Free stabilization

Sulfur-free stabilizers usually containing Sn-O bonds. 

In contrast to sulfur-containing tin compounds, tin carboxylates have to be used with antioxidants. The advantage of the use of sulfur-free stabilizers is the good photostability and the lack of odor. These stabilizers, too, need additional lubricants, since they tend to stick to the metal parts of calendars and extruders. ... 

The protection of the polymers against low doses occurring in the food irradiation may seem as a simpler task. The packaging films of irradiated food should tolerate much less dose, in the range of 1 kGy or less, but the extract-free stability of those materials in food-contact is even more important than the possible mechanical consequences of radiation degradation. 

FIGURE 3.4 First and second chemiluminescence peak curves versus time of metallocene polyethylene films free, stabilized with Irganox 1010 (0.05% w/w), and pigmented with micron- and nanoparticle titanium dioxide (0.5%), determined at 170°C under oxygen. 

In recent years, metal-free stabilizer systems have been developed because of environmental concerns of traditional lead and tin stabilizers. Chemically regarded nitrogen-based molecules are used, for example, P-aminocrotonates, dihydropyrimidines [15], trialkanolamines, as well as their reaction products and salts, for example, the perchlorate salt [16], etc. (Fig. 11.11). Owing to their good compatibility with other stabilizers, organic-based stabilizers are predestinated to be used in PVC recycling in case restabilization is needed [17]. 

Accordingly, Ciba Specialty Chemicals developed a new phenol-free stabilizer for fiber, designated Irgastab FS 533. To properly evaluate the product for gas fading, Qba knitted... 

Yu I, et al. A new phenol-free stabilizer solution for polypropylene fiber. International Polyolefins Conference, conference proceedings. Society of Plastics Engineers 2008. 

Features Solv.-free stabilized against discoloration during storage easy handling liq. 

For color-critical applications requiring phenol-free stabilization, synergistic mixtures of hindered amines (for both uv stability as well as long-term thermal... 

Additionally to the variability of the composition, SLN dispersions are normally heterogeneous with respect to the colloidal structure itself whereas excess of stabilizer(s) may led to the formation of additional colloidal structures presenting also a potential location of incorporated drugs. It is well known, that stabilizers show an own pharmacological effect. For this reason, an exact knowledge about actual concentration of stabilizers — preferably also the concentration of free stabilizer molecules — in the final formulations is important for the evaluation of, e.g. pharmacological effects after administration of SLN formulations. 

Another undesired reaction that can occur with sulfur-zinc stabilized PVC or PVC/ ABS films is a clearly perceptible smell of onions or garlic. Prerequisite for the occurrence of this phenomenon is direct contact between PVC film and PUR foam. The smell can occur in contact with both rigid PUR foams and PUR block foams. An intensive search for the cause of the smell concluded that the initiator is interaction between amine catalysts in the PUR systems with the sulfur-zinc stabilizer in the PVC or PVC/ABS film. The remedy for this is either to change the PUR foam or to use a sulfur-zinc-free stabilization in the PVC film [686]. 

The above considerations suggest that phenol-free stabilizers should be introduced to exclude gas fading in specific applications. 

Phenol-free stabilization system, gas fade resistant... 

For color-critical applications requiring phenol-free stabilization synergistic mixtures of sterically hindered amines (HA (L)S) and a hydroxylamine-based stabilizer, used during melt processing, with or without an organophosphate or organo-phosphonite, can be used to avoid the undesired discoloration typically associated with the oxidation of the phenolic antioxidants into products with quinoid stmctures. ... 

The use of phenol-free stabilization systems has been found to be very effeaive in color-critical products such as PP and polyethylene fibers, as well as selected TPO applications. 

---