Development of structural-heat-insulating lightweight concrete composition using production of aerated concrete waste as a porous aggregate

Annually enterprises in the field of manufacturing of products from aerated concrete generate from 5000 to 10000 m3 of solid production waste. One of the perspective and under-investigated direction is the practical application of solid waste using a porous aggregate in structural-heat-insulating lightweight concrete in the production of construction materials. The aim of this study was to evaluate the possibility of using crushed aerated concrete as a large aggregate in lightweight concrete for structural and thermal insulation purposes and to establish optimal conditions for obtaining products with the best characteristics. There were defined the qualitative indicators of crushed aerated concrete, analyzed factors influencing on the preservation of the properties of concrete in time, selected the composition of concrete aggregates from crushed concrete, studied the structure and properties of the obtained samples in the research. It has been found that to obtain effective constructive insulating lightweight concrete using waste production of aerated concrete as an aggregate is possible due to the fractionated pre-treatment of the aggregate with water dispersion of deep-penetration acrylic copolymers, insertion excess sealing water to concrete mixture, including optimization of the rheological properties of the concrete mix due to insertion of polycarboxylate hyperplasticizer.

Spectral and kinetic manifestations of chain flexibility and polarity in reversible photoisomerization of spironaphthoxazine-based acrylic copolymers

Future advances of photoresponsive materials essentially depend on our knowledge about how the substrates, and typically their Tg and polarity, affect photochromic properties. Here, these were followed in two separate...

Synthesis of Well-Defined Di- and Triblock Acrylic Copolymers Consisting of Hard Poly(dicyclopentanyl acrylate) and Soft Poly(alkyl acrylate) Segments by Organocatalyzed Group Transfer Polymerization and Their Glass Transition Behavior

A series of well-defined di- and triblock acrylic copolymers consisting of hard poly(dicyclopentanyl acrylate) (PdcPA) and soft poly(alkyl acrylate) (PAA) blocks are synthesized by the N-(trimethylsilyl)bis(trifluoromethanesulfonyl)imide (Me3SiNTf2) catalyzed group transfer...

Accelerated Ageing Procedures to Assess the Stability of an Unconventional Acrylic-Wax Polymeric Emulsion for Contemporary Art

This research evaluates the stability of an aqueous emulsion of acrylic copolymers and waxes. Edelwachs, generally applied on wood, has been recently used as an unconventional medium in contemporary painting. Through Pyrolysis–Gas Chromatography–Mass Spectrometry (Py-GC-MS) and Fourier Transformed Infrared Attenuated Total Reflectance (FT-IR-ATR) analyses, the composition of Edelwachs was defined as a mixture of acrylic polymers (MA, MMA, nBA, nBMA), Carnauba and microcrystalline waxes and additives. Mock-ups-obtained mixing Edelwachs with titanium white, zinc white and ultramarine blue were subjected to UV, high temperatures, and high relative humidity accelerated ageing. The effect of the ageing procedures was evaluated through optical microscopy, colourimetric measurements, FT-IR-ATR, Thermogravimetry and Differential Scanning Calorimetry (TG-DSC) and wettability measures. FT-IR-ATR spectra do not show significant variations in terms of chemical stability, indicating a fair stability of Edelwachs as a painting binder. UV and high temperature treatments show the most relevant effects in terms of colorimetric changes (increasing of b*) and thermal stability. The TG-DSC highlights the influence of the pigments (specifically zinc white) mainly on the thermal behaviour of the acrylates. The unexpected decrease of wettability of the paint films, registered after ageing, may indicate a possible phase separation among acrylates and waxes.

RESULTS OF TREATMENT OF EDENTULOUS PATIENTS WITH DENTURES MADE OF «FTORAX»

Background. The problem of providing high-quality dental care to edentulous patients remains one of the most important and unresolved to this day in the clinic of prosthodontics. The causes of complete loss of teeth can be both periodontal tissue diseases and diseases of hard tooth tissues of carious and non-carious origin, trauma and the like. It becomes necessary to fabricate complete removable dentures to prevent the occurrence of pathologies in such situations. Complete secondary adentia leads to a large number of local and general complications. The chewing apparatus undergoes a number of functional and morphological changes. Therefore, the complete absence of teeth sets the dentist the task of restoring the functions of full chewing, the appearance of the patient, and speech. The complexity of high-quality prosthetics for edentulous patients is also because the clinical characteristics of supporting tissues are diverse, constantly changing, so a personal approach to creating stable denture is needed. It should be added that the fabrication of high-quality complete removable dentures largely depends on the properties of the base material. The main group of materials for the fabrication of such dentures is acrylic plastics. The aim. The work is focused on the study of the functional state of the masticatory muscles and the restoration of masticatory effectiveness in edentulous patients, for whom dentures were made in the prosthodontics clinic from the acrylic base material «Ftorax». Material and methods. Hot curing plastic based on fluorine-containing acrylic copolymers «Ftorax» was used in the work. Our evaluation of the quality of all constructions was carried out using the «BOFSAS» test, determining the biopotentials of the masticatory muscles using electromyography, and determining the masticatory effectiveness according to I.S. Rubinov. Results. Based on our work, it can be noted that the use of the basic acrylic material «Ftorax» allows us to achieve good fixation and stabilization of complete removable dentures, which is subjectively confirmed by the «BOFSAS» test, objectively – by the electromyographic studies and time indices during chewing test according to I.S. Rubinov. The amplitude during volitional compression is 556.90±8.72 μV, which approaches the norm (641.58±10.01 μV), and almost four times higher than before prosthetics (188.11±8,13 μV) after 1 year of constructions using. A similar pattern is observed with arbitrary chewing: the amplitude (547.32±8.43 μV) approaches normal (643.92±9.11 μV) compared with the results before prosthetics (201.40±9.39 μV). As for the coefficient «K», its value decreased almost twofold compared with the results before prosthetics (2.44±0.14) and equals to 1.25±0.03, which is significantly closer to normal (1,02±0.01). After the test by Rubinov the following results were obtained: the average time that patients with intact dentitions spent chewing on the stimulus was approximately 12.97±0.13 seconds and the average time for patients before prosthetics (with old dentures) was approximately 45.16±0,41 sec. The time that patients spent chewing a nut after 1 month was 28.97±0.42 seconds, after 6 months – 26.94±0.44 seconds, and after 1 year of using the entures – 25.48±0.45 sec. Based on this, it can be summarized that adaptation to such dentures takes place at the appropriate time with minor corrections. Conclusion. The results of our clinical study indicate the feasibility of using «Ftorax» in prosthodontics clinic for treatment of edentulous patients.

Efecto de la adición de copolímeros reactivos a mezclas de PLA/ATP

In this work, the reactive compatibilization of Polylactic Acid/Thermoplastic Starch (PLA/TPS, 80/20% w/w) blends using acrylic copolymers of methyl methacrylate-glycidyl methacrylate (MMA-GMA) was examined. The compatibilization was studied using torque rheometry, thermal analysis (DSC), Scanning Electron Microscopy (SEM) and mechanical properties. During melt mixing, the torque of PLA/TPS blends decreased, this was related to the breakup of starch chains. The addition of MMA-GMA copolymer increased the torque during the mixing period. This torque increasing is evidence of a viscosity increase and it was related to the reactions between the epoxy group present in the acrylic copolymer, the end-groups of the PLA and TPS hydroxyl groups. The morphologies of the compatibilized blends showed a decrease in the particle size of the TPS domains and an increase in elongation of 30%. The reactive compatibilization is an interesting technique to expand the property range of PLA materials, which can potentially substitute oil-based materials.