Composites consisting of synthetic polymers and natural organic fillers have many applications. Plant-based materials, particularly wood, are used as fillers. Most frequently they are added to the polymer in the shape of wood flour or wood fibres. This type of polymer composite allows the possibility of modifying the components in accordance with the requirements of the application. Modifications to wood flour (WF) were carried out with a 10% solution of maleic anhydride (MA) in acetone in the presence of benzoyl peroxide and dicumene hydroperoxide. Lignin and cellulose were isolated from the WF and modified by the same method as the WF. They were characterized by Fourier Transform infrared spectroscopy and it was proved that there was a chemical reaction between the wood components and MA. This was confirmed by chemical analysis and by a determination of the hydroxyl groups in unmodified and modified WF. Composites of polypropylene and modified WF were obtained and studied by scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis and mechanical tests. They showed an improvement in adhesion between the polymer and the modified WF

ABSTRACT:In this study, conifer wood flour was evaluated as a filler to NBR or NBR/PVC compounds studying it influence on their cure characteristics and mechanical properties. It was shown that the filling by wood flour offers a possibility to obtain high modulus high elastic or less elastic or rigid wood like vulcanizates by varying of both the filling level and NBR/PVC mass ratio.It was established that in contrary to the mineral fillers usually causing significant delay of the vulcanization process, the wood flour shows a tendency to reduce the optimum cure time, 90 . Modulus M 100 and Shore hardness of the wood flour-filled vulcanizates of NBR or NBR/PVC compounds in which NBR is predominant, increase in a compliance with the increase of M max and DM when the filling level increases. The dependence is other when NBR and PVC are in equal amounts or PVC predominates. As a most probable explanation of the effect of the wood flour on the cure characteristics is accepted, the influence of the wood flour polar groups as well as of the presenting as wood flour humidity water molecules, the specific mechanical properties of the wood flourfilled NBR or NBR/PVC compounds could be connected (to some extend) with a specific interface interaction between the wood flour particles and the polymer matrix.

ABSTRACT:Composites of polyamide-6 (PA-6) and poly(butadiene acrylonitrile) (PBAN), varying in the quantity of the elastomer and the content of its nitrile groups, were examined during extrusion in a 45-mm extruder at 225 Ϯ 2°C and with a shear rate over 450 s Ϫ1 . It was established that these two incompatible polymers can be mixed and the blends display solubility in formic acid. This fact is explained by chemical transformation of the nitrile groups followed by chemical interaction between the polyamide and elastomer components. As a result, graft copolymers were most probably formed. The reaction proceeds easily if the PA-6 contains water. The extrusion leads to improved compatibility of the polymers and enhanced impact strength of the extrudates.

Investigations are reported on the polymerization kinetics of an unsaturated polyester resin, containing both styrene and acrylonitrile (AN), and on the possibility of making it water‐dilutable in order to use it for impregnating organic fibre materials. It is found that the unsaturated polyester resin, containing 31 wt.‐% styrene, can be diluted with almost no limits with acrylonitrile, but when the quantity of acrylonitrile is up to 14% the products are homogeneous and mono‐phase. After alkalizing with ammonium, the unsaturated polyester resin, containing acrylonitrile, becomes soluble in water in which it forms a fine emulsion. On polymerization of the resin, phase reversal takes place, water remaining dispersely included in the hardened resin. The copolymerization rate as a function of the water quantity is studied.

SUMMARY:The effect of some additives with low molecular weights upon the effective viscosity and slipping in poly(ethylene), poly(propy1ene) and poly(styrene) flow through circular capillaries is studied as a consequence of previous work done. The capillaries are made from different materials: Iron, alloy of copper and zinc, aluminium and poly(tetrafluor0-ethylene). It is noticed that in cases with capillaries made of poly(tetrafluoroethy1ene) the rate of the flow of pure polymers is increased, compared with the rate of the flow through metal capillaries. This effect increases with the increasing of stress and finally reaches 50 percent.One can observe a profound change in slipping and in viscosity behaviour when adding additives with low molecular weight to polymer melts. This effect is characteristic when silicon oil is added to poly(propy1ene) flowing through a poly(tetrafluoroethy1ene) capillary. The relative change of the flow when the conditions are all the same reaches 400%, whereas change through metal capillaries can be neglected.The results show that additives with low molecular weight change the viscosity of the polymer, and when the polymer flows through a poly(tetrafluoroethy1ene) capillary, those additives also change the slipping.