A indústria alimentícia utiliza variados materiais para embalagens, sendo o polietileno de baixa densidade linear (PELBD) um dos materiais de maior importância, por possuir características únicas e adequadas à produção de embalagens. A geração de espécies químicas em embalagens de alimentos vem sendo foco de estudos no mundo. Este controle de compostos é denominado como estudo de Substâncias Não Intencionalmente Adicionadas (NIAS) e tem sua importância justificada pela preocupação com a saúde humana devido à capacidade de contaminação do alimento embalado. Para este estudo foram escolhidas duas resinas PELBD amplamente aplicadas na produção de embalagens alimentícias, analisadas na forma de pellets. As amostras foram nomeadas como PELBD1 e PELBD2 e analisadas antes e após exposição natural e acelerada (estufa a 50°C) de um, dois e três meses. Ambas apresentaram grande aumento no número de NIAS detectadas por Cromatografia Gasosa com detecção de Massas (GC-MS) após envelhecimentos, quando comparadas à resina virgem, chegando a 1100% em PELBD1 e 100% em PELBD2, com surgimento de substâncias oxigenadas e tóxicas. O aditivo antioxidante ativo foi sendo consumido e analisado via Cromatografia Líquida de Alta Eficiência (HPLC) ao longo das exposições, confirmando os efeitos do envelhecimento. Através do Infravermelho por transformada de Fourier (FTIR) foi verificada degradação inicial em PELBD1 exposto por três meses à estufa. Porém, até mesmo em períodos menores de exposição natural, a formação de grupos cromóforos foi comprovada pela análise de cor, onde houve pequeno e gradual aumento do amarelecimento e diminuição da brancura principalmente em PELBD1. Por Cromatografia de Permeação à Gel (GPC), as amostras apresentaram pequena tendência para diminuição de M̅z. Já nas análises de Reometria Rotacional com variação de Frequência (DSR), Índice de Fluidez (IF) e Calorimetria Exploratória Diferencial (DSC), foram observadas mínimas tendências de degradação. Pode-se concluir a partir destes resultados que a maior degradação e produção de NIAS ocorreram em ambiente acelerado. Esta pesquisa trouxe grandes contribuições para futuros trabalhos que envolvam o estudo de NIAS e suas condições de formação. / The food industry uses various packaging materials being linear low density polyethylene (LLDPE) one of the most important materials, have unique features suitable for the production and packaging. The generation of chemical species in food packages has been the focus of research in the world. This control compounds is referred to as study Non-Intentionally Added Substances (NIAS) and has its importance justified by concern human health because of capacity contamination the food packaging. For this study it was chosen two LLDPE resins widely applied in the production of food packaging, analyzed in the form of pellets. The samples were named as PELBD1 and PELBD2 and analyzed before and after natural and accelerated exposure (oven at 50°C) of a two and three months. Both showed huge increase in the number of NIAS detected by Gas Chromatography with Mass detection (GC-MS) after ageing, when compared to virgin resin, reaching of 1100% in PELBD1 and 100% in PELBD2 with the appearance of oxygen substances and toxic substances. The active antioxidant additive was being consumed and analyzed via High-Performance Liquid Chromatography (HPLC), during the exposures, confirming the effects of ageing. For Fourier Transform Infrared (FTIR) was observed in initial degradation PELBD1 exposed for three months in an oven. However, even at under natural exposure periods, the formation of chromophoric groups were confirmed by analysis of color where there was a slight and gradual increase in yellowing and brightness decreased mainly PELBD1. For the Gel Permeation Chromatography (GPC), the samples showed a slight tendency to decrease M̅z. Already in the analysis of Rheometry Rotational Varying Frequency (DSR), Melt Flow Index (MFI) and Differential Scanning Calorimetry (DSC), were observed minimum trends of degradation. It can concluded from these results that the greatest degradation and NIAS production occurred in an accelerated environment. This research has brought great contributions to future work involving the study of NIAS and their conditions of training.

