Reactive extrusion of recycled bottle waste material

The objective of this study is to investigate the effect of reactive processing of commingled bottle waste polymer in an extruder. A variety of peroxides and monomers were tested to assess their influence on the final mechanical properties of the product. The reactive extruded polymer blends were prepared in two types of extruders: a co‐rotating twin‐screw extruder and a Buss co‐Kneader single‐screw extruder. Blends were analyzed for mechanical and thermal properties. The effectiveness of the different monomers and peroxides was evaluated in terms of improvement in impact properties. It has been found that the toughness of the polymer blend is improved by reactive processing. Depending on the amount and type of reactants, the impact strength can be improved by 220%, with a slight reduction in the modulus compared to an unmodified physical blend. The most suitable monomers were n‐butylmethacrylate (BMA), t‐butylamino ethylmethacrylate (TBAEMA) and a combination of styrene/maleic anhydride (ST/MAH). The peroxide should have a short half‐lifetime compared to the average residence time in the extruder. The most effective monomers have a high initial reactivity and low rate of evaporation at the processing conditions used. Changes in processing conditions in the extruder influence the reaction conditions and therefore the final properties of the blend. Results were interpreted in terms of residence time, melting profile and peroxide concentration.     

PA/PE回收料的再生改性

通过添加扩链剂KL-E4370、氧化钙和氧化聚乙烯蜡对PA/PE回收料进行扩链、除水和原位生成相容剂的再生改性。结果显示,扩链剂KL-E4370用量为0.7%,氧化钙用量为2%,改性效果最好,添加1%的氧化聚乙烯蜡改善了PA和PE的相容性。     

再生热塑性聚氨酯/聚氯乙烯共混材料性能的研究

通过对再生热塑性聚氨酯与聚氯乙烯共混材料力学性能等的研究,发现当ＴＰＵＲ含量在４０％时具有较好综合性能。     

Fire‐retardant plastic material from oyster‐shell powder and recycled polyethylene

A series of plastic materials from recycled polyethylene (PE) and oyster‐shell powder were prepared to test their fire‐retardant properties with an aim of finding a practical way of waste recycling. Oyster‐shell powder was found to be mainly composed of calcium carbonate and it decomposed to calcium oxide and carbon dioxide at temperature higher than ～800°C, thus preventing fire from access of oxygen by the produced carbon dioxide. This fire‐retardation mechanism is environmental‐friendly, since another available method, the inclusion of halogen‐containing compounds, normally generates toxic chemicals like dioxine during incineration. To improve mechanical properties of this composite material, surface of oyster‐shell powder was coated with cetyltrimethylammonium bromide (CTAB). Flame retardation and the mechanical properties of these composite resins were analyzed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1583–1589, 2006     

Properties of recycled material containing poly(vinyl chloride), polypropylene,and calcium carbonate nanofiller

Even at low content, polypropylene significantly worsens mechanical properties of the recycled PVC composite, i.e. tensile strength at break and elongation at break. But, if small quantities of surface modified nanofiller calcium carbonate is added, an applicable composite that contains 10–30% of waste material can be made. It was determined that nanosized calcium carbonate lowers melting point of polypropylene, perhaps by changing its crystalline form and has no influence on thermooxidative degradation of poly(vinyl chloride). Addition of nanofiller slightly lowers the surface free energy of the composites what is more prone when the low content of polypropylene is present. The recovery of tensile strength and elongation at break occurs and those properties reach the highest value at about 6% of CaCO₃. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Sago starch and its acrylamide modified products as coating material on handsheets made from recycled pulp fibers

This study was carried out to determine the suitability of sago starch as a paper additive. The basic properties (i.e., pH, viscosity, and solid content) of the 5% weight over volume basis of unmodified and modified sago starch (sago starch blended with acrylamide, sago starch grafted with acrylamide in an acidic and adjusted to alkaline conditions) were determined. The starches were then used to coat laboratory handsheets made from recycled pulp fibers. The incorporation of acrylamide into sago starch through grafting significantly reduced the viscosity of the solution. Generally, coating the handsheets with unmodified sago starch significantly improved some properties as compared to the uncoated handsheets. Among the three types of sago starch modification methods, blending gave superior performance when coated on the handsheets, except for smoothness and air permeance, due to insufficient curing shown by the micrographs. FTIR spectra showed that the interactions between the blended acrylamide–starch solutions and the pulp fiber were weak. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 154–158, 2004     

Examples of recycled vinyl products

We describe examples in which we have demonstrated the feasibility of collection, separation, cleaning, and manufacture of several recycled products. We show that vinyl in municipal solid waste can be recycled into bottles, drainage pipe, and drainage pipe fittings with good appearance and properties. We also demonstrate the feasibility that vinyl wire and cable can be recycled into a variety of applications, including wire and cable traffic cones and drainage pipe with good appearance and properties.     

