Effect of Type and Content of Diizocyanate on the Thermal and Mechanical Properties of Polyurethane/Polycarbonate Blends

U ovom radu istražen je utjecaj vrste i udjela diizocijanata u poliuretanskim elastomerima (PU) na njegovu mješljivost s polikarbonatom (PC) te je dobivena korelacija između sastava mješavina, vrste i udjela diizocijanata u PU-u, toplinskih i reoloških svojstva važnih za primjenu te mehaničkih svojstva. Mješavine PU/PC pripravljene su miješanjem elastomera PU na osnovi poliesterskog tipa poliola uz aromatski (MDI) i cikloalifatski (H12MDI) diizocijanat, različitih udjela diizocijanata (NCO/OH = 2/1 i 4/1) i PC-a u Brabender mikseru. Rezultati mjerenja DSC-om pokazali su kristalnu strukturu PU-a na osnovi tipa diizocijanata MDI u odnosu na PU s H12MDI tipom diizocijanata, koji ima amorfnu strukturu. Rezultati mjerenja DMA-om ukazuju na djelomičnu mješljivost mješavina PU/PC. Bolja mješljivost postignuta je kod mješavina PU/PC s tipom diizocijanata H12MDI i uz veći udjel tvrdog segmenta u odnosu na tip diizocijanata MDI. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.The miscibility of polyurethane/polycarbonate, PU/PC, blends prepared by mixing of PU elastomers based on polyester polyol as a soft segment and different type and content (NCO/OH=2/1 and 4/1) of hard segments (aromatic (MDI) and cycloaliphatic (H12MDI) diisocyanate) with PC was investigated. The correlation between the composition of the blends, different type and content of PU diisocyanate, thermal and rheological properties important for the application and the mechanical properties was obtained. The PU/PC blends of PU-elastomers and PC were prepared via melt mixing in a Brabender mixer. Differential scanning calorimetry (DSC) indicated that PU elastomers based on aromatic type of diisocyanate (MDI) had crystalline structure, while the PU elastomers based on cycloaliphatic type of diisocyanate (H12MDI) were of amorphous structure. The results obtained by dynamic mechanical analysis (DMA) indicated partial miscibility of PU/PC blends. The PU elastomers made from H12MDI type of diisocyanate and with higher hard segment content had better miscibility with PC than the PU elastomers made from MDI type of diisocyanate. This work is licensed under a Creative Commons Attribution 4.0 International License

Applications of Advanced Polymer Materials

Sve intenzivniji razvoj naprednih polimernih materijala kao što su polimerne mješavine i (nano)kompoziti nude brojna inovativna rješenja za različitu upotrebu, što ima velik ekonomski značaj za plastičnu industriju i područja u kojima se primjenjuju. Napredne tehnike modificiranja polimera razvile su se gotovo do krajnjih granica, a znatno su poboljšale omjer troškova i svojstava nastalih modifikacijom strukture polimera. Miješanje različitih polimera, priprema (nano)kompozita te stvaranje višeslojnih materijala, laminata neke su od najznačajnijih tehnika modifikacije. Pri tome postoje sinergistička djelovanja između komponenti, kako bi se postigli izvrsni učinci koji su prilagođeni specifičnim primjenama, kao npr. antimikrobno djelovanje, blokiranje ultraljubičastog svjetla, smanjenje gorivosti, fotokatalitičko djelovanje, a u radu su prikazani rezultati ispitivanja polimernih nanokompozita s ciljem modifikacije navedenih svojstava. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.The intense development of advanced polymer materials, such as polymer blends and (nano)composites, offers a number of innovative solutions for different applications, which is of great economic importance for the plastics industry and the fields in which they are applied. Advanced polymer modification techniques have pushed the limit, and have significantly improved the cost/properties ratio engendered by manipulating the structure of polymers. Blending dissimilar polymers, preparing composites where polymer matrix is modified by fillers, and creating multilayer structures and laminates are some of the most significant polymer modification techniques. In such modification, synergistic effects between the components are required in order to achieve excellent performances tailored to specific applications, such as antimicrobial activity, blocking ultraviolet light, reducing flammability, photocatalytic activity. This paper presents the results of the research on polymer nanocomposites aimed at the modification of the aforementioned properties. This work is licensed under a Creative Commons Attribution 4.0 International License

