Sequence Distribution of Commercial SBR by Ozonolysis-GPC Measurement

1986 ◽  
Vol 59 (1) ◽  
pp. 16-26 ◽  
Author(s):  
Yasuyuki Tanaka ◽  
Hisaya Sato ◽  
Junichi Adachi
Keyword(s):  
High Resolution ◽  
Relative Intensity ◽  
Anionic Polymerization ◽  
Block Structure ◽  
Broad Peak ◽  
Sequence Distribution ◽  
Pure Block ◽  
Styrene Butadiene

Abstract Sequence distribution of commercially obtained styrene-butadiene copolymers (SBR) was investigated by high-resolution-GPC measurement of ozonolysis products. The ozonolysis-GPC of emulsion SBR samples showed peaks corresponding to 1 to 4 styrene sequences and styrene-1,2-butadiene sequences flanked by 1,4-butadiene units. In random SBR samples with anionic polymerization, long styrene sequences of from 8 to 19% were detected in addition to the short styrene sequences. So-called tapered-block structure was clearly observed in partially block SBR samples; a broad peak derived from block styrene sequences in a relative intensity of 49 to 55% was overlapped by peaks due to styrene sequences longer than 10 styrene units. The content of pure-block styrene sequences in S-B-S type triblock SBR samples was found to be 85 to 99% or above.

A conduction-cooled stage for high-resolution Cryo-SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1282-1283
Author(s):  
John G. Sheehan
Keyword(s):  
High Resolution ◽  
Liquid Nitrogen ◽  
Mechanical Stability ◽  
Cooling System ◽  
Cold Trap ◽  
Nitrogen Gas ◽  
Particulate Suspensions ◽  
Advantages And Disadvantages ◽  
Convection Cooling ◽  
Styrene Butadiene

The goal is to examine with high resolution cryo-SEM aqueous particulate suspensions used in coatings for printable paper. A metal-coating chamber for cryo-preparation of such suspensions was described previously. Here, a new conduction-cooling system for the stage and cold-trap in an SEM specimen chamber is described. Its advantages and disadvantages are compared to a convection-cooling system made by Hexland (model CT1000A) and its mechanical stability is demonstrated by examining a sample of styrene-butadiene latex.In recent high resolution cryo-SEM, some stages are cooled by conduction, others by convection. In the latter, heat is convected from the specimen stage by cold nitrogen gas from a liquid-nitrogen cooled evaporative heat exchanger. The advantage is the fast cooling: the Hexland CT1000A cools the stage from ambient temperature to 88 K in about 20 min. However it consumes huge amounts of liquid-nitrogen and nitrogen gas: about 1 ℓ/h of liquid-nitrogen and 400 gm/h of nitrogen gas. Its liquid-nitrogen vessel must be re-filled at least every 40 min.

scholarly journals High-resolution haplotype block structure in the cattle genome

BMC Genetics ◽  
2009 ◽  
Vol 10 (1) ◽  
Author(s):  
Rafael Villa-Angulo ◽  
Lakshmi K Matukumalli ◽  
Clare A Gill ◽  
Jungwoo Choi ◽  
Curtis P Van Tassell ◽  
...  
Keyword(s):  
High Resolution ◽  
Haplotype Block ◽  
Block Structure ◽  
Cattle Genome ◽  
Haplotype Block Structure

Determination of Sequence Distribution in Styrene-Butadiene Copolymer I. 1H-NMR Study of Styrene Oligomers

1981 ◽  
Vol 54 (4) ◽  
pp. 685-691 ◽  
Author(s):  
Y. Tanaka ◽  
H. Sato ◽  
K. Saito ◽  
K. Miyashita
Keyword(s):  
Relative Intensity ◽  
Methine Proton ◽  
Degree Of Polymerization ◽  
Sequence Length ◽  
Methylene Proton ◽  
Nmr Study ◽  
Average Sequence Length ◽  
Phenyl Proton ◽  
Two Peaks ◽  
Styrene Butadiene

Abstract The 1 H-NMR spectra of styrene oligomers were measured as a model of styrene sequences in SBR. The ortho-phenyl proton, methine proton, and methylene proton signals shift to a higher magnetic field as the degree of polymerization increased. The methine proton signal split into two peaks, reflecting the tacticity. The methylene proton flanked by methylene and methine protons had a higher chemical shift value than the methylene proton flanked by two methine protons. It is demonstrated that the average sequence length of the styrene units in SBR can be determined by the relative intensity ratio of the two methylene proton signals. It is also found that the fraction of styrene sequences longer than 6 units can be estimated from the relative intensity of ortho-phenyl proton signals resonated higher than 6.7 ppm.

CHARACTERISTIC FEATURES OF Lγ1 X-RAYS IN Nb METAL AND COMPOUNDS AND COMPARISON WITH AMORPHOUS ALLOYS

1993 ◽  
Vol 03 (03) ◽  
pp. 215-220 ◽  
Author(s):  
J. IIHARA ◽  
K. YOSHIHARA
Keyword(s):  
High Resolution ◽  
Amorphous Alloys ◽  
Intensity Ratio ◽  
Broad Peak ◽  
X Rays ◽  
X Ray ◽  
Characteristic Features ◽  
Metal And Alloys

It was revealed that by high resolution x-ray measurements that the L γ1 spectra of metallic Nb and Nb-Ni amorphous alloys showed only one broad peak, while those of NbC and NbN had two components. The reason why the amorphous alloys had FWHM’s broader than that in Nb metal was explained by the formation of a mixed band from Nb-4d and Ni-3d electrons. Proton excitation of Nb metal and alloys resulted a smaller L γ1/ L β1 intensity ratio compared to electron or x-ray excitation. Possible interpretation of this difference has been proposed.

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