Structure and Solution Properties of High Molecular Weight Butadiene-Styrene Copolymers

1957 ◽  
Vol 30 (1) ◽  
pp. 315-325
Author(s):  
R. B. MacFarlane ◽  
L. A. McLeod
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Complex Structure ◽  
Mixed Solvents ◽  
Solution Time ◽  
Solution Viscosity ◽  
Solution Properties ◽  
Molecular Weight Range ◽  
Viscosity Measurements ◽  
Commercial Practice

Abstract Production of high molecular weight copolymers of butadiene and styrene for use in oil-extended rubbers has aroused interest in the solution properties of copolymers above the molecular weight range commonly encountered in commercial practice. It has been observed that solubility of such polymers in toluene is a time-dependent phenomenon and the apparent solubility can increase continuously, in the absence of agitation, for as long as 800 hours. Although a standard Harris cage solubility test may show the presence of 50% gel, other properties do not confirm the presence of any appreciable quantities of insoluble material. Mild agitation rapidly promotes almost complete solubility. Dilute solution viscosity measurements are very misleading unless the influence of solution time is recognized and apparent intrinsic viscosities rise progressively with time of contact of the sample with solvent. This time-dependence of solution has been found to occur at conversions higher than 50% and is also a function of the amount of modifier used in the polymerization recipe. It has not been possible to shorten the solution time for viscosity measurements by mild heating or gentle agitation. Mixed solvents cause a change in the amount of increase of the apparent intrinsic viscosity but do not shorten the time to equilibrium. Measurement of the slope constant in the Huggins viscosity equation indicate that these solubility and viscosity effects coincide with the appearance of a marked degree of branching in the polymer molecules. The effect is, therefore, interpreted as being caused by the relatively slow disentanglement of molecules of complex structure.

scholarly journals Lab-on-a-Chip method uncertanties in determination of high-molecular-weight glutenin subunits

2013 ◽  
Vol 19 (4) ◽  
pp. 553-561 ◽  
Author(s):  
Dragan Zivancev ◽  
Branislava Nikolovski ◽  
Aleksandra Torbica ◽  
Jasna Mastilovic ◽  
Nevena Djukic
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Wheat Variety ◽  
Lab On A Chip ◽  
Good Resolution ◽  
Glutenin Subunits ◽  
Bread Making ◽  
Molecular Weight Range ◽  
Essential Information ◽  
Significant Difference

Polymeric wheat endosperm proteins, especially the high-molecular-weight glutenin subunits (HMW-GS), are probably the most interesting protein fraction giving the essential information about bread-making quality of wheat flour. A relatively new method that shows a great potential for a fast, reliable and automatable analysis of protein purity, sizing and quantification is microfluidic or Lab-on-a-Chip (LoaC) capillary electrophoresis. This work was aimed to explore the possibilities of implementation of LoaC method to analysis of protein samples isolated from a Serbian common wheat variety, emphasizing the steps that might bring uncertainties and affect reproducibility of obtained glutenin subunits quantitation results. A good resolution of protein bands in a molecular weight range of 14.0 to 220.0 kDa was achieved. The reproducibility of HMW-GS sizing and quantitation were good, with the average coefficient of variation values of 1.2% and 12.2%. The ratio of HMW-GS to low-molecular-weight glutenin subunits (LMW-GS) was about 20%. The investigation ruled out influences of the extract solution addition and the buffer addition steps of the applied method, as well as the individual chip influence on GS quantitation results. However, there was statistically significant difference between HMW-GS quantitation results of multi-step and one-step extraction procedures applied prior to glutenin subunits extraction step.

High-Molecular-Weight, High-Unsaturation Copolymers of Isobutylene and Conjugated Dienes. I. Synthesis

1976 ◽  
Vol 49 (4) ◽  
pp. 960-966 ◽  
Author(s):  
W. A. Thaler ◽  
D. J. Buckley
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cationic Polymerization ◽  
Critical Role ◽  
Conjugated Dienes ◽  
Solution Properties ◽  
Insight Into

Abstract This investigation has provided insight into the critical role of solution properties on the course of cationic polymerization and has led to a technique for reconciling the opposing demands for synthesis of isoolefin-diene copolymers both free from gel and high in molecular weight. By this technique, the synthesis of a broad range of intermediate-unsaturation elastomers of quality has been realized.

scholarly journals Real-time metabolic heat-based specific growth rate soft sensor for monitoring and control of high molecular weight HA production by Streptococcus zooepidemicus.

2020 ◽  
Author(s):  
Naresh Mohan ◽  
Satya Sai Pavan ◽  
Anjali Jayakumar ◽  
Sivakumar Rathinavelu ◽  
Senthilkumar Sivaprakasam
Keyword(s):  
Molecular Weight ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Real Time ◽  
High Molecular Weight ◽  
Specific Growth ◽  
Fed Batch ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Metabolic Heat

