We illustrate our new team Artisti Veneti a new entry in the Middle-size league from The University of Padua (Italy). The team is composed of heterogeneous robots that use only vision as perception system. The vision systems have been designed separately for each robot. Our players are coordinated in the frame of ADE (Artisti Veneti’s Development Environment), a multi-thread distributed real-time Environment working under Linux OS. Cooperative abilities, like exchanging a ball, can be achieved through the use of efficient collision avoidance algorithms using roles swapping triggered using an enhanced reactivity approach.

The formation of a polyethylene/polyurethane blend polymer via in situ polymerization of diols and diisocyanate monomers dispersed in a molten polyethylene matrix was investigated in an internal mixer. Two urethane systems were used in this study. The evolution of the blend morphology with increasing molecular weight of the polyurethane phase was discussed. The difference in viscosity between the minor and major phases has a controlling influence on the qualitative compounding behaviour exhibited. Furthermore, the viscosity ratio appears to be the physical parameter which governs the blend morphology development. The phase inversion was observed at ηdghm = 0.05. Beyond the phase inversion point, Wu's model (Polym. Eng. Sci., 1987, 27, 335) quantitatively predicts the decrease of the size morphology with increasing molecular weight of the polyurethane phase. Nevertheless, high solubility of isocyanate monomers and low solubility of alcohols in molten polyethylene induce an imbalance stoichiometry which limits the degree of polymerization (molecular weight) during the blending process. A pre-polymerizing step of the urethane system limits this solubility phenomenon.

The transesterification reaction in the molten state of ester groups of ethylene vinyl acetate (EVA) copolymers and ethylene acrylic ester (EMA) copolymers has been used to crosslink the chains of this polymeric system. The relative EVA copolymers (or EMA copolymers) concentration dependence of the network formation by co-crosslinking of EVA/EMA miscible blends has been assessed. EVA/EMA networks were characterized by swelling experiments, theological measurements, and determination of the extent of the reaction through a chromatographic technique. All results can be compared in a master curve. The influence of the polydispersity and the microstructure of EVA and EMA samples was put in evidence. On the other hand, a scaling law (v2 similar to M(c)(-3/5)) was observed in agreement with predictions of the Flory-Rhener expression. (C) 1994 John Wiley and Sons, Inc.

The transesterification reaction in the molten state of ester groups of ethylene vinyl acetate copolymers and ethylene acrylic ester copolymers, in the presence of dibutyltin oxide as a catalyst, leads to crosslinking of the copolymer chains. The kinetics of this crosslinking reaction has been assessed by two different experimental methods: viscoelastic measurements of the dynamic storage modulus and thermogravimetric analysis coupled with gas chromatography which allows measurement of the evolved methyl acetate which is a volatile product of the crosslinking reaction. The equilibrium storage modulus calculated from theories of elastic modulus has shown that the kinetics of the crosslinking reaction may be determined through variations of the dynamic storage modulus.

Thermal degradation of emulsion statistical copolymers of acrylonitrile and vinylidene chloride and/or terpolymers with glycidyl methacrylate or glycidyl acrylate was carried out in the temperature range from 25 to 450-degrees-C in nitrogen and was studied by conductometry and by gas chromatography. We have found that epoxy groups of the third component of terpolymers favourably affect the beginning of dehydrochlorination because they bind the first amounts of the releasing hydrogen chloride. With decreasing molecular mass of a sample, the rate of the HCl abstraction considerably increases. With samples of the lowest molecular masses, almost complete dehydrochlorination occurs.

Transesterification may be used to crosslink a copolymer such as ethylene vinyl acetate with poly(ethylene acrylate-co-propylene) in the presence of dibutyltin oxide as a catalyst. A rheological study of the mechanism of this exchange reaction has been made: The kinetics of the crosslinking reaction was determined by studying the time and temperature dependence of the dynamic storage modulus G'(t, T)omega. Kinetic curves obtained for different reactive blends (EVA, PP/EVA, and PPf/EVA) allowed for the evaluation of the activation energy of the reaction and, thus, specified the appropriate parameters (temperature and time) for carrying out this reaction in a molten state.

Pellicular resins have been prepared from polypropylene spherical beads after successive peroxidation by ozone, grafting of poly(styrene-co-chloromethystyrene) by radical polymerization, and finally a chemical two-step modification, to yield anchored sulfoxide groups. Under three-phase catalysis conditions, pellicular resin sulfoxides, —CH2SOCH3, display higher catalytic activity in alkylation reaction than conventional gel-type or macroporous resins carrying the same amount of sulfoxide groups. The catalytic activity of pellicular resin sulfoxides was found to depend on their composition; they were found to be more effective than the low-molecular dimethylsulfoxide analogue.

