Highly Hydrophobic Organosilane-Functionalized Cellulose: A Promising Filler for Thermoplastic Composites

The aim of this work is to design and optimize the process of functionalization of cellulose fibers by organosilane functional groups using low-pressure microwave plasma discharge with hexamethyldisiloxane (HMDSO) precursor in order to prepare a compatible hydrophobic filler for composites with nonpolar thermoplastic matrices. Particular attention was paid to the study of agglomeration of cellulose fibers in the mixture with polypropylene. In our contribution, the dependence of the surface wettability on used process gas and treatment time was investigated. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses were applied to characterize the surface morphology and chemical composition of the cellulose fibers. It was observed that the plasma treatment in oxygen process gas led to the functionalization of cellulose fibers by organosilane functional groups without degradation. In addition, the treated cellulose was highly hydrophobic with water contact angle up to 143°. The use of treated cellulose allowed to obtain a homogeneous mixture with polypropylene powder due to the significantly lower tendency of the functionalized cellulose fibers to agglomerate.

Preparation of Polypropylene Powder by Dissolution-Precipitation Method for Selective Laser Sintering

Polypropylene (PP) powder with spherical morphology and suitable particle size for selective laser sintering (SLS) was successfully produced by dissolution-precipitation method. The influence of preparation condition on properties of PP powder was investigated. The experimental results show that the optimal preparation conditions are as follows: dissolution temperature being about 166°C, pressure being about 0.7MPa, and the solid-to-solvent ratio being about 0.067g/ml. The prepared PP powder displayed a narrow size distribution with the mean size of about 42.7μm and the apparent density of powder about 0.40 g/cm3. The specimens produced by laser sintering of the PP powder showed smooth appearance and good dimensional accuracy. The tensile strength and impact strength of the sintered parts were 27.9MPa and 6.3KJ/m2, respectively, which are basically equal to the properties of the injection molded parts.

Preparation of SLS Polypropylene Powder by Solvent Method

The application of solvent method in the preparation of polypropylene powders was investigated, including the influence of various technological conditions, such as the raw material melt index of polypropylene, processing temperature, dosage of the solvent and the packing pressure. The experimental data show that using solvent method can effectively produce polypropylene powder, and the optimal technological conditions are: melt index of polypropylene being about 17.8 g/10min, processing temperature being about 166.0 ℃, dosage of the solvent being about 0.067g/ml and the packing pressure being about 0.7MPa.Under this technological conditions, polypropylene powder with excellent sphericity could be prepared, the apparent density of powder can reach 0.40 g/cm3 and the prepared powder displayed a narrow size distribution with the mean size of about 42.7 µm.

Cold Air Plasma To Decontaminate Inanimate Surfaces of the Hospital Environment

ABSTRACTThe hospital environment harbors bacteria that may cause health care-associated infections. Microorganisms, such as multiresistant bacteria, can spread around the patient's inanimate environment. Some recently introduced biodecontamination approaches in hospitals have significant limitations due to the toxic nature of the gases and the length of time required for aeration. This study evaluated thein vitrouse of cold air plasma as an efficient alternative to traditional methods of biodecontamination of hospital surfaces. Cultures of methicillin-resistantStaphylococcus aureus(MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum-β-lactamase (ESBL)-producingEscherichia coli, andAcinetobacter baumanniiwere applied to different materials similar to those found in the hospital environment. Artificially contaminated sections of marmoleum, mattress, polypropylene, powder-coated mild steel, and stainless steel were then exposed to a cold air pressure plasma single jet for 30 s, 60 s, and 90 s, operating at approximately 25 W and 12 liters/min flow rate. Direct plasma exposure successfully reduced the bacterial load by log 3 for MRSA, log 2.7 for VRE, log 2 for ESBL-producingE. coli, and log 1.7 forA. baumannii. The present report confirms the efficient antibacterial activity of a cold air plasma single-jet plume on nosocomial bacterially contaminated surfaces over a short period of time and highlights its potential for routine biodecontamination in the clinical environment.

Glass Fiber Functional Warp Sizing

The sizing agent is made by polypropylene powder in blending method and then sizing the warp with it. The result of its sizing performance shows that the sizing capacity of the newly made sizing agent could meet the requirement of waving property compared with the traditional sizing agent. The composite material is made by Glass fiber texturized yarn cloth as reinforce materials after the weaving is completed. And, subsequently, test the properties of the composite material. Result shows that the properties of the composite material which is processed by polypropylene powder slurry have been improved, compared with the composite material processed by traditional slurry. The use of new slurry can remove the calcine process. Therefore, it will save energy and reduce the pollution.