Advanced Search
Displaying 21-30 on page 3 of 308. Per Page  
  • Adsorption Behavior of Reducing End-Modified Cellulose Nanocrystals: A Kinetic Study Using Quartz Crystal Microbalance
  • Abstract In this work, we studied the adsorption of modified cellulose nanocrystals onto solid surfaces by quartz crystal microbalance with dissipation monitoring (QCM-D). Cellulose nanocrystals obtained from tunicate (CNC) were modified at reducing end by amidation reactions. Two different functionalities were investigated: a polyamine dendrimer (CNC-NH2), which interacts with gold surface by the amine groups; and a biotin moiety (CNC-Biot), which has a strong affinity for the protein streptavidin (SAV). QCM-D results revealed different adsorption behaviors between modified and unmodified CNCs. Hence, unmodified CNCs covered almost all the surface forming a rigid and flat layer whereas reducing end modified CNCs remained…
  • More
  •   Views:351       Downloads:195        Download PDF
  • Mechanical Properties and Stress Strain Relationship Models for Bamboo Scrimber
  • Abstract In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique, a large quantities of experiments have been carried out. Based on the analysis of the test results, the following conclusions can be drawn. Two main typical failure modes were classified for bamboo scrimber specimens both under tension parallel to grain and tension perpendicular to grain. Brittle failure happened for all tensile tests. The slope values for the elastic stages have bigger discreteness compared with those for the specimens under tensile parallel to grain. The failure modes for bamboo…
  • More
  •   Views:1148       Downloads:836        Download PDF
  • Thermally Reversible, Self-Healing Polyurethane Based on Propyl Gallate and Polyurethane Prepolymers with Varied Isocyanate Content
  • Abstract Thermosetting polyurethanes are widely used in various fields owing to their excellent elasticity, strength and solvent resistance. Three environmental friendly propyl gallate-based self-healing polyurethanes were prepared from polyurethane prepolymers with varying isocyanate content. The thermal stabilities of the polyurethanes were tested using thermogravimetric analysis. Their self-healing and mechanical properties were analyzed using a universal testing machine and dynamic thermomechanical analysis. The polyurethanes were found with high self-healing ability and excellent mechanical properties due to the absence of phenolic carbamate. These qualities improved with increased isocyanate content and the prolonged selfhealing time. We found, therefore, that the propyl gallate-based polyurethane has…
  • More
  •   Views:310       Downloads:327        Download PDF
  • Effect of Acetylation on the Mechanical and Thermal Properties of Soy Flour Elastomers
  • Abstract Biobased fillers were utilized as components in soy-elastomer composites. Soy flour is lightweight, low cost, and high strength, which makes it an ideal alternative to petroleum-derived fillers. However, poor interfacial adhesion and low dispersion within the polymer matrix are limiting factors for composite performance. Soy flour chemically pretreated by acetylation was compounded with synthetic rubber elastomers. In general, soy flour (as received) concentration in the composite is proportional to the ultimate strength. However, soyelastomer composites with acetylated filler performed similar to the neat elastomer. In addition, the pretreated composite’s thermal stability increased and exhibited less phase seperation compared to the…
  • More
  •   Views:113       Downloads:72        Download PDF
  • Biodegradability of Polyethylene/Hydrolyzed Collagen Blends in Terrestrial and Marine Environmental Conditions
  • Abstract In this study, blends of low-density polyethylene (PE) containing 20 wt% of hydrolyzed collagen (HC) from the leather industry were processed by the film blowing technique. A biodegradation study of these innovative materials was performed by two different biodegradation tests, one in terrestrial environment, the other one under aquatic conditions. Degradation rates were determined for both systems and an environmental degradability parameter was calculated. The results proved the positive influence of hydrolyzed collagen on degradation of polyethylene, but also showed a relatively low biological degradability of PE/HC blends under the applied test conditions.
