Plastic Compounds Research Articles

Strong Adhesion and Cohesion of Chitosan in Aqueous Solutions

Chitosan, a load-bearing biomacromolecule found in the exoskeletons of crustaceans and insects, is a promising biopolymer for the replacement of synthetic plastic compounds. Here, surface interactions mediated by chitosan in aqueous solutions, including the effects of pH and contact time, were investigated using a surface forces apparatus (SFA). Chitosan films showed an adhesion to mica for all tested pH ranges (3.0-8.5), achieving a maximum value at pH 3.0 after a contact time of 1 h (Wad ~ 6.4 mJ/m(2)). We also found weak or no cohesion between two opposing chitosan layers on mica in aqueous buffer until the critical contact time for maximum adhesion (chitosan-mica) was reached. Strong cohesion (Wco ~ 8.5 mJ/m(2)) between the films was measured with increasing contact times up to 1 h at pH 3.0, which is equivalent to ~60% of the strongest, previously reported, mussel underwater adhesion. Such time-dependent adhesion properties are most likely related to molecular or molecular group reorientations and interdigitations. At high pH (8.5), the solubility of chitosan changes drastically, causing the chitosan-chitosan (cohesion) interaction to be repulsive at all separation distances and contact times. The strong contact time and pH-dependent chitosan-chitosan cohesion and adhesion properties provide new insight into the development of chitosan-based load-bearing materials.

A Complete Denture Impression Technique Survey of Postdoctoral Prosthodontic Programs in the United States

The purpose of the study was to survey program directors of postdoctoral prosthodontic programs in the United States regarding their programs' complete denture impression techniques. The key objectives of the survey were to identify the current trends in complete denture impression making and to determine which techniques and materials are taught in US postdoctoral prosthodontic programs. An online survey was sent to all program directors of US postdoctoral prosthodontic programs. The survey comprised two sections: preliminary impressions and final impressions. The survey contained 22 questions that would take approximately 5 minutes to complete. All responses remained anonymous throughout the survey. The response rate for the survey was 87%. A majority of the programs did not separately border mold the tray prior to making the preliminary impressions (82%). The impression material of choice for the preliminary impression was irreversible hydrocolloid (88%). Selective pressure was the predominantly used impression philosophy (80%). All programs border molded the custom tray, and 95% recorded the borders in sections. The material of choice for border molding the custom tray was modeling plastic impression compound (71%). The most commonly used impression material for the final impressions was polyvinylsiloxane (PVS) (42%), and the second most commonly used impression material was polysulphide (32%). The most common technique for locating the posterior palatal seal was marking intraorally and transferring onto the final impression (65%). Most programs routinely advised their patients not to wear their existing dentures for at least 24 hours before the final impressions were made (83%). Based on the results of this study, the following conclusions can be drawn: (1) The most commonly used material for the preliminary impression was irreversible hydrocolloid and for the final impression was PVS. (2) Modeling plastic impression compound was used by most programs to border mold the custom trays. (3) Selective pressure was the predominantly used impression philosophy. (4) A majority of the programs made a special consideration for excessive movable (flabby) tissue. (5) Most programs routinely advised their patients to not wear their existing dentures for at least 24 hours before the final impressions were made.

