A New Derivation of Postgel Properties of Network Polymers

1976 ◽  
Vol 49 (5) ◽  
pp. 1219-1231 ◽  
Author(s):  
D. R. Miller ◽  
C. W. Macosko

Abstract The probability of a finite or dangling chain on an ideal polymer network has been derived by a simple recursive scheme. In contrast to the method of Dobson and Gordon, probability generating function formalism is not required. The general result, Equations (21), and its specific solutions, Equations (23), (24), and (30), give the finite chain probability as a function of reactant type and extent of polymerization. They cover most of the important types of network forming polymerizations. From the finite chain probability, useful property relations such as sol fraction, crosslink density, and the number of elastically effective network chains are developed. Because of their simplicity, we expect these relations to be further developed and applied to network polymer property measurements.

2016 ◽  
Author(s):  
A. D. Jenkins ◽  
P. Kratochvĺl ◽  
R. F. T. Stepto ◽  
U. W. Suter

Vestnik MGSU ◽  
2021 ◽  
pp. 347-359
Author(s):  
Andrey A. Askadskii ◽  
Sergey V. Matseevich ◽  
Tat’yana A. Matseevich

Introduction. For the first time, a model and a principle for constructing an appropriate computer program for the selection of polymer networks with a given interval of a number of physical characteristics are proposed. These characteristics include density, the temperature of the onset of intense thermal degradation, thermal conductivity, water permeability, and the stress-optical coefficient. As an example, 16 smallest base fragments are given, which, when attached to each other, allow the selection of structural fragments of repeating fragments of polymers of the following classes: polyolefins, vinyl polymers, polystyrene, polyamides, polyethers and polyesters, polycarbonates, polyetherketones, polyimides, polysulfides, polysulfones, silicone polymers, polyurethanes, cellulose derivatives, methacrylic polymers, etc. The purpose of the study is to develop a model for writing a computer program that allows the selection of structural fragments of network polymers possessing specified intervals of physical characteristics. For polymers used in the construction industry, the most important are the glass transition temperature, the stress-optical coefficient, density, water permeability, and thermal conductivity. Materials and methods. A repeating fragment of the network is selected from the smallest basic fragments, which are connected to each other using a control matrix of interactions. The matrix contains labels that allow you to control the interaction of carbon with three carbon atoms, with a carbon atom and two nitrogen atoms, with two carbon atoms and one oxygen atom, with two carbon atoms and one nitrogen atom, with four carbon atoms. There are also labels that control the interaction of carbon atoms included in the aromatic cycles with two carbon atoms and one oxygen atom, with four carbon atoms, with four nitrogen atoms, with two carbon atoms and one sulfur atom, and three oxygen atoms. This makes it possible to select a huge amount of cross-linked polymer. Results. As an example, the possible chemical structure of 14 cross-linked nodes of the polymer network is presented and the corresponding calculations are carried out, showing the adequacy of the model and the principle of constructing a computer program. The structures of the five cross-linked nodes of polymer network were used and the following physical characteristics of the resulting networks were calculated: density, the temperature of the onset of intense thermal degradation, water permeability, thermal conductivity, and the stress-optical coefficient. All these characteristics are important for the manufacture of building materials. Conclusions. The results of the work allow us to write a real computer program for the selection of repeating fragments of polymer networks that have a given interval of a number of important physical characteristics of network polymers. Among these characteristics are not only those listed above, but also other characteristics, such as glass transition temperature, Hildebrand solubility parameter, surface energy, heat capacity, intermolecular interaction energy, permittivity, etc.


1967 ◽  
Vol 40 (2) ◽  
pp. 476-483 ◽  
Author(s):  
Kyoichi Shibayama ◽  
Yasukira Suzuki

Abstract Copolymerization of vinyl and divinyl monomer is a typical method for preparing a network polymer. A multiple network structure, in which one network entangles with another, is supposed to be produced when a network polymer is swollen in the monomer mixture and then polymerization of absorbed monomer is carried out so as to superpose the second network on the first. Viscoelastic properties and degree of swelling in solvents were investigated for composite polymers prepared from styrene and divinylbenzene. Results were consistent with presumed characteristics of multiple network structures.


