Cellulose - In this work, composites of ultra high molecular weight polyethylene (UHMWPE) and various loadings of cellulose nanocrystals (CNCs) were prepared exploiting different methods. Besides,... 相似文献
The system formed by a polypropylene containing random low ethylene content (EP copolymer) of and a hydrogenated hydrocarbon resin (HR) is investigated in order to study the influence of resin (up to 20% in wt) on properties of blends and derived films. The random EP copolymer used is MoplenEP2C37F and the resin is MBG273 of Hercules Chemical Co. DSC and DMTA analyses of the blends show increase of Tg with resin content indicating that the two components are compatible in the amorphous phase. WAXD spectra show that MBG273 influences slightly the crystalline structure of EP copolymer. In fact the diffractograms of the EP copolymer and 95/5 blend present, beside the predominant peak of α form, also a small span denoting presence of γ form; this span is not detectable on spectra of 90/10 and 80/20 samples. The crystallization during the cooling is found to be only lightly delayed by the HR: in fact, only 4 degrees is the difference between the Tc values of EP copolymer and 80/20 blend. Stress-strain test performed at room temperature show that MBG273 induces increase of Young's modulus and small decrease of elongation at break as function of resin content. An important effect is on the water vapour permeability, which decreases with resin content. The permeability and tensile properties are related to the increase of the glass transition with the addition of MBG273 that transforms gradually the amorphous of the material from rubbery to glassy. The results reported in this work indicate that an addition of 5–10% of MBG273 changes favourably properties, as Young' modulus and water vapour permeability, of an EP copolymer designed for the production of films for packaging application. 相似文献
The isothermal crystallization behavior and the structure and morphology of isotactic poly(propylene) (iPP) and iPP/hydrogenated hydrocarbon resin (HR) 90/10 blend were analyzed. To cover the entire temperature range, isothermal crystallizations were studied using superfast calorimetry at a high cooling rate in the range 0 to 110 °C, and by conventional DSC at a low cooling rate in the range 120 to 140 °C. Structural and morphological changes due to the different thermal treatments were also analyzed. The complete crystallization curve ranging from Tg to Tm showed bimodal crystallization behaviors for both iPP and iPP/HR 90/10 blend. This result is explained by taking into consideration the polymorph properties of iPP. It is in fact assumed that the curve from Tg to 60 °C referred mainly to the crystallization kinetics of the iPP mesomorphic form by homogeneous nucleation, whereas the curve from 60 °C to Tm mainly represented the crystallization kinetic curve for the monoclinic α form by heterogeneous nucleation. This hypothesis is confirmed by the analysis of the structures obtained using wide angle X‐ray experiments. Moreover, the addition of HR to iPP causes a drastic reduction in the crystallization rate of iPP in both regions due to the diluent effect of the miscible resin.