Graft Copolymerization onto Starch Nanoparticle Using Peroxymonosulfate/ Mandelic Acid as a Novel Redox Pair

Unreported peroxymonosulfate/mandelic acid as a redox pair initiation system has been used to graft copolymerizes acrylonitrile onto our previously prepared starch nanoparticle (SNPs) in aqueous medium under nitrogen atmosphere. Optimization of the grafting conditions was studied and the grafting parameters were expressed in terms of graft yield %, graft reaction efficiency % and homopolymer %. Fourier transformer infrared spectroscopy (FTIR), Scanning electron microscope (SEM) and thermal gravimetric analysis (TGA) techniques confirmed the synthesis of the precursor’s materials and the success of the grafting onto starch nanoparticle. The resultant copolymer was found to be more thermally stable and more resistance to biodegradability than the starch nanoparticle counterparts. Besides, the optimum conditions were obtained when using 1 g starch nanoparticle, 2 ml of AN (based on weight of substrate), 30 m mol/l potassium peroxymonosulphate, 8 m mol/l mandelic acid, 2 hours reaction time and 45°C of temperature.

The Microstructure of GNR and the Mechanical Properties of Biobased PLA/GNR Thermoplastic Vulcanizates with Excellent Toughness

A series of different contents of glycidyl methacrylate (GMA)-grafted natural rubber (GNR) copolymers were fabricated via green bulk melt-grafting reactions, and super-tough bio-based poly (lactic acid) (PLA)/GNR thermoplastic vulcanizates (TPVs) were achieved by in-situ dynamic vulcanization. Increasing the graft yield, gel fraction, and crosslinking density of GNR vulcanizates effectively improved the ductility of the PLA/GNR TPVs, while prolonging the dynamic vulcanization time and increasing the GMA graft yield led to a notable enhancement in the impact toughness of the PLA/GNR TPVs. PLA/30 wt % GNR TPVs exhibited a significantly increased elongation (410%) and notched impact strength (73.2 kJ/m2), which were 40 and 15 times higher than those of the PLA/30 wt % NR TPVs, respectively. The new bio-based PLA/GNR TPVs offer promise as replacements for petroleum-based polymers in the automotive, 3D printing, and packaging fields.

Atmospheric Pressure Plasma Grafting of a Vinyl-Quaternary Compound to Nonwoven Polypropylene and Cotton

Nonwoven polypropylene and cotton fabrics are grafted to a vinyl quaternary compound using atmospheric-pressure plasma. Two different atmospheric plasma devices are used -the NCAPS (North Carolina Atmospheric Plasma System), a dielectric barrier discharge device created by North Carolina State University, and a plasma device from APJeT® Inc. The addition of additives such as Mohr's salt, potassium persulfate, and diacrylates are assessed to see if graft yield can be increased. Acid dye tests, SEM, and XPS reveal successful grafting of the vinyl quaternary compound. A combination of all four additives is found to yield the highest graft yields and greatest uniformity.

SYNTHESIS AND CHARACTERIZATION OF LAURYL METHACRYLATE – GRAFT - POLYPROPYLENE FIBER

The graft polymerization of lauryl methacrylate (LMA) onto polypropylene fiber (PP) was investigated by using 2,2’-azobisisobutyronitrile (AIBN) as initiator. The grafting was influenced by AIBN concentration, monomer concentration, the reaction time and reaction temperature. On the basis of a detailed investigation of these factor, the optimal conditions for the grafting of LMA onto PP with the said initiator were as follows: [AIBN] = 0.015 mol/l, [LMA] = 1.25 mol/l, reaction time 240 min, reaction temperature 80 oC, in which the graft yield (%GY) of 15.7 % was obtained. Characterization of the polypropylene fiber-graft-lauryl methacrylate was done by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).

IMPROVE THE NATIVE CHARACTERISTICS OF POLYSACCHARIDES BY GRAFTING THROUGH THE GAMMA RADIATION: A REVIEW

Polysaccharides are bio-degradable, inexpensive and easily available from consistent agricultural resources. Polysaccharides and their derivatives represent a group of polymer widely used in pharmaceutical and biomedical fields. The biodegradability of natural polymers reduces their shelf life. Grafting copolymerization technique is a most effective fascinating way for chemical modification of native characteristics of polysaccharides with maximum possibilities for improving the properties of polysaccharides and enhanced the range of exploitation.While the major difficulty facing us during synthesizing a graft copolymers reaction, is the lack of commercial methods of synthesis and lower percent graft yield. It is well known that the most important methods of synthesis engage the employ of chemical free radical initiator i.e. conventional based methods. Graft copolymerization through γ-radiation method is a better method of grafting in comparison to a chemical method and exhibits a great potential to synthesize the graft copolymers by virtue of its higher efficiency, low cost, higher thermal stability as well as enhanced the yield of the graft copolymer. Future prospective of irradiation technique would be significant impacts to develop of polymerization.