Author(s):  
A. G. GÜREK ◽  
Ö. BEKARO ĞLU

1,7-dithia (12-crown-4)-bridged phthalocyanine network polymers were prepared from tetracyanodibenzo-[1,7-dithia(12-crown-4)]. In addition, the synthesis of two 1,7-dithia (12-crown-4) linked peripherally octa-substituted dimeric phthalocyanines, which contain a combination of hexakis(alkylthia) side chains, is described. These extremely soluble compounds were prepared by the condensation of an iminoisoindoline derivative and a subphthalocyanine. The novel compounds are characterized by elemental analyses, UV/vis, IR, mass, 1 H NMR and 13 C NMR spectroscopy. The electrical conductivity measurements of three of the four network polymers were unsuccessful; however chemical doping with NOBF 4 could be increased to a measurable value. The electrical conductivity of the dimeric phthalocyanines are in the semiconductor range.


1967 ◽  
Vol 40 (2) ◽  
pp. 544-555 ◽  
Author(s):  
Thor L. Smith

Abstract Ultimate tensile properties of amorphous unfilled elastomers can be characterized by a failure envelope which results from a plot of log log  σbT0vs.log  (λb− 1) where  σb is the stress at break based on the cross section area of an unstressed specimen,   λb is the corresponding ultimate extension ratio, and T0 and T are, respectively, an arbitrarily selected reference temperature and the test temperature expressed in °K. Values of  σb and   λb are normally obtained from tests made at different extension rates at a series of temperatures. To determine the effect of crosslink density on the failure envelope, a study was made of eight vulcanizates of a hydrofluorocarbon elastomer, Viton A-HV. The number of effective network chains, νe, in these vulcanizates varied from 0.38× 10−4to 9.46× 10−4mole/cm.3 Ultimate tensile properties were determined at temperatures between −5 and 230° C and at seven to ten extension rates at each temperature. The data gave a master failure envelope on a plot of λbσb273/Tvs.log  Ee(λb−1) 273/T, where Ee is the equilibrium tensile modulus. This behavior shows that λbσbT0/T is a function of Ee(λb−1); thus the maximum value of (λb−1) is inversely proportional to νe. Ultimate tensile properties of one vulcanizate were also determined under constant loads at four temperatures and the data were found to yield the same envelope as those from tests made at constant rates of extension.


2017 ◽  
Vol 9 (3) ◽  
pp. 1 ◽  
Author(s):  
Naofumi Naga ◽  
Yasuto Sugano ◽  
Arie Senda

Network polymers containing Si-vinylene units have been synthesized by Mizoroki-Heck reaction of cyclic siloxane or cubic silsesquioxane compounds with vinyl groups, as joint molecules, and dibromo aryl compounds, as linker molecules, using a Pd catalyst. The reaction of 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane (TVMCTS) or octavinyloctasilsesquioxane (PVOSS) with o, m, p-dibromobenzene (DBB) or 4,4'-dibromobiphenyl (DBBP) yielded the corresponding network polymers, except TVMCTS-oDBB system. Optical properties of the network polymers were studied by UV-vis and photoluminescence spectroscopy, and absorption and emission derived from s-p conjugation of the Si-vinylene units were detected. Copolymerization of TVMCTS-DBB/bromobenzene yielded CHCl3 soluble fraction due to formation of the network fragments. The network polymers of TVMCTS or PVOSS with 2,7-dibromofluorene (BFl) or 9,9-dihexyl-2,7-dibromofluorene were synthesized by the same procedures. Scanning electron microscope image of TVMCTS-BFl network polymer indicated formation of porous structure. The network polymers have been also synthesized by the reactions of multifunctional aryl bromide, as the joint molecules, with divinyl or dially silane compounds, as the linker molecules. The molecular structure of the multifunctional aryl bromide affected the emission wavelengths of the network polymers. In the case of the 2,2’,7,7’-tetrabromo-9,9’-spirobifluorene-based network polymers, the emission spectra widely ranged from 450 to 500 nm, which were sensitive to molecular structure of the divinyl or dially silane compounds.


2016 ◽  
Vol 52 (66) ◽  
pp. 10109-10112 ◽  
Author(s):  
Hitesh Khandelwal ◽  
Gilles H. Timmermans ◽  
Michael G. Debije ◽  
Albertus P. H. J. Schenning

An adjustable broadband reflector based on a polymer stabilized chiral nematic liquid crystal has been fabricated.


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