Investigation of the Role of Plasticizers in Film-forming Coats for Protecting Cooled Meat

As a result of theoretical studies on problems of protection and prolongation of storage terms of meat, it was revealed, that one of promising directions is to use protecting coats, based on natural biopolymers.The topicality of this study is in studying film-forming coats, based on natural polysaccharides, because they have high mechanical indices, absence of a smell, taste and are subjected to biological destruction. For regulating mechanical properties, the composition of film-creating coats is added with plasticizers of different origins.The aim of this work is in describing characteristics of food films, based on carrageenan, sodium alginate and plasticizers of different origins.There were mechanical, rheological properties of protecting coats. The comparative characteristic of these properties, depending on an added plasticizer, was realized. The type and mechanisms of interaction of components of the film-forming coat and plasticizers were completely described. The viscosity of the film-forming coat with a plasticizer has less values comparing with other solutions. Adding plasticizers resulted in increasing the film elasticity, but at the same time some increase of the firmness was observed.Film-forming coats with adding a plasticizer had a higher limit of fluidity, so they were firmer than complex film-forming coats without a plasticizer. From the other side, deformation values of film-forming coats without adding a plasticizer were higher than ones of complex film-forming coats with adding a plasticizer, because they were firmer.The study of physical properties of developed film-forming coats, based on hydrocolloids, demonstrated that coats with a plasticizer have more gas permeability.According to the results, obtained at experiments it was established, that the film-forming coat, based on sodium alginate, carrageenan and glycerin, has best mechanical, physical and rheological indices

Investigation of Polymer–Plasticizer Blends as SH-SAW Sensor Coatings for Detection of Benzene in Water with High Sensitivity and Long-Term Stability

We report the first-ever direct detection of benzene in water at concentrations below 100 ppb (parts per billion) using acoustic wave (specifically, shear-horizontal surface acoustic wave, SH-SAW) sensors with plasticized polymer coatings. Two polymers and two plasticizers were studied as materials for sensor coatings. For each polymer–plasticizer combination, the influence of the mixing ratio of the blend on the sensitivity to benzene was measured and compared to commercially available polymers that were used for BTEX (benzene, toluene, ethylbenzene, and xylene) detection in previous work. After optimizing the coating parameters, the highest sensitivity and lowest detection limit for benzene were found for a 1.25 μm thick sensor coating of 17.5%-by-weight diisooctyl azelate-polystyrene on the tested acoustic wave device. The calculated detection limit was 45 ppb, with actual sensor responses to concentrations down to 65 ppb measured directly. Among the sensor coatings that showed good sensitivity to benzene, the best long-term stability was found for a 1.0 μm thick coating of 23% diisononyl cyclohexane-1,2-dicarboxylate-polystyrene, which was studied here because it is known to show no detectable leaching in water. The present work demonstrates that, by varying type of plasticizer, mixing ratio, and coating thickness, the mechanical and chemical properties of the coatings can be conveniently tailored to maximize analyte sorption and partial chemical selectivity for a given class of analytes as well as to minimize acoustic-wave attenuation in contact with an aqueous phase at the operating frequency of the sensor device

Blends of Nitrile Butadiene Rubber/poly (Vinyl Chloride): the Use of Maleated Anhydride Castor Oil Based Plasticizer

Recently, much attention has been focused on research to replace petroleum-based plasticizers, with biodegradable materials, such as biopolymer which offers competitive mechanical properties. In this study, castor oil was modified with maleic anhydride (MAH) to produce bioplasticizer named maleated anhydride castor oil (MACO), and used in nitrile butadiene rubber (NBR)/poly vinyl chloride (PVC) blend. The effect of MACO on its cure characteristics and mechanical properties of NBR/PVC blend has been determined. The reactions were carried out at different castor oil (CO)/xylene ratios, i.e. 1:0 and 1:1 by weight, and fixed CO/MAH ratio, 1:3 by mole. DOP, CO, and MACO were added into each NBR/PVC blend according to the formula. It was found that the viscosity and safe process level of NBR/PVC blend is similar from all plasticizer, however, MACO (1:0) showed the highest cure rate index (CRI). MACO-based plasticizer gave a higher value of the mechanical properties of the NBR/PVC blend as compared to DOP based plasticizer. MACO (1:1) based plasticizer showed a rather significance performance compared to another type of plasticizers both before and after aging. The value of hardness, elongation at break, tensile strength, and tear strength were 96 Shore A, 155.91 %, 19.15 MPa, and 74.47 MPa, respectively. From this result, NBR/PVC blends based on MACO plasticizer can potentially replace the DOP, and therefore, making the rubber blends eco-friendly

Material properties of nanoclay PVC composites

Nanocomposites of poly(vinyl chloride) have been prepared using both hectorite- and bentonite-based organically-modified clays. The organic modification used is tallow-triethanol-ammonium ion. The morphology of the systems was investigated using X-ray diffraction and transmission electron microscopy and these systems show that true nanocomposites, both intercalated and exfoliated systems, are produced. The mechanical properties have been evaluated and the modulus increases upon nanocomposite formation without a significant decrease in tensile strength or elongation at break. Thermal analysis studies using thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis were conducted. Thermal stability of the PVC systems was assessed using a standard thermal process evaluating the evolution of hydrogen chloride and by color development through the yellowness index. Cone calorimetry was used to measure the fire properties and especially to evaluate smoke evolution. The addition of an appropriately-modified bentonite or hectorite nanoclay leads to both a reduction in the total smoke that is evolved, and an increase in the length of time over which smoke is evolved. Along with this, a reduction in the peak heat release rate is seen. It is likely that the presence of the clay in some way interferes with the cyclization of the conjugated system formed upon HCl loss

