Dioctyl Adipate Research Articles

Thermally induced phase separation of UHMWPE mixture with dioctyl adipate: Competition of liquid–liquid phase separation and polymer crystallization

The thermal behavior of ultra-high molecular weight polyethylene (UHMWPE) with dioctyl adipate (DOA) was investigated by the differential scanning calorimetry (DSC) method. Capillary-porous bodies were obtained via thermally induced phase separation of DOA mixtures with polyethylenes of different molecular weight at different cooling rates. Analysis of the morphology of the prepared porous bodies together with DSC data and results of cloud point estimation revealed an unexpected effect of a cooling rate on the type of phase separation occurring in the mixture during its cooling from homogeneous state. Particularly it was shown that increase in the cooling rate reduces the probability of realization of liquid – liquid phase separation in the mixture. It was argued that such behavior, different from the standard semicrystalline polymers, is a result of kinetic hindrance of liquid – liquid phase separation in mixtures containing a polymer with such a high molecular weight.

Investigating the mechanism of Au(III) transport using a polymer inclusion membrane with dibutyl carbitol as a carrier

In this article, firstly, the separation and transfer of Au(III) from gold chloride solution was investigated using a polymer inclusion membrane (PIM) system containing dibutyl carbitol (DBC) as carrier molecules, dioctyl phthalate (DOP), bis(2-ethyl hexyl) adipate (dioctyl adipate) (DOA) and tris (2-ethyl hexyl) phosphate (T2EHP) as plasticizers and high molecular weight polyvinyl chloride (PVC) as the base polymer. Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM) were used to identify PIMs. Kinetic studies featuring a two-step reaction, with the first step being reversible, were conducted across various sections to investigate the processes of extraction, stripping, and transport. The effects of different stripping agents such as water, HCl, thiourea, sodium thiosulfate, and oxalic acid was investigated, and the best results were obtained with thiourea. Also, the mechanisms of Au(III) extraction and transport were studied. Under the conditions of source solution, tetrachloroaurate anionic complex AuCl4− with protonated DBC (ROR2OHM+) was extracted by ion solvation mechanism. The validity of the proposed extraction mechanism was confirmed through the use of nuclear magnetic resonance (1H NMR) spectroscopy. In order to make the membrane with the best composition and the highest efficiency, the effect of weight percentage of the carrier and plasticizer was investigated. There was an optimal value for the weight percentage of plasticizer (10–20% by weight) and carrier (40%), in which the highest flux and permeability in the membrane occurred. The effect of the viscosity of different plasticizers (DOP, DOA, and T2EHP) on the Au(III) flux was also investigated. It was found that the flux increases linearly with the reduction of plasticizer viscosity. Effect of membrane thickness on the permeability, initial flux, and efficiency of Au(III) transfer, were conducted with thickness of 120, 80, 45, and 30 μm. By reducing the thickness of the membrane, the transfer flux, permeability and percent of Au(III) transport, were improved from 12.9 × 10−3mh−1, 45.3 × 10−7molm−2s−1 and 18.2% to 26.4 × 10−3mh−1, 83.5 × 10−7molm−2s−1 and 37.3%, respectively. According to the results, a membrane with a combination of PVC:DBC:D2EHP with a weight percentage ratio of 50:40:10 with a thickness of 30 μm was suggested. Optimized results with the proposed membrane were obtained to be: extraction rate constant of 1.43 h−1, extraction percent of 99.1%, stripping rate constant of 37.5 × 10−4h−1, stripping percent of 40.9%, and permeability of 27.0 × 10−3mh−1, initial flux of 82.1 × 10−7molm−2s−1.

