GENERAL INFORMATION

PVOH®725 is a 72.5 mole% hydrolyzed, polyvinyl alcohol which has been specially developed for use as a primary suspending agent for vinyl chloride suspension polymerisation. Using our exclusive batch process which in that it allows more efficient control over the degree of hydrolysis and particle size of product.
PVOH®725 has lower molecular weight and lower viscosity in the grade. It was leading to uniform PVC of good morphology over the entire K value range. Its high level of conjugated carbonyl groupings in the polymer chain give it superior grain size efficiency.

USES

Specifically, PVOH®725 is a suspending agent for suspension polymerisation of vinyl chloride monomer (VCM). The use of PVOH®725 requires no significant plant modification.

STORAGE

1.PVOH®725 should be stored away from wet areas and naked flames. Ingress of moisture should be avoided to maintain product quality.
2.As supplied, the product should remain fit for use for 12 months from the date of delivery. Beyond that date, the material may still be fit for use, but we would advise that it is good practice to test the material. As such, we advise that material stored for 12 months or more after delivery should be tested before use.
3.Aqueous solutions of PVOH®725 if stored for long periods at elevated temperatures are prone to mould and bacterial attack.

FOR USED IN VCM SUSPENDING POLYMERISATION

PVOH®725 has an influence on the PVC resin grain size distribution, porosity and bulk density. This is due to the products surface active nature, reducing the interfacial tension and enhancing distribution of initiator throughout the batch.
The principal advantages of using PVOH®725 can be summarized as follows.
1.The desired PVC grain size can be achieved using low levels of PVOH®725, over a wide range of polymerisation temperatures, to produce high bulk density resins.
2.The PVC grains made with PVOH®725 tend to be more spherical such that higher bulk density may be combined with minimum reduction in porosity and with optimum flow characteristic.
3.The combination of PVOH®725 and PVOH®88 grades or secondary suspending agent grades give PVC resins of narrow grain size distribution and a good balance of bulk density and porosity.

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