The non-isothermal crystallization of the isotactic Polypropylene (iPP) was studied using differential scanning calorimetry and polarizing optical microscopy. Jeziorny’s model Ozawa’s theoretical approaches were applied to study kinetics iPP. approach proved be most relevant present material. Simultaneously, activation energy calculated with Kissinger’s method Vyazovkin’s iso-conversional appro...

Silica sol prepared by sol-gel method was introduced into poly(butyl acrylate) (PBA)/poly(butyl acrylate-styrenemethacryloxypropyl trimethoxysilane) (PSBM) core-shell emulsions to prepare a series of paper surface sizing agents. The rheological measurement indicated that PSBM emulsions exhibited shear-thinning behavior, and the phenomena became more pronounced with increasing silica sol concent...

The rising concerns in terms of environmental protection and the search for more versatile polymer-based materials have led to an increasing interest in the use of polymer composites filled with natural organic fillers (biodegradable and/or coming from renewable resources) as a replacement for traditional mineral inorganic fillers. At the same time, the recycling of polymers is still of fundame...

Microfibrillated cellulose (MFC) employed as reinforcement of polymeric matrices can increase elastic modulus, stiffness and strength a composite. In this work, the assessment mechanical, thermal properties tensile tests assisted by digital image correlation (DIC) was performed for curaua fiber MFC-reinforced polylactic acid (PLA) composites function MCF content. First, MFC incorporated into PL...

In this article, we investigate the principal structural features of the DNA double helix and their effects on its elastic mechanical properties. We develop, in the pursuit of this purpose, a helical continuum model consisting of a soft helical core and two stiff ribbons wrapping around it. The proposed model can reproduce the negative twist-stretch coupling of the helix successfully as well as...

l-tyrosine, b6 and folic acid are involved in biosynthesis of dopa and consequently dopamine. the aim of this study was to investigate the antiparkinsonian effect of these agents in perphenazine-induced catatonia in rats. murprogo method or scored muscular rigidity, which is induced by a phenothiazine, was used to evaluate the antiparkinsonian effect of these agents. a significant decrease in m...

Base-stacking is a key factor in the energetics that determines nucleic acid structure. We measure the tensile response of single-stranded DNA as a function of sequence and monovalent salt concentration to examine the effects of base-stacking on the mechanical and thermodynamic properties of single-stranded DNA. By comparing the elastic response of highly stacked poly(dA) and that of a polypyri...

The degradation of PVC at a processing temperature is mostly caused by its abnormal and unsta— ble molecular structures. It has been pointed out that its allyl chloride structures play a significant role as the abnormal and unstable structures. Inasmuch as the allyl chloride struc— tures are markedly more chemically active than the normal structure, the selective chemical treatments are applica...

The semi-IPN hydrogel membranes of polyvinyl pyrrolidone (PVP) and beta-chitosan were synthesized by crosslinking beta-chitosan with glutaraldehyde. Hydrogel membranes were characterized by spectroscopic, swelling, thermal and mechanical properties. The in vitro biocompatibility of hydrogel membranes was studied by haemorheological method. These hydrogels have water contents in the range of 60-...

Hot tearing: from organic alloys to superalloys. The appearance of solidification cracks or hot tears during casting is a serious defect. EPF-Lausanne has developed a criterion for the appearance of hot tears which is based upon a mass balance performed over the liquid and solid phases and which takes into accounts for the tensile deformation of the solid skeleton perpendicular to the growing d...