Effect of Cellulose Nanocrystals on the Coating of Chitosan Nanocomposite Film Using Plasma Mediated Deposition of Amorphous Hydrogenated Carbon a C H Layers

The substitution of petroleum-based polymers with naturally derived biopolymers may be a good alternative for the conservation of natural fossil resources and the alleviation of pollution and waste disposal problems. However, in order to be used in a wide range of applications, some biopolymers’ properties should be enhanced. In this study, biocompatible, non-toxic, and biodegradable chitosan (CS) film and CS reinforced with 10 wt% of cellulose nanocrystals (CN–CS) were coated with amorphous hydrogenated carbon layers (a–C:H) of different thickness. To investigate the effect of the nano-reinforcement on the a–C:H layer applied, mild radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) was used to coat the CS and its CN–CS bio-nanocomposite film. Both the surface characteristics and the chemical composition were analyzed. The surface morphology and wettability were examined by ex-situ atomic force microscopy (AFM) and contact angle measurements (CA), respectively. Hereby, the relationship between sp2/sp3 ratios on a macroscopic scale was also evaluated. For the investigation of the chemical composition, the surface sensitive synchrotron X-ray radiation techniques near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) as well as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) were used

The Growth Behavior of Amorphous Hydrogenated Carbon a C H Layers on Industrial Polycarbonates A Weak Interlayer and a Distinct Dehydrogenation Zone

Polycarbonate (PC) is a material that is used in many areas: automotive, aerospace engineering and data storage industries. Its hardness is of particular importance, but some applications are affected by its low wettability or scratch susceptibility. This can be changed either by blending with other polymers, or by surface modifications, such as the application of an amorphous hydrogenated carbon layer (a-C:H). In this study, individual a-C:H layers of different thicknesses (10–2000 nm) were deposited on PC by RF PECVD. Both the layer morphology with AFM and SEM and the bonding states of the carbon on the surface with synchrotron-assisted XPS and NEXAFS were studied. The aim was to investigate the coatability of PC and the stability of the a-C:H. Special attention was paid to the interlayer region from 0 to 100 nm, since this is responsible for the layer to base material bonding, and to the zone of dehydrogenation (from about 1000 nm), since this changes the surface composition considerably. For PC, the interlayer was relatively small with a thickness of only 20 nm. Additionally, a correlation was found between the evolving grain structure and the development of the C‒H peak according to NEXAFS C K-edge measurements

Photoaging phenomena of biodegradable polybutylene succinate and conventional low density polyethylene by artificial weathering A comparative surface study

Polybutylene succinate PBS is a promising eco friendly alternative to many conventional plastics. It is not intended for outdoor use when a longer shelf life is desired. Research about the weatherability of PBS is important to expand its applicability. In the present study, the degree of aging on injection molded sheets of biobased PBS and additive free LDPE was investigated. These were subjected to accelerated photo aging by 14 , 28 , and 56 days daylight exposure and 7 days UV irradiation. The comparison with LDPE confirmed that photo initiated degradation processes occurred. The aging phenomena were monitored by atomic force microscopy, contact angle goniometry, Fourier transform infrared spectroscopy, and synchrotron assisted X ray photoelectron spectroscopy and near edge X ray absorption fine structure. The results demonstrated effects in early stages of aging for PBS on surface morphology, roughness and wetting behavior. No significant chemical changes were detected on the surface of exposed PBS samples. For LDPE chemical changes in sp2 sp3 ratio, atomic oxidation state, and wetting behavior were observed for UV and daylight weathered LDPE. However, no effects were apparent on the LDPE surface morphology. The biobased PBS is thus chemically more stable, but more surface sensitive to accelerated photoaging than the LDPE used her

Plasma Supported Deposition of Amorphous Hydrogenated Carbon a C H on Polyamide 6 Determining Interlayer Completion and Dehydrogenation Effects during Layer Growth

Polyamide 6 (PA6) is a commonly used material in many different sectors of modern industry. Herein, PA6 samples were coated with amorphous carbon layers (a-C:H) with increasing thickness up to 2 µm using radio frequency plasma enhanced chemical vapor deposition for surface adjustment. The morphology of the carbon coatings was inspected by ex situ atomic force microscopy and scanning electron microscopy. Surface wettability was checked by contact angle measurements. The chemical composition was analyzed using the surface sensitive synchrotron X-ray-based techniques near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy, supported by diffuse reflectance infrared Fourier transform spectroscopy. Particular attention was paid to the coating interval from 0 to 100 nm, to specify the interlayer thickness between the PA6 polymer and a-C:H coating, and the region between 1000 and 2000 nm, where dehydrogenation of the a-C:H layer occurs. The interlayer is decisive for the linkage of the deposited carbon layer on the polymer: the more pronounced it is, the better the adhesion. The thickness of the interlayer could be narrowed down to 40 nm in all used methods, and the dehydrogenation process takes place at a layer thickness of 1500 nm