High Temperature Non Aqueous Volatile Acid Titration in Recycled Polyethylene
High temperature non-aqueous titration strips volatile carboxylic acids from hot PE melt into organic media to quantify corrosion risks and thermal stability.
Xylene Dissolution
Meaning
Isolating specific fractions of a polyolefin blend with an aromatic hydrocarbon solvent at elevated temperatures allows for the determination of crystallinity. Xylene dissolution is most frequently used to measure the xylene soluble fraction of impact copolymers where the rubbery phase must be separated from the rigid matrix.
Process
Steps begin by heating the polymer in xylene until the entire sample has dissolved into a clear solution. During xylene dissolution, the temperature must be carefully controlled to ensure that even the high molecular weight crystalline segments are fully broken down.
Controlled
Cooling of the solution allows the crystalline polypropylene to precipitate while the amorphous ethylene propylene rubber remains in the liquid. After filtering the solids, the remaining liquid is evaporated to quantify the amount of material that underwent xylene dissolution and remained in the solvent.
Weight
Measurements of the recovered extract provide a direct measure of the modifier content in the resin. This value is used by manufacturers to verify that the impact properties of the grade meet the datasheet requirements for toughness and flexibility. Because the soluble content influences the stiffness and the heat deflection temperature of the final part, maintaining a consistent result across different batches is necessary for high volume production.