The diploma thesis deals with the study of Inter-Laminar Shear Strength (ILSS) of polymer composites, based on unsaturated polyester resin with unidirectionally oriented basalt or glass fibers. The basis of the experimental part is the preparation of composite samples with different types of surface treatment of a fibers (a reinforcement) as well as the surface treatment itself. The untreated, the commercially treated fibers and the plasmatreated fibers used as reinforcement in the polymer composites were analysed by a short beam shear test and their ILSS was determined. The effect of various deposition conditions during Plasma-Enhanced Chemical Vapour Deposition (PECVD) on the value of ILSS of the composite with originally unsized glass or basalt fibers was studied. The impact of aging on the interlaminar shear strength of the composites was investigated for commercially treated glass fibers. The Scanning Electron Microscopy (SEM) is also used in the thesis together with the Energy Dispersive Spectroscopy (EDS). Based on all the results a proposal was made to correct and improve the deposition conditions and thus improve the interphase to achieve the required shear properties of polymer composites.

Accurate three-dimensional stress-strain constitutive properties are essential to understanding complex deformation and failure mechanisms for materials with highly anisotropic mechanical properties. The large number of different methods and specimen types currently required to generate three-dimensional allowables for structural design slow down the material characterization. Also, some of the material constitutive properties are never measured due to prohibitive cost of the specimens needed. A method for measurement of three-dimensional constitutive properties using short-beam specimens subject to three-point bend load has been recently developed. This method is based on the Digital Image Correlation (DIC) full-field deformation measurement and closed-form stress approximation. The purpose of this work is to improve the accuracy of the constitutive properties through accurate stress solution. A method is developed based on a combination of full-field strain measurement and nonlinear finite element stress analysis in the material characterization. The nonlinear shear stress-strain relations are the major concern in this work. An iterative procedure is applied to update the nonlinear shear properties using iterative finite element simulations. The accuracy of the numerical procedure is verified by comparing the finite element strain results with full-field measurements. The procedure is further verified using the V-notched beam test results. Excellent agreement has been achieved in the verification. Simplicity of the short-beam specimens and accuracy of the constitutive property approximations make the present method attractive for measurement of three-dimensional stress-strain relations for anisotropic materials at various load rates.

The dissertation thesis deals with the preparation and characterisation of a-CSi:H and a CSiO:H thin films prepared using the process of plasma enhanced chemical vapour deposition (PECVD). Tetravinylsilane (TVS) and its mixtures with argon and oxygen were used to deposit films on both planar substrates and fibre bundles. Main characterisation techniques were employed to study the topography of films, namely atomic force microscopy (AFM). Their mechanical properties were studied through nanoindentation; the nanoscratch test was used to assess the film adhesion to the substrate. Other analysed properties were internal stress and friction coefficient. The particular attention was paid to the work of adhesion and its determination. This knowledge was further applied to the preparation of surface treatments of glass fibres and, subsequently, polymer composites. Those were tested using the push-out test and the short beam shear test. Based on the results, the effects of deposition conditions and the relationships between the studied properties and quantities were determined.