The degree of plasticization of the alloscutal cuticle of a 'hard' (ixodid) tick, Amblyomma hebraeum, and a 'soft' (argasid) tick, Ornithodoros moubata, was assessed throughout the blood-feeding period. Cuticle viscosity was calculated from rate of creep of cuticle under constant load using a Maxwell model. Feeding-related plasticization (i.e. increased rate of extension under a constant load) ...

A simple device was used to quantify changes in the mechanical properties of the cuticle of Rhodnius prolixus and Triatoma infestans that take place when these insects feed, i.e., plasticization. Different stimuli were presented for 1min to test for their ability to trigger plasticization. These were: a blood meal, a Ringer solution meal, contact with a warm surface and thermal stimulation with...

1. The mechanism of plasticization of the abdominal cuticle in Rhodnius larvae has been investigated, using the properties of loops of cuticle under varying test conditions as a model for the behaviour of the cuticle in vivo. 2. It is supposed that plasticization is effected by a change in the intracuticular environment. A number of model mechanisms for plasticization may be proposed, which sup...

This study analyzed the correlation between the degree of conversion (DC) and the plasticization (P) of experimental dimethacrylate-based polymeric matrices. Six polymeric matrices produced with Bis-GMA (G), UDMA (U) and TEGDMA (T) dimethacrylate monomers were studied: G, U, GT55, GT73, GU55, GU73 - (55 = 50/50wt% and 73 = 70/30wt%). Photoactivation was induced by camphoroquinone/ethyl N, N-dim...

We have applied in situ FTIR, ATR-IR and photoacoustic spectroscopy to identify for the first time specific molecular interactions between CO2 and polymers that may be responsible for the plasticization of glassy polymers. The changes in IR spectra of CO2 incorporated into various polymers indicate a specific interaction between CO2 and polymer functional groups. Increased polymer segmental mob...

Injections of 5-hydroxytryptamine (5-HT, serotonin) are found to cause plasticization of the abdominal cuticle of Rhodnius larvae. This plasticization is a direct action of 5-HT on some element in the body wall; the central nervous system is not required. It is probable that 5-HT acts directly at a receptor on the epidermal cells. The relationship between structure and plasticizing activity for...

For the investigation of the plasticizing effect of carbon dioxide on polymers used for gas separation membranes new experimental methods have been developed that measure the sorption kinetics as well as the dilation kinetics. Comparing dilation and sorption kinetics at low and elevated pressures gives information about different types of swelling behaviour depending on the pressure level. Volu...

The influence of water vapour conditions on mass transport and barrier properties of chitosan based films and coatings were studied in relation to surface and structural properties. Water contact angles, material swelling, polymer degradation temperature, barrier properties (PO2, PCO2, WVP) and aroma diffusion coefficients were determined. The solvent nature and the presence of carvacrol influe...

The incorporation of self-assembled nanoparticles, a.k.a. hydroxylated nanoballs, into poly(2-hydroxyethyl methacrylate)(PHEMA) gives rise to a cross-linked network/hydrogel with enhanced interfacial interaction, whereas its inclusion in poly(methyl methacrylate)(PMMA) results in plasticization.