Padma L. Nayak

Biodegradable Soy-Based Plastics: Opportunities and Challenges

Todays plastics are designed with little consideration for their ultimate disposability or the effect of the resources (feedstocks) used in making them. This has resulted in mounting worldwide concerns over the environmental consequences of such materials when they enter the mainstream after their intended uses. This led to the concept of designing and engineering new biodegradable materials–materials that have the performance characteristics of todays materials but that undergo biodegradation along with other organic waste to soil humic materials. Hence, the production of biodegradable materials from annually renewable agricultural feedstocks has attracted attention in recent years. Agricultural materials such as starches and proteins are biodegradable and environmentally friendly. Soybean is a good candidate for manufacturing a large number of chemicals, including biodegradable plastics, as it is abundantly available and cheap. Soy protein concentrate, isolate, or flakes could be compounded with synthetic biodegradable plastics such as polycaprolactone or poly (lactic acid) to make molded products or edible films or shopping bags and make the environment cleaner and greener.

Synthesis and characterization of polymers from cashewnut shell liquid (CNSL), a renewable resource II. Synthesis of polyurethanes

Abstract A novel copolyester was synthesized by solution polycondensation of terephthaloyl chloride with 4-[(4-hydroxy-2-pentadecenylphenyl)diazenyl] phenol (HPPDP) and 1,4-butane diol. The monomer (HPPDP) has been synthesized from 3-pentadecenyl phenol, a renewable resource and a by-product of the cashew industry characterized earlier [1] . The copolyester was characterized through elemental analysis, 1 H -NMR, IR, and UV spectroscopy. Dilute solution viscosity of its solution was also determined by viscometry. The intrinsic viscosity [η] was 0.98 dl/gm. The melting temperatures of the copolyester were 63 and 127°C as observed from Differential Scanning Calorimetric (DSC) studies. Thermogravimetric analysis show that degradation commences at 290°C in nitrogen atmosphere. Wide-angle X-ray diffraction study of the copolyester indicates absence of any crystallinity, whereas DSC studies indicate the presence of two melting peaks. Thus, it is presumed that the copolyester has short range crystallinity.

Grafting of Vinyl Monomers onto Wool Fibers

Abstract Chemical modifications have been devised to give natural macro-molecules more desirable properties, and the application of synthetic macromolecules forms an important area of such chemical modification. The literature abounds with the examples of successful formation of copolymers from natural and synthetic macromolecules. The molecular architecture of the natural substrate is not affected by the presence of polymer, but the nature of the polymer formed in the environment of a natural substrate may be quite different from the homopolymer formed under similar polymerization conditions.

Redox Polymerization Initiated by Metal Ions

Abstract During the last four decades there has been rapid development of the use of redox systems [1–30], that is, systems containing both an oxidizing and reducing agent, for the initiation of vinyl polymerization. Polymerizations which are initiated by the reaction between an oxidizing and a reducing agent may be called redox polymerizations.

Polymerization of acrylonitrile initiated by thiourea-vanadium(V) redox system

Abstract The kinetics of polymerization of acrylonitrile initiated by V5+-thiourea or V5+-ethylene thiourea have been studied at 30, 35 and 40°C in nitrogen. The rates of polymerization and V5+ disappearance, and the chain lengths of polymers were measured. The kinetics are consistent with the formation of an intermediate complex between the thiol form of thiourea or ethylene thiourea and the oxidant decomposition of which leads to the initiating radical. The effects of certain organic solvents (water miscible) and salts on the rate of polymerization have been studied. A kinetic scheme has been proposed and the various rate and energy parameters evaluated.

Thermal Degradation Analysis of Biodegradable Plastics from Urea-Modified Soy Protein Isolate

Environmental pollution caused due to petroleum-based plastics is growing worldwide. Soy protein isolate, a potential alternative to some petrochemical polymers, is cheap and available in plenty. This natural biopolymer is chemically modified with urea at 5, 10, and 20% (w/w) and 2M (molar) for better processing conditions. The FTIR spectra of the compounds have been studied to know the structure of biopolymers. The differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) of these samples have been monitored. TGA of the modified material has been followed using a computer analysis method, LOTUS package, developed by us, for assigning the degradation mechanism and evaluating the kinetic parameters using a number of equations. The thermal degradation mechanism of this biopolymer is explained on the basis of the kinetic parameters.

Polymers from renewable resources. Part 3. Thermal analysis of the interpenetrating polymer networks derived from castor oil, polyurethane—polyacrylates

Abstract A number of polyurethanes (PU) were synthesized by reacting castor oil with hexamethylene di-isocyanate and varying the NCO/OH ratio. All polyurethanes were reacted with acrylamide using EGDM cross-linker and benzoyl peroxide initiator. Thermogravimetric analyses of the polymers were followed, using a computer analysis method, the LOTUS package, for assigning the kinetic mechanism. Various kinetic equations have been used to evaluate the kinetic parameters. The suggested mechanism of degradation of the interpenetrating polymer networks (IPN) are based on the kinetic parameters.

Unperturbed Dimension of Polymer Molecules from Viscosity Measurements in Different Solvents

Abstract An expression for the determination of the cross-over point concentration, CX, of the polymer in a number of solvents has been derived, and an expression relating Cx with the unperturbed dimension of polymer molecules (r0 2)½ has been proposed. The unperturbed dimensions for polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polyacrylonitrile, and polyvinyl pyrrolidone have been calculated.

Grafting Vinyl Monomers onto Silk Fibers. V. Graft Copolymerization of Methyl Methacrylate onto Silk with Potassium Permanganate as Initiator

Abstract The graft copolymerization of methyl methacrylate onto silk fibers in aqueous solution with the use of manganese (IV) ions as initiator was investigated. The rate of grafting was determined by varying monomer, acidity of the medium, temperature, nature of silk, and the reaction medium. The graft yield increases significantly with increase of manganese (IV) concentration up to 15 meq/liter; with further increase of manganese (IV) concentration, the graft yield decreases. The effect of the increase of monomer concentration brings about a significant enhancement in the graft yield up to 7%, and with further increase of monomer concentration the graft yield decreases. The graft yield is considerably influenced by chemical modification prior to grafting. The effect of some inorganic salts and anionic surfactants on the rate of grafting has been investigated.

Aqueous polymerization of acrylonitrile initiated by the Mn3+/citric acid redox system

Abstract Kinetics of polymerization of acrylonitrile initiated by the redox system Mn 3+ /citric acid were investigated in aqueous sulphuric acid in the range of 20–25°; initial rates of polymerization and Mn 3+ disappearance etc. were measured. The effects of certain water miscible organic solvents and certain cationic and anionic detergents on the rate of polymerization have been examined. A mechanism has been suggested involving formation of a complex between Mn 3+ and citric acid, decomposition of which yields the initiating free radical and with polymerization being terminated by mutual interaction of growing radicals.