Effect of the plasticizer on permeability, mechanical resistance and thermal behaviour of composite coating films

Thin layer deposit of a composite material on solid particle surfaces used in the food industry aims to ensure the protection of food powder against aggressive environments such as amoist atmosphere. The layer, having a thickness of a few fractions of millimetre, must have certain physico-chemical properties: it must be compatible with the product, itmust be impermeable to water and oxygen, itmust have goodmechanical strength and good adhesion to the surface of the coated powder. Furthermore the layer must fulfil the regulatory requirements for food ingredients. Film properties like continuity, permeability, and mechanical resistance depend on the choice of the excipients included in the formulation and the operating conditions which can modify the constraints generated at the interface film-powder. As a consequence, the scientific issue consists of combining the local phenomena happening at amicroscopic level on the surface of the particle with the processing technology and the process parameters. In a first step, the attention is focussed on the film and its formulation. For this step, films are prepared separately and they are dried under very smooth conditions. Test samples are taken from the formed composite films and contain hydroxypropyl methylcellulose asmatrix (67% of driedmaterial),micronised stearic acid as hydrophobic filler (20% of driedmaterial) and a plasticizer (13% of driedmaterial). The filmformation procedure and the testmethod are described in detail. The effect of the type of plasticizer (different grades of PEG) onmechanical, thermal and permeability properties of the coating film is studied. The results show that PEG with higher molecular rate provides a better plasticizing effect for the film but increases the water vapour permeability of the film

Use of response surface methodology (RSM) to optimize pea starch-chitosan novel edible film formulation

The aim of this study was to develop an optimal formulation for preparation of an edible film from chitosan, pea starch and glycerol using response surface methodology (RSM). Three independent variables were assigned comprising chitosan (1-2%), pea starch (0.5-1.5%) and glycerol (0.5-1%) to design an empirical model best fit in physical, mechanical and barrier attributes. Impacts of independent variables on thickness, moisture content (MC), solubility, tensile strength (TS), elastic modulus (EM), elongation at break (EB) and water vapor permeability (WVP) of films were evaluated. All the parameters were found to have significant effects (p<0.05) on physical and mechanical properties of film. The optimal formulation for preparation of edible film from chitosan, pea starch and glycerol was 1% chitosan, 1.5% pea starch and 0.5% glycerol. An edible film with good physical and mechanical properties can be prepared with this formulation and thus this formulation can be further applied for testing on coating for fruit and vegetables

Plasticization and antiplasticization of polymer melts diluted by low molar mass species

An analysis of glass formation for polymer melts that are diluted by structured molecular additives is derived by using the generalized entropy theory, which involves a combination of the Adam-Gibbs model and the direct computation of the configurational entropy based on a lattice model of polymer melts that includes monomer structural effects. Antiplasticization is accompanied by a "toughening" of the glass mixture relative to the pure polymer, and this effect is found to occur when the diluents are small species with strongly attractive interactions with the polymer matrix. Plasticization leads to a decreased glass transition temperature T_g and a "softening" of the fragile host polymer in the glass state. Plasticization is prompted by small additives with weakly attractive interactions with the polymer matrix. The shifts in T_g of polystyrene diluted by fully flexible short oligomers are evaluated from the computations, along with the relative changes in the isothermal compressibility at T_g to characterize the extent to which the additives act as antiplasticizers or plasticizers. The theory predicts that a decreased fragility can accompany both antiplasticization and plasticization of the glass by molecular additives. The general reduction in the T_g and fragility of polymers by these molecular additives is rationalized by analyzing the influence of the diluent's properties (cohesive energy, chain length, and stiffness) on glass formation in diluted polymer melts. The description of glass formation at fixed temperature that is induced upon change the fluid composition directly implies the Angell equation for the structural relaxation time as function of the polymer concentration, and the computed "zero mobility concentration" scales linearly with the inverse polymerization index N.Comment: 12 pages, 15 figure

Mechanical properties of plastics predetermined by empirical method

To predetermine the mechanical properties of rigid plastics as a function of plasticizer content and composition, a set of equations has been empirically derived. These relate strain rate, yield stress, temperature, and weight fraction of the plasticizer

Influence of water on localized and delocalized molecular mobility of cellulose

The influence of hydration on cellulose molecular mobility is investigated by two dielectric methods at different molecular scale. The mobility of side groups, assigned to c mode, for dried cellulose increases. The water molecules have an anti-plasticizer effect on c mode due to the water–polymer hydrogen bonding. For the b relaxation mode, only observed by the Thermo Stimulated Current technique, the hydration plays a role of plasticizer. The a relaxation mode assigned to the delocalized cooperative mobility of long chain segments of cellulose is plasticized by water. The study of activated parameters deduced from fractional polarization procedure, shows an increase of the activation enthalpy range with dehydration. It permits to conclude that reduction of hydrogen bonds density leading to a more extended cooperative mobility