Polysulfide Polymers

1951 ◽  
Vol 24 (3) ◽  
pp. 709-723
Author(s):  
E. M. Fettes ◽  
J. S. Jorczak
Keyword(s):  
Molecular Weight ◽  
Stress Relaxation ◽  
Cross Linking ◽  
Condensation Polymerization ◽  
Solvent Resistance ◽  
Polymer Properties ◽  
End Groups ◽  
Different Types ◽  
Liquid Polymers ◽  
Polysulfide Polymers

Abstract The chemistry of the condensation polymerization is reviewed briefly. The structures of the polymeric products as well as the effects of copolymerization, cross-linking, end groups, and molecular weight upon polymer properties are discussed. The composition and properties of the commercial crude rubbers, water dispersions, and liquid polymers are presented together with ideas on the mechanism of their vulcanization. The reason for the odor of polysulfide polymers is discussed. Some information is presented on solvent resistance, stress relaxation, and other characteristics of the polymers. Applications for the different types of products are summarized.

Polysulfide Liquid Polymers

1951 ◽  
Vol 24 (3) ◽  
pp. 724-735
Author(s):  
J. S. Jorczak ◽  
E. M. Fettes
Keyword(s):  
Molecular Weight ◽  
Diffusion Rate ◽  
Service Temperature ◽  
Good Resistance ◽  
Resistance To Oxidation ◽  
Wide Range ◽  
Liquid Polymers ◽  
Milling Equipment ◽  
Rubber State ◽  
Polysulfide Polymers

Abstract Polysulfide liquid polymers are a comparatively recent development conceived at the Thiokol Laboratories in 1943. The development was initiated by the problem of finding methods to reduce the molecular weight of a polysulfide rubber which was too tough to process on conventional rubber milling equipment. The problem was solved by reduction of a few of the disulfide links present in the polymer chain. It was soon found that the method was applicable to the preparation of polymers low enough in molecular weight to be liquids. The method produces dithiols of high purity which are extremely active in a wide variety of chemical reactions. Some formulations have been developed which depend on conversion from the liquid to rubber state at temperatures as low as 50° F in about 30 minutes. Most of the converting agents function through oxidation with hydrogen removal from the thiol and a linkage of sulfurs to reform the disulfide group. The converted polymers have the general properties of polysulfide polymers: good solvent resistance to a wide range of solvents, low diffusion rate of gases, good resistance to oxidation, ozone, and weathering, and a service temperature range from −65° to +250° F. (Some compounds can withstand intermittent temperatures as high as +350° F.) The low temperature properties are inherent in the polymer and do not depend on special compounding techniques.

Amine Terminated Reactive Liquid Polymers; Modification of Thermoset Resins

1981 ◽  
Vol 54 (2) ◽  
pp. 374-402 ◽  
Author(s):  
C. K. Riew
Keyword(s):  
Molecular Weight ◽  
Elevated Temperatures ◽  
Average Molecular Weight ◽  
Impact Resistance ◽  
Secondary Amide ◽  
Amine Group ◽  
Low Viscosity ◽  
End Groups ◽  
Liquid Polymers ◽  
Reactive Liquid

Abstract Amine terminated reactive liquid polymers (AT-RLP) are synthesized from corresponding carboxyl terminated reactive liquid polymers (CT-RLP) and diamines. The CT-RLPs have a functionality of close to two, the average molecular weight ranging from 2500 to 4000, and Brookfield viscosity ranging from 30 to 600 Pa · s at 27°C. AT-RLPs made from the CT-RLPs have about the same physical properties as the CT-RLPs given above. N-(2-aminoethyl)piperazine (AEP2) is the best diamine among the diamines tried to produce low viscosity and low molecular weight AT-RLPs. Structure of end-groups of AT-RLP is unequivocally identified as a secondary amide and a secondary amine group resulting from the reaction of carboxyl end-groups of CT-RLP and a primary amine group of AEP,. The AT-RLP can be used as a modifier for epoxy resins at room or elevated temperatures to produce castable formulations with properties ranging from plastics to elastomers. The formulations may be useful as a modifier for improvement of crack and/or impact resistance of normally brittle epoxy plastics, as castable elastomers, paints and coatings, sealants, adhesives, especially as solventless adhesives for conveyor belts, hoses, shoes, and as binders for woven or non-woven fibers and cords.

