Functionalization of polyethylenes and their use in reactive blending

Abstract

SynopsisThe grafting of maleic anhydride (MAn) to low density polyethylenes (PEs) dissolved in 1,2-dichlorobenzene ( DCB) has been studied. Grafting was successful a t temperatures of about 160°C both in air without initiator and under nitrogen with the radical initiator 2.5-di ( t-butylperoxy -2,5-dimethyl-3-hexyne (LPO). The presence of succinic anhydride grafts was shown by FTIR spectroscopy of the product; 'H-NMR spectroscopy indicates that the grafts consist of single succinic anhydride units. The graft content was determined by nonaqueous titration, and the extent of crosslinking inferred from the melt flow rates (MFR) of the products. The effects of concentration of initiator, MAn, and PE on the graft content were determined; the influence of PE structure, reaction time, and temperature was also studied. Melt blending of the grafted PE with polystyrene containing oxazoline functional groups (OPS) was investigated using a Rheomix mixer. The interpolymer reaction which occurs during blending was studied by means of FTIR, and the morphology of the blends by scanning electron microscopy (SEM). Information was also gained from the change in torque viscosity during the blending process.

Grafting of tetrahydrophthalic and maleic anhydride onto polyolefins in solution

“…One of the most common methods to achieve the polyolefin modification with MA is the reactive process in the presence of a peroxide. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] A comprehensive review of the free radical reactions mechanism involved in this process was published by Moad. 16 The main advantage of such reactive process are the absence of solvent, the short reaction time and it is a continuous process.…”

Chemical modification of blends of poly(vinyl chloride) with linear low density polyethylene

“…The deterioration in mechanical properties is also reduced by co-crosslinking the PVC/PE blend using dicumyl peroxide [8]. Functionalization or chemical modification of the polymers is another common means for improving the physical and mechanical properties of the blends [10][11][12].…”

Obtenção e caracterização de poliolefinas modificadas com anidrido maléico e anidrido tetrahidroftálico

“…Os valores altos de .18 indicam alta rugosidade e ou heterogeneidade química da superfície; (7) não houve variação significativa no grau de funcionalização quando utilizado poliolefinas com diferentes comonômeros; (8) o aumento na concentração de poliolefina promove uma maior funcionalização. (9) o método de funcionalização desenvolvido levou à reticulação mínima da poliolefinas.…”

“…Por outro lado, as cadeias alifáticas conferem às poliolefinas características apoiares [3], superfícies quimicamente inertes e uma baixa tensão superficial [4], que geram incompatibilidades com outros polímeros, baixa dispersão em compósitos [3] e dificuldade, ou mesmo impedimento, na adesão com outros substratos. Com o objetivo de melhorar estas características, as poliolefinas podem ser modificadas por tratamentos mecânicos [4], químicos [8] ou gases ionizados [5], processos esses conhecidos como de funcionalízação [6-1 O].…”

“…Liu e Baker [8], realizaram a funcionalização do LDPE com AM e 1,2-diclorobenzeno como solvente, a uma temperatura de 160ºC, e como iniciador 2,5-di (tbutilperoxi)-2,5-dimetil-3 hexino (LPO) sob atmosfera de nitrogênio e outra de oxigênio.…”