Global Analysis of Anthropogenic Debris Ingestion by Sea Turtles

Ingestion of marine debris can have lethal and sublethal effects on sea turtles and other wildlife. Although researchers have reported on ingestion of anthropogenic debris by marine turtles and implied incidences of debris ingestion have increased over time, there has not been a global synthesis of the phenomenon since 1985. Thus, we analyzed 37 studies published from 1985 to 2012 that report on data collected from before 1900 through 2011. Specifically, we investigated whether ingestion prevalence has changed over time, what types of debris are most commonly ingested, the geographic distribution of debris ingestion by marine turtles relative to global debris distribution, and which species and life-history stages are most likely to ingest debris. The probability of green (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) ingesting debris increased significantly over time, and plastic was the most commonly ingested debris. Turtles in nearly all regions studied ingest debris, but the probability of ingestion was not related to modeled debris densities. Furthermore, smaller, oceanic-stage turtles were more likely to ingest debris than coastal foragers, whereas carnivorous species were less likely to ingest debris than herbivores or gelatinovores. Our results indicate oceanic leatherback turtles and green turtles are at the greatest risk of both lethal and sublethal effects from ingested marine debris. To reduce this risk, anthropogenic debris must be managed at a global level.Análisis Global de la Ingesta de Residuos Antropogénicos por Tortugas MarinasLa ingesta de residuos marinos puede tener efectos letales y subletales sobre las tortugas marinas y otros animales. Aunque hay investigadores que han reportado la ingesta de residuos antropogénicos por tortugas marinas y la incidencia de la ingesta de residuos ha incrementado con el tiempo, no ha habido una síntesis global del fenómeno desde 1985. Por esto analizamos 37 estudios publicados, desde 1985 hasta 2012, que reportan datos colectados desde antes de 1900 y a lo largo del 2011. Investigamos específicamente si el predominio de la ingesta ha cambiado con el tiempo, qué tipos de residuos se ingieren comúnmente, la distribución geográfica de la ingesta de residuos por tortugas marinas en relación a la distribución global de residuos y cuáles especies y etapas de vida tienen más probabilidad de ingerir residuos. La probabilidad de que las tortugas verdes (Chelonia mydas) y laúd (Dermochelys coriacea) ingieran escombros incrementa significativamente con el tiempo; plástico fue el residuo que más se ingirió. Las tortugas en casi todas las regiones estudiadas ingieren residuos, pero la probabilidad de ingesta no estuvo relacionada con las densidades modeladas de residuos. Además de esto, tortugas más pequeñas, en etapa oceánica de vida, tuvieron una mayor probabilidad de ingerir residuos que las tortugas forrajeras terrestres, mientras que las especies carnívoras tuvieron menos probabilidad de ingerir residuos que las herbívoras o las gelatinívoras. Nuestros resultados indican que las tortugas verdes y laúd tienen el mayor riesgo de efectos letales y subletales de la ingesta de residuos marinos. Para reducir el riesgo, los residuos antropogénicos deben manejarse en un nivel global.

Synthesis and application of an alternative plasticizer Di(2‐Ethylhexyl)‐1,2‐cyclohexane dicarboxylate

ABSTRACTCyclohexane dicarboxylic acid esters are environmentally friendly and non‐toxic plasticizers, and have similar performance with phthalates which have potential toxicity to human health. In this article, di(2‐ethylhexyl)‐1,2‐cyclohexane dicarboxylate (DEHCH) was synthesized via esterification between hexahydrophthalic anhydride (HHPA) with iso‐octanol by using concentrated sulfuric acid as a catalyst. The effects of reaction parameters on esterification were studied by investigating the temperature, reaction time, molar ratio of iso‐octanol‐to‐HHPA, and catalyst content. Conversions of HHPA to esters were determined. Functional group analysis was conducted by using FTIR and 1H‐NMR spectroscopy. PVC compounds after addition of the synthesized plasticizer DEHCH presented similar plasticizing performance with DEHP and DINCH, as demonstrated by comparisons of the results of mechanical properties, transparency, and volatilization and migration tests obtained for plasticized PVC compounds. DEHCH can also be considered as an alternative plasticizer for DEHP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39763.

Preparation and Characterization of Cellulose Acetate Butyrate/Organoclay Nanocomposites Produced by Extrusion

Nanocomposite films based on cellulose acetate butyrate, modified montmorillonite (Cloisite® 30B), plasticizer (triethyl citrate) and antimicrobial compounds (carvacrol and cinnamaldehyde) were prepared by extrusion. The effects of the Cloisite® 30B content and antimicrobial compound types on the morphology of the nanocomposite films were investigated by X‐ray diffraction and transmission electron microscopy. The thermal characteristics of films were analysed by thermogravimetry and differential scanning calorimetry; oxygen and water vapour permeability and tensile strength were determined. The film's antimicrobial behaviour against Listeria innocua, Staphylococcus aureus, Escherichia coli O157:O7 and Saccharomyces cerevisiae was investigated and determined using a viable cell count method. Nanocomposites with a Cloisite® 30B content of 3 wt% showed better dispersion than nanocomposites with a 5 wt% content. For films with antimicrobial compounds, tensile strength and Young's modulus decreased and water vapour permeability increased (150%) because of the plasticization effect of the antimicrobial compounds (essential oils). The nanocomposites with carvacrol and cinnamaldehyde were effective against the tested Gram‐positive bacteria (reduction of at least 3.0 log CFU/ml) and yeast (reduction of at least 4.0 log CFU/ml). This study demonstrates that antimicrobial cinnamaldehyde and carvacrol can be successfully incorporated into cellulose acetate butyrate nanocomposites and that they have an inhibitory effect against microbial growth in solid medium. It shows the potential use of cellulose acetate butyrate for food packaging applications. Copyright © 2013 John Wiley & Sons, Ltd.