Adhesion, heterogeneous catalysis, electrochemistry, and many other important processes and properties are driven by interactions at surfaces and interfaces. Vibrational sum frequency generation spectroscopy (VSFG) is an increasingly popular analytical technique because it can provide information about the nature and physical orientation of functional groups at these surfaces and interfaces. Analysis of VSFG data can be complicated by the presence of SFG signal that is not associated with a resonant vibration. This nonresonant sum frequency generation (NR-SFG) signal can interfere with the resonant signal and influence the detected spectrum. Methods have been developed to remove NR-SFG signal; however, these methods tend to be complicated and expensive. In fact many SFG practitioners do not have the ability to remove NR-SFG signal components, and systems designed to remove NR-SFG signal contributions may not be able to do so for some materials. We have worked to help develop a better understanding of NR-SFG. As part of this work, a better understanding of the temporal and phase behavior of NR-SFG signal has been developed, based on the behavior of NR-SFG signal from Si(111) wafers. This work calls into question some assumptions underlying nonresonant suppression methods based on time-domain detection. A new method for nondestructively testing (NDT) materials has been developed that uses nonresonant second harmonic generation, the degenerate form of SFG. This new NDT technology has the potential to detect several forms of material damage, such as aluminum sensitization, and plastic deformation of materials, which are largely invisible to current NDT technologies. Methods for extracting functional group orientation from VSFG data that contains NR-SFG contributions are also demonstrated and used to investigate how the surface of high density polyethylene changes in response to mechanical deformation. This work shows that the inability to remove NR-SFG contributions from VSFG spectra does not mean that these instruments cannot be used to make important discoveries. It simply means that NR-SFG contributions must be properly understood and accounted for during experimental design, and kept in mind during the analysis of VSFG spectra.

Thesis (M.Sc. (Agriculture)) --University of Limpopo, 2006 / Two experiments were carried out to determine the effect of the level of Acacia nilotica leaf meal supplementation plus 23 g polyethylene glycol 4000 on diet intake, digestibility, and growth rate of indigenous Pedi goats fed ad libitum Buffalo grass, Buchloe dactyloides, hay. The first experiment lasted for 37 days, with the first 30 days being for adaptation and the last 7 days being for collection. Twenty yearling male Pedi goats weighing 22 ± 0.5 kg live weight were allocated to 4 treatments in a 2 x 2 Factorial arrangement in a Completely Randomised Design. Acacia nilotica leaf meal contained 120 g crude protein per kg DM, indicating its potential as a browse source for ruminants. It, also, contained high amounts of total phenolics (2.04 % DM) and low amounts of condensed tannins, both extracted (0.37 % DM) and unextracted (1.83 % DM). Increasing the level of Acacia nilotica leaf meal supplementation to 120 g increased (P<0.05) crude protein intake (38 g/kg DM) when compared to 80 g supplementation (34 g/kg DM). Supplementation with 23 g PEG 4000 increased (P<0.05) the crude protein intake where goats were supplemented with 120 g of A. nilotica leaf meal. However, PEG 4000 supplementation did not have an effect (P>0.05) on intake when goats were supplemented with 80 g of Acacia nilotica leaf meal. Supplementation with 120 g of Acacia nilotica leaf meal increased (P<0.05) diet digestibility of DM (0.57), OM (0.60) and CP (0.71) by the goats. Similarly, supplementation with 23 g PEG 4000 increased (P<0.05) DM (0.65), OM (0.66) and v CP digestibilities (0.76) where goats were supplemented with 120 g of A. nilotica leaf meal. Polyethylene glycol 4000 also increased (P<0.05) diet CP digestibility where goats were supplemented with 80 g of Acacia nilotica leaf meal. However, 23 g PEG 4000 did not have a significant (P>0.05) effect on diet digestibility of DM and OM where goats were supplemented with 80 g of Acacia nilotica leaf meal. In vivo NDF and ADF digestibility were not affected by the treatments. Level of Acacia nilotica leaf meal supplementation plus 23 g of PEG 4000 had a significant (P<0.05) effect on the daily live weight change of the goats. The effect was higher where goats were supplemented with 120 g of A. nilotica leaf meal when compared to 80 g supplementation. Blood urea concentrations were improved (P<0.05) by level of A. nilotica supplementation and PEG supplementation. It is concluded that PEG 4000 has the potential to improve the feeding value of Acacia nilotica leaf meal and can, therefore, be used in the feeding systems for ruminant animals. The second experiment determined the effect of A. nilotica leaf meal supplementation and PEG 4000 supplementation on in vitro diet digestibility. Level of Acacia nilotica leaf meal supplementation plus 23 g PEG supplementation improved (P<0.05) in vitro diet DM, OM and CP digestibilities where 120 g Acacia nilotica leaf meal was supplemented. Similarly, 23 g PEG 4000 supplementation also improved (P<0.05) in vitro diet CP digestibility where 80 g Acacia nilotica leaf meal was supplemented. However, level of A. nilotica supplementation plus PEG 4000 supplementation had no vi effect (P>0.05) on in vitro NDF and ADF digestibilities. In vivo diet DM, OM and CP digestibilities were positively and significantly (P<0.05) correlated with in vitro diet DM, OM and CP digestibilities. It is, therefore, concluded that in vitro diet DM, OM and CP digestibilities have good capacity to predict in vivo diet DM, OM and CP digestibilities. / National Research Foundation. Working Solutions International