Molecular dynamics study on the effect of rheological performance of asphalt with different plasticizers

The main aim of this study is to explore how various plasticizers affect the rheological properties of asphalt and the causes of their varying effects on asphalt. Four plasticizers, namely dioctyl phthalate (DOP), dioctyl adipate (DOA), acetyl tributyl citrate (ATBC), and trioctyl trimellitate (TOTM), were used to modify the base asphalt. The rheological properties of the modified asphalts were assessed by bending beam rheometer (BBR) and dynamic shear rheometer (DSR) tests. The molecular weight distribution and glass transition temperature in the modified asphalts were determined using gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) tests. Finally, molecular dynamics simulations were performed to calculate parameters such as glass transition temperature, mean square displacement, and relative concentration, which elucidate the mechanism of different plasticizers on asphalt. The results suggest that DOA-modified asphalt with 2% modifier admixture exhibits the best low-temperature performance, whereas ATBC has the least effect. The four plasticizers can decrease the size and proportion of large and medium molecular groups in asphalt, reducing the intermolecular forces that impede the asphalt flow at low temperatures. The plasticizer molecules can generate more free space for the thermal movement of asphalt molecules, decreasing the glass transition temperature of the asphalt. Additionally, plasticizer molecules with greater flexibility can insert more easily between asphalt molecules, enhancing their diffusion ability through lubrication. DOA and ATBC can improve the dispersion of both asphaltenes and resins, while DOP and TOTM primarily affect asphaltenes. The distribution of aromatics and saturates is not significantly influenced by any of the four plasticizers.

Toxicity evaluation of Pinus radiata D.Don bark wax for potential cosmetic application.

Radiata pine bark is a widely available organic waste, requiring alternative uses due to its environmental impact on soil, fauna, and forest fires. Pine bark waxes could be used as cosmetic substitutes, but their toxicity requires evaluation since pine bark may contain toxic substances or xenobiotics, depending on the extraction process. This study evaluates the toxicity of radiata pine bark waxes obtained through various extraction methods on human skin cells grown in vitro. The assessment includes using XTT to evaluate mitochondrial activity, violet crystal dye to assess cell membrane integrity, and ApoTox-Glo triple assay to measure cytotoxicity, viability, and apoptosis signals. Pine bark waxes extracted via T3 (acid hydrolysis and petroleum ether incubation) and T9 (saturated steam cycle, alkaline hydrolysis, and petroleum ether incubation) exhibit non-toxicity up to 2% concentration, making them a potential substitute for petroleum-based cosmetic materials. Integrating the forestry and cosmetic industries through pine bark wax production under circular economy principles could promote development while replacing petroleum-based materials. Extraction methodology affects pine bark wax toxicity in human skin cells due to the retention of xenobiotic compounds including methyl 4-ketohex-5-enoate; 1-naphthalenol; dioctyl adipate; eicosanebioic acid dimethyl ester; among others. Future research will investigate whether the extraction methodology alters the molecular structure of the bark, affecting the release of toxic compounds in the wax mixture.

A novel bulk optode for ultra-trace detection of antimony coupled with spectrophotometry in food and environmental samples

A novel bulk optode was modified for ultra-trace detection of antimony. The optode was synthesized by incorporating fabricated ionophore, 6-{4-(2,4-di-hydroxyphenyl)diazenyl)phenyl}-2-oxo-4-phenyl-1,2-dihydropyridine-3-carbo-nitrile (DDPODC), 3-octadecanoylimino-7-(diethyl‑amino)-1,2-benzophenoxa-zine (ETH5294) as a chromoionophore, sodium tetraphenyl borate (NaTPB) as an anionic additive, and dioctyladipate (DOA) as a plasticizer in a poly vinyl chloride (PVC) membrane. In determining Sb3+, various parameters were implemented. Spectrophotometric procedure (λmax of 661 nm) was applied to define Sb3+ within optimal conditions. The optode has a wide range of 2.5 × 10−8 to 4.0 × 10−5 M Sb3+ with the detection and quantification limits as low as 7.0 × 10−9 and 2.4 × 10−8 M, respectively. The response time of optode was 3.0 min, with a RSD% of 1.75% (for 2.0 × 10−5 M, n=6). A 0.15 M HCl solution could be used to regenerate the optode. The interfering ions were studied. It was revealed that the optode was highly selective to Sb3+ ions and had no significant response to common cations and anions. It can be appealed that the optode can specifically detect Sb3+ ions. The optode was favorable applied to assess total antimony ions after reduction of Sb5+ to Sb3+ using potassium iodide and ascorbic acid as reducing agents in various water, food and biological samples.

