Effect of molecular orientation on permeability and optical grating for polymeric agricultural films

Abstract

Blends of natural rubber (NR) with linear low-density polyethylene (LLDPE) were prepared by chill roll cast film extrusion. Theaddition of NR and epoxidzed natural rubber (ENR) to LLDPE significantly decreased the MFI of LLDPE. The effect of increasing the amount of NR in binary blends, and ENR in reactive blends, was to reduce molecular orientation, lower crystallinity, lower yield stress, give higher oxygen permeability and shift UV absorption to the visible region. For pure LLDPE, when increasing DR that affected to increase orientation, and crystallinity, and to lower UV absorption that shifted to lower wavelength. The melting (Tm) and crystallization (Tc) changed slightly with increasing draw ratio. The uniaxial orientation in chill roll cast film process was investigated by infrared dicoism. Molecular orientation increased with DR for the LLDPE pure, binary blend and reactive blends. Film yield strengths of both binary and reactive blendsdecreased with increasing NR content even at increased DR. LLDPE being of lower viscosity showed lower crystallinity, higher gas permeability and produce thinner ilms. Good oxygen permeability and selective visible light allows the reactive blended film to be used in agricultrual application.