Utjecaj sadržaja nanočestica silicijeva dioksida (SiO2) na mehanička svojstva cementne ploče iverice proizvedene od lignoceluloznih materijala

The influence of Nano-SiO2 (NS) content and lignocellulosic material addition on hydration behaviour of cement paste was studied through measurement of hydration temperature, initial and final setting time of cement paste and compressive strength of hardened cement paste. Besides, the amount of NS, particle size of reed and bagasse as lignocellulosic materials and bagasse to reed particles weight ratio were selected as manufacturing variables for cement-bonded particleboard (CBPB) each at five levels. The relationships between independent parameters and output variables (modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding (IB)) were modeled using response surface methodology (RSM) based on mathematical model equations (second-order multiple linear regression model) by computer simulation programming. The results indicated that cement pastes containing 3 wt.% Nano-SiO2 content mixed with milled reed or bagasse particles enhanced maximum hydration temperature; however, the time of reaching the main rate peak shortened. Besides, the increase of SiO2 replacement shortened the setting time. On the other hand, using reed particles, initial and final setting times of cement prolonged, while bagasse particles shortened initial and final setting times. Analysis of variance (ANOVA) was performed to determine the adequacy of the mathematical model and its respective variables. The interaction effect curves of the independent variables obtained from simulations showed a good agreement between the measured MOR, MOE and IB of CBPB and predicted values obtained by the developed models, and hence, the proposed concept was verified.Utjecaj sadržaja nanočestica silicijeva dioksida (NS) i dodatka lignoceluloznih tvari ispitivan je na temelju hidratacijskog ponašanja cementne paste uz pomoć mjerenja temperature hidratacije, početnoga i završnog vremena vezanja cementne paste te tlačne čvrstoće očvrsnute cementne paste. Od varijabli koje utječu na svojstva cementnih ploča iverica (CBPB) ispitivana je količina NS-a, veličina čestica lignoceluloznih materijala (trske i otpadaka u preradi šećerne trske) te težinski omjer različitih lignoceluloznih materijala. Za svaku varijablu odabrano je pet vrijednosti. Odnos između nezavisnih parametara i izlaznih varijabli – modula loma (MOR), modula elastičnosti (MOE) i čvrstoće raslojavanja (IB) – modeliran je s pomoću metodologije odziva površine (RSM-a) i računalnim simulacijskim programiranjem utemeljen na jednadžbama matematičkih modela (model višestruke linearne regresije drugoga reda). Rezultati su pokazali da cementne paste koje (težinski) sadržavaju 3 % čestica NS-a pomiješanih s mljevenim česticama trske ili otpadaka u preradi šećerne trske pokazuju povećanje maksimalne temperature hidratacije, no skraćeno je vrijeme postizanja maksimuma. Osim toga, s povećanjem udjela NS-a skraćeno je vrijeme vezanja cementne paste. Nasuprot tome, primjenom čestica trske produljeno je početno i završno vrijeme vezanja cementa, a primjenom čestica od otpadaka u preradi šećerne trske skraćuje se početno i završno vrijeme vezanja cementa. Kako bi se utvrdila adekvatnost matematičkog modela i njegovih odgovarajućih varijabli, provedena je analiza varijance (ANOVA). Krivulje interakcije nezavisnih varijabli dobivenih iz simulacija pokazale su dobru podudarnost izmjerenih vrijednosti MOR-a, MOE-a i IB-a cementnih ploča iverica s pretpostavljenim vrijednostima dobivenim razvijenim modelima, te je stoga predloženi koncept potvrđen

The effect of some technological production variables on mechanical and physical properties of particleboard manufactured from cotton (Gossypium hirsutum) stalks

The current study aims to improve properties of particleboard manufactured from cotton (Gossium hirsutum) stalks glued with urea formaldehyde. To this aim, panel density (at three levels: 0,5; 0,65 and 0,8 g/cm3), press temperature (at two levels: 150 and 180 °C) and press closing speed (at two levels: 4 and 8mm/s) were selected as independent variables. The mechanical properties consist of modulus of rupture, modulus of elasticity and internal bonding and physical behaviors such as water absorption and thickness swelling of panels were determined. Results showed that with increasing the density of panels and press temperature modulus of rupture, modulus of elasticity and internal bonding of panels increased, while bending strengths of panels were differently affected by press closing speedcompared to the internal bonding, so that with increasing the press closing speed modulus of rupture increased, but internal bonding decreased. Moreover, increasing panel density and press temperature, water absorption and thickness swelling of panels decreased. The press closing speed affected the waterabsorption and thickness swelling, insignificantly

