The Mechanical and Thermal Properties of MWCNT/ZnO/Polyethylene Composites

In this paper, multiwall carbon nanotube-ZnO (MWCNT/ZnO) was melt-blended with polyethylene (PE) by a Haake-Buchler Rheomixer. The mechanical properties, thermal stability and dispersion degree of the composite materials was characterized. Differential scanning calorimetry, X-ray diffraction analysis, thermogravimetry, tensile test and SEM were carried out. The results showed that with the addition of MWCNT/ZnO, the crystallinity and thermal degradation temperature of PE changed. 0.2phr MWCNT/ZnO/PE exhibited crystallinity that was 10% higher than PE. With the addition of MWCNT/ZnO, the tensile strength of PE decreased gradually, but the elongation at break increased first and then decreased. When MWCNT/ZnO content is 0.2phr, the elongation at break of the composite is close to 532.21%, which is 116% higher than that of pure PE.

Synthesis of a New Phosphorus/Nitrogen Durable Flame Retardant for Cotton Fabrics

Phosphorus/nitrogen flame retardant ammonium three phosphoric acid glycerol ester (FR) with reactive -P-O−NH4+ groups was synthesized from glycerol, phosphoric acid and urea. At high temperature, the -P-O−NH4+ group in FR is decomposed into -P-O−H+ group. Under the action of catalyst dicyandiamide, -P-O−H+ forms phosphonic anhydride. Phosphonic anhydride can dehydrate and condense with the hydroxyl group on the 6-position carbon atom in the glucose ring of cotton fiber, forming a firm P-O-C bond, thus fixing FR molecule firmlyon cotton fiber. XRD suggested that the finishing process only slightly affected the cotton fiber structure and the surface morphology, elemental composition of char residue in cotton fabrics were tested by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Confirmed that FR was grafted well with slight damage to the cotton structure. When the treated cotton with 25.3% weight gain(WG) in FR, the treated cotton has self extinguishing property and passed UL-94 vertical burning V-0 classification, the limiting oxygen index (LOI) was improved from 17.0–40.5%, and the LOI can still reach 30.9% after 50 laundering cycles, the cone calorimetry(CONE) analysis indicated that the peak heat release rate (PHRR) of the treated cotton was reduced from 190.3 kW/m2 to 17.9 kW/m2, and the total heat release (THR) was reduced from 2.8 MJ/m2 to 1.8 MJ/m2, The thermogravimetric(TG) and Differential scanning calorimeter (DSC) showed that the addition of FR inhibited the initial thermal degradation temperature of the treated cotton under heating conditions, and TG showed that the initial thermal degradation temperature of treated cotton in nitrogen and air was 225.9 ℃ and 221.8 ℃, respectively, which was lower than that of untreated cotton. The mechanical properties are in the usable range, which showed that treated cotton had excellent flame retardancy, durability and good flexibility.

Synthesis and characterization of methyltetrahydrophthalic anhydride esterified corn starch by wet method

The main purpose of this paper is to synthesize a novel esterified starch with an alicyclic structure. Herein, methyltetrahydrophthalic anhydride (MeTHPA), an alicyclic anhydride, was used to synthesize esterified corn starch (CS) with different degrees of substitution (DS) by a wet method. Compared with CS, the crystallinity and thermal degradation temperature of MeTHPA esterified CS (MeCS) decreased, while the hydrophobicity and light transmittance of MeCS films increased. The esterification modification significantly improved the toughness of the starch film. Between CS and MeCS films, the 15% Me/CS film shows a maximum elongation at break of 24.2% and a tensile strength of 8.0 MPa. Furthermore, 15% Me/CS was blended with CS as a sizing agent for polyester/cotton blended yarns and showed significantly increased adhesion to the blended yarns. Hence, the CS blended MeCS has a potential application in wrap sizing.