The formation of cyclic oligomers during step-growth polymerization

2004 ◽  
Author(s):  
Abderrazak Ben Haida ◽  
Philip Hodge
Keyword(s):  
Molecular Weight ◽  
Linear Molecule ◽  
Side Reactions ◽  
Order Process ◽  
Polymer Properties ◽  
End Groups ◽  
Cyclic Oligomers ◽  
Linear Molecules ◽  
Step Growth ◽  
Step Growth Polymerization

Step-growth polymerization is controlled both by the efficiency of the synthetic routes chosen (as indicated in Chapter 4) and by statistical considerations. In particular, the formation of the desired polymer is almost always accompanied by a cyclic oligomer fraction. As the dilution increases, the chances of cyclization also increase, since polymerization is a second-order process involving the reaction between linear species, whereas cyclization, involving the (intramolecular) reaction between the two ends of a linear molecule, is inherently a first-order process. Cyclization is a particular feature of the early stages of a step-growth polymerization (up to extents of reaction of 98–99%), where a proportion of the end groups that react are on the same molecule. Hence, cyclics form. Since the chances of meeting of the end groups decrease rapidly as the distance between them increases, the cyclics are of relatively low molecular weight, that is, they are oligomers. Further reaction leads mainly to linear molecules, although at extremely high conversions the number of end groups is quite small and intramolecular reactions essentially terminate the process, such that it might be expected that all chains ultimately cyclize. Practically though, the levels of conversion necessary to obtain these very large rings are extremely high and difficult to obtain (either by virtue of side reactions, monomer imperfections, or simply the level of viscosity of high molecular weight polymer solutions). What is usually obtained, therefore, is a mixture of cyclics and linear molecules. However, since cyclic oligomers often differ considerably in, for example, solubility compared to their high molar mass linear homologues, separation is often relatively straightforward. The commercial importance of polymers produced by step-growth polymerization gives a particular significance to understanding the nature of such materials. The presence of cyclic oligomers can be detrimental to the polymer properties since their presence could cause problems during processing. For instance, cyclic oligomers of polyethylene terephthalate (PET) tend to migrate to the surface of spun fibres and, under certain conditions, they crystallize to produce a surface ‘bloom’ which interferes with subsequent dyeing. More recently, it is the reverse of cyclization, namely ring-opening polymerization, which has been a particular focus of attention.

Catalyst-transfer condensation polymerization for precision synthesis of π-conjugated polymers

2012 ◽  
Vol 85 (3) ◽  
pp. 573-587 ◽  
Author(s):  
Tsutomu Yokozawa ◽  
Yutaka Nanashima ◽  
Haruhiko Kohno ◽  
Ryosuke Suzuki ◽  
Masataka Nojima ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Conjugated Polymers ◽  
Ni Catalyst ◽  
Condensation Polymerization ◽  
End Groups ◽  
Precision Synthesis ◽  
Polymerization Method ◽  
Low Solubility ◽  
End Group ◽  
Coupling Polymerization

Catalyst-transfer condensation polymerization, in which the catalyst activates the polymer end-group, followed by reaction with the monomer and transfer of the catalyst to the elongated polymer end-group, has made it feasible to control the molecular weight, polydispersity, and end-groups of π-conjugated polymers. In this paper, our recent progress of Kumada–Tamao Ni catalyst-transfer coupling polymerization and Suzuki–Miyaura Pd catalyst-transfer coupling polymerization is described. In the former polymerization method, the polymerization of Grignard pyridine monomers was investigated for the synthesis of well-defined n-type π-conjugated polymers. Para-type pyridine monomer, 3-alkoxy-2-bromo-5-chloromagnesiopyridine, afforded poly(pyridine-2,5-diyl) with low solubility in the reaction solvent, whereas meta-type pyridine monomer, 2-alkoxy-5-bromo-3-chloromagnesio-pyridine, yielded soluble poly(pyridine-3,5-diyl) with controlled molecular weight and low polydispersity. In Suzuki–Miyaura catalyst-transfer coupling polymerization, t-Bu3PPd(Ph)Br was an effective catalyst, and well-defined poly(p-phenylene) and poly(3-hexylthiophene) (P3HT) were obtained by concomitant use of CsF/18-crown-6 as a base in tetrahydrofuran (THF) and a small amount of water.