Combined effects of plasticizers and D-lactide content on the mechanical and morphological behavior of polylactic acid

Nowadays, research into environmentally friendly, renewable materials is the focus of materials science. One of the best candidates for these purposes is polylactic acid (PLA), whose properties are determined mainly by its D-lactide content. PLA is often plasticized to achieve proper toughness. Our aim was to investigate the combined effects of plasticizers and D-lactide content on PLA. We investigated two different plasticizers: oligomeric lactide acid (OLA) and dioctyl adipate (DOA). An internal mixer was used to prepare the compounds, and then sheets were prepared by hot pressing. After mechanical and morphological analyses, we found that tensile strength and modulus of neat PLAs and PLA-OLA compounds decreased almost linearly with increasing D-lactide content. The mechanical properties of PLA-DOA compounds depended far less on D-lactide content than in the case of PLA-OLA compounds. Plasticizers promote the crystallization of crystallizable PLAs by their chain mobilizing effect—we obtained a higher crystalline fraction. The latter effect reduces the impact of the plasticizing effect of plasticizers in the product. The compatibility and dispersibility of plasticizers also have a significant effect on the properties of the materials. OLA is more compatible with PLA than DOA, which resulted in better plasticization, but caused more defects in the crystallites, thus reducing the crystalline melting temperature, and so the processing temperature of the compound containing plasticizers.

Study on compatibility mechanism of plasticizer and asphalt based on molecular dynamics

This work aims to reveal the compatibility mechanism of different plasticizers with the base asphalt using molecular dynamics (MD) simulation. For this purpose, four kinds of plasticizers were chosen, namely dioctyl phthalate (DOP), dioctyl adipate (DOA), acetyl tributyl citrate (ATBC), and trioctyl trimellitate (TOTM). The compatibility between those plasticizers and the asphalt was evaluated by various MD simulation parameters, including electric dipole moment, solubility parameters, and binding energy, and the simulation results were verified using macroscopic tests. The results show that the four plasticizers are effectively miscible with asphalt within the temperature range of 130 °C to 170 °C. The optimal temperatures for DOP, DOA, ATBC, and TOTM in modified asphalt preparation are 140 °C, 130 °C, 140 °C, and 150 °C respectively. The saturate component is more miscible with weak polar plasticizers, while the other three asphalt components are more miscible with strong polar plasticizers. TOTM has the best stability in combination with asphalt and ATBC has the worst. Aromatics and saturates have better torsional and bending deformation ability, and are more likely to form stable blending systems with strong polar plasticizers. Asphaltenes and resins have more stable benzene ring structures, they have greater binding energy with DOA, which is chain-variable and weakly polarized.

Inhibition of dissolution‐induced crystal transformation of ϵ‐Hexanitrohexaazaisowurtzitane in plasticizers by polydopamine coating**

AbstractIn order to avoid the crystal transformation of ϵ‐Hexanitrohexaazaisowurtzitane (ϵ‐HNIW) dissolved in plasticizers, a suitable bonding agent was selected to inhibit the crystal transformation of ϵ‐HNIW. Interfacial interaction simulations were carried out using Materials Studio2017 software for selected neutral polymer bonding agent (NPBA), polyene polyamine bonding agent (LBA) and polydopamine (PDA) and ϵ‐HNIW. Results showed that the interaction order of the three polymers on the ϵ‐HNIW crystal surface is PDA>NPBA> LBA; ϵ‐HNIW@ PDA crystal phase was more stable. Therefore, ϵ‐HNIW@ PDA crystal particles were constructed by the in‐situ self‐polymerization coating technology. Scanning electron microscope (SEM) showed that the ϵ‐HNIW@ PDA was square with smooth surface. The thermal properties of ϵ‐HNIW@ PDA were investigated by differential scanning calorimetry (DSC), which showed that the coating of PDA effectively increased the transition temperature of ϵ‐HNIW crystal. Moreover, the solubility and crystal transformation mechanism and law of ϵ‐HNIW/ϵ‐HNIW@ PDA in four plasticizers were further studied and compared systematically, ϵ‐HNIW@ PDA showed significantly lower solubility compared with ϵ‐HNIW. The solubility size was ranking as isodecyl nonanoate (IDP)>dioctyl sebacate (DOS)>dioctyl adipate (DOA)>paraffin liquid (RH). Variable‐temperature X‐ray diffraction (XRD) tests showed that PDA increased the ϵ‐HNIW crystal transformation temperature by about 35 °C. The small amount of dissolution of ϵ‐HNIW by the four plasticizers had a facilitative effect on the ϵ‐HNIW crystal transformation, which was consistent with the solubility magnitude. These results indicated that PDA‐coated ϵ‐HNIW enhances crystal interfacial interaction, reduces the solubility in plasticizers, and has a significant inhibitory effect on the dissolution‐induced crystal transformation of ϵ‐HNIW.

