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Polyetheretherketone (PEEK) polymers are increasingly used in tribological applications where fretting damage occurs. Fretting wear results from the repeated sticking and slipping of mutually loaded contacts. In this study, a custom built multi-axis tribometer is used to replicate fretting of filled and unfilled PEEK in a pin-on-flat configuration in both dry and wet conditions. The performance of...
Polymer monoliths had wide application possibilities due to their unique porous structures. Non-solvent induced phase separation (NIPS) method was a convenient and simple method to fabricate polymer monolith. In this study, the modeling work of the thermodynamics and dynamics for the polymer/solvent/non-solvent ternary system was carried out. The Flory-Huggins theory was employed to the thermodynamics...
The drying behavior of blade casting aqueous chitosan solution was investigated by means of a custom designed real time characterization system that can track the thickness, weight, temperature and in-plane and out-of-plane birefringence. Beyond a critical solvent concentration, initially isotropic cast solution rapidly develops optical anisotropy as detected by out of plane birefringence measurement...
An in-depth examination of the self-healing properties of both dienophile and diene functionalized ladder-like structured polysilsesquioxane copolymers and terpolymers was investigated. Through functionalization of both diene and dienophile on the double-stranded siloxane backbone with ternary n-alkyl functional groups acting as chain mobility control, the effect of chain mobility and chemical structure...
Multi-phase compatibilizers are potentially attractive, not only for the preparation of ternary or multi-phase immiscible polymer blends with high performance, but also for recycling and reuse of waste plastics mixture. In this study, the maleic anhydride (MAH) and styrene (St) dual monomers grafted PP, PP-g-(MAH-co-St) is prepared as a multi-phase compatibilizer, which exhibits highly effective compatibility...
Design of novel multifunctional polymeric materials combining electrically conducting properties with patterning capability is a significant challenge in materials science. Herein, we report on the synthesis of multifunctional interpenetrating polymer networks (IPN) by the in-situ oxidative polymerization of thiophene-based monomers with Cu(ClO4)2 inside a novolac-based photoresist. The resulting...
This paper reports the first synthesis of sulfonated poly(arylene perfluorocyclobutane)s by direct polycondensation of a new sulfonate ester-containing bis(trifluorovinylether) precursor and subsequent hydrolysis of the resulting polymers. The multi-step synthesis of a bis(trifluorovinylether) monomer bearing sulfonic acid groups protected as sulfonate esters (SE-TFVE) is described. Based on this...
The effects of diffusion of crystallizable polymer to a developing spherulite embryo are treated. Using the classical nucleation theory result for the size of a critical-size embryo and an existing model for the growth of a small pure component sphere in a bicomponent matrix, the time τd for a critical-size embryo to develop under diffusion control is given. The nucleation rate is lowered inversely...
Alginate, a polysaccharide that gels in the presence of divalent ions is an obvious component of an injectable gel for regenerative medicine. Covalent bonding peptides to alginates is routinely used tailor alginate's biofunctionality. Here, we present a systematic investigation of the effect of three arginine-glycine-aspartic acid (RGD) -containing peptides, G6KRGDY, A6KRGDY and V6KRGDY, on the mechanical...
Calorimetric studies on poly(ethylene glycol) Mn = 400 g mol−1, encapsulated in polystyrene fibers show non-trivial crystallization behavior. Analysis, assuming constant Avrami exponent n, is unsuitable. Approach allowing for changes in the exponent n, requires assumption of the crystallization rate function, derived from the nucleation theory. Changes in Avrami exponent n, follow the changes in geometry...
Surface-active amphiphilic diblock copolymers, Si-EFS14 and Si-EFS71, consisting of a poly(dimethyl siloxane) block (degree of polymerisation 11) and a poly(4-(triethyleneglycol monomethyl ether)-2,3,5,6-tetrafluorostyrene) block (average degree of polymerisation 14 and 71) were synthesised by ATRP. Films were prepared by incorporating each copolymer (4 wt%) into a PDMS matrix, which was then condensation...
Polymerizations of l-lactide (LA) were initiated with hydroxyalkylated strong organic bases functioning simultaneously as catalysts (INICATs). Organocatalysts used until now in Ring-Opening Polymerization, particularly of l-lactide, had to be combined with separately added initiators (most often alcohols) in order to provide control of polymerization. At the conditions used in the present work, polymerizations...
Thermoplastic polycarbonate urethanes (PCUs), have promise in many biomedical applications due to their low stiffness, favorable biocompatibility, and high strength. The long-term performance of PCU implants in load-bearing applications remains to be seen, and will depend in part on the material fatigue properties. Optimizing implants for success in fatigue-prone applications depends on a strong understanding...
The velocity transition in crack-growth dynamics and the accompanying changes in crack tip shapes are investigated for the elastomers composed of styrene-butadiene rubber and silica filler (SBR/SI). The concentrations of filler and cross-link (ϕf and cx, respectively), and temperature (T) are extensively varied in order to change the degree of nonlinearity in elasticity of the elastomers. The shapes...
A photolatent base ((1,5-diazabicyclo [4.3.0]non-5-ene) DBN) is used for the first time as photocatalyst for the curing of a formulation, which undergoes crosslinking by Michael addition reaction between acetoacetate and acrylate groups together with the reduction of graphene oxide.The reduction degree of graphene oxide during in situ irradiation is monitored by XPS analysis. The effect of the graphene...
In this study, the potential of amphiphilic diblock copolymers on the example of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and poly(4-methylstyrene)-b-poly(4-vinylpyridine) (P4mS-b-P4VP) for producing open-celled foams was evaluated. The porous foam structure was realised by employing carbon dioxide and water as environmental-friendly blowing agents. Rheological measurements in shear and elongation...
The presence of an ionic liquid in the plasticized polylactide (PLA) contributes to enhancement of dielectric permittivity due to its electrical conductivity. Phase separation, induced by thermal annealing and mechanical stretching, respectively, can further enhance dielectric permittivity. It offers opportunities to monitor phase separation in the ionic liquid plasticized PLA by dielectric spectroscopy...
The convenient synthesis of core-shell nanoparticles containing degradable components is very desirable given the potential applications of such nanoparticles in biomaterials. A facile approach for producing monodisperse starch-polystyrene nanocomposites with well-defined core-shell structures in the absence of a surfactant was developed. The initially-formed Pickering emulsions underwent conversion...
A series of hybrid polyimide-SiO2–TiO2 nanocomposites were fabricated from functionalized multi-block polyimides, tetraethyl orthosilicate (TEOS), and titanium isopropoxide (TIP). Polyimides were solution imidized utilizing 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA), and stoichiometric amounts of 4,4′-hexafluoroisopropylidene diamine (6FpDA) and 3,5-diaminobenzoic acid (DABA). Organic...
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