Electromagnetic Processing Line

A method for manufacturing a film, the method having the steps creating a cast film having a polymer component, a monomer component, a nanoparticle component, a magnetic-filler component, or a combination thereof; shearing the cast film; aligning a cast-film component by applying an electric field to the cast film; aligning a cast-film component by applying a magnetic field to the cast film; curing or polymerizing a cast-film component; annealing the cast film; and evaporating solvent from the cast film

Kinetics of structural evolution during crystallization of preoriented PET as followed by dual wavelength photometric birefringence technique

A two-color laser photometric measurement system was used to follow birefringence changes in annealing of prestretched PET films. This technique was shown to be capable of detecting large retardation (and thus birefringence) changes beyond one wavelength of the light. The use of green and red lasers in the photometric system allows the detection of the reversals in birefringence during the course of annealing. Unless critical orienialion/erystallinity levels are developed by stretching the films, heat setting the films at temperatures close to glass transition temper ature results in complete elimination of preferential orientation. At Intermediate stretch ratios, crystalline regions form and Ihe acl as anchor points establishing a network for the orienied amorphous chains. These Dims exhibit partial relaxation followed by rapid increase in birefringence due to the accelerating effect of orientation on crystallization. At high stretch ratios, where substantially oriented and strain crystallized structures are obtained, the initial relaxation stage disappears and birefringence continue to increase throughout the heat setting process even at temperatures very close to glass transition temperature. In these films, however, the total change of birefringence decreases as more of the chains are oriented and crystallized in the stretching stage, leaving a smaller fraction of polymer chains to rearrange during Ihe annealing stage. The kinetics of the structural change exhibit a complex behavior and the largest rates of structural changes were observed in films exhibiting intermidiate birefringence levels

Phase Behavior of Rapidly Quenched PVDF/PMMA Blends as Characterized by Raman Spectroscopy, X-Ray Diffraction and Thermal Techniques

Although PVDF/PMMA blends have been studied extensively, the phase behavior as a function of melt quenching conditions has not been examined in detail in the past. In this paper we report our results on the isotropic blends of PVDF/PMMA quenched into ice water as well as on a casting roll set at 30°C in all composition ranges. The results confirm the miscibility of this blend for all composition ranges, although at high PVDF (∼85%) concentration micro heterogeneities were evidenced through thermal analysis. Though pure PVDF is observed to be mostly in the α crystalline form, the addition of PMMA favors the β crystal structure in composition range 85/15–60/40. Ice water quenching yields amorphous blends containing more than 40% PMMA and these films are deemed good candidates for rubbery state processes (between Tg and Tcc), including tenter frame biaxial stretching, where they can be oriented significantly at these low temperatures while undergoing strain induced crystallization

The Effect of Deformation and Composition on the Structure Evolution in the Pre-Oriented PET/PEI Blend Films during the Heat Setting Process

The objective of this research is to affect the deformation and thermal behavior PET through synergistic blending strategies. For this purpose, a series of crystallizable compositions of PET (Tg=70°C) and PEI (Tg=215°C) were prepared. The structure evolution during uniaxial deformation was investigated. The very fast structural rearrangement processes that take place during the heat setting process were investigated using the newly developed Spectral Birefringence Technique. In 100/0 PET/PEI samples, above the onset of strain hardening the birefringence rapidly increases with time. The total increase in birefringence decreases with the increased levels of orientation and crystallinity imparted during the stretching stage. The introduction of PEI and the increase of its concentration tend to dilute the crystallizable PET chains. This, in turn, introduces a relaxation step at the early stages of heat setting at 180°C even in samples that were stretched to high stretch ratios. We also demonstrated that our Spectral Birefringence Technique is fast enough to keep up with the very rapid changes that take place at 180°C where the fastest crystallization is experienced

The influence of molten fraction on the uniaxial deformation behavior of polypropylene: Real time mechano-optical and atomic force microscopy observations

