Journal of Polymer Science Part B: Polymer Physics, Vol.43, No.3, 314-322, 2005
Preparation and physical properties of novel nonionic surfactants and their grafting copolymers with linear low density polyethylene (LLDPE)
Three nonionic surfactants, S1, S2, and S3 and their acrylates, AS1, AS2, and AS3, were synthesized with poly(ethylene oxide) and diols such as glycol, 1,6-hexanediol, and 1,10-decanediol as the main starting materials. Their chemical structures were characterized by means of Fourier transform infrared (FTIR) spectroscopy and H-1 NMR. The surface activity and surface tension (gamma) of S1, S2, and S3 were evaluated by a drop weight method. The surface tension was found to decrease with the length of the lipophilic spacer in the molecular chains (gamma(S1) < gamma(S2) <(S3)). AS1, AS2, and AS3 were adopted as functionalizing monomers and grafted onto linear low density polyethylene (LLDPE) with a melt reactive extrusion procedure. The graft degrees of LLDPE were determined by FTIR. Three grafted LLDPE samples with grafting degrees of 1.16% (AS1), 0.82% (AS2), and 0.71% (AS3) were prepared. Thermal and rheological properties of grafted LLDPE samples were studied with differential scanning calorimetry and a rotational rheometer. Crystallization rates of grafted LLDPE were faster than that of plain LLDPE at a given crystallization temperature because graft chains could act as nucleating agents. The isothermal crystallization behavior of grafted LLDPE was in accordance with the Avrami model only in the first stage, and deviated from the model with an increase in the crystallization time. Shear thinning at high shear rates and shear thickening at low shear rates were observed for the grafted LLDPE. (C) 2004 Wiley Periodicals, Inc.
Keywords:nonionic surfactant;linear low density polyethylene;reactive extrusion;poly(ethylene oxide);acrylate;functionalization of polymers;graft copolymers;reactive extrusion