Fotodegradação do Polipropileno. Um Processo Essencialmente Heterogêneo
Rabello, Marcelo S.; White, James R.
http://dx.doi.org/10.1590/S0104-14281997000200007
Polímeros: Ciência e Tecnologia, vol.7, n2, p.47-57, 1997
Resumo
Este trabalho analisa alguns aspectos da fotodegradação heterogênea do polipropileno (PP) e compósitos de PP com talco. Amostras moldadas por compressão e por injeção foram expostas à radiação ultravioleta em laboratório por períodos de até 48 semanas. Procedimentos sistemáticos de exposição e coleta de material para análise foram adotados visando-se minimizar as variabilidades inerentes deste estudo. As amostras foram caracterizadas por cromatografia de permeação em gel, espectroscopia de infravermelho, calorimetria diferencial de varredura, difração de raios-X, comportamento mecânico e microscopia ótica e eletrônica. As heterogeneidades na fotodegradação do PP podem estar relacionadas com três principais aspectos: (i) natureza semi-cristalina do polímero; (ii) perfil de degradação; (iii) variações estruturais em diferentes posições nos corpos de prova As consequências da fotodegradação heterogênea foram discutidas, enfatizando-se os efeitos nas propriedades fisicas.
Palavras-chave
Fotodegradação, polipropileno, envelhecimento, degradação heterogênea
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