Graft copolymerization of poly(vinyl acetate) onto starch using KMnO4-H2SO4 redox system

The graft copolymerization of poly(vinyl acetate) [poly(VAc)] onto starch was studied using the KMnO4-H2SO4 redox system. The grafting parameters are favored by changing the concentration of KMnO4, the concentration of acid, the temperature, the time, and the concentration of monomer. A maximum graft yield of 38.3% was obtained at optimum conditions: KMnO4 concentration=3.0×10-3 mol/l, concentration of acid=1.5×10-2 mol/l, temperature=40°C, time=3 h, and concentration of monomer=1 mol/l. The grafting of poly(VAc) onto starch was confirmed by the IR spectra of pure sago starch, poly(VAc), and poly(VAc) grafted starch. Both swelling power and solubility increased with the increase in temperature. Graft copolymerization increased swelling power and reduced solubility. This material may have use as an application as a biodegradable plastic.

Grafting of Methyl Acrylate and Methyl Methacrylate onto Jute fiber: Physico-Chemical Characteristics of the Grafted Jute

The graft copolymerization of methyl acrylate and methyl methacrylate vinyl monomers onto jute fiber using potassium persulfate and ferrous sulfate redox system was investigated in an aqueous medium. Optimized reaction conditions for the graft copolymerization were established for parameter variables, of monomer concentration, initiator concentration, catalyst concentration, reaction time, and reaction temperature. The grafting degrees were found to depend on the above mentioned variables. A maximum graft yield of 17.3% for MA and 19.4% for MMA was obtained under effective optimized conditions for grafting. The attachment of the monomer on the grafted fiber was confirmed by FTIR studies. Dyeing was affected by monomer characteristics, and due to the development of hydrophobic nature on jute fiber by grafting, a lower amount of dye absorption occurred. Grafting has a favorable influence on tenacity, color fastness, and other properties of jute fiber.

Study of Novel Pregelled Starch for Sizing of Cotton Textiles

Several research and developmental work attempts have been made in this manuscript to synthesize what is called tailored polymeric materials with new characteristics based on pregelled starch through a number of processes which, in turn, entail several chemical treatments. This is done by subjecting pregelled starch as a starting substrate to acid hydrolysis to obtain different molecular sizes. Pregelled starch with different molecular sizes are carbamoylethylated by using acrylamide and sodium hydroxide at different durations, then grafted with different monomers by using a potassium permanganate/citric acid redox system to initiate grafting. Furthermore, application of the newly tailored pregelled starch derived products as a sizing agent of cotton textiles is systematically studied. It is shown from the data that (a) the extent of carbamoylethylation expressed as N% increases by increasing the extent of hydrolysis and duration; (b) the graft yield expressed as mmol. monomer/100 g sample of different monomers onto carbamoylethylated and carbamoylethylated hydrolyzed pregelled starches increases by increasing the extent of carbamoylethylation and degree of hydrolysis, and follows the order: methacrylamide (MAam) > methacrylonitrile (MAN) > methacrylic acid (MAA), and (c) cotton fabrics sized with grafted carbamoylethylated hydrolyzed pregelled starch acquire higher mechanical properties, i.e. TS, elongation at break, and abrasion resistance values than hydrolyzed, carbamoylethylated and carbamoylethylated hydrolyzed pregelled starches. Finally, the use of the above tailored modified pregelled starch derived products in the sizing of cotton textiles contribute to reinforcement of the cotton textile after sizing to overcome the forced loss in fabrics/yarns during the spinning process as shown above.

Synthesis and Evaluation of Advanced Graft Copolymers

The paper deals with characterisation and evaluation of the transformations in waste biomass Hibiscus sabdariffa stem fibre on graft copolymerisation with ethyl acrylate (EA) and butyl acrylate (BA) monomer, using a ceric ammonium nitrate–nitric acid initiator system. Different reaction parameters, such as temperature, time, initiator concentration, monomer concentration, and pH, were optimised to obtain the maximum graft yield. The graft copolymers thus formed were characterised by FTIR, SEM, TGA, DTA, and XRD techniques. The swelling behaviour of graft copolymers in different solvents was studied and screened for dye uptake behaviour in 0.1% gentian violet dye. With increase in percentage grafting, the percentage crystallinity, crystallinity index, and moisture absorption were found to decrease, whereas the chemical resistance (against 1N HCl and 1N NaOH), thermal resistance, and solubility in organic solvents were found to increase.

Synthesis and characteristics of graft copolymers of poly(butyl acrylate) and cellulose fiber with ultrasonic processing as a material for oil absorption

A series of materials used for oil absorption based on cellulose fiber grafted with (BuAc) have been prepared by radical polymerization under ultrasonic waves processing. Effects of ultrasonic dose for the maximum graft yield were considered. The dependency of optimum conditions for oil absorption rate on parameters such as ultrasonic processing time and ultrasonic power were also determined. Fourier infrared (FT-IR) analysis was used to confirm the chemical reaction taking place between cellulose and butyl acrylate. The thermogravimetric behavior of the graft copolymer was characterized by thermogravimetric analysis (TGA). Scanning electron microscope (SEM) analysis was used to determine the surface structure of the grafted material. With the increase of the ultrasonic treatment dose, the surface of the ultrasonic processed material became more regular, and the material was transformed into a homogeneous network polymer having a good structure and good adsorbing ability.