Synthesis of a New Phosphorus/Nitrogen Durable Flame Retardant for Cotton Fabrics

Phosphorus/nitrogen flame retardant ammonium three phosphoric acid glycerol ester (FR) with reactive -P-O−NH4+ groups was synthesized from glycerol, phosphoric acid and urea. At high temperature, the -P-O−NH4+ group in FR is decomposed into -P-O−H+ group. Under the action of catalyst dicyandiamide, -P-O−H+ forms phosphonic anhydride. Phosphonic anhydride can dehydrate and condense with the hydroxyl group on the 6-position carbon atom in the glucose ring of cotton fiber, forming a firm P-O-C bond, thus fixing FR molecule firmlyon cotton fiber. XRD suggested that the finishing process only slightly affected the cotton fiber structure and the surface morphology, elemental composition of char residues in cotton fabrics were tested by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Confirmed that FR was grafted well with slight damage to the cotton structure. When the treated cotton with 25.3% weight gain(WG) in FR, the treated cotton has self extinguishing property and passed UL-94 vertical burning V-0 classification, the limiting oxygen index (LOI) was improved from 17.0–40.5%, and the LOI can still reach 30.9% after 50 laundering cycles, the cone calorimetry(CONE) analysis indicated that the peak heat release rate (PHRR) of the treated cotton was reduced from 190.3 kW/m2 to 17.9 kW/m2, and the total heat release (THR) was reduced from 2.8 MJ/m2 to 1.8 MJ/m2, The thermogravimetric(TG) and Differential scanning calorimeter (DSC) showed that the addition of FR inhibited the initial thermal degradation temperature of the treated cotton under heating conditions, and TG showed that the initial thermal degradation temperature of treated cotton in nitrogen and air was 225.9 ℃ and 221.8 ℃, respectively, which was lower than that of untreated cotton. The mechanical properties are in the usable range, which showed that treated cotton have excellent flame retardancy, durability and good flexibility.

Influence of Starch Content on the Thermal and Viscoelastic Properties of Syndiotactic Polypropylene/Starch Composites

In this study, syndiotactic Polypropylene/Starch (sPP/starch) composites were prepared using a solution mixing technique. The thermal characterization was performed using Differential Scanning Calorimetry (DSC), and the melting point was measured for all polymer composites. The thermal degradation temperature was measured using thermal gravimetric analysis. The viscoelastic measurements were performed using the Atomic Rheometric Expansion System (ARES). Both melting point and thermal degradation temperatures were found to decrease with increasing starch content. Moreover, the elastic modulus was found to decrease when the starch content increased.

Thermogravimetric analysis-based characterization of suitable biomass for alkaline peroxide treatment to obtain cellulose and fermentable sugars

To characterize a suitable biomass for alkaline peroxide treatment, four types of lignocellulosic biomass (rice straw, two Miscanthus spp., and Japanese cypress) were characterized using thermogravimetric analysis. Before the alkaline peroxide treatment, rice straw had the lowest initial thermal degradation temperature and Japanese cypress had the highest. After alkaline peroxide treatment, this trend was reversed, such that the highest initial thermal degradation temperature was for alkaline-peroxide treated rice straw. Hemicellulose and lignin content significantly affected the thermal degradation behavior and alkaline peroxide treatment efficiency. Among the four lignocelluloses, raw rice straw exhibited the highest reducing capability, whereas the treated rice straw exhibited the lowest reducing capability. Surface morphology and crystallinity indicated that when the rice straw was subjected to AP treatment at room temperature for 10 min, crystalline cellulose microfibrils were exposed and concentrated on the surface. Thus, among the samples tested, rice straw was found to be the most suitable biomass for alkaline peroxide treatment.

Low Temperature Dissolution of Yeast Chitin-Glucan Complex and Characterization of the Regenerated Polymer

Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris. Different NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63–68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although the acetylation degree decreased from 61.3% to 33.9–50.6%, indicating that chitin was converted into chitosan, yielding chitosan-glucan complex (ChGC). Consistent with this, there was a reduction of the crystallinity index and thermal degradation temperature. Given these results, this study reports a simple and green procedure to solubilize CGC and obtain aqueous ChGC solutions that can be processed as novel biomaterials.

Thermomechanical Properties of SiC-Filled Polybutylene Succinate Composite Fabricated via Melt Extrusion

Polybutylene succinate (PBS) composites filled with various mass fractions of silicon carbide (SiC) particles were fabricated via slow melt extrusion. The morphological analysis revealed that the fabrication technique assisted in achieving a good adhesion between the PBS and SiC, along with excellent filler dispersion throughout the PBS matrix. The inclusion of 40 wt.% SiC in the PBS composite afforded a 10 °C increase in the thermal degradation temperature and a 160% enhancement in the thermal conductivity relative to the neat PBS. The crystallization temperature also increased with the inclusion of SiC particles, thus making the composites easier to process. Furthermore, the improvement in the Young’s modulus of the PBS composites increased their rigidity and stiffness relative to the neat PBS.