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Abstract
The influence of different steric properties of methylamine (MA), dimethylamine (DIMA) and trimethylamine (TRMA) on the type of interactions with Ni-exchanged montmorillonite and thermal properties of these materials were studied. The results of diffraction, spectral (IR) and thermal (TG, DTG) analysis show that MA, DIMA and TRMA are intercalated into the interlayer space of montmorillonite. Thermal decomposition in the temperature interval 20–450°C of studied samples with MA and DIMA proceeds in three steps (the release of chemisorbed amines, coordinated amines and alkylammonium cations) while the sample with TRMA decompose only in two steps (the peak corresponds to the release of coordinated TRMA is absent). The effect of different steric properties of individual amines is evident.
Abstract
The article presents the results of testing thermal properties and combustibility of butadieneacrylonitrile rubber with 18% contents of bounded acrylonitrile, NBR 18. Two types of silica, Zeosil 175C and Ultrasil VN-3, with different specific surfaces were used as filler. Zeosil 175C and Ultrasil VN-3 were modified via cryogenic dezaggregation method. The activity of unmodified and cryogenic modified silica toward butadiene-acrylonitrile rubber were investigated. The sulphur and peroxide vulcanizates contained 20, 30, 40, and 50 phr. of the filler were studied. The article discusses also the test results of thermal stability and flammability of NBR 18 containing silica prepared "in situ" from alkoxysilane precursor. The test results were obtained with the use of derivatograph, measurements of flammability by the method of oxygen index, and in air. The effect of the silica modification on the SEM and AFM was also examined. The method of cryogenic modification enables to achieve increase of mineral fillers activity towards elastomer and reduction in the flammability of NBR 18 vulcanizates. It has been found that the modification of the vulcanizates of NBR 18 with tetraethoxysilane that makes it possible to form silica "in situ" reduces the flammability of cross-linked rubbers.
Abstract
This article focuses on the thermal properties of PA 6 and additives, i.e. ternary copolyamides, concentrates consisting of binary or ternary copolyamides + nanoadditive montmorillonite Bentonite 11958 or Cloisite 15A and PA 6 fibres modified with Bentonite, copolyamide and concentrate. The copolyamides are prepared from ε-caprolactam as a major comonomer and nylon salts AN2 from adipic acid + 1-(2-aminoethyl)piperazine and ADETA from adipic acid + diethylenetriamine. All copolyamides and concentrates exhibit lower melting temperatures T m and lower melting enthalpies ΔH m compared to neat PA 6. PA 6 fibres modified with 0.25–2.5 wt% MMT exhibit higher melting enthalpies in comparison with unmodified PA 6 fibres. PA 6 fibres modified with 10 wt% of ternary copolyamide containing 21.4 wt% of comonomers AN2 and ADETA have higher melting enthalpy as well. PA 6 fibres modified with 10 and 20 wt% of concentrate containing the same ternary copolyamide + 5 wt% of MMT have higher melting enthalpies and higher tensile strength in comparison with these characteristics of unmodified PA 6 fibres.
Abstract
Thermal properties and morphology of crystal in NYLON 1010 formed isothermally at melting peak temperature were studied by using DSC, TEM and ED. It turns out that the crystal on the time scale of the DSC experiment is stable, which is not transformed from the crystal with low melting point. Its electron diffraction pattern shows symmetrical and clear electron diffraction spots of single crystal and is proved to be the electron diffraction pattern of single crystal by means of index with parameters of unit cell of Nylon 1010
DTA and TG methods were used to study the melting, polymorphic transformation and thermal decomposition processes of alkali metal and ammonium mixed bifluorides formed by mutual replacement of the cations in the crystal lattice. We studied the structural features and the characteristics in the changes of thermal properties of individual compounds, solid solutions with unlimited solubility and solid solutions with limited solubility.
Abstract
The effect of mineral fillers such as Ultrasil VN-3, Ze−O−Sil P-45, Aerosil 200, Frantex 8, Kaolin and precipitated calcium carbonate on the thermal properties sulphur vulcanizates ofcis-1,4-polyisoprene were studied by means of thermal analysis. It was found that the addition of a mineral filler did not change the nature of the thermal processes in isoprene vulcanizates essentially, but it distinctly affected the positions of the peaks recorded in the DTA curves. The mineral fillers affected the temperatures and rates of degradation and destruction of polyisoprene cross-linked with sulphur. The presence of a mineral filler brought about a decrease in the flammability ofcis-1,4-polyisoprene sulphur vulcanizates.
The effect of carbon black with various particle sizes and specific surfaces on the thermal properties of the sulphur vulcanizates ofcis-1,4-polyisoprene was studied by means of thermal analysis. It was found that the addition of carbon black does not change the nature of the thermal processes in isoprene rubber vulcanizates essentially, but it distincly affects the positions of the peaks recorded in the DTA curves. The specific surface of carbon black affects the temperature of the first exothermic process and the temperature and rate of destruction of cross-linked polyisoprene. The presence of carbon black brings about a reduction in the flammability ofcis-1,4-polyisoprene vulcanizates. The specific surface of carbon black influences the value of the oxygen index OI.
Abstract
The exfoliated poly(vinyl chloride) (PVC)/montmorillonite (MMT) nanocomposites were synthesized by in situ intercalated polymerization of vinyl chloride (VC) in the presence of organic-intercalated montmorillonite (OMMT). Their structures and thermal properties were characterized. The results showed that layered silicates are well exfoliated and uniformly distributed in PVC matrix during in situ intercalated polymerization of VC in the presence of OMMT. The glass transition temperatures of PVC phases in the PVC/MMT nanocomposites are all lower than that of pristine PVC due to the incorporation of the exfoliated silicate layers in PVC matrix. The 5% mass loss temperature (T 5%), the dehydrochlorination temperature (T max1) of the PVC matrix decreased due to the free and interlayer water in MMT, the low thermal stability, and the enhanced dehydrochlorination of the PVC matrix by alkyl ammonium pre-treated MMT. However, the thermal decomposition temperature of the dehydrochlorinated PVC (T max2) and char at 600C are slightly increased in the presence of silicate layers.
Six adducts of the tctrakis(8-hydroxyquinolinato) complex of thorium(IV) with 8-hydroxyquinoline, pyridine, urea, dimethylsulphoxide, dimethylformamide and 1,10-phenanthroline were prepared and characterized, the infrared bands for the room-temperature forms are given and their particular thermal properties are reported. The thermal analyses were performed mostly in the presence of air, but in some cases an argon atmosphere was used for comparison. The adducts were lost from the principal complex at temperatures varying between 110 and 290°. Intermediate oxygenated complexes were formed in each case at about 400°. The thermal data suggest the standardization of a procedure for the formation of Th(C9H6NO)4.
The cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and mercury(II) complexes of diethyldithiocarbamic acid were prepared and their thermal properties determined by TG, DTA, and high temperature reflectance spectroscopy. It was found that the copper(II), nickel(II), and zinc(II) chelates were completely volatile and thus represent a new class of volatile metal chelates. Vapor pressure measurements were made on four of the metal complexes; heats of vaporization ranged from 9.3±0.2 kcal/mole for Na[Co(DDC)3] to 24.2±0.6 kcal/mole for Zn(DDC)2.
