Radiation Degradation of Polypropylene-Molecular Weight and Melt Viscosity Change

1983 ◽  
Vol 19 (7) ◽  
pp. 228-231 ◽  
Author(s):  
D. Babić ◽  
A. Šafranj ◽  
V. Marković
Keyword(s):  
Molecular Weight ◽  
Melt Viscosity ◽  
Viscosity Change ◽  
Radiation Degradation

Investigating the Rheological Properties and Heat Stability of Polyarylsulphone Sulphides of Domestic Grades

2017 ◽  
Vol 44 (1) ◽  
pp. 23-26
Author(s):  
A.B. Baranov ◽  
I.D. Simonov-Emel'yanov ◽  
T.I. Andreeva ◽  
T.N. Prudskova ◽  
V.I. Sazikov
Keyword(s):  
Molecular Weight ◽  
Heat Stability ◽  
Chain Structure ◽  
Low Flow ◽  
Processing Temperature ◽  
Rheological Characteristics ◽  
Melt Viscosity ◽  
Full Curve ◽  
Temperature Range ◽  
Service Characteristics

The rheological characteristics of melts of polyarylsulphone sulphides of domestic grades were investigated in the temperature range 240–360°C. Full curves of heat stability were obtained, and formulae were proposed for their description. Polyarylsulphone sulphides (PSPSs) are heat-resistant polymers of structural designation of the polysulphone (PSP) class, the domestic production technology of which was developed at OAO “Institut plastmass”, which makes it possible to carry out the production of a wide grade range of PSP of different polymer chain structure and molecular weight. The main problem in the processing of PSPSs is their high melt viscosity and fairly low flow. Increase in the processing temperature lowers their melt viscosity, but there is then the danger of thermooxidative degradation of the polymer and consequently of deterioration in the service characteristics and appearance of articles. The aim of this work was to investigate the rheological characteristics and to obtain the full curve of heat stability for domestic grades of PSPSs and PSP of different molecular weight in a wide processing temperature range.

scholarly journals Radiation Degradation of β-Glucan Extracted from Brewer’s Yeast for Enhancing Growth Promotion and Immunostimulant Activities on Broilers

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Nguyen Thanh Long ◽  
Tran Le Truc Ha ◽  
Hoang Nghia Son ◽  
Le Quang Luan
Keyword(s):  
Molecular Weight ◽  
Growth Promotion ◽  
Water Soluble ◽  
Brewer’S Yeast ◽  
Feed Conversion ◽  
Brewer's Yeast ◽  
Radiation Degradation ◽  
Growth Promoting ◽  
Feed Conversion Rate ◽  
Average Body

Water-soluble low molecular weight β-glucan (WSLMG) was successfully prepared via γ-irradiation of insoluble β-glucan extracted from brewer’s yeast cell walls. The WSLMG content in an irradiated sample increased as the irradiation dose increased. The WSLMGs with a molecular weight (Mw) of 49, 25, and 11 kDa, obtained at correlative doses of 100, 200, and 300 kGy, respectively, were tested using growth promotion and immune stimulant effects in broilers. Supplementation with 500 ppm WSLMGs not only increased the survival rate (33.3%) and average body weight (40%) but also reduced the feed conversion rate (35.4%) in tested broilers. In addition, WSLMGs enhanced both nonspecific and specific immune components in the blood of supplemented broilers. The WSLMG with Mw ~25 kDa showed the highest effect on the growth performance and immunomodulatory capability in the immune systems of the tested broilers. In conclusion, this product demonstrates substantial promise as an immunostimulant and growth-promoting additive for poultry.

The melt viscosity-molecular weight relationship for linear polymers

1987 ◽  
Vol 20 (9) ◽  
pp. 2226-2237 ◽  
Author(s):  
Ralph H. Colby ◽  
Lewis J. Fetters ◽  
William W. Graessley
Keyword(s):  
Molecular Weight ◽  
Linear Polymers ◽  
Melt Viscosity ◽  
Weight Relationship

scholarly journals Reactive Extrusion of Maleic-Anhydride-Grafted Polypropylene by Torque Rheometer and Its Application as Compatibilizer

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 495
Author(s):  
Asra Tariq ◽  
Nasir M. Ahmad ◽  
Muhammad Asad Abbas ◽  
M Fayzan Shakir ◽  
Zubair Khaliq ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Maleic Anhydride ◽  
Benzoyl Peroxide ◽  
Melt Flow Index ◽  
Reactive Extrusion ◽  
Side Chain ◽  
Flow Index ◽  
Viscosity Change ◽  
Chain Reactions ◽  
Molecular Weight Product

This study is based upon the functionalization of polypropylene (PP) by radical polymerization to optimize its properties by influencing its molecular weight. Grafting of PP was done at different concentrations of maleic anhydride (MAH) and benzoyl peroxide (BPO). The effect on viscosity during and after the reaction was studied by torque rheometer and melt flow index. Results showed that a higher concentration of BPO led to excessive side-chain reactions. At a high percentage of grafting, lower molecular weight product was produced, which was analyzed by viscosity change during and after the reaction. Percentage crystallinity increased by grafting due to the shorter chains, which consequently led to an improvement in the chain’s packing. Prepared Maleic anhydride grafted polypropylene (MAH-g-PP) enhanced interactions in PP-PET blends caused a partially homogeneous blend with less voids.

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