Stress Whitening in Polypropylene. I. Light Scattering Theory and Model Experiments

1995 ◽  
Vol 60 (11) ◽  
pp. 1875-1887 ◽  
Author(s):  
Jaroslav Holoubek ◽  
Miroslav Raab

Theoretical background for an optical method is presented which makes it possible to distinguish unambiguously between voids and particles as light scattering sites in polymeric materials. Typical dependences of turbidity as a function of diameter of scattering elements, their volume fractions and also turbidity curves as a function of the wavelength of the incident light were calculated, based both on the Lorenz-Mie theory and the fluctuation theory. Such dependences calculated for polypropylene-containing voids on the one hand and particles, differing only slightly from the surrounding matrix in their refractive index, on the other hand, are markedly different. The most significant results are: (i) Turbidity is at least by two orders of magnitude larger for voids in comparison to embedded particles of ethylene-propylene (EPDM) rubber of the same size, concentration and at the same wavelength. (ii) The wavelength dependence of turbidity for EPDM particles and the inherent refractive index fluctuations in the polypropylene matrix is much steeper as compared to voids for all considered diameters (0.1-10 μm). Thus, the nature of stress whitening in complex polymeric materials can be determined from turbidity measurements.

2012 ◽  
Vol 83 (4) ◽  
pp. 355-362 ◽  
Author(s):  
Ni Wang ◽  
Wenyan Pan ◽  
Meiwu Shi ◽  
Jianyong Yu

Mie scattering theory has been widely used to solve the problem of light scattering by single spherical particles in many fields. In this article, it was applied for the development of opaque fiber for the first time. Firstly, the spheroid particles were simplified as equivalent spherical particles. Then, the extinction coefficient was calculated using the Matlab program and the influences of the size parameter, refractive index and the wavelength of the incident light on the extinction coefficient were discussed in detail. Finally, the results indicated that the extinction coefficient depended greatly on the dimension and the refractive index of the particles, and also the wavelength of the incident light. For the development of the opaque fiber, it would be better to choose particles that had the higher refractive index and a certain diameter distribution to achieve the most effective light scattering.


Author(s):  
Chris W. Drew ◽  
Christopher G. Rylander

The highly disordered refractive index distribution in biological tissue causes multiple-scattering of incident light and inhibits optical penetration depth. “Tissue optical clearing” increases penetration depth of near-collimated light in biological tissue, potentially resulting in improved optical analysis and treatment techniques. Numerous methods of tissue optical clearing have been hypothesized using hyperosmostic agents [1]. These methods propose reduction in light scattering by means of dehydration of tissue constituents, replacement of interstitial or intracellular water with higher refractive agents, or structural modification or dissociation of collagen fibers [2,3]. It has been suggested that dehydration of tissue constituents alone can reduce light scattering by expulsing water between collagen fibrils, increasing protein and sugar concentrations, and decreasing refractive index mismatch [4].


2015 ◽  
Vol 29 (07) ◽  
pp. 1550040 ◽  
Author(s):  
Hyun Cheol Lee

We propose a theoretical framework which can treat the nonresonant and the resonant inelastic light scattering on an equal footing in the form of correlation function, employing Keldysh–Schwinger functional integral formalism. The interference between the nonresonant and the resonant process can be also incorporated in this framework. This approach is applied to the magnetic Raman scattering of two-dimensional antiferromagnetic insulators. The entire set of the scattering cross-sections are obtained at finite temperature, the result for the resonant part agrees with the one obtained by the conventional Fermi golden rule at zero temperature. The interference contribution is shown to be very sensitive to the scattering geometry and the band structure.