INCREASING THE ENERGY OF alpha, omega - DIHYDROXYPOLIBUTADIENE (HTPB) USED IN SOLID HETEROGENEOUS ROCKET PROPELLANT

Solid heterogeneous rocket propellants (SHRP), which are very popular and widely used in the armaments industry (guided missile propulsion engines and long-range, short-range and medium-range anti-aircraft rockets) have inert binders that significantly affect the final performance parameters of propulsion charges. In this study, the popular HTPB binder was modified by introducing azide groups into the polymer chain during three different syntheses. Compounds with different content of explosive groups were obtained and tested for compatibility with the essential SHRP components: ammonium chlorate(VII) and dioctyl adipate. Then, preliminary application tests of the obtained HTPB derivative were carried out, showing the potential of the obtained energetic polymer and the possibility of its use as a binder in solid heterogeneous rocket fuels. HTPB, energetic binder, azide groups

Synthesis and evaluation of epoxidized vegetable oleic acid as a novel environmental benign plasticizer for polyvinyl chloride

AbstractA bio‐based plasticizers, acetyl‐oleate triethylene glycol (AOT), was successfully synthesized by using oleic acid as a raw material through esterification, epoxidation, and acetylation. Its structure was analyzed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance. The plasticizing performances of this plasticizer was compared with those of two commercial ones: dioctyl terephthalate (DOTP) and dioctyl adipate (DOA). This was done by blending these plasticizers with PVC, respectively. Thermal gravimetric analysis results showed that the 5% weight loss temperature of PVC with AOT was 53°C higher than that of DOA and 36°C higher than that of DOTP. The tensile results showed that the AOT plasticized PVC had excellent stretchability: its elongation at break with 50 phr AOT reached 697.7%. Furthermore, its transmittance was as high as 90%, showing better compatibility of ATO with PVC.

Chemical, thermal and mechanical evaluation of poly(vinyl chloride) plastisol with different plasticizers

The most widely used plasticized polymer is poly(vinyl chloride) (PVC) due to its excellent plasticizer compatibility characteristics. Traditionally, PVC plasticizers belong to the phthalate family; however, they have harmful effects on human health and the environment. In this work, we evaluated the effect of six types of plasticizers (dioctyl phthalate, dioctyl adipate, Lestarflex (a polymeric polyester plasticizer), polycaprolactone, polyester polyol, and 1,2,3-propanetriol triacetate) on the properties of PVC plastisol used in manufacturing shoes and toys. The mechanical properties (hardness, tensile strength, tear strength, and elongation at break) were evaluated before and after accelerated aging tests (in an ultraviolet oven and at 50°C). A thermal study was also carried out using differential scanning calorimetry and thermogravimetric analysis, while possible structural changes during deformation were investigated using the small-angle X-ray scattering technique. In general, the results have shown that in the plasticization and stabilization of PVC, the plasticizer dioctyl phthalate can be replaced by dioctyl adipate or Lestarflex without relevant changes in the final properties of the material, even after accelerated aging.

