Polyethylene terephthalate (PET) is the most common thermoplastic polymer resin of the polyester family and is used in fibers for clothing, containers for liquids and foods, thermoforming for manufacturing, and in combination with glass fibers for engineering resins. The majority of the world's PET production is for synthetic fibers (in excess of 60%), with bottle production accounting for about 30% of global demand. PET consists of polymerized units of the monomer ethylene terephthalate, with repeating (C10H8O4) units. PET is also commonly recycled. Depending on its processing and thermal history, polyethylene terephthalate may exist both as an amorphous or a semi-crystalline polymer. The semi-crystalline material may require more vigorous conditions for dissolution. The purpose of the analysis is to determine the repeatability of this PET DSV method. The samples were analyzed using an HMJ Y501 Dual Capillary Relative Viscometer (DSV) system. The analysis conditions are listed below.

Solvent	60/40, Phenol/Tetrachloroethane
Sample Concentration	0.5 g/dL
Prep Temperature	110C
Dissolution Time	60 Minutes
Analysis Temperature	30C

RSD of DSV data is typically less than 1% and the following data supports that claim.

Samples	IV (dL/g)		Samples	IV (dL/g)
PET-1A	0.6255		PET-3A	0.6273
PET-1B	0.6261		PET-3B	0.6316
PET-2A	0.6266		PET-4A	0.6330
PET-2B	0.6292		PET-4B	0.6256

​In addition to the precision of the data demonstrated above, the relative viscometer presents an easy opportunity to automate a particularly laborious task. Automation can range from a simple autosampler system to fully automated Vortex operation.