymerise rapidly at room temperature. A number of modifiers have been added to impart a range of desired properties and these include stabilisers, inhibitors, thickeners, plasticisers, tracers, colorants and preservatives. 

A correct definition of dry has already been commented upon because even the most hydrophobic organic substances, e.g. polystyrene, absorb water vapour to some extent. Water has therefore been called Nature s ubiquitous plasticiser . Apart from this softening role, water, being itself a very reactive and versatile molecule, might also have other effects on amorphous solid substrates, some of them unexpected, and most of them deleterious. The role of low water contents (< 1 % w/w) in affecting the behaviour of solid solutions is a subject that deserves further investigation. 

Flame retardants prevent polymeric materials from supporting a flame, sufficiently to meet the requirements of standards. They are used either as additives mixed with the polymer or as coreactants, in which the reactive flame retardant is covalently bonded with the polymer. Polybrominated diphenyl ethers and organophosphate esters are both used as flame retardants as well as having plasticising properties. Tetrabromobisphenol A can be used either as an additive or as a reactive flame retardant [20]. 

Usually prepared as viscous, immobile pastes - basically suspensions of PVC particles in a combination of liquids, usually composed of plasticisers and reactive monomers. 

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