Quantification and characterization of additives, plasticizers, and small microplastics (5–100 μm) in highway stormwater runoff

Highway stormwater (HSW) runoff is a significant pathway for transferring microplastics from land-based sources to the other surrounding environmental compartments. Small microplastics (SMPs, 5–100 μm), additives, plasticizers, natural, and nonplastic synthetic fibers, together with other components of micro-litter (APFs), were assessed in HSW samples via Micro-FTIR; oleo-extraction and purification procedures previously developed were optimized to accomplish this goal. The distribution of SMPs and APFs observed in distinct HSW runoff varied significantly since rainfall events may play a crucial role in the concentration and distribution of these pollutants. The SMPs' abundance varied from 11932 ± 151 to 18966 ± 191 SMPs/L. The dominating polymers were vinyl ester (VE), polyamide 6 (PA6), fluorocarbon, and polyester (PES). The APFs' concentrations ranged from 12825 ± 157 to 96425 ± 430 APFs/L. Most APFs originated from vehicle and tire wear (e.g., Dioctyl adipate or 5-Methyl-1H-benzotriazole). Other sources of these pollutants might be pipes, highway signs, packaging from garbage debris, road marking paints, atmospheric deposition, and other inputs. Assessing SMPs in HSW runoff can help evaluating the potential threat they may represent to receiving water bodies and air compartments. Besides, APFs in HSW runoff may be efficient proxies of macro- and microplastic pollution.

Circular economy implementation in the development of fire-retardant materials used in construction, industry, and general-purpose products

During a fire, passive fire protection systems are designed to prevent the spread of flames, smoke, and toxic gases. The new fire-retardant (FR) material, used for passive fire protection, is created by combining copolymers (VC–co–VAc) (Slovinyl KV 173) and PVC K70 with expanded graphite and plasticizers/modifiers such as diisononyl phthalate - DINP, diisononyl terephthalate - DINTP, dioctyl adipate - DOA, as well as plasticizers that are synthesized based on tertiary recycling of waste poly(ethylene terephthalate) (PET), 1-hexadecene, azodicarbonamide (ADC), tri(p-cresyl phosphate), epoxidized soybean oil (ESO) and acrylate emulsion (DH50, Ecrylic, or Flexryl, etc.). The obtained material's morphology was examined using an emission scanning electron microscope (FESEM) field. Tensile testing was used to determine the mechanical properties of the obtained samples, as well as Shore A hardness and toughness using the Charpy impact test. All samples obtained were tested according to non-flammability standards. To conform to the new trend of "green economy," the development of novel eco-friendly FRs with improved thermal and mechanical properties will include careful consideration of environmental protection and sustainable development.

Examining the Effect of Trimethylol Propane Crosslinker on Butanetriol Trinitrate Plasticized Polycaprolactone Polymer Networks of Propellant Binder System

AbstractThe knowledge of polymer network characteristics is important to tune the properties of advanced energetic propellants based on nitrate ester plasticized polyol binder system. In this article, plasticized polyurethane networks of polycaprolactone (PCP) and hydroxyl‐terminated polybutadiene (HTPB) with different crosslinker content [0 to 0.20 parts] at various stoichiometric ratios (r‐value) [0.8 to 1.0] were studied. Five numbers of polyurethane networks of 1,2,4‐butanediol trinitrate (BTTN) plasticised PCP were formulated at each r value 0.8, 0.9 and 1.0 using 0, 0.05, 0.10, 0.15 and 0.20 parts of trimethylolpropane (TMP) crosslinker. Similarly, five numbers of dioctyl adipate (DOA) plasticized HTPB based polyurethane networks were formulated at r‐value of 0.8. FT‐IR spectra of these polyurethane networks (PUNs) were recorded for functional group identification. Stress‐strain behavior of PUNs was studied for understanding the effect of TMP content and r value on mechanical properties. Hard segment content of PUNs were calculated and its influence on network characteristics and mechanical properties was evaluated. CLD values (ν) increased with increase of hard segment content of PUN and the values quantified by different approaches followed the trend νe (by solvent swelling method) > νne2(by Initial modulus method)>νne1 (by Mooney Rivlin method).