Thermal and thermomechanical properties of biocomposites made from modified recycled cellulose and recycled polypropylene

Residual cellulose fibers from the paper industry have been used as reinforcements in recycled polypropylene (PP) composites. The main obstacle to obtaining good properties with this biocomposite is deficiencies in the compatibility between the nonpolar matrices and the polar cellulose fibers used as reinforcements. The aim of this work was to improve the compatibilization between these cellulose fibers and the PP matrix with four different methods: modification by the addition of polypropylene–maleic anhydride copolymer (PPgMA) during the process of blending, preblending modification of the cellulose with a solution of PPgMA, modification of cellulose by silanes (vinyltrimethoxysilane), and acetylation of cellulose. Blends with all of the differently modified celluloses were prepared with the cellulose content varied up to 40%, and then all of the blends were subjected to thermal (differential scanning calorimetry and thermogravimetric analysis) and thermomechanical (dynamic mechanical thermal analysis) analyses. The results showed that the addition of cellulose fibers improved the thermomechanical behavior of the PP, increasing the value of the log of the dynamic modulus, and affected the thermal and thermooxidative behavior. Moreover, an advantage of the use of a recycled PP containing a small quantity of ethyl vinyl acetate (EVA) as a prime material in the composition was the enhancement of mechanical properties. The use of these methods for the modification of cellulose led to more desirable thermal and thermooxidative stabilities. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2353–2360, 2003     

Clay-bricks from recycled rock tailings

The aim of this work is to optimize the industrial applications of granite and kaolinite rock tailings in ceramics industry. Three rock tailings are selected to be characterized and equally mixed for testing. The samples are characterized using XRD, XRF, polarizing light microscope, cathodoluminescence, X-ray micro-computed tomography (3d-µCT) and SEM microscopy attached with EDAX. The rock tailings mixed batch is non-bloatable and is located in the mullite field on the FeOFe₂O₃-Al₂O₃-SiO₂ phase diagram. In addition to primary mullite, type II secondary mullite of aspect ratio (3-10:1) is characteristic within aluminosilicate glassy matrix. The 3d-µCT shows pores of lower surface area at 1200 °C due mainly to the existence of isolated rounded closed pores. The physical characteristics of the fired batch, at 1200 °C show that it can be used in the manufacture of building clay-bricks.     

Transparency of recycled polypropylene film

Turbidity of quenched polypropylene films was measured as a function of the film thickness and number of times film was recycled. Turbidity τ is defined by τ = (1/d) ln (I_o/I_t), where I_o and I_t are the intensity of the incident and transmitted lights, respectively, and d is the thickness of the sample. We assume here that most of the attenuation of light is due to scattering from superstructure in the film, such as spherulites, since no characteristic absorption bands are present in the wavelength region studied in this work. Turbidity varied sigmoidally with film thickness. It remained constant when the film thickness was lower than ca. 400 μm and then increased with film thickness and reached a plateau around 800 μm. When the film preparation was repeated, turbidity increased exponentially with the number of recycles. The spherulite size, however, was an invariant against the number of recycles and was dependent upon film thickness. The variation of turbidity with film thickness and the number of recycles is discussed.     

Melt filtration of recycled PVC

The separation of PVC from contaminants is one of the most important steps in recycling PVC. Earlier works have shown that one can separate PVC from other polymers by using the X-ray fluorescence technique. However, in many cases, even after careful separation, there is a remaining impurity level of about 0.1% due to the limitations of the separation processes. In many applications, impurities, particularly nonmeltables, cause defects in the PVC matrix and must be removed for best performance and appearance. Melt filtration appears to be the best technique to remove the nonmeltable impurities.