Effect of organic solvents on the physical-chemistry behavior of high density polyethylene (HDPE) and polypropylene (PP)

Recently, the brazilian packing market of polymeric materials applied to storage of petroleum and its devired is growing every year, being basically constituted from two polymers: high density polyethylene (HDPE) and polypropylene (PP). However, during the storage process, the polymeric matrix can interact with the oil, thus compromising, its physical-chemical properties and durability. Therefore, it is necessary to study the migration mechanism existent between organic solvents and polymeric materials. In this work, the interaction of HDPE and PP with different organic solvents (toluene, n-heptane, n-decane and n-tetradecane) was studied as function of temperature (25, 50 and 80 ºC). Values of weight gain, coefficients of diffusion, sorption and permeability and mechanism of transport were calculated. The values of weight gain for PP were higher than PEAD in all temperatures studied. Among the solvents used, the toluene had the highest weight gain, reaching consequently, an equilibrium plateau in a lower time period. This result is good agreement with the diffusion and permeability coefficients, which the values increased in the following order: toluene > n-heptane > n-decane > n-tetradecane. An appositive behavior was observed for aliphatic solvents when the sorption coefficient values were analyzed. The mechanism of transport phenomenon was also studied, being classified as anomalous transport.

High density polyethylene; HDPE; polypropylene; PP; aging; weight gain; diffusion; sorption; permeability

Associação Brasileira de Polímeros Rua São Paulo, 994, Caixa postal 490, São Carlos-SP, Tel./Fax: +55 16 3374-3949 - São Carlos - SP - Brazil
E-mail: revista@abpol.org.br