Cross-Linked αsγt-Chain Hybrids in Plasma Clots Studied by 1D- and 2D Electrophoresis and Western Blotting

1993 ◽  
Vol 70 (03) ◽  
pp. 438-442 ◽  
Author(s):  
B Grøn ◽  
C Filion-Myklebust ◽  
S Bjørnsen ◽  
P Haidaris ◽  
F Brosstad
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibodies ◽  
Human Plasma ◽  
Western Blotting ◽  
Isoelectric Point ◽  
Factor Xiii ◽  
Cross Linking ◽  
2D Electrophoresis ◽  
Complex Phenomenon ◽  
Fibrinopeptide A

SummaryFibrinogen and fibrin related chains in reduced human plasma as well as the bonds interlinking partially cross-linked fibrin from plasma clots have been studied by means of 1D- and 2D electrophoresis and Western blotting. Immunovisualization of reduced plasma or partially cross-linked fibrin with monoclonal antibodies specific for the α-chains or the γ-chains have shown that several bands represent material belonging to both chains. In order to decide whether these bands constitute αγ-chain hybrids or superimposed α- and γ-chain dimers, the cross-linked material was separated according to both isoelectric point (pI) and molecular weight (MW) using Pharmacia’s Multiphor II system. Western blotting of the second dimension gels revealed that partially cross-linked fibrin contains αsγt-chain hybrids and γ- polymers, in addition to the well-known γ-dimers and α-polymers. The main αsγt-chain hybrid has a pI between that of the α- and the γ-chains, a MW of about 200 kDa and contains Aα-chains with intact fibrinopeptide A (FPA). It was also observed that soluble fibrinogen/fibrin complexes as well as partially cross-linked fibrin contain degraded α-dimers with MWs close to the γ-dimers. These findings demonstrate that factor XIII-catalyzed cross-linking of fibrin is a more complex phenomenon than earlier recognized.

scholarly journals Synthesis and Characterization of Clay Polymer Nanocomposites of P(4VP-co-AAm) and Their Application for the Removal of Atrazine

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 721 ◽  
Author(s):  
Jorge A. Ramírez-Gómez ◽  
Javier Illescas ◽  
María del Carmen Díaz-Nava ◽  
Claudia Muro-Urista ◽  
Sonia Martínez-Gallegos ◽  
...  
Keyword(s):  
Polymer Nanocomposites ◽  
Nanocomposite Materials ◽  
Synthesis And Characterization ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
Numerous Species ◽  
X Ray ◽  
Different Types ◽  
Synthesized Materials

Atrazine (ATZ) is an herbicide which is applied to the soil, and its mechanism of action involves the inhibition of photosynthesis. One of its main functions is to control the appearance of weeds in crops, primarily in corn, sorghum, sugar cane, and wheat; however, it is very toxic for numerous species, including humans. Therefore, this work deals with the adsorption of ATZ from aqueous solutions using nanocomposite materials, synthesized with two different types of organo-modified clays. Those were obtained by the free radical polymerization of 4-vinylpyridine (4VP) and acrylamide (AAm) in different stoichiometric ratios, using tetrabutylphosphonium persulfate (TBPPS) as a radical initiator and N,N′-methylenebisacrylamide (BIS) as cross-linking agent. The structural, morphological, and textural characteristics of clays, copolymers, and nanocomposites were determined through different analytical and instrumental techniques, i.e., X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Adsorption kinetics experiments of ATZ were determined with the modified and synthesized materials, and the effect of the ratio between 4VP and AAm moieties on the removal capacities of the obtained nanocomposites was evaluated. Finally, from these sets of experiments, it was demonstrated that the synthesized nanocomposites with higher molar fractions of 4VP obtained the highest removal percentages of ATZ.

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