Abstract Background: Hyaluronic acid (HA) is an important mucopolysaccharide of higher molecular weight range and holds sheer economic interest. Its applications are widely acknowledged in rheumatoid arthritis treatment, tissue engineering, and cosmetics industries. This present investigation aims for the fed-batch production of high molecular weight range HA by application of real-time metabolic heat measurements. Results: Fed-batch strategies based on Feedforward (FF) and Feedback (FB) control was devised to improve the Molecular Weight (MW) of HA production by S. zooepidemicus . Metabolic heat measurements (Fermentation calorimetry) were modeled to decipher real-time specific growth rate, [[EQUATION]] was looped to the PID circuit, envisaged to control [[EQUATION]] to their desired setpoint values 0.05 [[EQUATION]] , 0.1 [[EQUATION]] and 0.15 [[EQUATION]] respectively. The developed FB strategy established a robust control on maintaining the specific growth rate (µ) close to the [[EQUATION]] value with a minimal tracking error. Exponential feed rate carried out with a lowest [[EQUATION]] of 0.05 [[EQUATION]] improved the MW of HA significantly to 2.98 MDa and 2.94 MDa for the FF and FB based control strategies respectively. An optimal HA titer of 4.73 g/L was achieved in a FF control strategy at [[EQUATION]] . Biomass and Lactic acid (LA) concentrations were found to be concomitant with the increase in [[EQUATION]] from 0.05 [[EQUATION]] to 0.15 [[EQUATION]] . Superior control of µ at low [[EQUATION]] value was observed to influence positively the HA polymerization attributing to improved MW and desired Polydispersity Index (PDI) of HA. Conclusions: This present investigation attempts to address the metabolic bottleneck in synthesis of high MW HA by S. zooepidemicus and illustrates the application of calorimetric fed-batch control of µ at a narrower range. PID control offers advantage over conventional fed-batch method to synthesize HA at an improved MW. Calorimetric signal based µ control by PID negates adverse effects due to the secretion of other metabolites albeit maintaining homeostasis.

P1099EVALUATION OF THE DEPURATION OF SOLUTES IN THE MIDDLE TO HIGH MOLECULAR WEIGHT RANGE WITH DIFFERENT TECHNIQUES OF HAEMODIALYSIS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Barbara Cancho Castellano ◽  
Rosa Diaz Campillejo ◽  
Cristina López Arnaldo ◽  
Julián Valladares Alcobendas ◽  
Rosa María Ruiz Calero Cendrero ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Continuous Variables ◽  
Serious Adverse Events ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Statistical Program ◽  
On Line ◽  
Comparative Results ◽  
The One

Abstract Background and Aims Haemodialysis is the most commoly used replacement therapy for chronic kidney disease. We are looking for new solutions to remove solutes in the middle to high molecular weight range. Our objective is to evaluate and compare the purification of small and middle to high molecular weight between 15-45 KDa with Haemodyafiltration On Line postdilutional (HDF-OL-post) technique, Haemodialysis High-Flux (HD-HF) and Haemodialysis Expanded (HDx) using specific high permeability membranes: in the first two techniques polyphenylene membranes (1.7m2) and in the HDx technique cut point membranes PAEs/PVP (1.7 m2). Method 10 chronic prevalent patients on haemodialysis, older than 18 years, without diuresis and stable, 60% males. Mean age 65.3±17.47 years. Time in HD, mean 49.5 months. Etiologies: 20% NAE, 30% ND, 10 % Glomerulopathies, 40% unaffiliated. Vascular Accesses: 50% FAVn, 20% FAVp, 30% CVC-T. They were evaluated for three consecutive weeks with analytics in the intermediate session, modifying the technique and the membrane, keeping the dialysis patient stable. Post-dialysis concentrations of solutes in the middle to high molecular weight range were corrected in relation to haemoconcentration. A comparison of the reduction percentages (RP%) of various molecules was performed. The possible normal distribution was studied in the continuous variables with the Shapiro-Wilk test and the comparison of means using the t-Student or Wilconson test as the most appropriate. SPSS statistical program 17.0. Results No serious adverse events or allergies were recorded. The comparative results between the three techniques are shown in the figure 1. Conclusion The mean reduction of medium molecules (β2-microglobulin, cystatin-C) was not lower in HDx compared to HDF-OL-post. From 20 KDa there is no greater capacity to reduce solutes in HDx in our sample than in the other techniques. Between the three techniques, the HDF-Ol-post is the one that shows a higher percentage of mean reduction of α1-acid glycoprotein and albumin.

Glomerular Permeability to High Molecular Weight Dextrans in Acute Ischaemic Renal Failure and Postural Proteinuria

1970 ◽  
Vol 38 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Pamela R. MacLean ◽  
J. J. B. Petrie ◽  
J. S. Robson
Keyword(s):  
Molecular Weight ◽  
Renal Failure ◽  
High Molecular Weight ◽  
Plasma Protein ◽  
Healthy Subjects ◽  
Plasma Proteins ◽  
Normal Subjects ◽  
Glomerular Permeability ◽  
Molecular Weight Range ◽  
Postural Proteinuria

1. Renal permeability to dextran of a molecular weight range approximating to that of the plasma proteins has been studied in six patients with acute ischaemic renal failure, four patients with postural proteinuria and six healthy subjects. 2. Results are expressed in terms of dextran selectivity indices which relate the clearance of dextran to its molecular weight. Indices of dextran selectivity were found to be high in acute ischaemic renal failure, postural proteinuria and in normal subjects. Comparable indices of plasma protein selectivity in these groups were low. 3. It is suggested that in postural proteinuria and acute ischaemic renal failure the proteinuria is not glomerular in origin, and that in these conditions macromolecules are filtered quite normally and urinary protein arises from a post glomerular source characterized by a lack of selectivity.

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