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Compounding Issues

Potable waterThe effect on water quality is the most critical

part to meet. Test results are influenced by thefollowing items:

Insufficient reproducibility of some testmetods;

Compound formulation and used ingredients

Sampling

curing characteristics

sample preparation

storage time (before sampling)

The water quality itself andor sensiti!ity ofthe testmethod can cause the lac" onreproducibility. #hen ta"ing into account thedifferent standards$ the limitations with respect tocompounding ingredients$ are

e%istence of a positi!e list;

type of prescribed testmethod

#ith the choice of compounding ingredients someimportant points ha!e to be considered. Thepositi!e list only allows a limited selection and ama%. concentration of these ingredients. &ig. 'shows an o!er!iew of the influences of the differentcompounding ingredients on the most importanttest parameters used to in!estigate the effect onthe water quality.

&ig.' (influence ingredients on test parameters positi!e;* negati!e; o neutral)Ingredient Type +,-, Cl consumpt. Cytoto%ic Taste-dour onge!ity

/olymer/lasticiser

&iller0ntidegradant

Curing agent0ccelerator

1etarder

2/,+/araffinic3aphtenic0romatic4ydrophobic4ydrophylic#a%/henolic(Cl)0mineSulphur/ero%ideThiuram+ercaptan5uanidine+etal comple%Sulphenamide/thalimide (ctp)

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Some conclusions of this study were :

Clean 2/,+ polymers(low cat.rests) $ li"e 6eltan are beneficial w.r.t hygienic(tasteodour) and

cytoto%ic properties

high molecular weight products$ e.g. plasticisers and accelerators$ are more stable with respect to

bacterial attac"

long linear molecules$ e.g. paraffinics are more easily attac"ed by bacteria compared to hindered ones$

e.g. naphtenics and aromatics;

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biostabiliser deri!ati!es$ e.g. metal comple%es$ phtalimides (c.t.p.)and phenolics

showing fungicidial properties.oo"ing to the different testmethods required by countries$ e.g. li"e 5ermany and the 76 $ it will be clear that acombined appro!al is nearly impossible to reach$ because 5ermany has a positi!e list which only allowsmedicinal paraffinic plasticisers (long linear molecules). 4owe!er to pass the +,-, test prescribed by the 76$a naphtenicaromatic plasticiser will be necessary.The same is due with respect to additi!es li"e microcrystalline wa%es$ which are !ery beneficial to pass the5erman chlorine consumption requirement (water repellent)$ but which will ha!e a detrimental effect on the+,-, !alue because of its nutrient effectrecipes

WRc listed recipes (BS 6920) Ingredients R200! R2009 R20"0

#eltan $!02%n&Stearic acidB'P0 blac*

W+iting(non,coated)ap+tenic oil-B.,!0.-.,!0/e-CS,!0

899.9'.99.9.'9.9

'.9'9.98.

.otal p+r =>?.@@ =@.@@ =.8< 8'.< 8'.8

'ardness IR' ' >' 8

.ensile strengt+ -pa 89.9 8>.9 8>.=

5longation at brea* '9 '99 ?99

Compression set

70 +rs4 2 deg4C >

22 +rs4 70 deg4C 8= 8 8=

.otal p+r =@9.=< =@9.

2$ +rs470 deg4C 8< 8>

Stress relaation

"6! +rs4 2 deg4C @? @