Mehmet Gürsoy

Chemical and plasma surface modification of lignocellulose coconut waste for the preparation of advanced biobased composite materials

In this study, surface-modified grinded coconut waste (CW) particles were used as bio-fillers to prepare polymeric composite materials with enhanced properties. Epoxy resin modified with acrylated and epoxidized soybean oil (AESO) was used as the polymer matrix. Two different strategies, namely chemical treatment and plasma enhanced chemical vapor deposition (PECVD) were utilized to modify the surface of CW particles for using them as compatible bio-fillers in composite preparation. Chemical modification involved the treatment of CW particles in a highly alkali NaOH solution, while PECVD modification involved coating of a thin film of hydrophobic poly(hexafluorobutyl acrylate) (PHFBA) around individual CW particle surfaces. Untreated and surface-modified CW particles were used in 10-50wt% for preparation of epoxy composites. FTIR analysis was performed to study the effect of modification on the structures of particles and as-prepared composites. The composite morphologies were investigated by XRD and SE. TGA test was conducted to study the thermal behavior of the composites. Also, the effects of CW particle surface modification on the mechanical and water sorption properties of epoxy resin composites were investigated in detail. It was observed that PECVD-treated CW particles had much more positive effects on the thermal, mechanical, wettability and flammability properties of composites.

Initiated plasma enhanced chemical vapor deposition (i-PECVD) of poly(alkyl acrylates)

Initiated plasma enhanced chemical vapor deposition (i-PECVD) is a novel technique that can produce well defined defect free polymeric films on many different substrates with low energy inputs. Although thin polymeric films could be formed using the solution based methods, the solvents used in such methods are not compatible for most of the fragile substrates and it causes major environmental problems. Fast deposition rates, high degree of functional group retention and conformal deposition are desired for most of the applications. In iPECVD, the chemical species called the initiator can easily be dissociated into reactive chemical species at low plasma powers due to their weak bonds. The basic reason behind the use of initiator in PECVD is to keep the plasma power low enough just to break the weak initiator bonds, so that the undesired monomer fragmentation ad chemical functionality lost would be avoided.