FARREL POMINI publishes follow-up white paper on processing polylactide (PLA)

February 9, 2021

FARREL POMINI has completed a second research study on processing Ingeo™ polylactide (PLA) with Farrel Continuous Mixing Technology. The original study, conducted in 2018, compared the results of processing PLA compounds with various levels of talc mineral filler utilizing the FARREL POMINI CPeX®, a laboratory scale continuous technology mixer, and a twin screw extruder to evaluate the effects on molecular weight retention and melt temperature. The CPeX® has a nominal production range of 10-30 kg/h.

The original study found that processing with the CPeX® resulted in significantly better molecular weight retention with values as high as 95% depending on the level of filler. In addition, the trials demonstrated that FCM™ technology provided distinct advantages over the twin screw extruder for lower processing temperature and specific energy input.

In this follow-up study, a production size and scalable CP550 Compact Processor was utilized to confirm the results of talc loading levels on both molecular weight and processing temperatures found with the CPeX® and determine output rate.

The research on the CP550 determined:

• The molecular weight retention followed the trend seen with the CPeX®. With the addition of 1% of EBS, a common additive used when processing PLA, the molecular weight retention on the CP550 was 84% at a 60% talc loading level. The rate is also significantly better than the molecular weight retention on the twin screw extruder found on the initial study.
• Process temperatures on the CP550 were higher than those seen on the CPeX®, albeit still lower than temperatures on the twin screw extruder. However, due to the short residence time provided by continuous mixing technology, molecular weight retention is still maintained to an enhanced level.

This study successfully replicated the processing performance of PLA and talc compounds and masterbatches from the CPeX®, Laboratory Compact Processor to the CP Series II™ CP550, a production sized compact processor utilizing continuous mixing technology. A throughput rate of 450 kg/h was achieved, which falls within the nominal production range for this model. However, achieving maximum production rate was not a consideration for this study and we believe higher production rates are easily achievable.

The results established processing PLA and talc filled compounds on the production sized CP550 with verified scale-up to larger models demonstrate that FARREL POMINI continuous mixing technology can viably produce PLA filled concentrates at high production rates in a commercial setting. The CP550 Compact Processor used in this study features an FCM™, Farrel Continuous Mixer feeding a single screw extruder, mounted on a unitized frame.