Juniper Publishers Journal of Polymer science

JUNIPER PUBLISHERS- ACADEMIC JOURNAL OF POLYMER SCIENCE Abstract This review summarized the progress on transition metal catalysts for olefin polymerization, and focuses on the olefin polymerization by the late transition metal catalysts and the recent advances in catalyst design. In recent years, nickel and palladium complexes for olefin polymerization have received extensive researches owing to the precise control of branching microstructure, molecular weights and properties of the resulting polyolefins. Keywords: Nickel and palladium complexes; Olefin polymerization; Chain-walking; Branched polymer Abbrevations: MAO: Methylaluminoxane; CGC: Constrained Geometry Catalysts; LDPE: Low Density Polyethylene; LLDP: Linear Low-Density Polyethylene; HDPE: High-Density Polyethylene; PP: Polypropylene Introduction The research of the ethylene and α-olefins polymerizations using late transition metal catalysts should be highlight ...

JUNIPER PUBLISHERS- ACADEMIC JOURNAL OF POLYMER SCIENCE Abstract In order to break down the glycoside bond in glucomannan obtained from the bulb of the Konjac in Việt Nam, we used the extract from bacteria bacillus subtilis. The reaction was carried out at 40oC for 6h, pH 5 and the E/S ratio of 0.4(w/w). The obtained oligo-glucomannan after hydrolysis that had molecular weight lower than 1748Da was tested for glucose tolerence in experimental animals. The test results showed that the hydrolyzed glucomannan at a dose of 6g/kg was more effective in lowering blood glucomannan in mouse models that were made to have blood sugar increase exogenously by oral admistration, as compared to original glucomannan. Keywords: Hydrolyzed glucomannan; Enzyme; Blood sugar Introduction Glucomannan is a water-soluble polysaccharide consisting of D-mannose and D-glucose units linked with β - (1→ 4) glucosidic bonds, with the degree of branching of a...

JUNIPER PUBLISHERS- ACADEMIC JOURNAL OF POLYMER SCIENCE Abstract In this research, a fractal structure of beads of different sizes obtained by spray-drying of aqueous dispersions of microcrystalline cellulose (MCC) was studied. These beads are formed as a result of aggregation of rod-shaped cellulose nanocrystalline particles (CNP). It was found that increasing the average radius (R) of the formed MCC beads results in increased porosity (P) and reduced density (ρ). The dependences of P and ρ on scale factor (R/r) can be expressed by power-law equations: p=(R/r) k-dp and p-d (R/r) DP-K ,where the fractal dimensions PD= 2.887 andPD=2.986 are close to Euclidean dimension E=3 for three-dimensional space; r=3nm is radius of cellulose nanocrystalline particles, Po = 0.03cm3/g is porosity and d=1.585g/cm3 is true density (specific gravity) of CNP, respectively. Thus, with the increase in the size of formed MCC beads, the order in the packing of the beads is distorted...

JUNIPER PUBLISHERS- ACADEMIC JOURNAL OF POLYMER SCIENCE Abstract In order to create polymer nanocomposites with high performance on the basis of polyurethane acrylates (PUA) with montmorillonite (MMT), three methods of chemical modification of the layered silicate surface have been developed. The first modification method is based on using of two different functional modifiers (organophilic and reactive), the second method is based on modification with synthesized by us compound which contains urethane groups, and the third one in based on using synthesized by us modifier containing urethane and reactive groups. Exchange capacity of the MMT surface was determined by adsorption of indicator “methylene blue”. Intercalation of modifier into the interlayer space of MMT was confirmed by X-ray analysis; the content of organic component in the modified MMT (MMT/M) was determined by thermogravimetric analysis. The resulting organoclay is purposed for the formation of nanost...

Juniper publishers- Academic Journal of Polymer Science Authored by  Darvishi R VCM suspension polymerization is performed as the batch-wise process. For this, the productivity of this high demand product is low. As VCM suspension polymerization is an exothermic process, the full capacity of the cooling system remains idle most of the time during the course of the polymerization.There are three strategies for keeping the reaction rate constant during the entire polymerization process. fast initiator dosage during reaction, cocktail initiator system and the temperature trajectory are the strategies that one can utilize to maintain the polymerization reaction rate at a constant value close to the allowed maximum rate. There are several reports that investigated separately the PVC resin properties obtained by these modes of polymerization. However, no report is published to compare the specifications of each mode together and also the PVC resin properties prepared...