The thermal‐oxidative and thermal‐mechanical stability of high density polyethylene (chromium based catalyst technology) was examined at many different temperatures using a rheological approach. The changes in molecular structure, which take place during processing, have been studied using a Clextral co‐rotating twin‐screw extruder in comparison with dynamic measurements performed with a rotational rheometer under definite conditions of temperature, strain and frequency and in presence of air. In order to evaluate the degradation response, an investigation of elastic modulus G′ as a function of frequency ω on the residual sample after ageing has been carried out. The molecular weight increase, probably due to the formation of small amounts of long chain branching, is clearly observed through the growth of the elastic properties, mainly at low frequencies (i.e. high relaxation times). The stabilised polymer shows a less pronounced tendency towards degradation, even if a critical temperature (240 °C) has been found at which antioxidant has not any effect in avoiding degradation.

The housing sector is responsible for more than 50% of global resource extraction, about 50% of world energy consumption, 1/3 of water consumption and furthermore generates about 1/3 of all produced waste. A new, circular approach is needed to enable better decision-making on the selection of innovative architectural solutions for all phases of a building's life cycle. The current building sector's business model must be redesigned to include the application of new and improved methods, solutions and innovative services, and advance a positive transition from a linear economy to a circular economy. We will present the circular interventions carried out on a centenary building located in Vienna in the framework of the HOUSEFUL project. HOUSEFUL is an EU-funded initiative with the objective to develop and demonstrate integrated circular services, focusing on the optimal management of resources throughout the life cycle of new or existing buildings. The demonstration will include technologies to circulate all process flows while reducing the overall energy demand. These technologies will be offered as integrated services to produce treated rain and wastewater for internal reuse, the generation of renewable energy from biogas, compost production combined with urban gardening and for the use of nutrients in a greenhouse. The design of more efficient processes, such as green walls, innovative conservatories, building-integrated solar thermal and photovoltaic panels will improve building energy efficiency. All process flows will be intensely monitored to ensure safety and collect data for further replication cases. The solutions will also include the use of sustainable and upcycled materials and the implementation will be based on the principles of reversibility and de-constructability. The final services of the building will be elaborated in co-creation workshops with a multitude of stakeholders. Additional service-oriented modelling facilitates replication for the transition to the circular housing sector.

SUM MARY:Several MgC1,-supported catalysts containing different amounts of titanium and hafnium were prepared. These systems are active for the polymerization of ethylene and a-olefins as well as for their copolymerization, giving much broader molecular weight distributions as compared with similar systems containing titanium only. Polymer properties, such as melt flow index and shear sensitivity can be varied by catalyst composition and addition of a Lewis base (ethyl benzoate). Gel permeation chromatography curves obtained in a single reactor (one-stage process) are comparable to those obtained in two reactors (two-stage process). An analysis of comparative kinetics for various conditions and the corresponding polymer properties suggests that Hf-containing sites produce much longer chains than do Ticontaining sites; at the same time Hf-containing sites display lower activity and higher tendency to interact with ethyl benzoate. Similar investigations with model catalysts are described to support these hypotheses.

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The crystallization and melting behaviour of two sets of ethylenellbutene copolymers have been analysed by DSC. The samples, with comonomer content in the range from 0 to 21.5 mol%, were obtained by industrial processes using both Mg/Ti-based and Ti/V-based catalyst systems. The composition dependences of melting and crystallization temperatures were found to be strictly affected by the catalyst type. Moreover, logarithmic plots of the melting and crystallization enthalpy as a function of the ethylene content (mol%,) in the copolymers fitted linear relationships whose slopes have been related to the critical sequence length of crystallizable ethylene units, depending on the catalytic system. These results are compared with those reported in the literature for ethylene/l-butene copolymers synthesized by other catalysts and are accounted for by a different distribution of the comonomer units in the macromolecules of the two sets of samples.