Concentration profile for a polymer-polymer interface. 1. Identical chemical composition and molecular weight

1989 ◽  
Vol 22 (7) ◽  
pp. 3018-3021 ◽  
Author(s):  
Huanzhi Zhang ◽  
Richard P. Wool
Keyword(s):  
Molecular Weight ◽  
Chemical Composition ◽  
Concentration Profile ◽  
Polymer Interface ◽  
Identical Chemical Composition

Surface Enrichment and Evaporation in a Polymer Mixture of Long and Short Chains

1989 ◽  
Vol 166 ◽  
Author(s):  
Russell J. Composto ◽  
Richard S. Stein ◽  
Gian P. Felcher ◽  
Abdelkader Mansour ◽  
Alamgir Karim
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
Concentration Profile ◽  
Scattering Length ◽  
Weight Fraction ◽  
Polymer Mixture ◽  
Light Chains ◽  
Neutron Reflectivity ◽  
Surface Enrichment ◽  
Polymer Interface

ABSTRACTNeutron reflectivity has been used to determine the concentration profile at the vacuum-polymer interface for a two polymer blend. To quantify surface enrichment and evaporation due to differences in chain length, we have measured the reflectivity of a mixture of short deuterated and long protonated polystyrene chains (DPS & PS), with a weight fraction of 0.5. When a mixture of DPS and PS chains of molecular weight 720 and 910k respectively were annealed, a small but measurable increase in asymptotic reflectivity occured, coupled with a decrease of film thickness and scattering length density. This is indicative of surface enrichment and evaporation of the light chains (DPS). Ellipsometry studies confirmed that the short chains evaporated and its rate was established as a function of the temperature. Upon increasing the DPS molecular weight to 9600, the enrichment becomes considerably greater whilst the evaporation becomes negligible.

The Reactive Formation of Diblock Copolymer at a Polymer/Polymer Interface and its Effect on Interfacial Structure

2000 ◽  
Vol 629 ◽  
Author(s):  
Jonathan S. Schulze ◽  
Timothy P. Lodge ◽  
Christopher W. Macosko
Keyword(s):  
Molecular Weight ◽  
Interfacial Structure ◽  
Root Mean Square Roughness ◽  
Radius Of Gyration ◽  
Interfacial Region ◽  
Force Microscopy ◽  
Amino Terminal ◽  
Polymer Interface ◽  
Atomic Force ◽  
Time Required

ABSTRACTThe reaction of perdeuterated amino-terminal polystyrene (dPS-NH2) with anhydrideterminal poly(methyl methacrylate) (PMMA-anh) at a PS/PMMA interface has been observed with forward recoil spectrometry (FRES). Bilayer samples were constructed by placing thin films of PS containing ∼8.5 wt % dPS-NH2 on a PMMA-anh layer. Significant reaction was observed only after annealing the samples at 174°C for several hours, a time scale at least two orders of magnitude greater than the time required for the dPS-NH2 chains to diffuse through the bulk PS layer. The topography of the interfacial region as copolymer formed was measured using atomic force microscopy (AFM). Roughening of the PS/PMMA interface was observed to varying degrees in all annealed samples. Furthermore, the extent of this roughening was found to depend on the PS matrix molecular weight. Reaction in the samples with a high molecular weight PS matrix resulted in a root mean square roughness approximately equal to the radius of gyration Rg of the copolymer. However, approximately twice as much roughening was observed in the low molecular weight PS matrix. This study reveals how the molecular weight of one of the phases can affect the rate of reaction at a polymer/polymer interface.

Ag2S2O8 meets AgSO4: the second example of metal–ligand redox isomerism among inorganic systems

2016 ◽  
Vol 45 (45) ◽  
pp. 18202-18207 ◽  
Author(s):  
Tomasz E. Gilewski ◽  
Piotr J. Leszczyński ◽  
Armand Budzianowski ◽  
Zoran Mazej ◽  
Adam Grzelak ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Physicochemical Properties ◽  
Inorganic Systems ◽  
Redox Isomerism ◽  
First Time ◽  
Identical Chemical Composition ◽  
Metal Ligand

Ag(i)2S2O8 – prepared here for the first time – constitutes a redox isomer of the already known Ag(ii)SO4. These “electromers” have identical chemical composition but they differ in all important physicochemical properties.

