Online monitoring of birefringence development in heat‐setting polymer films with a fast dual‐wavelength optical technique. I. Uniaxially oriented poly(ethylene naphthalate)

Galay, J.; Çakmak, Mükerrem

doi:10.1002/polb.1087

Cited by 24 publications

(24 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A film is considered to be uniform film when the standard deviation divided by the mean thickness is less than 5%. 51 The data shown in Figure 4 indicate that films are uniform at two temperatures 583 and 608 K when the draw ratio is between 1.4 and 3. On the basis of the above analysis, an operating window for film stretching the window, bounded by temperature and draw ratio, is presented in Figure 1.…”

Section: Resultsmentioning

confidence: 91%

Thermal and mechanical properties of stretched recyclable polyimide film

Wang

Liu

et al. 2011

J of Applied Polymer Sci

View full text Add to dashboard Cite

An operating window, which is bounded by two temperatures and draw ratios, defines the stable and defect-free stretching region of a polymer film. Physical properties including the coefficient of thermal expansion (CTE), birefringence, and Young's modulus of a recyclable polyimide (PIR) film were measured under stretching conditions. While values of birefringence and Young's modulus increased with increasing stretching stress in the machine direction, the CTE was found to decrease. A semiempirical model for the prediction of birefringence and Young's modulus under stretching conditions was developed, from which the CTE could be estimated from the Young's modulus data. Theoretically evaluated physical properties were found to be in qualitative agreement with the experimental data.

show abstract

Section: Resultsmentioning

confidence: 91%

Thermal and mechanical properties of stretched recyclable polyimide film

Wang

Liu

et al. 2011

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…One polarizer is parallel to the original polarization direction (+45 • ) and the other is perpendicular to the original polarization (−45 • ). The light acquired by these fiber optic cables is transmitted to the spectrometer for recording and subsequent retardation calculations (more detailed information is given elsewhere [40][41][42][43][44][45][46][47][48][49][50][51][52]. We calculate the in-plane birefringence by the ratio of the retardation values to the real-time thickness values (Eq.…”

Section: A Uniaxial Stretching Machinementioning

confidence: 99%

“…[33][34][35][36][37][38][39] Birefringence is calculated by using spectral measurement method. [40][41][42][43][44][45][46][47][48][49][50][51][52] A visible wavelength light source is used coupled with a +45 • linear polarizer. The polarized light is reflected through a metallic mirror (no change in the state of polarization) and focused on the sample.…”

Section: A Uniaxial Stretching Machinementioning

confidence: 99%

Rapid integrated rheo-optical and polarized Fourier-transform infrared spectrometry measurement system for polymer films undergoing chemo-mechanical changes

Ünsal

Nugay

Offenbach

et al. 2013

Review of Scientific Instruments

Self Cite

View full text Add to dashboard Cite

The design and performance of a multisensory instrument to track physical and chemical changes of thin polymer films (typically 5 μm < thickness < 100 μm) subjected to thermal and mechanical treatments are described in this paper. For the first time, real-time measurements of spectral birefringence, true stress, true strain, and temperature are integrated together with ultra-rapid-scan polarized FT-IR spectrometer (URS-FT-IR) to investigate the relationships between true mechanical measures and structural features at different length scales. The rheo-optical properties (birefringence-true stress-true strain) are collected at a rate of 10 data points∕s and URS-FT-IR data are collected at a rate of 300 complete spectra∕s. The IR dichroism measurement is performed by exposing the sample to non-polarized IR beam in transmission mode with two mutually perpendicular polarizations, parallel and perpendicular to the stretching direction, received by detector unit. This design allows to analyze both polarizations simultaneously wavenumbers in the range of 500 cm(-1)-4000 cm(-1). Controlled processing parameters include air speed, air temperature, stretching rate, stretching ratio, stretch cycling, and holding times; while simultaneously measuring optical retardation, sample width, temperature, load cell, and both parallel and perpendicular IR spectra. Calibration and performance of this instrument is demonstrated with several film samples. These are: A polystyrene standard, an atactic polystyrene (homo-polymer), a polyurethane (consists of hard and soft segments) for physical changes during uniaxial deformation, and a polyamic acid during imidization reaction. This measurement system is particularly useful in unraveling molecular level details of complex physical and chemical events that take place during very fast deformation schemes (uniaxial stretching, retraction, relaxation, annealing, etc.) relevant to industrial processes. These include specific orientation behavior of each phase, block or filler, crystallization, relaxation and orientation state. It is also suited to track reaction rates and products in polymers undergoing thermal or photo curing.