Terahertz plastic compound lenses

We present terahertz (THz) lenses made of highly refracting polymeric compounds which provide a better focusing performance and an increased functionality in comparison to conventional THz lenses. Using mixtures consisting of polypropylene (PP) and alumina as well as PP and zinc sulfide allows a significant increase of the refractive index while simultaneously keeping a low extinction and dispersion. With these new material combinations, lenses with an increased focusing capability are realized. This is evaluated by focal plane measurements using a fiber coupled THz time-domain spectrometer.

Europe considers total ban on cadmium in plastics

The European Commission is considering expanding its restriction on cadmium and its compounds in plastics from the current 16 materials listed in Annex XVII of REACH to all plastic materials. It has asked the Helsinki-based European Chemicals Agency (ECHA) to examine the case for an outright ban.

Polythiophene-coated Fe3O4 superparamagnetic nanocomposite: Synthesis and application as a new sorbent for solid-phase extraction

In the present work, a novel type of superparamagnetic nanosorbent, polythiophene-coated Fe3O4 nanoparticles (Fe3O4@PTh NPs), have been successfully synthesized. The synthesized NPs were characterized by scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR) spectroscopy, and thermal gravimetric analysis (TGA). The synthesized Fe3O4@PTh NPs were applied as an efficient sorbent for extraction and preconcentration of several typical plasticizer compounds (di-n-butyl phthalate (DBP), di-(2-ethylhexyl) phthalate (DEHP), and dioctyl adipate (DOA)) from environmental water samples. Separation of Fe3O4@PTh NPs from the aqueous solution was simply achieved by applying external magnetic field. Separation and determination of the extracted plasticizers was performed by gas chromatography–flame ionization detection (GC–FID). Several variables affecting the extraction efficiency of the analytes i.e., amount of NPs sorbent, salt concentration, extraction time, and desorption conditions were investigated and optimized. The best working conditions were as follows: amount of sorbent, 100mg; NaCl concentration, 30% (w/v); sample volume, 45mL; extraction time, 10min; and 100μL of ethyl acetate for desorption of the analytes within 2min. Under optimized conditions, preconcentration factors for DBP, DEHP, and DOA were obtained as 86, 194, and 213, respectively. The calibration curves were linear (R2>0.998) in the concentration range of 0.4–100μgL−1 for both DEHP and DOA and 0.7–100μgL−1 for DBP. The limits of detection (LODs) were obtained in the range of 0.2–0.4μgL−1. The intra-day relative standard deviations (RSDs%) based on four replicates were obtained in the range of 4.0–12.3%. The proposed procedure was applied to analysis of water samples including river water, bottled mineral water, and boiling water exposed to polyethylene container (after cooling) and recoveries between 85 and 99% and RSDs lower than 12.8% were obtained.

Age- and tanner stage-specific pediatric reference intervals for 7 sex hormones in healthy Canadian children and youth

Plasticizers are chemical compounds used to increase the softness and fluidity of polymer materials. Phthalate compounds constitute the most common class of compounds used as plasticizers. However, phthalate plasticizers, especially the predominant di(2-ethylhexyl)phthalate, have been shown to have adverse effects on environment and human health. Hence, efforts have been made to use safer and environmentally friendly alternate non-phthalate plasticizers in industrial applications. The present study involves structural binding studies on endocrine disrupting potential of three high volume alternate plasticizer compounds, i.e., di-(2-ethylhexyl) adipate (DEHA), acetyl tributyl citrate (ATBC) and 2,2,4-trimethyl 1,3-pentanediol diisobutyrate (TPIB) with sex hormone binding globulin (SHBG). This study showed that DEHA, ATBC and TPIB bind in the ligand binding pocket of SHBG and the structural binding results suggested that the three alternate plasticizers may interfere in the steroid binding of SHBG and thus may cause dysfunction in sex steroid homeostasis.

Pyrolysis and dehalogenation of plastics from waste electrical and electronic equipment (WEEE): A review