: Ibogane alkaloids were shown to have a very high arousal activity. Similarly, a stimulating CNS activity was demonstrated for vob-asine alkaloids. The influence of certain substituents was evidenced: a methoxy substituent increases the activity, while it is lowered by a methoxycarbonyl substituent.

A set of polystyrenes of comparable molecular weight around 4000, prepared by anionic polymerisation, were end-capped with various structures. Their thermal degradation behaviour (weight loss kinetics, nature and amount of volatile by-products) is governed by the nature of the chain ends. Some features of the degradation mechanisms are discussed.

Polystyrenes substituted with chloromethoxyphosphonated groups at chain ends undergo a condensation reaction at a relatively low temperature (ca. 200°C) prior to extensive degradation of the polymeric chain (280–430°C). The condensation leads to an increase in the molecular weight through the formation ofPOPbonds between phosphonated chain ends with elimination mainly of CH3Cl. Trace amounts of CH3OH are also evolved in this step. Mechanisms for the condensation reaction are proposed and its relevance to the fire retardant activity of these polymers is discussed.

On heating at volatilisation temperatures, polystyrene (PS) and telechelic chloromethoxyphosphonated polystyrene (TPPS) behave differently in the very early stage of the process. The initial rate of volatilisation of PS is zero and increases with conversion whereas TPPS polymers volatilise at an initial high rate which decreases with conversion. However, in the main stage of volatilisation (from 10–20 to 70% weight loss) both polymers liberate the same volatile products through the same basic mechanism of depolymerisation. Nevertheless, the overall rate of volatilisation of TPPS polymers in this stage is much lower than that of PS. This is attributed to the creation in degrading TPPS polymers of less reactive chain carriers of the depolymerisation process which are stabilised by the phosphoryl group.

Understanding the problem implicit in the title of this paper requires knowledge of the pyrolysis and combustion of the polymer itself, and also of its side compounds in the material and chiefly the plasticizers. These processes are now partly known and reasonably well understood, and the main points of our knowledge are stressed here. Although a very large number of additives have been proposed as smoke suppressors, little is known about their precise action. They probably react with HCl and air, and then they may be only precursors of active species. It is suggested that these active species may be either catalysts of intermolecular reactions during pyrolysis, which change the composition of the fuel to be burnt outside the material and reduce it to produce more char, or oxidation catalysts which cause the combustion of the char directly to CO and CO2. Dynamic experiments lead to a more scietific approach to the phenomena and, further, give results that can be compared in favourable cases with those of semi-natural scale tests.

AbstractWhatever the state of the iron compounds as smoke suppressant during the combustion of poly(vinyl chloride), they lead rapidly to native αFe2O3 in the char residue left after dehydrochlorination. It causes incandescence of the char residue and catalyzes its oxidation into carbon monoxide and carbon dioxide that contributes to decreasing the amount of available carbon for the soot formation after self‐ignition. FeCl2 and FeCl3 are the precursors of αFe2O3, which is the true compound as smoke suppressant. Nevertheless, as intermediate, iron chlorides are able to modify the degradation processes, and they favor the formation of light tars instead of heavy tars. For that reason the iron compounds cause the formation of smoke at lower temperature than for pure PVC, but, as αFe2O3 is formed, the smoke production levels off and then decreases. The higher the ease of the iron compounds to give chlorides through reaction with HCI and further native αFe2O3, the higher the ease of the additive to cause the oxidation of the char residue sooner and in consequence to decrease the smoke level. In the PVC combustion three main steps may be distinguised: dehydrochlorination step between 200–300°C; tars aerosols formation from the char residue between 300°C and self‐ignition; at temperature higher than self‐ignition, formation of soot from the previous tars as precursors.

Direct evidence is given of the initiating rôle played in the thermal degradation of anionic polystyrene by chain ends, either present originally or formed during the degradation. In the early stages of degradation, the most likely bond scission in polystyrenes with benzylic type units (CH 2 (C 6 H 5 )) at both chain ends involves the formation of toluene and an unsaturated terminal unit (CH 2 C(C 6 H 5 )CH 2 ). The depolymerisation of polystyrene to a mixture of monomer and dimeric, trimeric, etc., fragments is then initiated by further scission at such unsaturated chain ends, giving α-methyl styrene and a depolymerising macroradical. After the early stage of degradation, a further overwhelming contribution to the formation of unsaturated chain ends is derived from chain transfer which occurs during depolymerisation. The concentration of unsaturated chain ends increases throughout the degradation process, thus accelerating the formation of the volatile products of depolymerisation. According to this mechanism of initiation, a constant ratio is found between rates of weight loss and of α-methyl styrene evolution throughout the degradation, independently of the original molecular weight of the polymer.