Flow-rate dependent degradation of high-molecular-weight polyisobutylene in GPC

1980 ◽  
Vol 18 (8) ◽  
pp. 535-540 ◽  
Author(s):  
Christian Huber ◽  
Klaus H. Lederer
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Flow Rate ◽  
Rate Dependent ◽  
High Molecular Weight Polyisobutylene

scholarly journals A Complexed Initiating System AlCl3·Phenetole/TiCl4·H2O with Dominant Synergistic Effect for Efficient Synthesis of High Molecular Weight Polyisobutylene

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2121
Author(s):  
Yulong Jin ◽  
Liang Chen ◽  
Xing Guo ◽  
Linfeng Xu ◽  
Zhihua Zhu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Synergistic Effect ◽  
High Molecular Weight ◽  
Monomer Concentration ◽  
Catalyst System ◽  
Polymerization Temperature ◽  
Simple Preparation ◽  
Order Of Magnitude ◽  
Unique Approach ◽  
High Molecular Weight Polyisobutylene

A complexed initiating system AlCl3·phenetole/TiCl4·H2O was prepared by simply compounding AlCl3/phenetole and TiCl4/H2O and used for cationic polymerization of isobutylene. It was found AlCl3·phenetole/TiCl4·H2O exhibited activities 1.2–3 times higher than those of AlCl3/phenetole, and more than an order of magnitude higher than those of TiCl4/H2O, which indicated a notable synergistic effect produced in the complexed system. In addition, due to the higher activity of AlCl3·phenetole/TiCl4·H2O, lower coinitiator concentration and polymerization temperature, as well as higher monomer concentration were more favored for this complexed initiating system to produce polyisobutylene (PIB) with reasonable molecular weight (Mw) and molecular weight distribution (MWD). Furthermore, high molecular weight polyisobutylene (HPIB) with Mw = 1–3 × 105 g·mol−1 could be successfully produced by the complexed catalyst system at Tp = −60 to −40 °C. As a whole, the high activity as well as the simple preparation procedures of the complexed initiating system offer us a unique approach for the production of HPIB with improved efficiency.

Synergetic Effects of Pulsed Electric Field and Ozone Treatments on the Degradation of High Molecular Weight Chitosan

2014 ◽  
Vol 10 (4) ◽  
pp. 775-784 ◽  
Author(s):  
Guo Dan ◽  
Zhi Hong Zhang ◽  
Xin An Zeng ◽  
Zhong Han ◽  
Wen Bo Luo ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electric Field ◽  
High Molecular Weight ◽  
Flow Rate ◽  
Degradation Products ◽  
Pulsed Electric Field ◽  
Ozone Treatment ◽  
Solution Flow Rate ◽  
Experimental Conditions ◽  
High Molecular Weight Chitosan

Abstract A synergetic method integrating both pulsed electric field (PEF) and ozone treatment was developed as a novel approach to investigate the degradation of high molecular weight chitosan (Mw=4.5×105 Da). A device integrating both components was designed and assembled for the experiments. Results showed that the highest degradation percentage of chitosan was achieved with PEF/ozone co-treatment generated at experimental conditions of 1.2 L/min of ozone flow rate, 100 mL/min of 0.6% (w/v) chitosan solution flow rate, and 26.7 kV/cm of PEF intensity. The degradation percentage after 60 min PEF treatment was 24.89%, whereas it was improved to 94.89% by ozone treatment for 60 min. Combining the two treatments resulted in enhanced degradation percentage of 99.56%, with low molecular weights sample (Mw<2,500 Da) obtained. FTIR analysis demonstrated that the amide structure of the degradation products was minimally affected by the co-treatment. XRD pattern indicated that the crystallinity of the degradation products decreased. In addition, it could complete dissolve in water after 60 min PEF/ozone co-treatment. These results demonstrated the synergetic PEF/ozone co-treatment as an effective method for degradation of high molecular weight chitosan.

A Rapid Chromatographic Method for Quantitation of High Molecular Weight Fibrinogen Derivatives in Plasma

1978 ◽  
Vol 39 (03) ◽  
pp. 555-563 ◽  
Author(s):  
Vincenzo Musumeci ◽  
Dolly Culasso ◽  
Paolo Boni
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Flow Rate ◽  
Glass Bead ◽  
Chromatographic Method ◽  
Plate Theory ◽  
Elution Profile ◽  
Theory Analysis ◽  
Chromatographic Plate ◽  
Effluent Monitoring

SummaryHigh molecular weight fibrinogen derivatives were precipitated from 3 ml of plasma by 0.88 M ammonium sulphate. The resuspended precipitate was analyzed by chromatography on a 2.5 × 30 cm glass bead Bio-Gel 5 M column by using a flow rate of 60 cm/hr and continuous effluent monitoring at O. D. 280 nm. Complete elution of fibrinogen occurred in 50 min. Elution profile was handled according to the chromatographic plate theory analysis. Results obtained by our method were not significantly different from those obtained by conventional chromatography.

Performance of High Molecular Weight Osmotic Solution for Opuntia Betacyanin Concentration by Forward Osmosis

2020 ◽  
Vol 8 (2) ◽  
pp. 116-126
Author(s):  
Ravichandran Rathna ◽  
Ekambaram Nakkeeran
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Flow Rate ◽  
Forward Osmosis ◽  
Fold Increase ◽  
Feed Solution ◽  
Soluble Solids ◽  
P Value ◽  
Transmembrane Flux ◽  
Osmotic Agent

Background: Forward osmosis is a sustainable membrane process employed for concentrating thermo-sensitive compounds to minimize storage and transportation costs with improved shelf life. Objective: In this study, the intervention of high molecular weight osmotic agents in the concentration of Opuntia betacyanin using forward osmosis was studied. Furthermore, the statistical model was used to estimate the probabilistic behavior of the forward osmosis process during concentration. Method: By using 2k-full factor analysis, the hydrodynamic variables, such as flow rate (50 and 150 mL/min) and temperature (20 and 50ºC) of the feed solution and osmotic agent solution (OAS) were selected. The study focused on inquiring and developing a statistically significant mathematical model using four independent variables on transmembrane flux, concentration factor and concentrate recovery. Results: Betacyanin feed flow rate of 50 mL/min at 28ºC, and OAS flow rate of 150 mL/min at 50ºC were determined as optimal conditions with a 2.5-fold increase in total soluble solids for a processing time of 4 h. Furthermore, forward osmosis enhanced the betacyanin concentration from 898 to 1004 mg/L and 98.7% recovery with 0.40 L/m2h transmembrane flux with comparable improvement in its physicochemical characteristics. The lower p-value of the main effects on the responses validated the significance of the process parameters on betacyanin concentration. Conclusion: The study suggested that a high molecular weight sucrose could be used as an osmotic agent for the concentration of Opuntia betacyanin during forward osmosis.

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