A study of radical graft copolymerization on polypropylene during extrusion using two peroxide initiators

Abstract

Functionalization of polypropylene (PP) during melt extrusion has been explored extensively. In this study, two different radical initiators were employed and compared in grafting acyclic halamine precursors to PP. 2,4‐Diamino‐6‐diallylamino‐1,3,5‐triazine (NDAM) was grafted onto PP during a melt‐extrusion process using either 2,5‐dimethyl‐2,5‐(tert‐butylperoxy)hexyne (DTBHY) or dicumyl peroxide (DCP) as initiator. The results confirmed the radical graft copolymerization of the monomer onto the PP backbone during the reactive extrusion process. It was revealed that, at low monomer concentration, when peroxide initiator concentration was increased, polymer chain scission became dominant. DCP was more efficient than DTBHY as an initiator in the graft polymerization. After exposure to chlorine bleach, the grafted structures could be easily transformed into N‐halamines, which provided powerful, durable and regenerable antibacterial activities against Escherichia coli and Staphylococcus aureus. It is concluded that both DCP and DTBHY could be used as radical initiators in reactive extrusion to graft certain vinyl monomers to PP. The NDAM‐grafted PP could provide expected antibacterial function after chlorination of the grafted product in a chlorine bleach solution. The modified PP showed great potential for use in medical devices and non‐woven textiles. Copyright © 2009 Society of Chemical Industry

Fabrication of Polypropylene-g-(Diallylamino Triazine) Bifunctional Nonwovens with Antibacterial and Air Filtration Activities by Reactive Extrusion and Melt-Blown Technology

“…Part of the macromolecular radical could initialize the grafting polymerization of NDAM monomer onto the backbones to create desired grafted PP. And the other part undergoes β-scission to form secondary radicals, which can still react with monomers [23], as shown in Scheme 1. Moreover, when the initial monomer concentration increased, this NDAM monomer that grafted onto PP backbones may react with more monomer molecules, and such a process may contribute to longer chain branches in PP molecules [24].…”

Chemical Insights into Antibacterial N-Halamines

“…On the basis of their structural characteristics, melamine-containing N -halamines belong to a subcollection of amine N -halamines due to the presence of amine N–X bonds. − However, the former have quite similar chemical properties to the latter, even though their strong electron-withdrawing effects result from different functional groups . According to Sun’s report, the biocidal activity and stability of melamine-containing N -halamines fall between those of amine N -halamines and amide N -halamines because the melamine-containing N -halamines combine the advantages of both.…”

“…Generally, 2,4-diamino-6-diallylamino-1,3,5-triazine (NDAM) is used in biocidal functionalization as the precursor of melamine-containing N -halamines. − For example, Sun’s group , grafted PP with NDAM via a reactive extrusion method using either 2,5-dimethyl-2,5-( tert -butylperoxy)­hexyne (DTBHY) or dicumyl peroxide (DCP) as the initiator; after chlorination, chloromelamine-based PP was obtained and demonstrated antibacterial properties. The same group developed novel composite membranes with poly­(vinyl alcohol- co -ethylene- g -diallylmelamine) (PVA- co -PE- g -DAM) nanofibers layered on poly­(propylene- g -diallylmelamine) (PP- g -DAM) meltblown nonwoven fabric.…”

In the melt, grafting of polycarbonate onto polystyrene-block -poly(ethylene-butylene)-block -polystyrene-grafted -maleic anhydride: Reactive extrusion

“…In the field of chemical polymer modification or polymerization, this process plays an important role . Bulk polymerization , polymer functionalization , and grafting reactions are examples of the wide field of reactive extrusion. The use of twin‐screw extruders as chemical reactors is explained by its mixing capability (even with high viscosity materials), and its modularity for a better control of chemical reactions .…”