Photo-chemically induced polycondensation of a pure phenolic resin for additive manufacturing

Bakelite© or phenoplasts are considered the first synthetic polymers in the world. These resins, produced by polycondensation, have always been known for their chemical resistance, excellent flame resistance and thermal...

Membranes adsorber from oil palm empty fruit branches (OPEFB): preparation and fabrication

Oil Palm empty fruit branches (OPEFB) are solid waste that are numerous produced from palm oil mills. OPEFB is economically and potentially used as membrane adsorber material due to has good thermal stability, chemical resistance and biodegradability. The objectives of this work is to preparate and fabricate the OPEFB membrane adsorber which is activated by physical activation. The OPEFB has been cleaned and dried, subsequently heated at 500 °C for 30 min via pyrolysis. The activated OPEFB was sieved using 200-400 mesh and followed by the addition of 2-propanol, NH4Cl, polyvinyl alcohol (PVA) and polyethylene glycol (PEG) to become a mixture. The activated OPEFB ratio were varied in the mixtures to obtain the best composition in order to produce a good membrane adsorber texture for casting. FTIR shows on wavenumber at 1082 cm−1 indicates that there is O-H stretching functional groups and bands at 943 cm−1 correspons to C=O functional group. It is concluded that the membrane mixtures can be employed as membrane adsorber due to carbon content which creates strong matrix applied for gas separation.

Mechanical and Durability Properties of Cementless Concretes Made Using Three Types of CaO-Activated GGBFS Binders

This study examined the mechanical and durability properties of CaO-activated ground-granulated blast-furnace slag (GGBFS) concretes made with three different additives (CaCl2, Ca(HCOO)2, and Ca(NO3)2) and compared their properties to the concrete made with 100% Ordinary Portland Cement (OPC). All concrete mixtures satisfied targeted air content and slump ranges but exhibited significantly different mechanical and durability properties. The CaO-activated GGBFS concretes showed different strength levels, depending on the type of additive. The added CaCl2 was the most effective, but Ca(NO3)2 was the least effective at increasing mechanical strength in the CaO-activated GGBFS system. The OPC concrete showed the most excellent freezing–thawing resistance in the durability test, but only the CaO-activated GGBFS concrete with CaCl2 exhibited relatively similar resistance. In addition, the chemical resistance was significantly dependent on the type of acid solution and the type of binder. The OPC concrete had the best resistance in the HCl solution, while all CaO-activated GGBFS concretes had relatively low resistances. However, in the H2SO4 solution, all CaO-activated GGBFS concretes had better resistance than the OPC concrete. All concrete with sulfate ions had ettringite before immersion. However, when they were immersed in HCl solution, ettringite tended to decrease, and gypsum was generated. Meanwhile, the CaO-activated GGBFS concrete with CaCl2 did not change the type of reaction product, possibly due to the absence of ettringite and Ca(OH)2. When immersed in an H2SO4 solution, ettringite decreased, and gypsum increased in all concrete. In addition, the CaO-activated concrete with CaCl2 had a considerable amount of gypsum; it seemed that the dissolved C-S-H and calcite, due to the low pH, likely produced Ca2+ ions, and gypsum formed from the reaction between Ca2+ and H2SO4.

Durability and chemical resistance of nanoparticles fly ash and silica fume belite cement pastes against sulfate and chloride aggressive media- Part II

The durability (chemical resistence) of the Portland cement (OPC), belite cement (BC) and the optimum belite cement (B4), which their physical and chemo/mechanical properties were perviously investigated in Part I, against 4 % MgSO4 and 4% MgCl2 solutions up to 12 months in terms of compressive strength, total sulfate and total chloride was evaluated and studied. Results showed that the optimum belite cement (B4) containing 15 % High pulverized fly ash (HPFA) and 5 % Silica fume (SF) could be resisted up to 6 months, while that of BC could be withstood only up to 5 months, and the OPC could not resist more than three months of immersion in 4% MgSO4 solution. The compressive strength values exhibited by the samples immesed in sulfate solution at 3, 5 and 6 months of immersion were 83.81, 76.38 and 91.13 MPa, respectively. The same trend was displayed when the same samples were exposed to 4% MgCl2 solution. The compressive strength values exhibited by the same samples exposed to chloride solution at 3, 5 and 6 months of immersion were 84.49, 82.23 and 93.32 MPa, respectively. The total sulfate and chloride contents were enhanced with immesion time up to 12 months, but their values were the minimum with B4 and the maximum with OPC, while with BC were the medium. The optimum cement batch (B4) achieved the highest resistance where it recorded the lowest values for sulfate and chloride ions, but the OPC exhibited the lowest resistance where it recorded the highest values of sulfate and chloride contents at all immersion ages till 12 months.

