Inter- and intramolecular interactions of polymers as studied by fluorescence spectroscopy. Part 13. Comparison between excimer- and exciplex-forming polymers having an identical main chain structure

1982 ◽  
Vol 86 (8) ◽  
pp. 1250-1252 ◽  
Author(s):  
Shigeo Tazuke ◽  
Hui Liang Yuan
Keyword(s):  
Fluorescence Spectroscopy ◽  
Main Chain ◽  
Chain Structure ◽  
Intramolecular Interactions

Stress Relaxation Studies of Scission in Rubber Vulcanizates

1960 ◽  
Vol 33 (1) ◽  
pp. 72-77
Author(s):  
A. Mercurio ◽  
A. V. Tobolsky
Keyword(s):  
Stress Relaxation ◽  
Main Chain ◽  
Crosslinking Agent ◽  
Chain Structure ◽  
Air Atmosphere ◽  
Diffusion Effects ◽  
Relaxation Experiments ◽  
Prime Objective ◽  
The Common ◽  
Vulcanization Process

Abstract Deterioration of many vulcanized hydrocarbon rubbers is known to be due to reaction with molecular oxygen. Such a process is independent of oxygen concentration down to several mm of oxygen pressure and hence proceeds quite readily in an air atmosphere provided that experiments are conducted with thin enough samples to eliminate oxygen diffusion effects. Two chemically distinct loci for attack by oxygen are available. These are the crosslinked sites which are added during the vulcanization process and the network chains which are essentially the same as in the unvulcanized material. The prime objective of this study is to show clearly that vulcanized natural rubber suffers oxidative scission predominantly along the polyisoprene chains and not at the crosslinked sites as proposed by Berry and Watson. Other literature has appeared which indicates that this important point needs further clarification. Stress relaxation experiments, which measure the rate of breaking of the weakest chemical bonds recurring throughout the structure, have been utilized. If the crosslinks are oxidized, then similar rates of scission should be obtained for different chain structures so long as the common crosslink is present in all of them. On the other hand, if chains are oxidized, then rates of scission should be essentially independent of the crosslinking agent used but rather depend markedly on each chain structure. The five chain structures used in this study are depicted in Table I. In each case at least a few per cent of double bond-containing segments are present in the main chain to allow for ordinary chemical vulcanization methods. All of these have been crosslinked by sulfur and by a nonsulfur containing agent.

Adsorption characteristics of PFPE lubricants with different main chain structure

2020 ◽  
Vol 2020.95 (0) ◽  
pp. 05_516
Author(s):  
Yuki YAMAJI ◽  
Hiroshi TANI ◽  
Norio TAGAWA ◽  
Shinji KOGANEZAWA ◽  
Renguo LU
Keyword(s):  
Main Chain ◽  
Chain Structure ◽  
Adsorption Characteristics ◽  
Pfpe Lubricants

Photoswitching Behavior of SiO2Inverse Opal Films Infiltrated with Azo-Tolane Copolymer: Effect of Polymer Main Chain Structure

2009 ◽  
Vol 513 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Tomomi Shirota ◽  
Masaki Moritsugu ◽  
Shoichi Kubo ◽  
Tomonari Ogata ◽  
Takamasa Nonaka ◽  
...  
Keyword(s):  
Main Chain ◽  
Chain Structure ◽  
Polymer Main Chain

scholarly journals Study on adsorption, rheology and hydration behaviours of Polycarboxylate(PCE) superplasticizer synthesized by different acid to ether ratio

2021 ◽  
Vol 2133 (1) ◽  
pp. 012007
Author(s):  
Zhijun Lin ◽  
Xiaofang Zhang ◽  
Zhanhua Chen ◽  
Yue Xiao ◽  
Yunhui Fang
Keyword(s):  
Molecular Weight ◽  
Adsorption Capacity ◽  
Cement Paste ◽  
Cement Hydration ◽  
Main Chain ◽  
Chain Structure ◽  
Hydration Process ◽  
Side Chain ◽  
Structure Parameters ◽  
Polycarboxylate Superplasticizer

Abstract Polycarboxylate superplasticizer is synthesised by different acid to ether ratio, which is changing the main chain structure parameters, obtained different microstructures. The effect of different microstructure PCE superplasticizer on the fluidity of cement paste, rheological thixotropy, adsorption capacity and hydration heat are studied. The results show that dispersing performance in cement with acid to ether ratio of 3.5 is the best, the molecular weight and side chain density have rather little effect on the cement hydration process.

scholarly journals Reactive Comb Polymer Compatibilized Immiscible PVDF/PLLA Blends: Effects of the Main Chain Structure of Compatibilizer

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 526
Author(s):  
Xin Yang ◽  
Jinxing Song ◽  
Hengti Wang ◽  
Qingqing Lin ◽  
Xianhua Jin ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Glycidyl Methacrylate ◽  
Main Chain ◽  
Vinylidene Fluoride ◽  
Chain Structure ◽  
Side Chains ◽  
Poly Methyl Methacrylate ◽  
Continuous Structure ◽  
Comb Structure ◽  
Compatibilizing Effect

The compatibilizer with double comb structure has a superior compatibilizing effect for immiscible polymer blends due to the symmetrical structure on both sides of main chains. Extensive study related to the architectural effects of compatibilizer on the compatibilization has mainly focused on the side chains. We investigated the influence of the compatibilizer-main-chain structure on the compatibilizing effect for immiscible poly(vinylidene fluoride)/poly(L-lactic acid) (PVDF/PLLA) blends. Two reactive-comb compatibilizers with polystyrene (PS) and polymethylmethacrylate (PMMA) as main chains and PMMA as the side chains have been synthesized. PS is immiscible with both PLLA and PVDF, while PMMA is miscible with PVDF. It was found that both compatibilizers can improve the compatibility between the PLLA and PVDF, with different compatibilization effects. In the PVDF/PLLA (50/50) blends, 1 wt.% poly(styrene-co-glycidyl methacrylate)-graft-poly(methyl methacrylate) (RC–SG) tuned the morphology from the droplet-in-matrix structure to the co-continuous structure, while the blends with poly(methyl methacrylate-co-glycidyl methacrylate)-graft-poly(methyl methacrylate) (RC–MMG) kept the sea-island structure with even 3 wt.% loading. Moreover, RC–SG induces a wider co-continuous interval range than RC–MMG. The co-continuous structure obtained by RC–SG was also more stable than that by RC–MMG. It was further found that RC–SG-compatibilized PVDF/PLLA blends exhibit higher mechanical properties than the RC–MMG-compatibilized blends.

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