Psoas abscess as the first manifestation of Crohn’s disease – case report

A case of 16-year-old female with secondary psoas abscess as the complication of the Crohn’s disease was analysed. Her pre-hospital, long lasting, non-specific symptoms led to ultrasound (US) and radiologic imaging confirming the diagnosis. The antibiotic treatment was insufficient and worsening of the patient’s condition required surgical treatment including descendent colectomy, abscess drainage and negative pressure wound therapy (NPWT). In spite of numerous complications the condition of the child gradually improved and she was discharged from the hospital on the 71st postoperative day. Two years after the colectomy, the occlusion of her colostomy was performed

Ružička days : International conference 16th Ružička Days “Today Science – Tomorrow Industry” : Proceedings

Proceedings contains articles presented at Conference divided into sections: open lecture (1), chemical analysis and synthesis (3), chemical and biochemical engineering (8), food technology and biotechnology (8), medical chemistry and pharmacy (3), environmental protection (11) and meeting of young chemists (2)

Motor skills and speech development in preschool children

Razvoj djetetova govora i motorike međusobno su povezani te se razvijaju paralelno. Poticanje tog razvoja i razumijevanje djetetovih mogućnosti od velike su važnosti u odgojno-obrazovnoj praksi. „Kvaliteta djetetova života u velikoj mjeri ovisi o njegovoj sposobnosti za komunikaciju. Jezik prožima sve aspekte njegova iskustva, to je značajni dio egzistencije, način povezivanja s drugima, kroz njega izražava sebe i vodi brigu o svojim potrebama” (Apel i Masterson, 2004: 26). Razvoj govora dijeli se na dvije faze, predverbalnu koja uključuje razvoj od rođenja do prve riječi i verbalnu koja kreće od prve smislene riječi do potpune automatizacije govora. Razvoj govora potiče se raznim sredstvima koja uključuju pjesmice, čitanje, različite verbalne medijske sadržaje, igru, okolinu u kojoj se dijete nalazi i govorne uzore. Kod poticanja razvoja govora biraju se tekstovi koji su bliski djetetu, sadrže rimu i ritmičnost, melodičnost i imaju multisenzoričko djelovanje na razvoj govora djeteta jer upravo takvi sadržaji olakšavaju učenje djetetu te ono uči neopterećeno kroz igru. Osnovne motoričke sposobnosti koje se razvijaju u predškolskoj dobi su koordinacija, ravnoteža, opća preciznost, opća snaga, opća izdržljivost, fleksibilnost i brzina reakcije na zvučne i vizualne podražaje. Kvalitetno poticanje motoričkih vještina razvijaju pravilno opterećenje mišićno-ligamentnog sustava odgovornoga za držanje tijela te pravilan rast i razvoj kostiju i pravilno držanje tijela. Fina motorika djeteta izravno je povezana s govorom tj. njihov se razvoj događa paralelno. „Formiranje važnih govornih zona u mozgu ostvaruje se pod utjecajem živčanih impulsa prstiju ruke” (Herljević i Posokhova 2007: 115). Dakle, poticanjem razvoja fine motorike potičemo i razvoj govora. Poznavanje razvojnih faza djeteta uvelike određuje uspješnost u odgojno-obrazovnoj praksi jer o tome ovisi znati pružiti djetetu potrebne poticaje za njegov rast i razvoj.The development of the child's speech and motor skills are interconnected and develop in parallel. Encouraging this development and understanding the child's abilities are of great importance in educational practice. „The quality of a child's life largely depends on his ability to communicate. Language permeates all aspects of its experience, it is a significant part of existence, a way of connecting with others, through it children can express themselves and take care of their needs.” (Apel and Masterson, 2004: 26). Speech development is divided into two phases, preverbal, which includes development from birth to the first word, and verbal, which starts from the first meaningful word to complete automatisation of speech. Speech development is encouraged by a variety of means that include poems, reading, media, play, the environment in which the child is born, and speech role models. When encouraging development of speech, we should choose texts that are close to the child, contain rhyme and rhythm, melody and have a multisensory effect on the child's development because such content facilitates the child's learning and he learns unencumbered through play. The basic motor skills that develop in preschool are coordination, balance, general precision, general strength, general endurance, flexibility, and speed of reaction to auditory and visual stimuli. Quality stimulation of motor skills develops the proper load of the musculoskeletal system responsible for posture and the proper growth and development of bones and proper posture. The fine motor skills of the child are directly related to speech, i.e. their development occurs in parallel. „The formation of important speech zones in the brain is realized under the influence of nerve impulses of the fingers” (Herljević and Posokhova 2007: 115). Thus, by encouraging the development of fine motor skills, we also encourage the development of speech. Knowledge of the child's developmental stages largely determines success in educational practice, because it depends on being able to provide the child with the necessary incentives for his growth and development

