Abstract
A lattice model proposed before for uniaxial stretching of polyethylene films was applied to estimate the oriented crystallization of ultra-high molecular weight polyethylene (UHMWPE) dry gel films under simultaneous biaxially stretching. In this model system, the preferred axis associated with the preferred orientation of amorphous chain segments was chosen along the direction between two successive cross-linked points and the preferred axis was assumed to deform in an affine fashion with respect to the stretching direction. As the application of the proposed model, the orientation distribution function of crystallites was calculated on the basis of the lattice model and oriented crystallization model. The oriented crystallization model is based on the concept that a kinetically determined distribution of crystal chain axes as the normalized distribution of clusters found at the saddle point corresponding to a non-uniform orientation under conditions of a steady-state nucleation rate. Of course, the crystallites are oriented randomly with respect to the film normal direction. The parameter fitting for the formulated orientation distribution function of crystallites was done for the film which was prepared by the gelation/crystallization from solution with 0.9 g/100 mL concentration, the solvent being decalin, since the concentration assured the highest drawability under simultaneous biaxially stretching. The calculated orientation distribution functions 2πqj(cosθj) of the reciprocal lattice vector of the crystal planes were in good agreement with the observed ones. Thus the numerical calculations indicate that the orientation of the c-axes depends on that of amorphous chain segments and the orientation behavior of crystallites is strongly affected by their rotation around the c-axis.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.