A. Ramesh

Les plastiques utilis s par les industries d'emballage alimentaire sont g n ralement fabriqu s partir de polyol fines qui sont des mat riaux enti rement issus de la p trochimie, comme par exemple: le polystyr ne (PS), le polypropyl ne (PP), le polyt r phtalate d' thyl ne (PET) et le poly thyl ne (PE). Les liquides chauds peuvent d former le plastique; c'est pourquoi le PP est utilis car il r siste la temp rature de d formation. Le PS trouve son application dans les emballages de protection, les bouteilles, les r cipients alimentaires et les emballages de services alimentaires. Le PET est mieux connu pour sa transparence et sa r sistance; il pr sente un excellent blocage pour les r actions avec l'oxyg ne, l'eau et le dioxyde de carbone. Sa r sistance aux chocs et la traction est plus lev e, ce qui en fait un mat riau id al pour l'emballage de boissons, d'eau, de jus et de boissons pour sportifs. La plupart des polym res utilis s dans l'emballage sont d'origine p trochimique, son utilisation dans des articles jetables pose de s rieux probl mes cologiques. Les nanocomposites biod gradables qui ont des propri t s thermiques, m caniques et de barri re sup rieures celles des mat riaux biologiques actuels peuvent tre synth tis s partir de bio-polym res et de nano-renforcements. Les mati res premi res de ces nouveaux composites nanostructur s seront des bio-polym res naturels (acide polylactique et esters de cellulose) avec de l'argile et des nano-moustaches.

Tworzywa sztuczne stosowane w przemyśle opakowań do żywności są zazwyczaj wytwarzane z poliolefin, kt re są calkowicie oparte na materialach petrochemicznych, takich jak np: Polistyren (PS), Polipropylen (PP), Poli(tereftalan etylenu) (PET) i Polietylen (PE). Gorące ciecze mogą znieksztalcac tworzywa sztuczne, dlatego też stosuje się PP, kt ry jest odporny na temperaturę odksztalcenia. PS znajduje zastosowanie w opakowaniach ochronnych, butelkach z żywnością i opakowaniach gastronomicznych. PET jest lepiej znany ze swojej przezroczystości i wytrzymalości; wykazuje doskonalą blokadę dla reakcji z tlenem, wodą i dwutlenkiem węgla. Posiadając wyższą udarnośc i wytrzymalośc na rozciąganie, doskonale nadaje się do stosowania w opakowaniach napoj w, wody, sok w i napoj w sportowych. Większośc polimer w stosowanych w opakowaniach ma pochodzenie petrochemiczne, jego zastosowanie w wyrobach jednorazowego użytku powoduje poważne problemy ekologiczne. Biodegradowalne nanokompozyty, kt re mają lepsze wlaściwości termiczne, barierowe i mechaniczne w por wnaniu do dzisiejszych biokompozyt w, mogą byc syntezowane z biopolimer w i nanokompozyt w wzmacniających. Surowcem dla tych nowych nanostrukturalnych kompozyt w będą naturalne bio-polimery (estry kwasu polimlekowego i celulozy) z gliną i nanowl knami.

Os pl sticos utilizados pelas ind strias de embalagem alimentar s o geralmente fabricados a partir de poliolefinas que s o materiais completamente petroqu micos, tais como: Poliestireno (PS), Polipropileno (PP), Politereftalato de Etileno (PET) e Polietileno (PE). Os l quidos quentes podem distorcer o pl stico; por conseguinte, o PP utilizado porque resiste temperatura de distor o. O PS encontra aplica o em embalagens de protec o, garrafas de alimentos e embalagens de servi os alimentares. O PET mais conhecido pela sua transpar ncia e tenacidade; mostra um excelente bloqueio para reac es com oxig nio, gua e di xido de carbono. Tendo uma maior resist ncia ao impacto e resist ncia trac o, ideal para utiliza o na embalagem de bebidas, gua, sumos e bebidas desportivas. A maioria dos pol meros utilizados na embalagem tem uma origem petroqu mica, a sua utiliza o em artigos descart veis causa s rios problemas ecol gicos. Os nanocomp sitos biodegrad veis que t m propriedades t rmicas, de barreira e mec nicas superiores s dos materiais biol gicos actuais podem ser s ntese a partir de refor os de bio-pol mero e nano tamanho. As mat rias-primas para estes novos comp sitos nano-estruturados ser o bio-pol meros naturais ( cido poli-l ctico e steres de celulose) com barro e nano bigodes.

Die von der Lebensmittelverpackungsindustrie verwendeten Kunststoffe werden in der Regel aus Polyolefinen hergestellt, bei denen es sich um vollst ndig petrochemisch basierte Materialien wie z. B: Polystyrol (PS), Poly-Polypropylen (PP), Poly-Ethylenterephthalat (PET) und Poly-Ethylen (PE). Hei e Fl ssigkeiten k nnen Kunststoff verformen; daher wird PP verwendet, da es der Verformungstemperatur widersteht. PS findet Anwendung in Schutzverpackungen, Flaschen, Lebensmittelbeh ltern und Food-Service-Verpackungen. PET ist besser bekannt f r seine Transparenz und Z higkeit; es zeigt eine ausgezeichnete Blockade f r Reaktionen mit Sauerstoff, Wasser und Kohlendioxid. Da es eine h here Schlagz higkeit und Zugfestigkeit aufweist, eignet es sich ideal f r die Verpackung von Getr nken, Wasser, S ften und Sportgetr nken. Biologisch abbaubare Nanokomposite, die im Vergleich zu den heutigen Biomaterialien berlegene thermische, Barriere- und mechanische Eigenschaften haben, k nnen aus Biopolymeren und Verst rkungen in Nanogr e synthetisiert werden. Rohstoffe f r diese neuen nanostrukturierten Komposite werden nat rliche Bio-Polymere (Polymilchs ure- und Celluloseester) mit Ton und Nanowhiskern sein.

