Molecular orientation behavior of poly(vinyl chloride) as influenced by the nanoparticles and plasticizer during uniaxial film stretching in the rubbery stage

Abstract

The structural evolution during uniaxial stretching of poly(vinyl chloride) films was studied using our real time spectral birefringence stretching machine. The effect of clay loading and the amount of plasticizer as well as the rate effects on the birefringence development and true mechanical response are presented with a final model summarizing the molecular phenomena during stretching. Mechano-optical studies revealed that birefringence correlated with mechanical response (stress, strain, work) nonlinearly. This was primarily attributed to the preexisting strong network of largely amorphous chains connected via small crystallites that act as physical crosslinking points. These crystallites are not easily destroyed during the high-speed stretching process as evidenced from the birefringence-true strain curves along with the X-ray crystallinity measurements. At high speeds, the amorphous chains do not have enough time to relax and hence attain higher orientation levels. The crystallites, however, orient more efficiently when stretched at slow speeds. Apparently, some relaxation of the surrounding amorphous chains helps rotate the crystallites in the stretching direction. Overall birefringence is higher at high stretching speeds for a given true strain value. When the nanoparticles are incorporated, the orientation levels are increased significantly for both the crystalline and amorphous phases. Nanoplatelets increase the continuity of the network because they have strong interaction with the amorphous chains and/or crystallites. This in turn helps transfer the local stresses to the attached chains and increase the orientation levels of the chains. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 724 -742, 2005 Keywords: uniaxial; poly(vinyl chloride) (PVC) nanocomposites films; poly(vinyl chloride) (PVC) orientation; birefringence ucts, the polymer is often oriented in the rubbery state and undergoes morphological and structural changes which in turn impart significant changes on its physical, mechanical, optical, and barrier properties and their anisotropy.To attain the desired set of properties, the link between the processing conditions, for example, temperature, rate, and extent of stretching, and the structural characteristics, for example, degree of orientation, crystal size, and shape evolution, should be well established. However, during fast deformation processes, structural transitions may occur rapidly and are rather difficult to elu-

Keys to Toughening of Non‐layered Nanoparticles/Polymer Composites

“…Consequently, the mobile nanoparticles might act as "plasticizer", improving orientation of the matrix. [20] This might induce the formation of a phase that is not accessible under normal conditions. For PP, the result lies in the appearance of b-crystal (see Supporting Information), in addition to the commonly occurring a phase.…”

The combined effect of plasticizers and graphene on properties of poly(lactic acid)

“…The authors also observed that such effect is not entirely due to the plasticizer chains, but there is a competition between the polymeric matrix and the plasticizer for the nanoparticle intercalation. In addition, Yalcin and Cakmak observed that there is a minimal concentration of each plasticizer, below which there's no ability to transmit the forces that reduce the particle size of the agglomerations. Correlating the FESEM images to TEM, it is possible to observe that the nanocomposites with the most regions of graphene agglomerates [Figure (c,f)] were the samples with the fewer regions with a second phase [Figure (c,f)], indicating that agglomerates alone can hinder the plasticizer molecules' movement.…”

Directed Electric Field Z‐Alignment Kinetics of Anisotropic Nanoparticles for Enhanced Ionic Conductivity

“…[ 33 ] They exhibit the same refractive index, 1.57, in all directions within the basal plane (001). [ 33 ] They exhibit the same refractive index, 1.57, in all directions within the basal plane (001).…”

“…Layered clay platelets with their high aspect ratio enhance gas barrier properties in nanocomposites, [ 28 ] particularly when they are oriented with their broad surfaces in the plane normal to the diffusion direction. This orientation is easy to achieve by traditional fl ow processes such as extrusion, [29][30][31] fi lm blowing, [ 32 ] and fi lm stretching including uniaxial [ 33 ] and biaxial [ 34 ] stretching.…”