The effect of some technological production variables on mechanical and physical properties of particleboard manufactured from cotton ("Gossypium hirsutum") stalks

The current study aims to improve properties of particleboard manufactured from cotton (Gossium hirsutum) stalks glued with urea formaldehyde. To this aim, panel density (at three levels: 0,5; 0,65 and 0,8 g/cm3), press temperature (at two levels: 150 and 180 °C) and press closing speed (at two levels: 4 and 8mm/s) were selected as independent variables. The mechanical properties consist of modulus of rupture, modulus of elasticity and internal bonding and physical behaviors such as water absorption and thickness swelling of panels were determined. Results showed that with increasing the density of panels and press temperature modulus of rupture, modulus of elasticity and internal bonding of panels increased, while bending strengths of panels were differently affected by press closing speedcompared to the internal bonding, so that with increasing the press closing speed modulus of rupture increased, but internal bonding decreased. Moreover, increasing panel density and press temperature, water absorption and thickness swelling of panels decreased. The press closing speed affected the waterabsorption and thickness swelling, insignificantly

Production of blockboard from small athel slats end-glued by different type of joint

This study evaluated the effect of joint type of short athel (Tamarix aphila) slats at three levels (butt joint, mitered joint, and half lap joint) in core layer veneer consisting of three wood species (Fir, Beech, and Oak). The joints were glued with PVAc and sandwiched by veneers with different ratios of melamine formaldehyde/urea formaldehyde resin (0:100, 25:75, and 50:50) in glue line to determine the modulus of rupture in dry and wet conditions. It was found that the highest dry and wet modulus of rupture was obtained in specimens having slats jointed with half lap joint veneered with fir by using MF/UF ratio of 50:50. The maximum modulus of rupture parallel to the face/back veneer grain value in dry condition (83.40 MPa) was observed to be higher than those values of modulus of rupture perpendicular to the face/back veneer grain (65MPa). However, the maximum modulus of rupture parallel to the face/back veneer grain value (53MPa) in wet condition were observed to be smaller than those values of modulus of rupture perpendicular to the face/back veneer grain value (56MPa).        G M T   Detectar idioma Afrikáans Albanés Alemán Árabe Armenio Azerí Bengalí Bielorruso Birmano Bosnio Búlgaro Canarés Catalán Cebuano Checo Chichewa Chino (Simp) Chino (Trad) Cincalés Coreano Criollo haitiano Croata Danés Eslovaco Esloveno Español Esperanto Estonio Euskera Finlandés Francés Galés Gallego Georgiano Griego Gujarati Hausa Hebreo Hindi Hmong Holandés Húngaro Igbo Indonesio Inglés Irlandés Islandés Italiano Japonés Javanés Jemer Kazajo Lao Latín Letón Lituano Macedonio Malayalam Malayo Malgache Maltés Maorí Maratí Mongol Nepalí Noruego Persa Polaco Portugués Punjabí Rumano Ruso Serbio Sesoto Somalí Suajili Sueco Sundanés Tagalo Tailandés Tamil Tayiko Telugu Turco Ucraniano Urdu Uzbeco Vietnamita Yidis Yoruba Zulú   Afrikáans Albanés Alemán Árabe Armenio Azerí Bengalí Bielorruso Birmano Bosnio Búlgaro Canarés Catalán Cebuano Checo Chichewa Chino (Simp) Chino (Trad) Cincalés Coreano Criollo haitiano Croata Danés Eslovaco Esloveno Español Esperanto Estonio Euskera Finlandés Francés Galés Gallego Georgiano Griego Gujarati Hausa Hebreo Hindi Hmong Holandés Húngaro Igbo Indonesio Inglés Irlandés Islandés Italiano Japonés Javanés Jemer Kazajo Lao Latín Letón Lituano Macedonio Malayalam Malayo Malgache Maltés Maorí Maratí Mongol Nepalí Noruego Persa Polaco Portugués Punjabí Rumano Ruso Serbio Sesoto Somalí Suajili Sueco Sundanés Tagalo Tailandés Tamil Tayiko Telugu Turco Ucraniano Urdu Uzbeco Vietnamita Yidis Yoruba Zulú                 La función de sonido está limitada a 200 caracteres     Opciones : Historia : Feedback : Donate Cerra