Filmes finos de carbono amorfo hidrogenado (a-C:H) têm sido depositados na superfície de materiais para melhorar propriedades mecânicas, ópticas e químicas. Nesse estudo, foi empregado o sistema de deposição química assistida por plasma (PECVD) para sintetizar filmes de a-C:H com fases DLC (tipo diamante) e PLC (tipo polimérico). As pressões parciais de acetileno em argônio foram variadas e as estruturas dos produtos analisadas pela técnica de espectroscopia de reflexão-absorção no infravermelho (IRRAS) e Raman. Além disso, a morfologia e as espessuras dos filmes foram determinadas por microscopia de força atômica (AFM) e perfilometria, respectivamente.Hydrogenated amorphous carbon (a-C:H) thin films were synthesized on the surface of materials to improve mechanical, optical and chemical properties. In the present study, plasma enhanced chemical vapor deposition (PECVD) was performed to produce a-C:H films with PLC (polymer like carbon) and DLC (diamond like carbon) phases. The influences of the acetylene partial pressure and chamber pressure on the chemical structures of the products were evaluated by infrared reflection absorption spectroscopy (IRRAS) and Raman spectroscopy. Moreover, the morphology and thickness of the films were investigated by atomic force microscopy (AFM) and profilometry, respectively.Keywords: amorphous hydrogenated carbon, PECVD, parameters, diamond like carbon, polymer like carbon IntroductionA considerable amount of research has been conducted on hydrogenated amorphous carbon (a-C:H) thin films 1,2 due to their beneficial effects on the mechanical, optical and chemical properties of materials, particularly for food packaging purposes because of the enhancement of gas barrier properties. [1][2][3][4][5] In addition, the a-C:H have been studied as a functional barrier to avoid or reduce the migration of possible residual contaminants from recycled polymers. 6 a-C:H films possess sp 3 -, sp 2 -and sp 1 -hybridized carbons, 7 whose proportion significantly affects their physical and chemical properties. Films with a high percentage of sp 3 carbon have properties similar to those of diamonds, such as superior hardness, chemical inertness and high electrical resistance. Alternatively, films with a significant amount of sp 2 -hybridized carbon are soft like polymers and called PLC (polymer-like carbon). 7,8,9 The a-C:H films can be synthesized by methods such as ion beam deposition, magnetron sputtering, pulsed laser deposition and plasma enhanced chemical vapor deposition (PECVD). 10-13 PECVD films are usually prepared with high frequency (13.56 MHz) low-temperature plasma from a hydrocarbon precursor gas, typically methane, acetylene, ethylene or benzene. The ions and radicals generated by dissociation/ionization of those gases impinge on the substrates leading to film growth. [13][14][15][16] The physical and chemical properties of a-C:H films deposited by PECVD are dependent on the deposition parameters, including the pressure and gas composition in the plasma chamber. The energy of the ...
Os resíduos sólidos urbanos (RSUs) são atualmente um dos maiores problemas ambientais, por serem gerados em grande quantidade e ocuparem extensos espaços por um longo período, resultando na diminuição do tempo de vida útil dos aterros sanitários. Os polímeros constituem um grande percentual da composição do RSUs, sendo que as embalagens plásticas contribuem com maior volume e massa. Apesar da reciclagem de polímeros estarem se consolidando no Brasil, graças ao seu mercado ascendente e promissor, existem ainda restrições quanto a sua utilização em contato com alimentos devido aos eventuais processos de migração de contaminantes que podem ocorrer da resina reciclada para o alimento. Por outro lado, dados recentes do setor indicam que a maior parte do consumo de resina virgem é destinada, justamente, para o mercado de embalagens alimentícias. Assim, o desenvolvimento e o gerenciamento de tecnologias que possibilitem o retorno destes materiais a sua aplicação original é de grande importância para sociedade contemporânea. Em um panorama geral, este trabalho aborda as exigências e limitações do uso de polímeros reciclados para contato com alimentos.
Despite having many potential applications, polypropylene (PP) has limitations that may make its application difficult when there is a requirement for high transparency and low‐gas permeability. In this context, studies have been reported about the usage of amorphous hydrogenated carbon thin films to act as a functional barrier in polymer packaging. Therefore, this current work evaluated the modification on the surface‐clarified polypropylene (cPP) by oxygen plasma to improve the adhesion of amorphous hydrogenated carbon films (a‐C:H) deposited by plasma‐enhanced chemical vapor deposition. However, some applications of these films are limited by the presence of microdefects and low adhesion when applied onto polymeric substrates. So, the surface of cPP was treated with oxygen plasma, and the adhesion between the a‐C:H films and cPP was evaluated. Contact angle goniometry, infrared spectroscopy, and atomic force microscopy were used to analyze chemical and morphological changes, respectively. Tape test and scanning electron microscopy were used to evaluate the adhesion of a‐C:H films deposited on a cPP surface. The results showed that the pretreatment increased the adhesion between the cPP and amorphous hydrogenated carbon, which is crucial for the application of these films in packaging with high‐barrier properties. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
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