It is well known that PP manufacturers modify flow of Polypropylene by making adjustments of molecular weight using peroxides to breakdown molecular chains. This process, known as "vis" breaking helps PP producers to rationalize polymerisation operation.

Most of these peroxides are liquid and extremely hazardous. The producers of PP have excellent safety setups capable of handling these peroxides. However, the converters, such as producers of PP non-wovens using melt blown process or manufacturers of large moulded products like bumpers, etc. would find it very difficult to handle peroxides directly on the processing equipments. These peroxides can be developed in the diluted solid form using one of the following methods.

Absorption in fillers:

Peroxides can be absorbed to almost 50% level by mineral fillers like CaCO3, chalk or sillica. Since the amounts of peroxide required is quite small (250-1000 ppm), the total usage of the peroxide concentrate in fillers is quite small, making usage feasible. The dispersion of filler in the main product would be difficult and can cause some quality problems (for instance, in melt blown fibers).

Absorption in Porous PP polymer:

Spheripol process has the ability to produce porous PP powder. Peroxides could be absorbed in this porous PP polymer almost to the extent of 20%. This option is more expensive than fillers, but offers better dispersion. There are some ultraporous PE/PP/EVA powders that can absorb more than 50% of peroxides. However these ultra porous polymers are very expensive.

Peroxide Masterbatches:

Peroxides have a very high flow characteristic, can be incorporated into a polymer carrier upto 10%, hence can be extruded/compounded at very low temperatures to avoid decomposition. There are very few suppliers of Peroxide Masterbatches due to a difficult manufacturing process, causing the cost of the peroxide masterbatches to be quite high.

However, the masterbatch offers significant advantages in terms of :

		Accurate dosing
		Excellent Homogenization
		Absence of fine powder
		Absence of special legislation required for storage, etc. {Since below 10% peroxide is not considered     dangerous} The converters can select one of the three products depending upon requirements. However, the masterbatches possibilty offers the best option.

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