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Magnesium hydroxide sulfate whisker (MHSH) was used as flame-retarded synergistic agent of intumescent flame retardant (IFR), and to prepare flame-retarded PBS composites. The mechanical performance and flame-retardant properties of composites were investigated. Experimental data showed that an appropriate MHSH loading favored the mechanical performance and flame-retardant properties of composites. When IFR and MHSH loadings were 23 and 2 wt%, respectively, the limited oxygen index value of 39.8% and UL-94 V0 rate of composite could be achieved. The tensile strength increased by 33.3% in comparison with that of composite only prepared by 25 wt% IFR. XRD analysis indicated that the addition of MHSH significantly increased the crystallization of composites. FT-IR analysis demonstrated that P-O-Mg-O-P bonds could be generated during pyrolysis process. TG and cone calorimeter analyses both indicated that the incorporation of MHSH and IFR lowered the flammability of composites by limiting heat and mass transfer. Based on the experimental and analyses data, especially the SEM analysis, possible mechanism was proposed. The combustion products of MHSH and IFR provided a flame shield during combustion process. MHSH played a reinforcement effect in the shield. A more stable three-dimensional intumescent charred layer could not only effectually prevent the melt from dripping but also hinder the diffusion of oxygen and heat into the interior substrate. [ABSTRACT FROM AUTHOR]

Bleached bagasse pulp was pretreated with dilute alkali and xylanase enzymes before isolation of microfibrillated cellulose using ultra-high friction grinding and high-pressure homogenization. The isolated nanofibers were used with chitosan polymer to prepare chitosan nanocomposites by solution casting at nanofiber loading from 2.5 to 20%. The effect of nanofibers loading on moisture sorption, dry and wet tensile strength, crystallinity, thermal stability, and dynamic mechanical thermal properties was studied using tensile testing, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). Nanocomposites with good transparency were obtained at the different nanofibers loadings. Chitosan nanocomposites made using nanofibers isolated from bagasse fibers treated with xylanase or alkali showed higher dry and wet tensile strength than those made using nanofibers isolated from untreated bagasse pulp. DMTA results showed higher storage modulus and indicated higher glass transition temperature for the chitosan nanocomposites than that of neat chitosan. XRD patterns showed that, at low nanofibers loading, addition of bagasse nanofibers to chitosan matrix increased ordering of chitosan chains upon drying the nanocomposites films. [ABSTRACT FROM AUTHOR]

The structure-property relationship between a biaxially oriented film from poly(ethylene terephthalate) and its fracture behaviour measured using the Trouser Tear method, has been explored. X-ray diffraction (XRD) was used to characterise the orientation distribution of crystalline and non-crystalline material in the plane of the film and compared with the fracture energy, Gc measured in four directions during tearing. The fracture energy averaged over the four directions ranged between 12 and 25 kJ m-2, and was found to correlate closely to the draw ratio during manufacture and therefore the degree of molecular orientation. However the individual values of Gc displayed a further level of complexity. The expected anisotropic character of the fracture energy was found to change systematically as a function of position across the original width of manufactured film. This feature compared well with the underlying, crystalline orientation distribution and provided strong evidence that under the mode III deformation of the tear test, the fracture mechanism involves the amorphous-crystallite surface boundary. Further support for this mechanism was provided by a simple model which, based on this assumption was shown to predict reliably, the anisotropic character of the film. [ABSTRACT FROM AUTHOR]