Analysis of Metabolite Compound Profiles of Miana Leaves Endophytic Bacteria (Coleus scutellariodes) using GC-MS

Exploration of bioactive compounds from endophytic bacteria as novel source of antibacterial need to be explored, as an alternative to substitute synthetic antibiotics. Based on previous studies, DM6 was a potential isolate that showed antibacterial activity. The isolate has been identified as Brevibacillus sp. based on 16S rRNA analysis. This study aimed to identify antibacterial compounds produced by DM6 isolate using GC-MS. The GC-MS results showed that the chloroform extract of DM6 isolate contained : 1-Octadecene (CAS).alpha.-Octadecene, Hexanedioic acid, dioctyl ester (CAS) Dioctyl adipate, Phenol, 3,5-bis(1,1-dimethylethyl)- (CAS) 3,5-Di-tert-butylphenol, and 1,4-diaza-2,5-dioxobicyclo[4.3.0]nonane. Adipic acid/hexanedioic acid and phenols are also known to contained in the leaves of Coleus scutellariodes. This indicated that endophytic bacteria were able to synthesize antibacterial compounds which similar with the host plant.

Evolution of HTPB/RDX/Al/DOA mixed explosives with 90% solid loading in resonance acoustic mixing process

ABSTRACT Resonance acoustic mixing (RAM) technology is an attractive and safe mixing method for material mass and energy exchange. However, the mixing mechanism of this technology and the evolution law of the material in the container are complicated, and improper mixing conditions will make the material unable to reach uniformity quickly and efficiently. In this paper, a 90% solid polymer-bonded explosive (PBX) was prepared by RAM, and the evolution of materials in different mixing containers, mixing acceleration, and mixing time was studied. The binder system consisted of hydroxyl-terminated polybutadiene (HTPB)/dioctyl adipate (DOA) and was cured by isophorone diisocyanate (IPDI). Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS) were used to observe the microcosmic change of the sample during the mixing process, and a rheometer was used to measure the viscosity change of the slurry at different stages. The results showed that the hemispherical bottom vessel could achieve uniform mixing of materials within 45 minutes, and the mixing efficiency was highest when the acceleration was 40 g. According to the evolution state of typical materials, the mixing process was divided into 3 stages: rough cladding stage, the stage of converging into a smooth ball, and the flat fluidization stage. In the range of shear rates from 0.1 to 100s−1, the apparent viscosity of the material tended to be flat with the extension of mixing time, and the rheological behavior index of the material had little change after the material aggregates into a smooth ball. The density test of the cured sample further proved that the PBX was very uniform.

Preparation of nonmigratory flexible poly(vinyl chloride)-b-poly(n-butyl acrylate)-b-poly(vinyl chloride) via aqueous reversible deactivation radical polymerization in a pilot reactor

Industrially-viable nonmigratory internal plasticization of poly(vinyl chloride) (PVC) is achieved by synthesis of the block copolymer poly(vinyl chloride)-b-poly(n-butyl acrylate)-b-poly(vinyl chloride) (PVC-b-PBA-b-PVC) by aqueous single electron transfer degenerative chain transfer living radical polymerization (SET-DTLRP). The introduction of a temperature step (42 °C to 80 °C) in the synthesis of PVC-b-PBA-b-PVC block copolymers from PBA macroinitiators resulted in materials with better overall performance than the commercial flexible PVC. The resulting copolymers were fully characterized by 1H NMR, SEC, SEM, TGA, DSC and DMTA to determine the composition, molecular weight, dispersity, morphology, thermal and mechanical properties, and compared with those of commercial formulations prepared with PVC and dioctyladipate (DOA). Most importantly, the plasticizing moieties of the PVC-b-PBA-b-PVC block copolymers are covalently bonded to the polymer, resulting in no migration upon extraction under conditions where DOA is readily extractable. Unlike commercial materials, the PVC-b-PBA-b-PVC block copolymers showed that the properties remain intact after extraction with n-hexane.

Synthesis, characterization, and photodynamic activity of new antimicrobial PVC based composite materials