Polyethylene oxide polymers are intrinsic to oil spill dispersants used in Macondo well blowout of 2010. We believe that effective thermo-physical modeling of these materials should assist the application of lab-scale results into ocean-scales. Fully defensible molecular scale theory of such materials will be challenging. This thesis is the first step towards that challenge. Molecular dynamics simulations are useful in generating structural and phase behavior data for these versatile polymers. Microstructures of PEO polymers, hydrophobic interactions, direct numerical test of controversial Pratt-Chandler theory, concentration dependence of Flory-Huggins interaction parameter and neutron scattering experiments will be discussed. / acase@tulane.edu

Le PRC (Polyéthylène réticulé chimiquement) est utilisé comme matériau de base pour la fabrication de l’enveloppe à isolation électrique des câbles HTA en raison de ces propriétés thermiques et diélectriques remarquables. Afin d’améliorer la fiabilité de ces câbles, des études de vieillissement sous différentes contraintes (thermique, humidité, tension) ont été réalisées sur les différentes couches du câble, et en particulier sur l’isolant en PRC.Dans un premier temps, nous avons identifié un certain nombre de marqueurs chimiques et physiques pouvant donner des informations sur le degré de vieillissement de l’isolant PRC des câbles HTA. Ces différents marqueurs sont caractéristiques d’une dégradation multi-échelle (moléculaire, microscopique et macroscopique) et peuvent être utilisés pour établir le diagnostic d’un câble électrique et ainsi évaluer son état de dégradation général. Parmi ces marqueurs, l’existence d’un phénomène de migration d’espèces polaires des semi-conducteurs vers l’isolant du câble aura particulièrement attiré notre attention. Des analyses supplémentaires ont donc été réalisées afin de mieux appréhender ce phénomène.Ensuite, nous avons déterminé l’impact de contraintes thermique et électrique simultanées sur les propriétés physico-chimiques et diélectriques d’un isolant en PRC. Les analyses physico-chimiques ont montré que l’ajout d’une forte tension ne semble affecter ni l’oxydation, ni la diffusion. Des vieillissements sous contraintes importantes ont néanmoins permis d’identifier un signal particulier en spectroscopie diélectrique. La détection de ce signal pourra être utilisée pour anticiper des claquages de câbles sur le réseau électrique. Nous avons également réussi à établir un lien entre certains marqueurs chimiques et la dégradation des propriétés diélectriques des isolants pour des mises sous contraintes particulièrement extrêmes. / Due to its outstanding thermal and dielectric properties, XLPE (Chemically Crosslinked Polyethylene) is commonly used as a base material for manufacturing the electrical insulating jacket of MV cables. With a view to improve the reliability of these cables, aging studies have been carried out under different stress conditions (temperature, humidity, tension) on the different constituting layers, and in particular on the XLPE insulating one.First of all, we have identified several chemical and physical markers that can provide information on the aging degree of the XLPE insulation from MV cables. These different markers are representative of a degradation at different scales (molecular, microscopic and macroscopic) and they can be used to establish a diagnosis on an electrical cable, and thus evaluate its general state of degradation. Among these markers, the existence of a polar species’ migration phenomenon from semiconductors to the insulating layer had particularly attracted our attention. Additional analyzes were thus conducted to gain more insight on this phenomenon.Then, we have determined the impact of simultaneous thermal and electrical stresses on physico-chemical and dielectric properties of the XLPE insulating material. The physico-chemical analyzes have demonstrated that the addition of an important tension did not affect the oxidation and diffusion phenomena previously identified. Aging under high stress allowed us to identify a special signal in dielectric spectroscopy. The identification of such a signal could be used to anticipate cable breakdowns on the power grid. In addition, we were successful in establishing a clear link between some chemical markers and the degradation of the insulator dielectric properties in the case of extreme ageing conditions.