Plastics from waste electrical and electronic equipment (WEEE) have been an important environmental problem because these plastics commonly contain toxic halogenated flame retardants which may cause serious environmental pollution, especially the formation of carcinogenic substances polybrominated dibenzo dioxins/furans (PBDD/Fs), during treat process of these plastics. Pyrolysis has been proposed as a viable processing route for recycling the organic compounds in WEEE plastics into fuels and chemical feedstock. However, dehalogenation procedures are also necessary during treat process, because the oils collected in single pyrolysis process may contain numerous halogenated organic compounds, which would detrimentally impact the reuse of these pyrolysis oils. Currently, dehalogenation has become a significant topic in recycling of WEEE plastics by pyrolysis. In order to fulfill the better resource utilization of the WEEE plastics, the compositions, characteristics and dehalogenation methods during the pyrolysis recycling process of WEEE plastics were reviewed in this paper. Dehalogenation and the decomposition or pyrolysis of WEEE plastics can be carried out simultaneously or successively. It could be ‘dehalogenating prior to pyrolysing plastics’, ‘performing dehalogenation and pyrolysis at the same time’ or ‘pyrolysing plastics first then upgrading pyrolysis oils’. The first strategy essentially is the two-stage pyrolysis with the release of halogen hydrides at low pyrolysis temperature region which is separate from the decomposition of polymer matrixes, thus obtaining halogenated free oil products. The second strategy is the most common method. Zeolite or other type of catalyst can be used in the pyrolysis process for removing organohalogens. The third strategy separate pyrolysis and dehalogenation of WEEE plastics, which can, to some degree, avoid the problem of oil value decline due to the use of catalyst, but obviously, this strategy may increase the cost of whole recycling process.

Migrating components in a polyurethane laminating adhesive identified using gas chromatography/mass spectrometry

Plastics are increasingly used as packaging materials for pharmaceuticals. However, diffusion of compounds in plastic into drugs may endanger patients' health. Regulatory authorities therefore demand detailed information about leachable compounds in plastics. Here we identify migrating components of a sterilization-resistant polyurethane (PUR) adhesive used in the primary packaging for an aqueous pharmaceutical. This identification is an essential first step for quantification and toxicological evaluation of the compounds. We used various hyphenated mass spectrometry (MS) methods: gas chromatography (GC/MS) with either electron impact ionization or chemical ionization, and high resolution liquid chromatography (LC/MS) with electrospray ionization. Of the 13 migrating substances detected, 11 are cyclic esters with characteristic fragmentation schemes apparent from their mass spectra. These esters are formed as by-products during the reaction of adipic and isophthalic acid with monoethylene glycol and diethyelene glycol. A cyclic ester of isophthalic acid and tetraethylene glycol and a product of the reaction of isophoron diisocyanate with methanol were clearly identified. Complementary use of several hyphenated mass spectrometric methods enables successful identification of leachable compounds in the PUR adhesive under study. This opens the way for quantification and evaluation of the potential toxicities of these compounds. Despite the range of compositions of PUR laminates, the approach presented here may be applicable for the qualitative assessment of all PURs.

Insulin resistance in regulation of metabolism

This paper highlights the main causes leading the development of insulin resistance (IR), its mechanisms, and the role it plays in living activity. The analysis of the available literature gives reason to believe that the source of IR is the constant requirement for plastic and high-energy compounds to be mobilized from the body's internal reserves. The mechanisms underlying the development IR involve all organ systems that interact between themselves and thereby govern the origin and evolution of insulin resistance via regulation of the energy generation and consumption processes. This concept is in excellent agreement with the laws of thermodynamics. The vital activity is based on the principle of continuous variations of IR. This inference provides a basis for addressing a number of clinical problems.

Compound Modified Asphalt Performance Research

The scrap rubber powder and the waste plastic compound modified bituminous mixture are used in the first-class highway asphalt concrete pavement. They can not only reduce the environment pollution, but also enhance the operational performance of bituminous pavement. It has the economical, social and the environment three aspect remarkable benefit. This article uses the appraisal system of the rubber asphalt to test the compound modified asphalt performance with the different rubber powder quantity and the waste plastic quantity in different mixture temperature and the time. By text, we can determine the best quantity of the waste plastic.

Compound Modified Asphalt Performance Research

The scrap rubber powder and the waste plastic compound modified bituminous mixture are used in the first-class highway asphalt concrete pavement. They can not only reduce the environment pollution, but also enhance the operational performance of bituminous pavement. It has the economical, social and the environment three aspect remarkable benefit. This article uses the appraisal system of the rubber asphalt to test the compound modified asphalt performance with the different rubber powder quantity and the waste plastic quantity in different mixture temperature and the time. By text, we can determine the best quantity of the waste plastic.