In this study, we have coupled the real time mechano-optical measurements with the off-line structural characterization techniques including AFM, WAXS, and DSC to establish the quantitative relationships between the “true mechano-optical behavior and developed morphology” as influenced by the fraction of molten phase present in the polypropylene films. Stretching PP in the solid state invariably leads to formation of fibrillar texture. The evolution of surface morphology in partially molten state was found to depend on the fraction of the molten phase present at the start of the deformation. If the samples are strained past the yielding in partially molten state, the birefringence begins a rapid rise. Concurrent with this, the equatorial zones of the spherulites begin to crack while meridional regions remaining intact. This leads to temporary reduction of crystallinity because of destruction of some of the crystals. If held in this strained state, the crystallite thickening was observed while the birefringence increases while the lost crystallinity is recovered. If the films are strained past the strain hardening point, the microfibrillar structure was found to dominate the surface morphology. When the films are stretched in the melting temperature range, they exhibit substantial nodular surface topology. These nodules that were absent in the solid state deformed samples are hard lamellae buried inside amorphous “soft matter”. The tangential lamellae increasingly become dominant as the processing temperature approaches substantially molten state leading to the observation of a* oriented crystallites in the X-ray analysis

Nonlinear mechanooptical behavior of uniaxially stretched poly (lactic acid): Dynamic phase behavior

The mechanooptical behavior of melt-cast amorphous poly(l-lactic acid) (PLA) films in the rubbery state was investigated using an apparatus that allows for direct measurement of true stress, true strain, and birefringence in real time under well-controlled temperature over a wide range of stretching rates. Three distinct regimes of stress−optical behavior are observed during uniaxial deformation of PLA films in the rubbery state. Regime I deformation is characterized by adherence to the stress optical rule; within this regime, birefringence remains linearly proportional to stress with a stress optical constant of 3.1 GPa-1. This is followed by either a positive deviation from linearity into regime II at higher temperature and/or lower rates or a negative deviation into regime IIIa at lower temperatures and/or higher rates. Films exhibiting regime II behavior eventually deviate into regime IIIc behavior at higher levels of deformation. The appearance of regime II is associated with strain-induced crystallization. In the absence of regime II behavior, the polymer remains uncrystallized, yet becomes highly oriented, exhibiting “nematic-like” order. This stable nematic-like order prevails at all large deformation levels with no sign of crystallization. When nematic-like order is present, the strain optical behavior was found to exhibit linear or near-linear behavior in a wide deformation range. Conversely, this behavior is nonlinear with the development of strain-induced crystallization. On the basis of the structural and true mechanical measurements, a dynamic phase diagram was constructed for defining the structure development during the rubbery state uniaxial deformation of PLA

Comparative study on development of structural hierarchy in constrained annealed simultaneous and sequential biaxially stretched polylactic acid films

Structural evolution during constrained annealing of PLA films biaxially stretched in simultaneous and sequential biaxial stretching was compared. Annealing of simultaneous biaxially stretched films yields films with in-plane isotropy with (100) crystallographic planes parallel to the surface. The first stage of sequential stretching where the films are stretched in Uniaxial constrained mode was found to yield films exhibiting transverse isotropy. The transverse stretching of these films lead to formation of a distinct second population of chains primarily oriented in transverse direction, generating bimodal orientation texture. When the extent of stretching in two directions are balanced, constrained annealed samples were found to exhibit uniplanar axial (100)[001] texture with the primary chain axial direction now switched to transverse direction. Two new superstructures, along [110] and [100] respectively were discovered in annealed PLA films

Nanoparticle induced network self-assembly in polymer carbon black composites

A novel percolation phenomenon with inorganic nanoparticle loading in polyamide 6-carbon based nanoparticle hybrids was identified. Percolation threshold substantially shifts to lower carbon black (CB) volume fractions in the presence of optimum concentration of chemically modified montmorillonite (organoclay) while the effective organoclay concentration can be optimized to lower the slope of percolation curve maintaining electrical conductivity within static dissipative 10−6–10−9 S cm−1 range. Organoclay/CB ‘nano-unit’ morphology was found in polyamide 6 ternary hybrids. It is composed of stacked organo-montmorillonite platelets that deform to wrap partially around one or two primary CB aggregates. This elementary nano-unit structure induces CB network self-assembly within polyamide 6 matrices. The structure was found to be prevalent throughout the polymer matrix. This morphology remains robust under wide range of thermal-deformation histories due to the strong preferred organoclay/polyamide 6/CB interactions that partially blocks the electron conduction and hopping mechanisms with clay ‘walls’ thereby reducing the slope of the percolation curve. Organoclay can be used as a dispersion control agent in these polymer–carbon systems to induce self-assembly of CB network at low CB content, simultaneously, partial blocking the electron hopping pathways to level the slope of percolation curves. High order exfoliation and nano-scale dispersion of organoclay is essential to induce this advanced percolation phenomenon