Wood-plastic composites as promising green-composites for automotive industries!

Environmentally beneficial composites can be made by replacing glass fibres with various types of cellulose fibres. Fibres from pine or eucalyptus wood and also one-year crops such as coir, sisal, etc. are all good candidates. The poor resistance towards water absorption is one of the drawbacks of natural fibres/polypropylene composites. New natural fibres/polypropylene composites were made and the water absorption in them was studied by immersion of the composites in water at three different temperatures, 23, 50 and 70 °C. The process of absorption of water was found to follow the kinetics and mechanisms described by Fick's theory. In addition, the diffusivity coefficient was dependent on the temperature as estimated by means of Arrhenius law. A decrease in tensile properties of the composites was demonstrated, showing a great loss in mechanical properties of the water-saturated samples compared to the dry samples. The morphology change was monitored by scanning electron microscopy studies of the samples before and after exposure to water and the devastating effect of water on the fibre structure was shown.

Comparison of water absorption in natural cellulosic fibres from wood and one-year crops in polypropylene composites and its influence on their mechanical properties

Short natural-fibre reinforced polyethylene and natural rubber composites: Effect of silane coupling agents and fibres loading

The effect of processing temperature on the interfacial adhesion, mechanical properties and thermal stability of bio-flour-filled, polypropylene (PP) composites was examined as a function of five different maleic anhydride-grafted PP (MAPP) types. To investigate the effect on the interfacial adhesion of the composites, the five MAPP types were subjected to characterization tests. The MAPP-treated composites with sufficient molecular weight and maleic anhydride (MA) graft (%) showed improved mechanical and thermal stability. The enhanced interfacial adhesion, and mechanical and thermal stability of the MAPP-treated composites was strongly dependent on the amount of MA graft (%) and the MAPP molecular weight. The morphological properties of the MAPP-treated composites showed strong bonding and a paucity of pulled-out traces from the matrix in the two phases. In addition, the improved interfacial adhesion of the MAPP-treated composites was confirmed by spectral analysis of the chemical structure using attenuated total reflectance (FTIR-ATR). The crystallinity of PP, MAPP, MAPP-treated composites and non-treated composites was investigated using wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC).

The effect of types of maleic anhydride-grafted polypropylene (MAPP) on the interfacial adhesion properties of bio-flour-filled polypropylene composites

hydrogen, transferring the radical site to a tertiary carbon atom of an other macromolecule or that of its own chain. The intermolecular radical transfer of 2 is followed by the β-scission reaction drawn in Scheme 12.3, resulting in a vinyl terminal group 3 and reproducing 2. This chain reaction produces n-propyl and 2-methylvinylene terminal groups in the fragments, which can be isoalkanes, 1-isoalkenes (oligomers) and α, ωisoalkadienes. The series of peaks above pentamer represent these fragment compounds in the pyrogram of PP in Figure 12.2. The considerably superior yield of trimer, tetramers and pentamers to that of the larger oligomers indicates the contribution of another reaction. Intramolecular radical transfer of a secondary macroradical to a tertiary carbon atom of its own chain leads to these oligomers, drawn in Scheme 12.5. The two possible directions of β-scission explain the occurrence of n-pentane among the wholly isoalkanoic products of PP. In the pyrolysis process of PP the intramolecular radical transfer is preferred to the intermolecular one, thus the low oligomer formation predominates. Consequently the pyrolysis oil of PP is much more volatile than that of PE, decomposing mainly through intermolecular radical transfer. The difference of the backbone structure of the products of these polymers is more important from the point of view of fuel properties. The isoalkanoic structure of PP is held in the thermal decomposition products, in this way the octane number of the pyrolysis oil might be high. In a batch reactor [26] the gasoline fraction (44–220◦C) of the pyrolysis oil obtained from 100 g PE and PP mixture at 440◦C has an octane number of 88.6 with 5.6 wt% aromatic content, and the diesel oil (151–347◦C boiling point range) had 56◦C ignition temperature, −4◦C cloud point and a cetane index of 59.5. Pyrolysing waste PP in an 1 L autoclave at 430◦C for 20 min

Feedstock recycling and pyrolysis of waste plastics : converting waste plastics into diesel and other fuels

Assessment of thermal and thermo-oxidative stability of multi-extruded recycled PP, HDPE and a blend thereof

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 i ...

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

Quality-determination of recycled plastic packaging waste by identification of contaminants by GC–MS after microwave assisted extraction (MAE)

Methods for the determination of the composition of two binary blends in mixtures of recycled polymeric materials were analyzed and compared. Recycled polypropylene/polyethylene (PP/HDPE) and recycled poly(acryl-butadiene-styrene) and polypropylene(ABS/PP) were used to develop and validate the methods. Diffuse reflectance near infrared spectroscopy (NIRS) offers high sensitivity and ease of operation and a possibility to perform multivariate data analysis. In comparison, differential scanning calorimetry (DSC) and Mid-IR, which are commonly used for this purpose require certain sample preparation and are indeed time consuming. In addition, the low sensitivity of these two methods to concentrations lower than 1% wt makes their application in quality control of recycled polymers inappropriate. NIR can be used for estimating the composition of the recyclate on-line in only a few seconds, no sample preparation is required, and high precision is achieved. We obtained a root mean square error of prediction (RMSEP) equal to 0.21% wt in the interval from 0-15% wt of PP in HDPE and a RMSEP equal to 0.91% wt in the interval 0-100%. For blends of PP/ABS a RMSEP of 0.74% wt in the range 0-100% and 0.32% wt in the range 0-15% wt PP was calculated. Most of the variation in the spectral data with respect to the polymer blend composition for all the studied blends were explained by two principal components (PC). The optimal number of factors (PC) was determined by cross-validation analysis.

NIR, DSC, and FTIR as quantitative methods for compositional analysis of blends of polymers obtained from recycled mixed plastic waste

The effects of moisture on the morphology and mechanical properties of polyamides have been extensively studied by a number of researchers. However, the assessment of water content in the resins has been carried out by thermal or thermogravimetric methods, which are destructive. In the present work partial least-squares (PLS) calibration models based on near-infrared (NIR) spectroscopy were produced in order to predict the moisture content of nylon 6,6. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the loss-on-drying (LOD) method were used as reference methods. TGA, LOD, DSC, and NIR analysis were performed in parallel, and the obtained data were used for multivariate calibration purposes. Data pretreatment techniques such as derivation and multiplicative scattering correction (MSC) successfully eliminated the baseline offset present in the raw spectra and compensated for differences in thickness and light scattering of the analyzed samples. Calibration models were validated by full cross validation with the help of a test set. A comparison of the prediction ability of PLS models based on pretreated data was also done. NIR spectroscopy is a rapid and nondestructive method for the determination of moisture in recycled nylon. The moisture content can be predicted with a RMSEP = 0.05 wt %.

http://anvalllu.webs.upv.es/papers/2003/2003_Determination%20of%20moisture%20content%20in%20nylon%206,6%20by%20near-i.pdf

Walker Camacho

Papers

Assessment of thermal and thermo-oxidative stability of multi-extruded recycled PP, HDPE and a blend thereof

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

Quality-determination of recycled plastic packaging waste by identification of contaminants by GC–MS after microwave assisted extraction (MAE)

NIR, DSC, and FTIR as quantitative methods for compositional analysis of blends of polymers obtained from recycled mixed plastic waste

Determination of moisture content in nylon 6,6 by near-infrared spectroscopy and chemometrics