Circulating levels of bisphenol A (BPA) and phthalates in an elderly population in Sweden, based on the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS)

The plastic manufacture compounds, bisphenol A (BPA) and phthalates, are ubiquitous and have therefore been detected in virtually all types of analyzed human samples. The aim of this study was: (1) to investigate concentrations of serum levels of BPA and phthalate metabolites in seniors residing in the city of Uppsala, Sweden (2) to evaluate gender differences in relation to serum levels of BPA and phthalate metabolites in the subjects. In the population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS), encompassing 1016 subjects, all aged 70, serum levels of BPA and phthalate metabolites were measured by Isotope Dilution–High Performance Liquid Chromatography–Tandem Mass Spectrometry. BPA and four out of ten phthalate metabolites, namely, Monoisobutyl phthalate (MiBP), Monomethyl phthalate (MMP), Monoethyl phthalate (MEP), Mono-(2-ethylhexyl) phthalate (MEHP), were detectable in almost all subjects. Of the remaining phthalate metabolites, Monobenzyl phthalate (MBzP), Mono-(2-ethyl-5-hydroxyhexyl) phthalate (MeHHP), and Mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) were seen in some 300–700 of the subjects, whereas Monoisononyl phthalate (MINP) and Mono-n-octyl phthalate (MOP) were found in only a few and Monocyclohexyl phthalate (MCHP) was not detected in any subject. Neither the circulation levels of BPA nor those of phthalate metabolites differ between the genders in this elderly population of residents in Uppsala, Sweden.

Estrogen Activity in Plastic Products: Yang et al. Respond

Estrogen Activity in Plastic Products: Yang et al. Respond

Rubber Modified Asphalt Mixture Properties and Mechanical Testing

To solve the high-temperature rutting problem of asphalt pavement, the old rubber of the tire rubber and plastic of general polyethylene waste composite modified asphalt mixture is proposed. The plastic and rubber compound particle was made by the rubber through efficient desulfurization additives, pre-swelling, twin-screw extrusion equipment. The particles mixed with the asphalt mixtures specimen preparation and the dynamic stability experiments, composite beam fatigue experiments, flexural tensile strength and modulus experiments and anti-reflective pavement cracks and other mechanical experiments are performed. The comparative data obtained by the rubber and plastic composited modified asphalt mixtures and SBS asphalt mixtures prove that the rubber and plastic composited modified asphalt mixtures have excellent rutting resistance and fatigue resistance.

Perfluoropolyether–tetrafluoroethylene (PFPE–TFE) block copolymers: An innovative family of fluorinated materials

A new technological platform, based on the chemistry of the peroxidic perfluoropolyethers, has been recently developed for the synthesis of innovative fluorinated materials. Perfluoropolyether–tetrafluorethylene (PFPE–TFE) copolymers are one of the most representative examples of the potential and the flexibility of this technology. By tuning the reaction parameters, the structure of these copolymers can be easily modulated to obtain products with the desired chemical–physical and rheological properties. Applications are endless, from thin film lubrication to gel based greases, to additives for plastics, rubber and other compounds. This technology will lead to entirely new classes of PFPE materials that will fill many of the gaps existing today in markets not currently served by PFPEs.

Did Hoffman Plastic Compounds, Inc. Produce Disposable Workers?

Did Hoffman Plastic Compounds, Inc. Produce Disposable Workers?

Dipentyl Phthalate Dosing during Sexual Differentiation Disrupts Fetal Testis Function and Postnatal Development of the Male Sprague-Dawley Rat with Greater Relative Potency than Other Phthalates

Phthalate esters (PEs) constitute a large class of plasticizer compounds that are widely used for many consumer product applications. Ten or more members of the PE class of compounds are known to induce male fetal endocrine toxicity and postnatal reproductive malformations by disrupting androgen production during the sexual differentiation period of development. An early study conducted in the rat pubertal model suggested that dipentyl phthalate (DPeP) may be a more potent testicular toxicant than some more extensively studied phthalates. Regulatory agencies require dose-response and potency data to facilitate risk assessment; however, very little data are currently available for DPeP. The goal of this study was to establish a more comprehensive data set for DPeP, focusing on dose-response and potency information for fetal and postnatal male reproductive endpoints. We dosed pregnant rats on gestational day (GD) 17 or GD 14-18 and subsequently evaluated fetal testicular testosterone (T) production on GD 17.5 and GD 18, respectively. We also dosed pregnant rats on GD 8-18 and evaluated early postnatal endpoints in male offspring. Comparison of these data to data previously obtained under similar conditions for di (2-ethylhexyl) phthalate indicates that DPeP is approximately eightfold more potent in reducing fetal T production and two- to threefold more potent in inducing development of early postnatal male reproductive malformations. Additionally, fetal testicular T production was more sensitive to inhibitory effects of DPeP exposure than was gene expression of target genes involved in male reproductive development, supporting the use of this endpoint as a critical effect in the risk assessment process.