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DIFFERENCES IN S-PVC RESINS

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Standardized methods such as Centrifuge Plasticizer Absorption (ASTM D3367) assume that all grains are homogeneous and therefore a single value is sufficient to describe Porosity, while other methods such as Mercury Intrusion Porosimetry (ASTM D2873) or a modification of Centrifugal Plasticizer Absorption method at high temperature and different times show a continuous penetration curve related to the internal structures formed within grains.
 
S-PVC resins with high heterogeneity are made up of grains ranging from very porous and easy to process grains to very compact grains that slowly absorb plasticizer and are difficult to melt (some do not even melt like "Fish Eyes" or gels).

Comparison:  

-    If Porosity of sample (B) is higher than your current resin A:

o    For rigid applications, expect faster fusion and easier processing.
o    For flexible applications, expect faster absorption and dispersion of plasticizer.

 
-    If Heterogeneity of sample (B) is higher than your current resin A:

 o    For rigid applications, you should expect imperfect additive dispersion and melt heterogeneities that could result in mechanical failure in your final product, so you'll have to compensate with increased energy and additive consumption to homogenize molten plastic.
 o    For flexible applications, you should expect inhomogeneous plasticizer concentration and melt heterogeneities that could result in cosmetic flaws or even mechanical failures in your final product, so you'll have to compensate with higher consumption of energy and additives to homogenize molten plastic.
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The following equation allows to calculate the percentage of volume occupied by porous grains in a sample of S-PVC, which gives an idea of how easy such PVC resin flows and packs by gravity:
 

Grains packing depends on several factors such as:
       o    Shape:  Round grains flow better
       o    Surface roughness:  Smooth grains flow better
       o    Size distribution:  Wide size distributions pack better
 

You should not assume that your S-PVC resins are optimized even if you have no Quality complaints from your customers and there are no Sales issues.

It is only a matter of time before a new competitor arrives in your region and offers optimized S-PVC resins with competitive advantages to your Clients, and if you wait for them to realize such advantages then you will be putting the competitiveness of your products at risk.
Let me help you diagnose and optimize your S-PVC resins so that your Customers realize your throughput and ensure their loyalty.
Do you have more questions regarding PVC resins? I have many answers.
View my PROFILE and visit my CONSULTING SERVICES page.

© 2022 Carlos Aguilar / PVC Expertise

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