O desafio da gestão dos resíduos gerados pela produção e consumo de produtos sempre acompanhou a humanidade, revelando-se um problema quando se trata do seu descarte e destinação. No entanto, nos últimos anos verifica-se um agravamento deste problema, dado o volume e diversidade de resíduos gerados. Em especial, os resíduos poliméricos merecem bastante destaque pelo seu grande volume nos aterros sanitários e pela poluição causada em diversos ecossistemas. A reciclagem deste material é apontada como uma alternativa e auxílio na solução do problema. O presente estudo teve como objetivo o desenvolvimento de um método de reciclagem do polietileno de baixa densidade que envolve operações de processamento mecânico e tratamento térmico e químico do material. Para isto, blendas de resíduos de polietileno de baixa densidade (PEBD) e polipropileno (PP) com até 30 % em massa de PP foram preparadas com a incorporação de catalisadores do tipo zeólita ZSM-5 e Ziegler-Natta e submetidas ao tratamento térmico em condições controladas de temperatura e atmosfera de nitrogênio. Os resultados obtidos mostram a ação do catalisador zeólita ZSM- 5 como modificador da estrutura polimérica já na etapa de processamento termomecânico do material. Os catalisadores proporcionam mudanças consideráveis nas propriedades das blendas PEBD/PP, de acordo com as condições em que os ensaios são realizados. O tratamento de resíduos poliméricos em presença de catalisadores apresenta potencial para a reciclagem de resíduos poliméricos podendo gerar materiais reciclados com propriedades melhoradas. / The challenge for the waste management generated by the production and consume of products has always followed the Humankind, showing as a problem for discard and destination. However, in the last years an aggravation of this problem has been verified due to the volume and diversity of the waste produced. Particularly, the polymeric waste has a great prominence due to the large amount in landfills and pollution caused in several ecosystems. The polymeric recycling is indicated as an alternative for the problem. The aims of this study had been the development of a method for the recycling of the low-density polyethylene (LDPE) that involves mechanical processing operations and thermal-chemical treatment of the material. For this reason, blends of LDPE waste and polypropylene (PP) containing until 30 wt% of PP has been prepared with incorporation of zeolite ZSM-5 and Ziegler-Natta catalyst and submitted to thermal treatment under controlled conditions of temperature and nitrogen flow. The results presents the action of zeolite catalyst as modifier of the polymeric structure during step of the thermomechanical processing of the material. The catalysts have caused considerable changes on the properties of LDPE/PP blends, according to the experimental conditions. The treatment of polymeric waste in presence of catalyst shows potential for the recycling of polymeric materials and can generate recycled materials with improved properties.

