Effect of polypropylene molecular weight distribution on the balance between the toughness and rigidity of the impact polypropylene composites

2021 ◽  
pp. 51834
Author(s):  
Fushi Li ◽  
Yunbao Gao ◽  
Nan Yan ◽  
Chunyu Zhang ◽  
Xuequan Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Polypropylene Composites ◽  
The Impact

Study on the Molecular Structure and the Performance of PE100 Resin for Tubing

2013 ◽  
Vol 850-851 ◽  
pp. 70-73
Author(s):  
Hua Wang ◽  
Hao Dong Song ◽  
En Guang Zou ◽  
Teng Jie Ge ◽  
Hong Fang
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Impact Strength ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Bending Strength ◽  
The Impact

The performance of JHMGC100S, a kind of HDPE for pipe, was studied, and the comparison with other typical PE100 resin in China and abroad was also did. The results show that: the impact strength of JHMGC100S was higher than other samples, and the bending strength was almost the same; the molecular weight distribution was obvious bimodal; the processability of JHMGC100S was good, and the hydrostatic strength of the pipe which was produced by JHMGC100S fulfilled the rule in GB/T 15558.1-2003.

The impact of ionic strength on the molecular weight distribution (MWD) of lignin dissolved during softwood kraft cooking in a flow-through reactor

Holzforschung ◽  
2016 ◽  
Vol 70 (6) ◽  
pp. 495-501 ◽  
Author(s):  
Binh T.T. Dang ◽  
Harald Brelid ◽  
Hans Theliander
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Average Molecular Weight ◽  
Ion Concentration ◽  
Small Scale ◽  
Kraft Cooking ◽  
Flow Through ◽  
Cooking Times ◽  
The Impact

Abstract The molecular weight distribution (MWD) of dissolved lignin as a function of time during kraft cooking of Scots pine (Pinus silvestris L) has been investigated, while the influence of sodium ion concentration ([Na+]) on the MWD was in focus. The kraft cooking was performed in a small scale flow-through reactor and the [Na+] was controlled by the addition of either Na2CO3 or NaCl. Fractions of black liquors (BL) were collected at different cooking times and the lignin was separated from the BL by acidification. The MWD of the dissolved lignin was analyzed by GPC. Results show that the weight average molecular weight (Mw) of dissolved lignin increases gradually as function of cooking time. An increase of [Na+] in the cooking liquor leads to Mw decrement. Findings from cooks with constant and varying [Na+] imply that the retarding effect of an increased [Na+] on delignification is related to the decrease in lignin solubility at higher [Na+].

Substrate-Dependent Features of Polyethylene Oxide (Peo) Adsorption from Aqueous Solution: Competitive Adsorption Versus Surface Relaxations

1994 ◽  
Vol 366 ◽  
Author(s):  
M. M. Santore ◽  
V. A. Rebar
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Polyethylene Oxide ◽  
Weight Distribution ◽  
Adsorption Process ◽  
Polymer Concentration ◽  
Hydroxyethyl Cellulose ◽  
Total Internal Reflectance ◽  
The Impact

ABSTRACTThis work employed total internal reflectance fluorescence (TIRF) to examine the adsorption kinetics of polyethylene oxide (PEO) on silica from aqueous solution in controlled shearing flow. Studies with PEO, fluorescently labeled such that TIRF tracked the chain number on the surface, exhibited an overshoot in the early stages of adsorption. This overshoot was not seen with other polymers such as polyvinyl alcohol, and hydroxyethyl cellulose, possibly because these other polymers were labeled such that TIRF measured the interfacial mass. Indeed, reflectometry studies of PEO adsorption, sensitive to interfacial mass, showed no overshoot. This suggests that the overshoot results from the selectivity of the surface for high molecular weight populations within a polydisperse sample. Initially short chains adsorb because they diffuse to the surface quickly. At longer times, higher molecular weight chains reach the surface and replace the short chains. This evolution occurs as the mass coverage increases (according to reflectivity) but the number of adsorbed chains, and hence the TIRF signal decrease at long times. A study of the impact of the molecular weight distribution confirmed this hypothesis.Several complications to the molecular weight selectivity hypothesis, however, arose: First, the same PEO samples which overshot during adsorption on silica showed no overshoot on a polystyrene substrate. This suggested that the ability to overshoot was governed by the substratesegment interactions, even though the molecular weight distribution within the sample determined the overshoot shape. Further, the effect of transport conditions (wall shear rate, bulk polymer concentration) were not completely consistent with the molecular weight competition hypothesis, which was based on surface-solution equilibrium, taking into account transport-limited rates of adsorption. Finally certain runs, where the adsorption process was interrupted by solvent flow and later allowed to proceed, never reached the full coverage seen for uninterrupted runs. Hence, the surface coverage and possibly the chain configurations can depend on the history of the adsorption process, a feature which points to surface relaxations and non-equilibrium structures.

Molecular Weight and Dispersity Affect Chain Conformation and pH-Response in Weak Polyelectrolyte Brushes

2021 ◽  
Author(s):  
Tzu-Han Li ◽  
Megan L. Robertson ◽  
Jacinta C. Conrad
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Degree Of Polymerization ◽  
Chain Conformation ◽  
Average Degree ◽  
Polyelectrolyte Brushes ◽  
Ph Response ◽  
The Impact

The impact of brush molecular weight distribution on the conformation and response of weak polyacid brushes was investigated. We show that weight-average degree of polymerization (N_w) and dispersity (Ð) alter...

The Impact of CO2Injection and Pressure Changes on Asphaltene Molecular Weight Distribution in a Heavy Crude Oil: An Experimental Study

2010 ◽  
Vol 28 (17) ◽  
pp. 1728-1739
Author(s):  
M. Sadeqimoqadam ◽  
H. Firoozinia ◽  
R. Kharrat ◽  
M. H. Ghazanfari
Keyword(s):  
Molecular Weight ◽  
Experimental Study ◽  
Crude Oil ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Heavy Crude Oil ◽  
Heavy Crude ◽  
Pressure Changes ◽  
The Impact

Extraction and Partial Purification of Protease from Bilimbi (Averrhoa bilimbi L.)

2013 ◽  
Vol 10 (2) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nur' Ain Mohamad Kharoe
Keyword(s):  
Molecular Weight ◽  
Protein Content ◽  
Ammonium Sulfate ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Protease Activity ◽  
Protein Concentration ◽  
Temperature Stability ◽  
Partial Purification ◽  
Ammonium Sulfate Precipitation

Unripe and ripe bilimbi (Averrhoa bilimbi L.) were ground and the extracted juices were partially purified by ammonium sulfate precipitation at the concentrations of 40 and 60% (w/v). The collected proteases were analysed for pH, temperature stability, storage stability, molecular weight distribution, protein concentration and protein content. Protein content of bilimbi fruit was 0.89 g. Protease activity of both the unripe and ripe fruit were optimum at pH 4 and 40°C when the juice were purified at 40 and 60% ammonium sulfate precipitation. A decreased in protease activity was observed during the seven days of storage at 4°C. Molecular weight distribution indicated that the proteases protein bands fall between IO to 220 kDa. Protein bands were observed at 25, 50 and 160 kDa in both the unripe and ripe bilimbi proteases purified with 40% ammonium sulfate, however, the bands were more intense in those from unripe bilimbi. No protein bands were seen in proteases purified with 60% ammonium sulfate. Protein concentration was higher for proteases extracted with 40% ammonium sulfate at both ripening stages. Thus, purification using 40% ammonium sulfate precipitation could be a successful method to partially purify proteases from bilimbi especially from the unripe stage. 

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