Distinguish between PA6 and PA66 in seconds

PA6 and PA66 are among the most wide­ly used pla­s­tics in the world. Howe­ver, a simp­le dif­fe­ren­tia­ti­on is tri­cky and only pos­si­ble with (time-con­sum­ing) labo­ra­to­ry work. The­re is often not enough time for the­se tests, espe­ci­al­ly in the inco­ming goods depart­ment. Near-infrared tech­no­lo­gy clo­ses the gap and helps to sepa­ra­te the two plastics.

No forwarding agent waiting

A fami­li­ar situa­ti­on at many pla­s­tic silos around the world: the arti­cu­la­ted lor­ry with the deli­very dri­ves onto the com­pa­ny pre­mi­ses and is to be unloa­ded immediately.

As PA6 and PA66 hard­ly dif­fer che­mi­cal­ly, it is not pos­si­ble to car­ry out a simp­le burn test direct­ly on site. Howe­ver, pro­ces­sing in the labo­ra­to­ry requi­res a con­sidera­ble amount of time and money.

PA6 & PA66: How to differentiate?

In this artic­le, I will show you how to dif­fe­ren­tia­te quick­ly and relia­bly using NIR. The fol­lo­wing image shows the NIR spec­tra of two samples: PA6 and PA66 - taken direct­ly from the silo. The human eye can­not detect any rele­vant dif­fe­ren­ces here:

PA6-PA66_Rohspekten-1

The raw spec­tra of PA6 and PA66 are very simi­lar. Dif­fe­ren­ces can hard­ly be detected.

Dif­fe­ren­ti­al dis­play shows clear dif­fe­ren­ces in the NIR spectrum

The dif­fe­rence dis­play also does not appear as clear as desi­red at first glan­ce. Howe­ver, the­re are clear dif­fe­ren­ces bet­ween the samples at the wave­lengths 1,190 nm, 1,220 nm, 1,375 nm, 1,400 nm and 1,620 nm:

PA6-PA66_Differenzdarstellung

The spec­tra of PA6 and PA66 dif­fer signi­fi­cant­ly at seve­ral wavelengths.

3D clus­ter dis­play cle­ar­ly groups lar­ge num­bers of NIR spectra

What is only hin­ted at in the dif­fe­rence dis­play is cle­ar­ly shown in the 3D clus­ter dis­play: the mate­ri­al of the PA6 sam­ple appears to be more homo­ge­neous: The spec­tra of the indi­vi­du­al mea­su­re­ments hard­ly dif­fer, reco­gnizable by the spa­ti­al pro­xi­mi­ty of the spec­tra in the 3D clus­ter display.

PA6-PA66_3D-Clusterdarstellung

The PA6 spec­tra vary less than the PA66 spec­tra. An indi­ca­ti­on of inho­mo­ge­neous sam­ple material.

Own references: Learn quickly

For this appli­ca­ti­on, it makes sen­se to teach in the actu­al samples as sepa­ra­te refe­ren­ces. The fol­der with the alre­a­dy saved and named spec­tra is stored as a refe­rence data­ba­se and auto­ma­tic iden­ti­fi­ca­ti­on is activated.

For the coun­ter sam­ple, only the samples are held in front of the scan­ner: first 5x the PA66 sam­ple and then 5x the PA6 sam­ple. All samples are reco­gni­zed cor­rect­ly. In the user inter­face, the reco­gni­zed sub­s­tances are mark­ed with an (*) in front of the mate­ri­al name.

I now store this data as my own refe­ren­ces for future mea­su­re­ments. A work­sta­tion equip­ped with a solid scan­ner and this refe­rence data now enables even non-experts to check the silo deli­very quick­ly, relia­bly and the­r­e­fo­re very easily.

PA6-PA66_Rohspekten_Gegenpruefung

The auto­ma­tic iden­ti­fi­ca­ti­on algo­rithm reco­gni­zes PA6 cor­rect­ly. Pre­vious­ly, PA66 and PA6 had alre­a­dy been reco­gni­zed cor­rect­ly seve­ral times.

Absolute reference data: NIR spectra from the reference database

The Basis refe­rence data­ba­se also helps with identification:

PA6-PA66_Rohspekten_Gegenpruefung.-mit-ReferenzdatenbankJPG

In this exam­p­le, the Basis refe­rence data­ba­se with abso­lu­te refe­ren­ces is used. This refe­rence data­ba­se makes it pos­si­ble to deter­mi­ne unknown mate­ri­als wit­hout having to teach them in beforehand.

Konfiguration

Für die­se Bei­spiel­an­wen­dung benö­ti­gen Sie fol­gen­de (Mindest-)Konfiguration:

Hard­ware

Soft­ware

NIR Refe­renz­spek­tren

Neugierig? Angebot für portables NIR Spektrometer anfragen

Falls ich Sie neu­gie­rig machen konn­ten und Sie wei­te­re Infor­ma­tio­nen oder ein kon­kre­tes Ange­bot wün­schen, schrei­ben Sie uns einfach.

Ger­ne dis­ku­tie­ren wir mit Ihnen, wie der Hand­scan­ner Ihre Pro­zes­se ver­ein­fa­chen und beschleu­ni­gen kann.