Improvement of the Launderability of Polypropylene Multifilament Yarns

1969 ◽  
Vol 39 (12) ◽  
pp. 1150-1158 ◽  
Author(s):  
Robert P. Weimer ◽  
Willard P. Conner
Keyword(s):  
Molecular Weight ◽  
Experimental Evidence ◽  
Concentration Profile ◽  
Consumer Products ◽  
Epidermal Layer ◽  
Loss Mechanism ◽  
Antioxidant Concentration ◽  
Multifilament Yarns

Polypropylene multifilament yarns are being used in a variety of industrial and consumer products. Penetration into some textile markets, however, has been hampered by poor resistance to laundering. Cyclic wash-dry laundering causes heat-stabilized yarns to lose antioxidant and strength more rapidly than the sum of the effects of washing or drying alone. This phenomenon plus other experimental evidence indicate that the dominating loss mechanism is one of diffusion or “thermal pumping.” It is suggested that during washing the antioxidant is leached from the epidermal layer of the fiber. During drying, the antioxidant diffuses to the surface from within as the antioxidant concentration profile is leveled throughout the fiber. Increasing the molecular weight of an antioxidant species reduces its diffusivity with a concomitant loss in antioxidant capability. Very long lifetimes, however, under home laundering conditions have been achieved by a compromise between diffusivity and capability of the antioxidant.

STUDY OF PROTEIN FRACTIONS OF HIGH-TEMPERATURE HYDROLYZATES OBTAINED FROM SMOKED SPRAT HEADS

Fisheries ◽  
2020 ◽  
Vol 2020 (2) ◽  
pp. 113-117
Author(s):  
Olga Mezenova ◽  
Vladimir Wolkov ◽  
Larisa Baydalinova ◽  
Natalia Mezenova ◽  
Svetlana Agafonova ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chemical Composition ◽  
Raw Materials ◽  
Weight Fraction ◽  
Water Soluble ◽  
Protein Fractions ◽  
Raw Material ◽  
Organoleptic Characteristics ◽  
Pre Treatment ◽  
Peptide Fractions

The authors study three fractions obtained as a result of hydrolysis of smoked sprat heads (under temperature of 130oC and presser of 0.25 MPa) – fat, protein water-soluble, and protein-and-mineral ones. Waste from sprat production of two fish canning complexes of the Kaliningrad Region - “RosCon” and “Kolkhoz for the Motherland” - was used as raw material. Hydrolysis was carried out in an aqueous medium in two ways - with preliminary separation of fat and without this operation. The protein fraction was sublimated and its quantitative and qualitative indices were examined - mass yield, solubility, chemical composition and molecular fractional composition of the obtained peptide fractions were determined. The output of sublimated protein fractions is practically independent of the type of raw material and the method of pre-treatment and is 6.47.9% of the mass of raw materials. The chemical composition of protein fractions varies widely in terms of fat (1.4–8.3%), minerals (9.8–13.4%) and proteins (72.1–80.2%). The solubility of the peptide fractions ranged from 91-98%. The molecular weight assessment results showed a high content of a low molecular weight fraction of peptides with an MM of less than 10 kDa in all experimental samples (about 38%). This indicates a high digestibility and biological value of the obtained peptide compositions. Sublimated peptide compositions had typical organoleptic characteristics, pleasant aroma and taste of smoked fish. Ключевые

Seasonal changes in the chemical composision of the red alga Hypnea musciformis

1973 ◽  
Vol 24 (3) ◽  
pp. 275
Author(s):  
AF Abdel ◽  
NM Abed ◽  
M Edrees
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Chemical Composition ◽  
Seasonal Changes ◽  
Free Amino ◽  
Glucuronic Acid ◽  
Red Alga ◽  
Low Molecular Weight ◽  
Hypnea Musciformis ◽  
Algal Material

Seasonal changes were observed in the chemical composition of the marine red alga Hypnea musciformis. Lipids, cholesterol, and lanosterol were found as constituents of the algal material. No low-molecular weight carbohydrates were found except small amounts of mannitol. The algal hydrolysate was shown to contain galactose, glucose, and xylose in all seasons and was characterized by a high content of glucuronic acid and its lactone in February. Definite seasonal variations were found in the patterns of free amino acids and of amino acid compositions of proteins.

Sign in / Sign up

Export Citation Format

Share Document