Influence of Glycidyl Methacrylate Grafting on the Mechanical, Water Absorption, and Thermal Properties of Recycled High-Density Polyethylene/Rubber Seed Shell Particle Composites

Rubber seed shell (RSS) was modified by grafting treatment using glycidyl methacrylate (GMA) at various concentrations. The RSS was then used to reinforce high-density polyethylene (HDPE). The effects of modification on the mechanical, water absorption, and thermal properties of the RSS/HDPE composites were studied using a mechanical testing instrument, weighing method, Vicat softening temperature (VST) testing, thermogravimetry, and dynamic mechanical analysis. The results showed that the GMA grafting produced an improvement in the flexural and tensile properties of the composites. The water absorption rate of the composites also had an obvious decrease. While a slight increase in VST was found, the various concentrations of GMA showed no improvement in VST. GMA modification also could elevate the thermal stability of the composites at the initial decomposition stage. The optimum grafting concentration of GMA (2.5%) led to the lowest thermal weight loss (37.07% and 26.56%) during the first and second decomposition stages. The E’ values of the composites had a significant increase with the addition of GMA. There were two peaks of tan δ for the untreated samples, but the modified samples exhibited a shift in the transition peak at higher temperatures; moreover, the second peak disappeared

Algal Decay Resistance of Conventional and Novel Wood-Based Composites

Measures of the resistance to algal decay of conventional (medium density fiberboard [MDF] and plywood) and novel wood-based composites (WPC) were investigated in the same or varying wood species by using an artificial accelerated test with four mixed algal suspensions (Chlorella vulgaris, Ulothrix sp., Scenedesmus quadricauda, and Oscillatoria sp.). The morphology characterization of the surface and fracture of the specimens was analyzed using scanning electron microscopy (SEM) and a digital instrument. The pH value and the mass loss rate of the different wood species were also tested. The results showed that the algal resistance of the MDF and plywood were superior to that of the WPC of the same wood species. Furthermore, the algal resistance capacity of WPC made from various wood species were ranked as: Liquidambar formosana > Cunninghamia lanceolata and Melaleuca leucadendra > Ricinus communis > Eucalyptus grandis × E. urophylla and Pinus massoniana. There was a close relationship between the pH value and the algal resistance level; as the pH value increased, the alga resistance of the WPC also increased. The algal colonization only had a negative effect on the appearance of the samples

Effects of Natural Chitosan as Biopolymer Coupling Agent on the Pyrolysis Kinetics of Wood Flour/ Polyvinyl Chloride Composites

The thermal degradation behavior and pyrolysis kinetic models of wood flour (WF)/PVC composites before and after adding chitosan were studied using thermogravimetry (TGA) and nine common kinetic model functions (f(α)). The results indicated that the thermal degradation temperature of WF/PVC composites was delayed to a higher value after adding chitosan. The first-order reaction order (L1) model and second-order reaction order (L2) model were found to be the best reaction order functions for the description of mass loss kinetics of WF/PVC without chitosan during the first and second stages. Two L2 models were suitable for both degradation stages of WF/CS/PVC. Activation energy (E) and frequency factor (A) for WF/PVC and WF/CS/PVC corresponded to 26.05 kJ·mol-1, 4.08×103 s-1, and 40.89 kJ·mol-1, 2.11×1010 s-1 at the first degradation stage, respectively, and 97.83 kJ·mol-1, 1.11×107 s-1 and 92.88 kJ·mol-1, 1.56×1011 s-1 at the second degradation stage

The Influence of Environmentally Friendly Plasticizer on the Bio-Durability of Wood Plastic Composites

The influence of epoxidized soybean oil (ESO) plasticizer on the mould and algal resistances of wood plastic composites (WPCs) was studied using artificial accelerated tests. The macro- and micro-morphology of the colonization of algae and mould on the surface and fracture morphology of the WPCs samples were observed by digital camera and scanning electron microscopy (SEM). The water absorption and thickness swelling rates of different WPCs specimens with various addition amounts of ESO were also tested. The results indicated that as more of the ESO was added, the mould or algal resistance became weaker, especially on the surfaces of the specimens, which became harshly colonized when the addition amount of ESO was beyond 15 phr. The colonization speed and intensity of the mould were higher than the algae at the same addition level of ESO and the same testing time. The hyphae and spores of mould, but not algae, were found on the inner fracture layers

Copper-Catalyzed Cascade Reaction via Intramolecular Hydroamination Cyclization of Homopropargylic Amines and Intermolecular Povarov Reaction with Imines

A new one-pot cascade reaction of homopropargylic amines with simple imines is developed in the presence of Cu­(OTf)₂ and affords a series of hexahydro-1<i>H</i>-pyrrolo­[3,2-<i>c</i>]­quinoline derivatives in good to high yields. This reaction proceeds through an intramolecular hydroamination cyclization of homopropargylic amine to generate a highly reactive dihydropyrrole intermediate in situ. It subsequently reacts with imine via an intermolecular inverse-electron-demand aza-Diels–Alder reaction and a 1,3-H shift to give the fused pyrroloquinoline structures, forming two new C–C bonds and one C–N bond and one N–H bond