Le materie plastiche utilizzate dalle industrie di imballaggio alimentare sono di solito fabbricate con poliolefine che sono materiali completamente a base petrolchimica, come ad esempio: Polistirolo (PS), polipropilene (PP), polipropilene (PP), polietereftalato di etilene (PET) e polietilene (PE). I liquidi caldi possono deformare la plastica; pertanto il PP viene utilizzato perch resiste alla temperatura di distorsione. Il PS trova applicazione negli imballaggi protettivi, nelle bottiglie dei contenitori per alimenti e negli imballaggi per la ristorazione. Il PET meglio conosciuto per la sua trasparenza e durezza; mostra un eccellente blocco per le reazioni con ossigeno, acqua e anidride carbonica. Avendo una maggiore resistenza all'urto e alla trazione, ideale per l'utilizzo nell'imballaggio di bevande, acqua, succhi di frutta e bevande sportive. La maggior parte dei polimeri impiegati nell'imballaggio ha un'origine petrolchimica, il suo utilizzo in articoli monouso causa seri problemi ecologici.i nano-compositi biodegradabili che hanno propriet termiche, barriera e meccaniche superiori rispetto ai bio-materiali odierni possono essere sintetizzati da bio-polimeri e rinforzi di dimensioni nano. Le materie prime per questi nuovi compositi nanostrutturati saranno biopolimeri naturali (acido polilattico ed esteri di cellulosa) con argilla e nano baffi.

Hardfacing is the process of depositing a layer or layers of metal of specific properties on certain areas of metal parts that are exposed to wear by one of the various welding techniques. Hardfacing offers more than other wear prevention treatments. It is part of a well-established practice and in the majority of cases, existing equipment can be used. Hardfacing provides protection in depth by depositing a layer or layers of metal. Hence it can be applied in a required thickness to give required protection. A wide variety of deposit types are available which are designed to withstand different forms of wear and service conditions. Hardfacing is applied only to specific areas of metal parts that are exposed to wear. Hence it can be applied selectively and in different thicknesses to suit the exact requirements of a workpiece. This is the most economical way of fighting wear. Hardfacing is a particular form of surfacing that excludes the application of materials primarily for corrosion prevention or resistance to high temperature scaling or the application of low hardness, friction over-lays to prevent galling.

The ever increasing demand for new materials that have a high degree of structural stability combined with a high degree of strength has focused attention on the possibility of manufacturing composites by unorthodox routes. Composites have extended the horizon of engineering materials beyond the realm of natural combinations to man-made combinations. Polymers are particularly attractive as matrix materials because of their relatively easy processability, low density, and excellent mechanical and dielectric properties. Polymer matrix reinforced composites are most commonly used in structural applications such as aircrafts, boats, automobiles etc. The main objective of this research work is to develop a new polymer based composite material. In the present study, the researcher has identified and selected a two-component polyurethane vacuum casting system used for rapid prototyping - Ureol 5236 TM. Part in minutes-vacuum grade polyurethanes procured from Ciba Specialty Chemicals Ltd, Bombay. This resin is used to produce functional prototype parts suitable for use in all major industrial areas including automotive, aerospace, consumer goods and leisure applications.

The plastics used by food packing industries are usually fabricated from polyolefins which are completely petrochemical-based materials such as: Polystyrene (PS), Poly Polypropylene (PP), Poly Ethylene Terephthalate (PET) and Poly Ethylene (PE). Hot Liquids can distort plastic; hence PP is used as it resists distortion temperature. PS finds application in protective packing, bottles food containers and food service packaging. PET is better known for its transparency and toughness; it shows an excellent blockade for reactions with oxygen, water and carbon-di-oxide. Having a higher impact strength and tensile strength, it is an ideal fit for usage in packing beverages, water, juices and sports drinks. Most of the polymers employed in packing have a petro-chemical origin, its use in disposable items cause serious ecological issues. Biodegradable nano-composites which have superior thermal, barrier and mechanical properties compared to today's bio materials can be synthesis from bio-polymer and Nano sized reinforcements. Raw materials for these new nano-structured composites will be natural bio-polymers (poly-lactic acid and cellulose esters) with Clay and nano whiskers

This Book describes the investigations carried out on base Al6061 alloy, Al6061-WC MMCs and Al6061-WC-Gr MMHCs. The composites were developed by liquid metallurgy technique. In the development of Al6061-WC MMCs and Al6061-WC-Gr MMHCs the tungsten carbide of 1-4 wt% used as a primary reinforcement, and a constant 4 wt% graphite (Gr) used as a secondary reinforcements in Al6061-WC-Gr MMHCs. The manufactured composites were treated with T6 heat treatment for different ageing times of 1, 3 and 5 h. As-cast and heat treated composites were characterized for their physical, mechanical and tribological properties. The mechanical and wear properties were investigated according to the ASTM standard testing procedures. The composites properties were investigated in as- cast and heat treated conditions. Scanning Electron Micrographs (SEM) of tensile fracture surfaces of the MMCs and MMHCs revealed that there was an excellent bond between matrix and reinforcements. The strong bond allows the effective transfer of applied load between the matrix and reinforcements. The fractured surfaces confirm the brittle failure mechanism of the composites.