Paraffin wax - inconsistent physical properties 1

[markdeg]

We have been formualting refined paraffin waxes for applications in histology. Here the paraffin is melted and poured hot into a mold to embed cell tissue. After cooling, the matrix is thin sectioned and analysed by optical microscopy. Ideally, upon rapid cooling, the wax matrix solidifies to a homogeneous and relativelty transparent, clear bulk. Recently. we have observed domains of cloudy, white material suspended in the wax matrix. We do not can't suggest a possible remedy - perhaps locating other suppliers of wax using alternalte oil feedstocks, QC each incoming lot, etc. Is anyone familiar with the paraffin wax production process such that they might suggest (a) the possible nature of the cloudy white material and (b) how that material might be ultimately linked to the paraffin manufactuing process. Many thanks in advance to any paraffin experts out there

 

[hacksaw]

your supplier is the best starting point. suspect that filtration and purity are the key players. it is possible that you are dealing with a mixture of parafins with a broad range of solidification temperatures.

 

[25362]

Mixtures of highly refined paraffin waxes and plastic polymers having a wider spectrum of (straight chain and branched paraffinic) hydrocarbons with a wider range of melting points, may show different shrinking properties on solidifying with consequent cloud patches.

As hacksaw suggests, asking the supplier/manufacturer may be the right approach.

One website that may be directionally helpful

http://www.emsdiasum.com/microscopy/products/histology/embedding.aspx?mm=10

Good luck.

 

[markdeg]

Thanks hacksaw and Dr 25362. Are either of you aware if paraffin manufacturers can control the distribution of linear vs branched paraffins by a) their manufacturing process or b) petroleum feedstocks. Will suppliers have a good handle on the composition of their material at this level of detail ?

 

[25362]

Bulk paraffin wax producers may, at a cost, and with great difficulty, adapt their operations to obtain narrow distillate cuts for further lube dewaxing, while using the necessary solvent composition, dosage, and temperatures in their dewaxing/deoiling operations. The final proportion of iso to normal paraffins in the refined wax product would be much dependent on the crude oil origin.

 

[nbucska]

Was the sample defatted ? Do you have the cloudy precipitation in the absense of the sample ?

<nbucska@pcperipherals DOT com> subj: eng-tips

 

[ChemEng2000]

There are two things that can cause this cloudiness. Longer paraffin chains have higher boiling points and lower cloud points. Also branched paraffins have a lower cloud point than straight chained paraffins. We used a GC to calculate the amount normal paraffins and branched paraffins.

 

[pkpbip]

The amount of iso/normal paraffin mix is determined by the crude mix as well as some of the processing steps including the vacuum distillation and hydroconversion steps. The narrower the vacuum cut the better the quality and the more consistent the product. There are also some hydroconversion processes for lubes that can affect the iso/normal mix. If these processes have become more severe over time due to changing operations or catalyst deactivation this could explain the change in quality you are seeing.

 

[unclesyd]

You might take a look a these peoples website and look at their specifications for different waxes.

http://www.hpwax.com