Orientation studies of poly(vinyl chloride). Part I: Intrinsic birefringence

Jabarin, S. A.

doi:10.1002/pen.760310904

Cited by 20 publications

(12 citation statements)

References 30 publications

(27 reference statements)

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“…The incompressibility assumption is reasonable for PVC because the density changes due to crystallization during stretching are negligible if not zero. The very small density change observed for PVC during stretching is suggested to be due to conformational changes and ordering rather than true crystallization 43. Although higher stretching temperatures (above the T g ) and/or plasticizer content increases this change, it remains around 0.01% 43…”

Section: Methodssupporting

confidence: 62%

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

Yalcin

Çakmak

2005

J Polym Sci B Polym Phys

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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-

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Section: Methodssupporting

confidence: 62%

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

Yalcin

Çakmak

2005

J Polym Sci B Polym Phys

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“…Rates of radiative transitions depend on the environment of the chromophore, in particular on the local index of refraction. Two independent effects can cause the refractive index of PVC to change upon stretching (for details see Table 2 and the Supporting Information, Section 2.3): 1) From reported density changes [26] the Lorentz-Lorenz equation [27] predicts index variations of the order of Dn % 4.6 10 À4 for relative elongations of 100 %.…”

Section: à2mentioning

confidence: 99%

“…[26,[28][29][30][31][32] By applying a modified Strickler-Berg approach, different cavity models have been developed, which should be taken into account to estimate the influence of refractive index changes on the fluorescence lifetime. [33] As the solvent is expelled from the volume occupied by the fluorescent molecule, a cavity is created in which the fluorophore is located.…”

Section: à3mentioning

confidence: 99%

Fluorophores as Optical Sensors for Local Forces

et al. 2009

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The main aim of this study is to investigate correlations between the impact of an external mechanical force on the molecular framework of fluorophores and the resultant changes in their fluorescence properties. Taking into account previous theoretical studies, we designed a suitable custom-tailored oligoparaphenylenevinylene derivative (OPV5) with a twisted molecular backbone. Thin foils made of PVC doped with 100 nM OPV were prepared. By applying uniaxial force, the foils were stretched and three major optical effects were observed simultaneously. First, the fluorescence anisotropy increased, which indicates a reorientation of the fluorophores within the matrix. Second, the fluorescence lifetime decreased by approximately 2.5% (25 ps). Finally, we observed an increase in the emission energy of about 0.2% (corresponding to a blue-shift of 1.2 nm). In addition, analogous measurements with Rhodamine 123 as an inert reference dye showed only minor effects, which can be attributed to matrix effects due to refractive index changes. To relate the observed spectroscopic changes to the underlying changes in molecular properties, quantum-chemical calculations were also performed. Semiempirical methods had to be used because of the size of the OPV5 chromophore. Two conformers of OPV5 (C(2) and C(i) symmetry) were considered and both gave very similar results. Both the observed blue-shift of fluorescence and the reduced lifetime of OPV5 under tensile stress are consistent with the results of the semiempirical calculations. Our study proves the feasibility of fluorescence-based local force probes for polymers under tension. Improved optical sensors of this type should in principle be able to monitor local mechanical stress in transparent samples down to the single-molecule level, which harbors promising applications in polymer science and nanotechnology.

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“…The linear relationship between the orientation function of the main chain

f_{normalm}

and

Δ n_{or}

in Eq . has been confirmed experimentally with polymers such as PMMA , PSt , poly(ethylene terephthalate) , poly(ethylene 2,6‐naphthalenedicarboxylate) , poly(bisphenol‐A carbonate) , and poly(vinyl chloride) . Furthermore, the intrinsic birefringence Δ n 0 and polarizability anisotropy Δ α can be related by the following equation, demonstrating the proportional relationship between Δ n 0 and Δ α :

Δ n^{0} = \frac{2 π}{9} \times \frac{N ρ}{M} \times \frac{{(n^{2} + 2)}^{2}}{n} \times Δ α

where n is the refractive index, N is Avogadro's number, ρ is the density, and M is the molecular weight of the repeat unit of the polymer .…”

Section: Resultsmentioning

confidence: 70%

“…1 has been confirmed experimentally with polymers such as PMMA [13], PSt [20], The intrinsic birefringence Dn 0 and photoelastic birefringence C of PMMA, PTFEMA, and PPFPhMA were analyzed in previous work [2,8]. poly(ethylene terephthalate) [21], poly(ethylene 2,6-naphthalenedicarboxylate) [21], poly(bisphenol-A carbonate) [22], and poly(vinyl chloride) [23]. Furthermore, the intrinsic birefringence Dn 0 and polarizability anisotropy Da can be related by the following equation, demonstrating the proportional relationship between Dn 0 and Da:…”

Section: Investigation Into the Mechanisms Of Birefringence Generationmentioning

confidence: 91%

Mechanisms of orientational and photoelastic birefringence generation of methacrylates for the design of zero–zero‐birefringence polymers

Shafiee

Beppu

Iwasaki

et al. 2015

Polymer Engineering & Sci

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The intrinsic birefringence Dn 0 and photoelastic coefficient C of poly(methyl methacrylate), poly(2,2,2-trifluroethyl methacrylate), poly(phenyl methacrylate), and poly(2,2,3,3,3-pentafluorophenyl methacrylate) were determined. We categorized these methacrylate polymers into four birefringence-types, even though their molecular structures differed only by the substituents on the side chains. Based on the results of Dn 0 and C, novel polymers that exhibit neither orientational nor photoelastic birefringence, i.e., zero-zero-birefringence polymers, were designed and synthesized by quaternary copolymerization system. Furthermore, we confirmed that the mechanisms of orientational birefringence and photoelastic birefringence generation were different in these methacrylate polymers. The conformation of the repeat unit of the polymers was nearly constant during the generation of orientational birefringence. In contrast, the conformation of the repeat unit of the polymers changed during the generation of photoelastic birefringence in the glassy state. These findings demonstrated the reasonability of evaluating orientational and photoelastic birefringence separately, as well as the adequacy of the classification of polymers into four birefringence-types. Given these results and the fact that zero-zero-birefringence polymers could be prepared successfully by four-birefringence type monomers, we demonstrated the reasonability of the method for designing the zero-zero-birefringence polymers. POLYM. ENG. SCI., 55:1330SCI., 55: -1338SCI., 55: , 2015

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Orientation studies of poly(vinyl chloride). Part I: Intrinsic birefringence

Cited by 20 publications

References 30 publications

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

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

Fluorophores as Optical Sensors for Local Forces

Mechanisms of orientational and photoelastic birefringence generation of methacrylates for the design of zero–zero‐birefringence polymers

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