Synthesis, chemical, and biological characterization of composite polyvinyl chloride (PVC)-based materials to be applied in the photodynamic inactivation (PDI) of pathogen microorganisms are reported. Different blends of PVC, plasticizers, and photosensitizers have been tested in their photokilling ability vs. Staphylococcus aureus, after irradiation using a multi-LED blue lamp at a fluence rate of 50 W/m2. Four common adipates, namely: dibutyl hexanedioate [di(n-butyl) adipate, BA, 1], bis(2-ethylhexyl) hexanedioate [bis(2-ethylhexyl) adipate, EA, 2], dioctyl hexanedioate (dioctyl adipate, OA, 3), and didecyl hexanedioate (dicapryl adipate, DA, 4), have been employed in this investigation, in combination with two photosensitizers: 5-(4-carboxy-phenyl)-10,15,20-triphenyl-21H,23H-porphyrin (TPP, 5), and the expanded porphyrin 20-(4-carboxyphenyl)-2,13-dimethyl-3,12-diethyl-[21]pentaphyrin (PCox, 6). The experimental evidence has established the essential role of the addition of a plasticizer to the polymer/photosensitizer mixture in transforming PVC into a photoactive material, being bactericidal properties dependent upon the type and amount of additive. Long-chain linear adipates were found more efficient in imparting the desired bactericidal activity to the final material, reaching in one case the complete abatement of the initial bacterial solution (108 CFU/ml) in 60 min. The obtained polymeric films proved to be stable over time and under oxidation conditions; in addition, no release of toxic components was observed over the experiments, definitely demonstrating that the bactericidal action was effectively due to the ROS generated by photosensitizers immobilized into the material. Moreover, SEM and FT-IR analyses proved that no photodegradation of the film took place during the irradiation experiment.

Thixotropic Behavior in Defining Particle Packing Density of Highly Filled AP/HTPB-Based Propellant

An alarming, asymmetric flame in rocket combustion originates from a composite solid propellant (CSP) containing defects. The defects are the result of a composition that exceeds the maximum particle packing density. Based on the structure analysis of CSP, the addition of plasticizer causes the correlation between the viscosity of CSP slurry and particle packing density to become uncertain. This work aims to investigate the influence of thixotropic behavior on the maximum particle packing density of CSP. A CSP with different thixotropic behavior was successfully produced using aluminum/plasticizer dioctyl adipate (DOA) of 12–24. During the curing process, viscosity and stress–growth were investigated. The structure of the CSP was defined using X-ray radiography. It is remarkably observed that the peak of thixotropy occurred at the 15th minute of the curing process. The particle packing density of CSP can be decisive for the relative viscosity at the peak time of thixotropic behavior. The CSP with the highest relative viscosity at the peak time was revealed to have voids in the upper part of the CSP. Thus, this parameter was proven to change the preceding parameter, viscosity that was measured at the end of mixing. Based on the stress–growth analysis, it is conceivable that the mechanism involves the time-dependent diffusion of DOA in weakening aluminum agglomerates.

SPECIAL PURPOSE PLASTICATORS FOR POLYVINYL CHLORIDE

Background Elastic materials based on polyvinyl chloride (PVC) are widely used in various fields: medical products, cables, shoes, hoses, floor coverings, seals, packaging films, etc. Polyvinyl chloride is a polar rigid polymer, and for plasticizers are used to give it softness and rubbery properties. The most widespread in the production of elastic PVC materials are dialkyl phthalate plasticizers for general purposes - dioctyl phthalate and diisononyl phthalate. Aims and Objectives The paper considers the efficiency of the use of an environmentally friendly oil-free plasticizer triethylene glycol bis (2-ethylhexanoate) in a PVC compound intended for the manufacture of frost-resistant hoses. Results The effect of triethylene glycol bis (2-ethylxanoate) in comparison with dioctyl adipate (DOA) and a polymer plasticizer, which is an ester of adipic acid Edenol 1215, on the physical and mechanical properties of PVC compounds, oil and petrol resistance, frost resistance and other performance characteristics, as well as a dynamo-mechanical analysis of the investigated materials was carried out on a NETZSCH DMA 242 device. The plasticizer triethylene glycol bis (2-ethylhexanoate) contributes to the greatest decrease in the glass transition temperature of PVC compound and provides higher elasticity at low temperatures and, as a consequence, better frost resistance in comparison with dioctyl adipate and Edenol 1215 The oil and petrol resistance of PVC compounds obtained with triethylene glycol bis (2-ethylxanoate) is comparable to the sample plasticized with DOA and is noticeably inferior to the material with the plasticizer Edenol 1215, which has a higher molecular weight. Triethylene glycol bis (2-ethylhexanoate) is a promising plasticizer for the industrial production of PVC compounds with increased frost resistance.