Motor skills and speech development in preschool children

Razvoj djetetova govora i motorike međusobno su povezani te se razvijaju paralelno. Poticanje tog razvoja i razumijevanje djetetovih mogućnosti od velike su važnosti u odgojno-obrazovnoj praksi. „Kvaliteta djetetova života u velikoj mjeri ovisi o njegovoj sposobnosti za komunikaciju. Jezik prožima sve aspekte njegova iskustva, to je značajni dio egzistencije, način povezivanja s drugima, kroz njega izražava sebe i vodi brigu o svojim potrebama” (Apel i Masterson, 2004: 26). Razvoj govora dijeli se na dvije faze, predverbalnu koja uključuje razvoj od rođenja do prve riječi i verbalnu koja kreće od prve smislene riječi do potpune automatizacije govora. Razvoj govora potiče se raznim sredstvima koja uključuju pjesmice, čitanje, različite verbalne medijske sadržaje, igru, okolinu u kojoj se dijete nalazi i govorne uzore. Kod poticanja razvoja govora biraju se tekstovi koji su bliski djetetu, sadrže rimu i ritmičnost, melodičnost i imaju multisenzoričko djelovanje na razvoj govora djeteta jer upravo takvi sadržaji olakšavaju učenje djetetu te ono uči neopterećeno kroz igru. Osnovne motoričke sposobnosti koje se razvijaju u predškolskoj dobi su koordinacija, ravnoteža, opća preciznost, opća snaga, opća izdržljivost, fleksibilnost i brzina reakcije na zvučne i vizualne podražaje. Kvalitetno poticanje motoričkih vještina razvijaju pravilno opterećenje mišićno-ligamentnog sustava odgovornoga za držanje tijela te pravilan rast i razvoj kostiju i pravilno držanje tijela. Fina motorika djeteta izravno je povezana s govorom tj. njihov se razvoj događa paralelno. „Formiranje važnih govornih zona u mozgu ostvaruje se pod utjecajem živčanih impulsa prstiju ruke” (Herljević i Posokhova 2007: 115). Dakle, poticanjem razvoja fine motorike potičemo i razvoj govora. Poznavanje razvojnih faza djeteta uvelike određuje uspješnost u odgojno-obrazovnoj praksi jer o tome ovisi znati pružiti djetetu potrebne poticaje za njegov rast i razvoj.The development of the child's speech and motor skills are interconnected and develop in parallel. Encouraging this development and understanding the child's abilities are of great importance in educational practice. „The quality of a child's life largely depends on his ability to communicate. Language permeates all aspects of its experience, it is a significant part of existence, a way of connecting with others, through it children can express themselves and take care of their needs.” (Apel and Masterson, 2004: 26). Speech development is divided into two phases, preverbal, which includes development from birth to the first word, and verbal, which starts from the first meaningful word to complete automatisation of speech. Speech development is encouraged by a variety of means that include poems, reading, media, play, the environment in which the child is born, and speech role models. When encouraging development of speech, we should choose texts that are close to the child, contain rhyme and rhythm, melody and have a multisensory effect on the child's development because such content facilitates the child's learning and he learns unencumbered through play. The basic motor skills that develop in preschool are coordination, balance, general precision, general strength, general endurance, flexibility, and speed of reaction to auditory and visual stimuli. Quality stimulation of motor skills develops the proper load of the musculoskeletal system responsible for posture and the proper growth and development of bones and proper posture. The fine motor skills of the child are directly related to speech, i.e. their development occurs in parallel. „The formation of important speech zones in the brain is realized under the influence of nerve impulses of the fingers” (Herljević and Posokhova 2007: 115). Thus, by encouraging the development of fine motor skills, we also encourage the development of speech. Knowledge of the child's developmental stages largely determines success in educational practice, because it depends on being able to provide the child with the necessary incentives for his growth and development

