Dielectric Investigation of Molecular Dynamics of Blends: IV. Effect of Blending on the Normal Mode Process of Polyisoprene/Polystyrene Blends

Polyisoprene/polystyrene (PI/PS) blends have been prepared and investigated for compatibility using dielectric and calorimetric measurements. Various blends were prepared from polystyrene (number average molecular weight, — _n=160 000 g mol^-1) and polyisoprene with — _n values of 13 800, 40 500 and 130000gmol^-1. Dielectric measurements have been carried out over a wide frequency range (10^-2–10⁶Hz) and in the temperature range of the glass and normal mode processes (-70 to +70°C). The glass transition, as well as the corresponding relaxation process, of polyisoprenes were shifted to higher temperatures in the different blends, indicating compatibility. The blends showed a lower critical solution temperature (LCST) at temperatures above 105°C. It was surprising to find that blending of polyisoprene with polystyrene led to a great shift to higher values in the relaxation frequency of the normal mode process for the isoprene segments. The measurements showed that the relaxation time of the normal mode process in the blends was longer than that of the glass process by a constant factor (3·2 decades), regardless of the molecular weight of the polyisoprenes used in the blends. This finding implied that the domain length responsible for the compatibility of the two polymers was consistent regardless of the molecular weight used (where — _n> — _c, the critical molecular weight). In view of the results obtained, and by using a molecular model, it was possible to determine the size of the structural domains responsible for the compatibility. The value obtained (16·7nm) is very similar to that suggested to be responsible for the glass transition in pure polymers. © 1997 SCI.     

Performance Evaluation of 5G Modulation Techniques

Wireless Personal Communications - Higher data rate, increased capacity, higher mobility, lower latency and better quality are the mobile communication prime objectives need to improve in the near...     

Dyeing properties of cationized and non-cationized cotton fabrics dyed with Vitis vinifera L. leaves extract

This study lays bare two main objectives. The first is to determine the amount of anthocyanins in the leaves of Vitis vinifera L. by the spectrophotometric method and the second is to dye cationized and non-cationized cotton fabrics with the V. vinifera L. leaves aqueous extract. We have thoroughly investigated the effects of dye bath pH and temperature on the dyeing proprieties of the aforementioned fabrics. The color strength (K/S value) of dyed cationized cotton fabrics (K/S = 12) has been better than the non-cationized ones (K/S = 4). Experimental results show that the fastness properties of dyed cationized cotton fabrics range from average to good. We find that the cationization of cotton fabrics has largely improved the dyeability and fastness properties of cotton fabrics dyed with V. vinifera L. leaves aqueous extract.     

Characteristics of low‐fat beefburgers as influenced by various types of wheat fibres

Hydrated wheat fibres (bran and white and red beeswings) were added at three levels (50, 100 and 150 g kg⁻¹ ) to beefburger as replacement for fat and evaluated for chemical and physical properties, energy content and sensory traits. Uncooked and cooked beefburgers formulated with wheat fibres had higher (P⩽0.05) moisture, protein and carbohydrate contents and lower (P⩽0.05) fat contents than that of the control. However, ash content was increased (P>0.05) by the addition of wheat fibres. The cholesterol content of uncooked and cooked beefburgers decreased as level of wheat fibres increased or fat content decreased. The addition of wheat fibres reduced the cholesterol content from 6 to 45% for uncooked and cooked beefburgers. The energy content of uncooked and cooked beefburgers was lower (P ⩽0.05) than that of control by between and 6 and 41%. The cooking yield and reduction in diameter of beefburgers were significantly (P⩽0.05) improved by the addition of wheat fibres. The addition of red and white beeswings showed an improvement in the texture trait. Colour traits, tenderness, juiciness, connective tissue amount, beef flavour intensity and overall palatability were not affected by the addition of wheat fibres to beefburgers. Hydrated wheat fibres can be used successfully as a fat substitute in ground meat products. © 1999 Society of Chemical Industry     

Studies on 1,2,4-triazine derivatives. III. The Behaviour of some Derivatives of 1,2,4-Triazine toward diazomethane,amines, ethyl monobromoacetate and tetra-O-acetyl-α-D-glucopyranosyl bromide

The reaction of diazomethane with 6-phenyl-3-thioxo-5-oxo-2,3,4,5-tetrahydro-1,2,4-triazine 2a , and with 6-phenyl-3-methylmercapto-5-oxo-4,5-dihydro-1,2-triazine 3a effected N-methylation to 2b and 3b , respectively. Compound 3a and 3-methyl-mercapto-5, 6-diphenyl-1,2,4,-triazine 4a react with amines to give 3-N-substituted-amino-triazines 5a–h and 6a–h , respectively. 3-Mercapto-5,6-diphenyl-1,2,4-triazine 4b underwent S-alkylation with ethyl monobromoacetate and with tetra-O-acetyl-α-D-glucopyraosyl bromide.     

Some New Heterocyclic Sulphonates with potential antimicrobial activity

4-(Phenylhydrazono-4′-benzenesulphonato)-3-methyl-2-pyrazolin-5-one ( 2 ) was prepared by treating 4-(4′-hydroxyphenylhydrazono)-3-methyl-2-pyrazolin-5-one ( 1 ) with benzenesulphonyl chloride. Heating 2 with acetic anhydride, chloroacetyl chloride and benzenesulphonyl chloride afforded the N-acetyl ( 3 ), N-chloroacetyl ( 4 ) and O-benzenesulphonyl ( 5 ) derivatives, respectively. 2 reacted with benzenesulphonyl chloride under cooling conditions to give the N-benzenesulphonyl derivative ( 6 ). 2 undergoes Mannich reaction to give the N-Mannich base ( 7 ). Reaction of 2 with formaldehyde in methanol afforded the N-hydroxymethyl derivative ( 8 ) which undergoes condensation with ethyl acetoacetate, ethyl cyanoacetate and malononitrile to give compounds 9 , 10 and 11 respectively. The antimicrobial activity of these products against gram-positive (+ve), gram-negative (−ve) bacteria and fungi was screened. They showed potential bactericidal activity and some of them exhibited high fungicidal activity.     

Reactivity of 4-acetyl-3-chloro-5,6-diphenylpyridazine towards some nucleophilic reagents,Synthesis of Some Fused Pyridazine Derivatives

4-Acetyl-3-chloro-5,6-diphenylpyridazine ( 1 ), prepared by the action of phosphorus oxychloride on 4-acetyl-5,6-diphenylpyridazin-3(2H)-one ( 2 ), reacts with hydrazine hydrate and phenylhydrazine to give the pyrazolinopyridazine derivatives ( 3a , b ) respectively. Reaction of 1 with hydroxylamine hydrochloride gave the isoxazolopyridazine derivative ( 5 ), while its reaction with sodium azide in dimethyl formamide gave the tetrazolopyridazine derivative ( 8 ). Primary amines react with 1 to give either 9 or 10 depending upon the reaction conditions. Treatment of 1 with piperidine or morpholine gave the products 11a , b , respectivly. 4-Acetyl-5,6-diphenylpyridazin-3(2H)-thione ( 13 ) was readily obtained by the action of thiourea on ethanolic solution of 1 . The reactions of 1 with phenols were also investigated.