Grafting of itaconic acid onto LDPE by the reactive extrusion: Effect of neutralizing agents

Abstract

Grafting of itaconic acid (IA) onto low-density polyethylene (LDPE) was performed by reactive extrusion where the initiator was dicumyl peroxide, and the neutralizing agents (NAs) were zinc oxides and hydroxides as well as magnesium oxides and hydroxides. The carboxyl groups were neutralized in molten LDPE directly in the course of acid grafting, and in prefabricated functionalized polyethylene (LDPE-g-IA). It was found that neutralizing agents introduced into the initial reaction mixture increase the yield of LDPE-g-IA while the carboxyl groups were neutralized partially or totally through chemical reactions. The physical structure of LDPE-g-IA did not in fact suffer any substantial changes. From the standpoint of neutralization activity, the NAs studied could be arranged as follows: Zn(OH) 2 Ͼ ZnO Ͼ Mg(OH) 2 Ͼ MgO. NA, added into the initial reaction mixture improved the grafting efficiency of IA onto LDPE. In case of the one-step process (neutralization simultaneously with grafting), the neutralizing effect appears stronger than that in the two-step process (neutralization of prepared LDPE-g-IA). This means that neutralization of carboxyl groups in IA was less effective when NA was introduced into LDPE-g-IA than for the case of the initial reactive mixture. Chemical neutralization of grafted IA results in products of improved resistance to thermal oxidation and thermal stability of melt. This result is of practical importance to the opportunities for widening the application range for PE modified by grafting IA, while preparing polymer blends to be compounded, processed, and used at elevated temperatures.

Graft copolymerization of itaconic acid onto sodium alginate using ceric ammonium nitrate as initiator

“…This is in good agreement with the results reported in the literature 13, 14. The band at 1563 cm −1 is also evidences a neutralization reaction as reported Krivoguz et al9…”

“…Doubly‐ionized carboxylic groups bring additional capability of chelate formation under certain cases 8. A few workers have carried out grafting reactions of IA onto low density polyethylene,9 polypropylene,10 and chitin 11. It was therefore decided to graft IA onto NaAlg.…”

Structure and properties of polyamide 6 blends with low‐density polyethylene grafted by itaconic acid and with neutralized carboxyl groups

“…LDPE-g-IA and LDPE-g-IA Ϫ M ϩ were prepared following procedures described elsewhere. 12 The neutralizing agents (NA) were the same as those in a previous work, 12 that is, chemically pure oxides and hydroxides of zinc and magnesium as powder having average particle sizes for: ZnO, 0.6 m; MgO, 2.0 m; Zn(OH) 2 , 0.7 m; and Mg(OH) 2 , 1.6 m. The carboxyl groups in the grafted IA were neutralized following a one-stage procedure combining the processes of grafting and neutralization. To do this, LDPE granules covered with peroxide initiator (e.g., dicumyl peroxide) and IA powder were treated with NA powder in an extruder reactor and grafted at melting and shearing.…”

Evolution of the chemical and morphological changes of HDPE when subjected to digestion in a strong acid medium

“…The peak around 1550 cm À1 corresponds to NO 2 aliphatic groups, whereas the peak around 1712 cm À1 corresponds to carbonyl CO groups. 20,22 There is no evidence of other collateral reaction, nor of branching 23 (889-895 cm À1 ) or double bonding 24 (909, 990 cm À1 , 880 cm À1 ) that could promote crosslinking.…”