Motor skills and speech development in preschool children

Razvoj djetetova govora i motorike međusobno su povezani te se razvijaju paralelno. Poticanje tog razvoja i razumijevanje djetetovih mogućnosti od velike su važnosti u odgojno-obrazovnoj praksi. „Kvaliteta djetetova života u velikoj mjeri ovisi o njegovoj sposobnosti za komunikaciju. Jezik prožima sve aspekte njegova iskustva, to je značajni dio egzistencije, način povezivanja s drugima, kroz njega izražava sebe i vodi brigu o svojim potrebama” (Apel i Masterson, 2004: 26). Razvoj govora dijeli se na dvije faze, predverbalnu koja uključuje razvoj od rođenja do prve riječi i verbalnu koja kreće od prve smislene riječi do potpune automatizacije govora. Razvoj govora potiče se raznim sredstvima koja uključuju pjesmice, čitanje, različite verbalne medijske sadržaje, igru, okolinu u kojoj se dijete nalazi i govorne uzore. Kod poticanja razvoja govora biraju se tekstovi koji su bliski djetetu, sadrže rimu i ritmičnost, melodičnost i imaju multisenzoričko djelovanje na razvoj govora djeteta jer upravo takvi sadržaji olakšavaju učenje djetetu te ono uči neopterećeno kroz igru. Osnovne motoričke sposobnosti koje se razvijaju u predškolskoj dobi su koordinacija, ravnoteža, opća preciznost, opća snaga, opća izdržljivost, fleksibilnost i brzina reakcije na zvučne i vizualne podražaje. Kvalitetno poticanje motoričkih vještina razvijaju pravilno opterećenje mišićno-ligamentnog sustava odgovornoga za držanje tijela te pravilan rast i razvoj kostiju i pravilno držanje tijela. Fina motorika djeteta izravno je povezana s govorom tj. njihov se razvoj događa paralelno. „Formiranje važnih govornih zona u mozgu ostvaruje se pod utjecajem živčanih impulsa prstiju ruke” (Herljević i Posokhova 2007: 115). Dakle, poticanjem razvoja fine motorike potičemo i razvoj govora. Poznavanje razvojnih faza djeteta uvelike određuje uspješnost u odgojno-obrazovnoj praksi jer o tome ovisi znati pružiti djetetu potrebne poticaje za njegov rast i razvoj.The development of the child's speech and motor skills are interconnected and develop in parallel. Encouraging this development and understanding the child's abilities are of great importance in educational practice. „The quality of a child's life largely depends on his ability to communicate. Language permeates all aspects of its experience, it is a significant part of existence, a way of connecting with others, through it children can express themselves and take care of their needs.” (Apel and Masterson, 2004: 26). Speech development is divided into two phases, preverbal, which includes development from birth to the first word, and verbal, which starts from the first meaningful word to complete automatisation of speech. Speech development is encouraged by a variety of means that include poems, reading, media, play, the environment in which the child is born, and speech role models. When encouraging development of speech, we should choose texts that are close to the child, contain rhyme and rhythm, melody and have a multisensory effect on the child's development because such content facilitates the child's learning and he learns unencumbered through play. The basic motor skills that develop in preschool are coordination, balance, general precision, general strength, general endurance, flexibility, and speed of reaction to auditory and visual stimuli. Quality stimulation of motor skills develops the proper load of the musculoskeletal system responsible for posture and the proper growth and development of bones and proper posture. The fine motor skills of the child are directly related to speech, i.e. their development occurs in parallel. „The formation of important speech zones in the brain is realized under the influence of nerve impulses of the fingers” (Herljević and Posokhova 2007: 115). Thus, by encouraging the development of fine motor skills, we also encourage the development of speech. Knowledge of the child's developmental stages largely determines success in educational practice, because it depends on being able to provide the child with the necessary incentives for his growth and development

The Influence of Different Hematite (α-Fe₂O₃) Particles on the Thermal, Optical, Mechanical, and Barrier Properties of LDPE/Hematite Composites

There is an increasing need to develop new polymer composites with improved properties compared to conventional pure polymer materials. This work aims to develop composites of low-density polyethylene (LDPE) and iron oxide hematite particles. For this purpose, different types of hematite particles with well-defined shapes and narrow size distributions were synthesized: HC2 sample with pseudocubic hematite particles of an average diameter of 1020 nm, HE1 sample with ellipsoidal hematite particles of an average diameter of 533 nm, and HS1 sample with spherical hematite particles of an average diameter of 168 nm. The mass fractions of hematite in the composites were 0.25%, 0.5%, and 1%. Prepared LDPE/hematite composites were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The mechanical and barrier properties were also studied. The obtained results showed that all prepared composites have improved properties compared to the pure LDPE, especially the composites with pseudocubic hematite particles of well-defined shapes. The results of this study indicate that LDPE/hematite composites can be promising materials for a wide range of applications, especially as packaging materials where improved thermal and mechanical properties as well as resistance to ultraviolet (UV) irradiation are required