  • More
  •   Views:105       Downloads:89        Download PDF
  • Study on Residual Stresses in Unidirectional Flax Fiber/ Vinyl Ester Composites by XRD Technique
  • Abstract The development of flax fiber reinforced polymer composites with improved properties has been increasingly studied by many researchers because of their sustainability. However, the effects of thermal residual stresses on the interfacial properties of flax composites have not been evaluated or very well understood. In this study, the thermal properties of flax, vinyl ester matrices and their composites were accessed by different techniques, including thermomechanical analyzer, dynamic mechanical analyzer, and X-ray diffraction combined with aluminum particles. The effects of thermal properties of flax fibers and vinyl ester resin systems on the mechanical properties of their biocomposites were studied. The theory…
  • More
  •   Views:81       Downloads:83        Download PDF
  • Examination of a Biobased Carbon Nucleating Agent on Poly(lactic acid) Crystallization
  • Abstract This article assesses the performance of a biobased carbon as a nucleator using common techniques to stimulate poly(lactic acid) crystallization and enhance the thermal stability of PLA during injection molding. The combination of a biodegradable plasticizer, poly(ethylene glycol) (PEG), along with biobased carbon-rich pyrolyzed biomass char residue and an industrially available microcrystalline talc, were tested for nucleating agent capabilities at additions of 10 wt%. Differential scanning calorimetry (DSC) data demonstrated that the inclusion of the plasticizer could increase the PLA crystalline content with further improvements when nucleating agent was present. With a higher mold temperature, the PLA crystallinity surpassed 40%…
  • More
  •   Views:104       Downloads:90        Download PDF
  • Cardboard-Based Packaging Materials as Renewable Thermal Insulation of Buildings: Thermal and Life-Cycle Performance
  • Abstract Cardboard-based packaging components represent a material that has significant potential as a renewable source for exploitation in buildings. This study presents the results of thermal and environmental analyses of existing packaging materials compared with standard conventional thermal insulations.
    Experimental measurements were performed to identify the thermal performance of studied cardboard packaging materials. Real-size samples were experimentally tested in laboratory measurements. The thermal resistance and conductivity of all the analyzed samples were measured according to the procedure indicated in the ISO8032 standard. A life-cycle assessment according to ISO 14040 was also performed to evaluate the environmental impacts related to the…
  • More
  •   Views:93       Downloads:83        Download PDF
  • Synthesis of Novel Biobased Polyol via Thiol-Ene Chemistry for Rigid Polyurethane Foams
  • Abstract The objective of this research is to prepare rigid polyurethane (PU) foams from α-phellandrene, a biobased compound. Two types of polyols were synthesized by reacting α-phellandrene with 2-mercaptoethanol and α-thioglycerol via thiol-ene chemistry route. The completion of the reaction was identified by using FTIR. PU foams from α-phellandrene polyols and commercial polyol were compared with regard to foam characteristics and properties. All the PU foams showed apparent density of 28–39 kg/m3 with closed-cell content above 90%. The highest glass transition temperature of 229 °C and compressive strength of 220 kPa were observed for the polyol synthesized by reacting α-phellandrene and…
  • More
  •   Views:82       Downloads:82        Download PDF
  • Pretreatment of Wheat Bran for Suitable Reinforcement in Biocomposites
  • Abstract Wheat bran, abundant but underutilized, was investigated for its potential as a reinforcement in biocomposites through different pretreatment methods. Pretreatment methods included were dilute sodium hydroxide (NaOH), dilute sulfuric acid (H2SO4), liquid hot water (LHW), calcium hydroxide (CaOH), organosolv such as aqueous ethanol (EtOH), and methyl isobutyl ketone (MIBK). Changes in chemical composition and fiber characteristics of the treated bran were studied using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Cellulose content increased to 35.1% and 29.6% in brans treated with H2SO4 and NaOH, respectively. The SEM micrographs showed surface cleaning of treated bran while maintaining sufficient…
  • More
  •   Views:101       Downloads:75        Download PDF
Displaying 21-30 on page 3 of 308. Per Page