Polycaprolactone Polyol Selection by Molecular Weight

The Three Numbers That Matter

Molecular weight decides how soft the soft segment is. Hydroxyl value decides how much isocyanate it consumes. Acid value decides how well the finished part survives hydrolysis. All three are listed per grade in our table.

The 200 Series Diols

PCL 205 at 530 molecular weight and 207 to 217 mgKOH/g hydroxyl value is the short chain end of the range. PCL 220 at 2000 molecular weight and 53 to 59 mgKOH/g is the general purpose grade. PCL 240 at 4000 and H1P at 10000 sit at the flexible end, supplied as waxy solid and granules respectively.

Acid Value Options

Standard grades are specified at 1.0 mgKOH/g maximum. Low acid value grades such as 210CP, 212CP and 220CPB come in at 0.5 or below, and 220CPT at 0.05 maximum. Where a part sits in warm humid service, that difference is the difference between three years and ten.

Hydrolysis Resistant and Narrow Distribution Grades

205H and 220EB are hydrolysis resistant liquid grades. 210B, 210N, 220N and 230N carry narrow molecular weight distribution, which tightens the mechanical property spread from batch to batch.

Triols Tetrols and Modified Grades

The 300 series triols run from 303 at 300 molecular weight and 530 to 550 mgKOH/g through to 320 at 2000. The 400 series tetrol 410 sits at 1000 molecular weight. The L series modified polyols such as L212AL and L220AL are liquid grades offering solubility stability and elastic recovery.

Physical Form and Handling

Liquid, paste, waxy solid and granular forms are all supplied. Melting points between 20 and 60 degrees C are listed per grade, because a grade that has to be melted changes what equipment you need on the day it arrives.