show abstract

“…23,24 At high stretch rates, comparable to industrial stretch rates, with which substantially oriented and strain-induced structures are obtained, the initial relaxation stage disappears, and birefringence continues to increase throughout the heat-setting process even at temperatures very close to T g . The kinetics of the structural changes exhibit a complex behavior, and the largest rates of structural changes have been observed in PET films exhibiting intermediate birefringence levels.…”

Section: Introductionmentioning

confidence: 98%

Shrinkage behavior after the heat setting of biaxially stretched poly(ethylene 2,6‐naphthalate) films and bottles

Schoukens

Samyn

Maddens

et al. 2002

J of Applied Polymer Sci

View full text Add to dashboard Cite

Amorphous preforms of poly(ethylene 2,6-naphthalate) (PEN) were biaxially drawn into bottles up to the desired volume under industrial conditions. These bottles were used to characterize the shrinkage behavior of the drawn bottles with or without heat treatment and to study structural variations during heat setting. During drawing, a rigid phase structure was induced, and the amount of the induced rigid phase structure was linearly related to the square root of the extra first strain invariant under equilibrium conditions. During the production of these bottles, this equilibrium was not attained because of high stretching conditions and rapid cooling after stretching. The structure after orientation contained a rigid amorphous phase and an oriented amorphous phase. The shrinkage behavior was a function of the temperature and time of heat setting. Long heat-setting times, around 30 min, were used to characterize the possible structural variations of the oriented PEN after heat setting at equilibrium. Under the equilibrium conditions of heat setting, the start temperature of the shrinkage was directly related to the heat-setting temperature and moved from 60°C without heat treatment up to a temperature of 255°C by a heat-setting temperature of 255°C; this contrasted with poly(ethylene terephthalate) (PET), for which the start temperature of shrinkage was always around 80°C. For heat-setting temperatures higher than 220°C, the structural variations changed rapidly as a function of the heat-setting time, and the corresponding shrinkage of the heat-set samples sank below 1% in a timescale of 30 -60 s for a film thickness of 500 m. The heat treatment of the oriented films taken out of the bottle walls with fixed ends stabilized the induced structures, and the shrinkage of these heat-set films was zero for temperatures up to the heatsetting temperature, between 220 and 265°C, if the heatsetting time was sufficient. According to the results obtained, a heat-setting time of 30 s, for a film thickness of 500 m, was sufficient at a heat-setting temperature of 255°C to stabilize the produced biaxially oriented PEN bottles and to take them out the mold without further shrinkage. During the drawing of PEN, two different types of rigid amorphous phases seemed to be induced, one with a mean shrinkage temperature of 151°C and another rigid amorphous phase, more temperature-stable than the first one, that shrank in the temperature range of 200 -310°C. During heat setting at high temperatures, a continuous transformation of the less stable phase into the very stable phase took place. The heat-set method after blow molding is industrially possible with PEN, without the complicated process of subsequent cooling before the molds are opened, in contrast to PET. This constitutes a big advantage for the blow molding of PEN bottles and the production of oriented PEN films.

show abstract

Online monitoring of birefringence development in heat‐setting polymer films with a fast dual‐wavelength optical technique. I. Uniaxially oriented poly(ethylene naphthalate)

Cited by 24 publications

References 26 publications

Thermal and mechanical properties of stretched recyclable polyimide film

Thermal and mechanical properties of stretched recyclable polyimide film

Rapid integrated rheo-optical and polarized Fourier-transform infrared spectrometry measurement system for polymer films undergoing chemo-mechanical changes

Shrinkage behavior after the heat setting of biaxially stretched poly(ethylene 2,6‐naphthalate) films and bottles

Contact Info

Product

Resources

About