Modification of Turkish Pumice Mineral and Its Use as Additive for Poly (Lactic Acid) Based Bio-Composite Materials

Abstract

In this study, pumice (P) mineral was treated with silane in order to increase the compatibility for poly(lactic acid) (PLA) which is a fully biodegradable polymer widely used in packaging and outdoor applications. Neat and treated P powders were compounded with PLA at the concentrations of 5, 10, 15 and 20 wt% by melt mixing process. Surface characteristics of P samples were examined using infrared spectroscopy. Mechanical, water uptake, melt-flow and morphological properties of prepared composites were investigated by tensile and impact tests, water absorption test, melt flow rate test (MFR) and scanning electron microscopy (SEM) technique, respectively. Mechanical test results revealed that the highest increase in tensile strength and modulus values was obtained for 15 wt% of silanized P containing composite which are found as 4.5% and 40% increase, respectively. Addition of silane-treated P into PLA resulted in an increase in impact strength of about 33% compared to samples containing that were not treated with silane with the same proportion of P. Impact strengths of composites increased with increasing P concentration. Silanized P filled composite gave slightly higher MFR values with respect to pristine P. Water absorption values of composites were found as about twofold higher than that of unfilled PLA. Composites containing silanized P exhibited lower water uptake values compared to untreated P samples because of the hydrophobic character of silicon containing surfaces. SEM micro-images of composites displayed that more homogeneous dispersion in PLA matrix was taken place for silane treated P particles than that of neat P stem from the increase of adhesion between P and PLA surfaces after silanization process.

Partial replacement of silica by naturally occurring pumice powder for enhancing mechanical and thermal properties of nitrile rubber cured by electron beam irradiation

“…The spectra of treated pumice displayed higher intensity for these peaks due to forming silanol bonds at powder surface. These findings confirm that neat pumice surfaces were covered by silane coupling agent (Dike, 2020).…”

“…The spectra of treated pumice displayed higher intensity for these peaks due to forming silanol bonds at powder surface. These findings confirm that neat pumice surfaces were covered by silane coupling agent (Dike, 2020). Figure 3 represents FTIR spectra for NBR composites loaded by 30 phr silica and, also that loaded by 5 phr treated pumice/25 phr silica, all irradiated at 75 kGy.…”