Mechanical Properties and Delamination Factor Evaluation of Cellulose (Nettle) Fiber Reinforced Polymer Composites using RSM

This paper discusses on fabrication, testing and evaluation of delamination factor of nettle fiber based composites for low duty applications. The randomly oriented nettle fibers were used to fabricate the biocomposite by conventional hand lap up technique. Epoxy and Nettle based composite plates were developed by varying fiber weight percentage from 5% to 25%. The flexural, tensile, impact, chemical resistance and water absorption rate of developed nettle fiber based biocomposite were examined for different fiber weight fractions in the randomly oriented patterns as a unique and innovative attempt. During the investigation, flexural strength and tensile strength were improved up to 20 wt% of fiber addition and then it was decreased. This resulted in a continuous rise in impact strength with an enhancement in fiber wt. %. The influence of fiber weight percentage on water absorption and chemical resistance of fabricated composite was examined in different environments. The result showed that the nettle fibers can be used as an essential reinforcing material to design and fabricate mechanical and structural members for low duty application. The chemical behavior of nettle based composite was studied by the FTIR spectroscopy method and the presence of chemical functional group was confirmed. The drilling behavior of developed nettle/SiC/epoxy hybrid composites was evaluated by consider cutting process parameters like feed rate (0.125, 0.212 and 0.3 mm/rev), spindle speed (400, 600, 800 rev/min) and drill diameter (4, 6, 8 mm). Analysis of variance was used in designing experiments for the current investigation. Feed rate was found to be a very impressive factor in influencing the delamination factor.

Artificial Ageing, Chemical Resistance, and Biodegradation of Biocomposites from Poly(Butylene Succinate) and Wheat Bran

The results of comprehensive studies on accelerated (artificial) ageing and biodegradation of polymer biocomposites on PBS matrix filled with raw wheat bran (WB) are presented in this paper. These polymer biocomposites are intended for the manufacture of goods, in particular disposable packaging and disposable utensils, which decompose naturally under the influence of biological agents. The effects of wheat bran content within the range of 10–50 wt.% and extruder screw speed of 50–200 min−1 during the production of biocomposite pellets on the resistance of the products to physical, chemical, and biological factors were evaluated. The research included the determination of the effect of artificial ageing on the changes of structural and thermal properties by infrared spectra (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). They showed structural changes—disruption of chains within the ester bond, which occurred in the composition with 50% bran content as early as after 250 h of accelerated ageing. An increase in the degree of crystallinity with ageing was also found to be as high as 48% in the composition with 10% bran content. The temperature taken at the beginning of weight loss of the compositions studied was also lowered, even by 30 °C at the highest bran content. The changes of mechanical properties of biocomposite samples were also investigated. These include: hardness, surface roughness, transverse shrinkage, weight loss, and optical properties: colour and gloss. The ageing hardness of the biocomposite increased by up to 12%, and the surface roughness (Ra) increased by as much as 2.4 µm at the highest bran content. It was also found that ageing causes significant colour changes of the biocomposition (ΔE = 7.8 already at 10% bran content), and that the ageing-induced weight loss of the biocomposition of 0.31–0.59% is lower than that of the samples produced from PBS alone (1.06%). On the other hand, the transverse shrinkage of moldings as a result of ageing turned out to be relatively small, at 0.05%–0.35%. The chemical resistance of biocomposites to NaOH and HCl as well as absorption of polar and non-polar liquids (oil and water) were also determined. Biodegradation studies were carried out under controlled conditions in compost and weight loss of the tested compositions was determined. The weight of samples made from PBS alone after 70 days of composting decreased only by 4.5%, while the biocomposition with 10% bran content decreased by 15.1%, and with 50% bran, by as much as 68.3%. The measurements carried out showed a significant influence of the content of the applied lignocellulosic fillers (LCF) in the form of raw wheat bran (WB) on the examined properties of the biocompositions and the course of their artificial ageing and biodegradation. Within the range under study, the screw speed of the extruder during the production of biocomposite pellets did not show any significant influence on most of the studied properties of the injection mouldings produced from it.

Study of the properties of chemically resistant repair mortar with the use of secondary raw materials

This paper deals with the research of a new silicate-based repair mortar modified with selected secondary raw materials. The aim of this work is to develop a chemically resistant material suitable for use in an extremely aggressive environment of sewers. The monitored parameters include key physical-mechanical characteristics, resistance to sulphate ions and to the attack of aggressive biogenic sulfuric acid. Chemical resistance was tested by simulating the exposure environment in laboratory conditions, according to the methodology of DIN 19573. The obtained results show that by suitable modification of the reference mortar it is possible to maintain the values of physical-mechanical characteristics and improve the chemical resistance of test samples.

Estimation of the chemical resistance of polyurethane compounds used in the manufacture of diaphragms of diaphragm-piston pumps

This study presents chemical resistance tests for three different grades of polyurethane bicomponent compounds: PolyFlex 80A, Silagerm 6080 and Advaform Mark 80. Samples of polyurethane bicomponent compounds were prepared in the form of squares, with a thickness not exceeding 3 mm. They were placed in previously prepared containers with aggressive technical me-dia: Lazurit herbicide, Rakurs fungicide and MAXCUT HD SAE 30 mineral motor oil. These technical media were selected taking into account the processing of agricultural legumes, and the concentration of preparations was calculated specifically for soybeans. The selected mineral motor oil MAXCUT HD SAE 30 is used in many pumping equipment used in the agri-cultural industry. According to the results of the study, it was proved that the greatest effect on the samples is exerted by the herbicide “Lazurit”, in which they swell and increase in weight. The experiment carried out to evaluate the chemical resistance of polyurethane compounds showed that the best materi-al for the manufacture of diaphragms used in piston diaphragms is Adva-form Mark 80. This type of two-component polyurethane compound has the best chemical resistance to the investigated chemically active substances.