Virittäjä ◽  
1970 ◽  
Vol 125 (1) ◽  
Author(s):  
Ildikó Vecsernyés

Tässä artikkelissa tarkastellaan, kuinka Suomen ja Unkarin pääministereitä puhutellaan Facebookissa. Tutkimuksen kohteena on se, mitä puhuttelukeinoja kommentoijat käyttävät kahdessa eri tarkoituksessa: toisaalta sympatian tai samaa mieltä olemisen, toisaalta erimielisyyden tai kritiikin ilmaisemisessa. Kahden sukukielen, suomen ja unkarin, puhuttelukeinot ovat samankaltaisia, mutta niiden käytössä on huomattavia eroja esimerkiksi sinuttelun ja teitittelyn yleisyydessä. Aineistona on viiteen Suomen pääministeri Juha Sipilän ja yhdeksään Unkarin pääministeri Viktor Orbánin vuosina 2015–2017 kirjoittamaan Facebook-päivitykseen tulleita kommentteja. Tarkastelun kohteena on 189 suomenkielistä ja 191 unkarinkielistä puhuttelumuotoa sisältävää kommenttia. Kommentit on jaettu myötäileviin ja vastustaviin ja näitä kahta kommenttityyppiä tarkastellaan kvantitatiivisesti ja kvalitatiivisesti pyrkimyksenä selvittää, mitä eroja puhuttelumuodon valinnassa ilmenee. Tutkimuksen teoreettis-metodisena taustana on aiempi sosiopragmaattinen puhuttelututkimus. Tutkimus osoittaa, että suomessa sinuttelu on hyvin yleistä riippumatta kommentin laadusta, mutta unkarissa sinuttelu on tavallisesti erimielisyyden osoittamisen keino. Tyypillinen kannustavan kommentin kirjoittaja käyttää suomessa sinuttelua ja pääministerin etunimeä, unkarissa teitittelyä, ön-teitittelypronominia ja pääministerin titteliä. Unkarin kielessä puhuteltavan yhteiskunnallinen asema vaikuttaakin puhuttelumuodon valintaan vahvemmin kuin suomessa. Toissijaisena strategiana unkarissa esiintyy jonkin verran myös uudenlaista kunnioittavaa sinuttelua yhdistettynä pääministerin etunimen käyttöön. Suomenkielisen aineiston vastustavissa kommenteissa esiintyy vielä todennäköisemmin sinuttelua kuin myötäilevissä kommenteissa sekä sinä-pronominia ja pääministerin sukunimeä, unkarinkielisessä aineistossa puolestaan sinuttelua, te ’sinä’ -pronominia ja pääministerin etu- tai sukunimeä tai nimenmuunnoksia. Toissijaisena strategiana joissain unkarin vastustavissa kommenteissa hyödynnetään ylikohteliaisuutta ja intentionaalista inkoherenssia. Aineiston perusteella näyttää siltä, että Facebook-kommenteissa käytetään suomessa etupäässä sinuttelua samoin kuin muissakin internetkeskusteluissa; kommentoijien mielipiteen ilmaisemisessa nominaalisilla puhuttelumuodoilla on tärkeä rooli. Unkarissa taas internetin yleisestä sinuttelupainotteisuudesta huolimatta tärkeimpänä keinona on sinuttelun ja teitittelyn vastakkainasettelu.   How to address a Prime Minister? Forms of address in comments to posts from the Prime Ministers of Finland and Hungary This article examines how the Prime Ministers of Finland and Hungary are addressed on Facebook. The aim of the study is to investigate which forms of address are used by commentators expressing, on the one hand, sympathy or consent, and on the other, disagreement or criticism. The repertoires of address forms of these two related languages, Finnish and Hungarian, bear many similarities, but the frequency and status of these forms are different. The data consists of comments on five posts written by Prime Minister of Finland Juha Sipilä and on nine posts written by Prime Minister of Hungary Viktor Orbán between 2015–2017, comprising a total of 189 comments in Finnish and 191 comments in Hungarian, all containing forms of address. The comments have been divided into two types: comments showing sympathy and comments showing disagreement or criticism. These two comment types have been analysed quantitatively and qualitatively aiming to determine how the address practices employed differ from each other. The theoretical background of this study is based upon previously conducted socio­pragmatic address research. The article shows that the use of T forms  is very common in Finnish, regardless of the type of comment, but that in Hungarian, T forms are typically used as a linguistic tool to express disagreement. In Finnish, a typical commentator showing sympathy will use T forms and address the Prime Minister by his first name, whereas in Hungarian V forms, the V form pronoun ön, and the title ‘Prime Minister’ are favoured. The social status of the addressee has a stronger effect on the choice of address forms in Hungarian than it does in Finnish. However, some Hungarian comments include a new, respectful type of T form used with the first name of the Prime Minister. In comments expressing disagreement in the Finnish data, writers favour T forms, especially T form pronouns, and the use of the Prime Minister’s surname, whereas in the Hungarian data T forms, the T form pronoun te ‘you’ and the use of the Prime Minister’s first name, surname or nicknames are the most typical address practices. In conclusion, commentators in the Finnish data seem to use mostly T forms on Facebook, thus imitating address practices common in other online conversations. Instead of the T/V opposition, nominal forms of address play an important role in expressing the commentators’ attitude. In the Hungarian data, despite the prevalence of the T forms in online chats, the most important resource in expressing relation to the Prime Minister seems to be the contrast between the T and V forms, reflecting their significant status in Hungarian.


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