Polymer composites formed from layered fillers with high surface volume ratio show enhanced reinforcement. Graphite oxide is a high modulus material that can be separated into thin layers with high surface area. The aim of this study is to prepare polymer layered graphite oxide composites using functionalised polyolefin to enhance compatibility with various forms of layered graphite oxide in varying concentration. Functionalised polyolefins reinforced with layered graphite oxides and expanded graphite oxides were prepared using solution blending and melt blending methods. Three different mixing methods with varying shear intensity were employed to prepare polymer layered graphite oxide composites. The crystalline structure, thermal and mechanical properties of the prepared polymer layered graphite oxide composites was studied. Oxidised graphite prepared from the Staudenmaier method and its exfoliated form were dispersed in poly(ethylene-co-methyl acrylate-co-acrylic acid) (EMAA) via solution blending to prepare EMAA layered composites. The thermal stability was determined using thermogravimetric analysis. The EMAA layered composites showed higher thermal stability in comparison with pure EMAA. The mechanical properties of these EMAA layered composites were determined through dynamic mechanical analysis. Shear modulus, yield stress and storage modulus of EMAA in the presence of graphite oxide fillers decreased. A solution blending method was used to prepare poly(propylene-grafted-maleic anhydride) layered expanded graphite oxide composites (PPMA-EGO). Two types of PPMA-EGO were prepared using different mixing methods - low and high shear were employed. The effects of preparative mixing methods on the PPMA-EGO properties were investigated. The mechanical properties of PPMA-EGO obtained from dynamic mechanical analysis indicated that EGO had a reinforcing effect on the elastic behaviour of PPMA-EGO. This is due to strong interfacial adhesion between PPMA and EGO as a result of hydrogen bonding. The elastic behaviour of PPMA-EGO was affected by the surface area of graphite flakes. Low sheared PPMA-EGO elastic behaviour was found to be higher compared with that of high sheared PPMA-EGO. A melt blending method was used to prepare PPMA-EGO with varying EGO concentration. The interconnected network structure of EGO in the PPMA-EGO was not observed as shown by its scanning electron microscopy images. Thermogravimetric analysis of PPMA-EGO indicates increased decomposition temperature of the PPMA matrix. Dynamic mechanical analysis showed enhanced storage modulus of PPMA-EGO. The maximum elastic modulus of PPMA-EGO was observed at 3 %wt of EGO. The electrical conductivity of PPMA-EGO was measured only for EGO concentrations above 2 %wt. The EGO concentration was found to be the most critical factor in the enhancement of the electrical conductivity of PPMA-EGO. Wide angle X-ray diffraction analysis of all polymer layered graphite oxide composites revealed no change in interlayer spacing of graphite layers, indicating the absence of EMAA intercalation in the graphite layers. The crystallisation temperature and crystallinity of all polymer layered graphite oxide composites were determined using differential scanning calorimetry. The results indicated that graphite oxide and expanded graphite oxides acted as nucleating agents in inducing the crystallisation of functionalised polyolefin in the layered composites. However, the degree of crystallinity of functionalised polyolefin decreased in the layered composites.

<p>In Lembang, a farming community on western Java, family-sized, plug-flow, polyethylene biogas systems fed with cow dung, are being used as an integrated solution to issues related to energy, agriculture and waste management. Through simple, on-farm research and observation, a number of key problems have been addressed and improvements made to the design. Due to the large supply of cow dung in the area, and the potential to spread the benefits of the technology beyond the homes of dairy farmers, the feasibility of developing a communal, polyethylene biogas system for several households, has been investigated. Experiments on small model-digesters were combined with observations of full-scale biogas systems in use. Measurement equipment and techniques were constructed and developed, in order to measure biogas production and other relevant process parameters. Results indicate that a communal system can be an appropriate choice, but only under a certain set of circumstances.</p>

A suitable management of the pharmaceutical property is needed and helpful to design a desired nanoparticulate delivery system, which includes the carrier nature, particle size and size distribution, morphology, surfactant stabiliser according to the technique applied, drug-loading ratio and encapsulation efficiency, surface property, etc. All will influence the in vitro release, in vivo behaviour and tissue distribution of administered particulate drug loaded nanoparticles. The main purpose of the present work was to determine the effect of drug loading ratio when employing TPGS as surfactant stabiliser and/or matrix material to improve the nanoparticulate formulation. The model drug employed was paclitaxel. / Singapore-MIT Alliance (SMA)

Biocompatible sensors have been demonstrated using traditional microfabrication techniques modified for polymer substrates and utilize only materials suitable for implantation or bodily contact. Sensor arrays for the measurement of the load condition of polyethylene spacers in the total knee arthroplasty (TKA) prosthesis have been developed. Arrays of capacitive sensors are used to determine the three-dimensional strain within the polyethylene prosthesis component. Data from these sensors can be used to give researchers a better understanding of component motion, loading, and wear phenomena for a large range of activities. This dissertation demonstrates both analytically and experimentally the fabrication of these sensor arrays using biocompatible polymer substrates and dielectrics while preserving industry-standard microfabrication processing for micron-level resolution. An array of sensors for real-time measurement of pressure profiles is the long-term goal of this research. A custom design using capacitive-based sensors is an excellent selection for such measurement, giving high spatial resolution across the sensing surface and high load resolution for pressures applied normal to that surface while operating at low power.