An Overview of the Potential of UV Modification of Polypropylene

This is the peer reviewed version of the following article: Amintowlieh, Y., Tzoganakis, C., & Penlidis, A. (2016). An Overview of the Potential of UV Modification of Polypropylene. Macromolecular Symposia, 360(1), 96–107, which has been published in final form at https://doi.org/10.1002/masy.201500110. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.UV radiation with a photoinitiator has been utilized to modify polypropylene (PP). Factors affecting solid state photomodification were studied and the optimal processing conditions for formation of three different structures (degraded, long chain branched and crosslinked) in PP were determined. A long radiation time (more than 5 minutes) is required to form long chain branched PP (LCBPP) and this exposure time is even higher for production of crosslinked PP (XPP). Trimethylolpropane triacrylate (TMPTA) was utilized to decrease UV radiation duration. Optimal concentrations of TMPTA and photoinitiator for formation of long chain branched and crosslinked PP were determined. Finally, a setup was suggested for continuous photomodification of PP using a twin screw extruder. In this design, PP strands are irradiated directly after the die. Optimal photoinitiator (benzophenone) concentration, coagent (TMPTA) concentration and radiation time required to form controlled rheology (CRPP) or long chain branched PP or crosslinked PP were identified.Natural Sciences and Engineering Research Council (NSERC) of Canada Canada Research Chair (CRC) progra

Nylon-6/Agricultural Filler Composites

Preparation of thermoplastics composites using engineering thermoplastics and plant fibers or fillers is a technical challenge because the processing temperature of the thermoplastics is generally above the temperature of degradation of plant fibers of fillers. There have been numerous attempts for processing high melting point engineering thermoplastics like Nylon-6 with plant natural fibers and fillers. Low temperature processing methods, fiber modification or addition of additives which drops polymer melting point are some of proposed solutions for this problem. The objective of this thesis was to develop a formulation using wheat straw (WS) as a reinforcing fiber for Nylon-6. The concentration of WS was 15 wt-%. The thermoplastic composites were prepared by mixing grinded wheat straw and Nylon-6 using a laboratory scale twin-screw extruder; follow by preparation of samples using injection moulding. The strategy investigated in this thesis was utilization of additives to lower the melting point or to decrease the viscosity of Nylon-6. Lithium chloride salt (LiCl) and N-Butyl benzene Sulfon amide plasticizer (N-BBSA) were used as process additives to decrease melting point and to reduce the processing temperature and time. The addition of the wheat straw (15 wt-%) to the Nylon-6 increased modulus by 26.9 % but decreased the strength by 9.9 %. Effect of different level of these two additives on mechanical, thermal, physical properties and processability of the composite runs were studied. Addition of 4 wt-% LiCl was found to decrease the melting point from 222 °C to 191 °C, to increase modulus by 14 % in comparison to Nylon-6/wheat straw (15 wt-%). However, it decreased the processability and strength by 12.7 %. Plasticizer was investigated to easing processability and decreasing the degradation by reducing the residence time in the extruder, it does not affect the melting point of Nylon-6. The addition of 4 wt-% of plasticizer (N-BBSA) increased modulus and strength only by 2.6 % and 3 %, respectively, in comparison to Nylon-6/wheat straw (15 wt-%) composites. The results of mechanical properties were used as a benchmark for comparisons among samples with different formulations (levels of additives) to find out levels of LiCl and N-BBSA for the best mechanical properties. It was found that samples with 2 wt-% LiCl and 2 wt-% of N-BBSA had 29.3 % higher tensile modulus than neat Nylon-6, while its strength was almost same as neat Nylon-6 and 6.3 % higher than Nylon-6/WS (15 wt-%). These results were used to correlate the mechanical properties as a function of percentage of salt and plasticizer in the formulation. Differential scanning calorimetry (DSC) was used to evaluate the percentage of crystallinity and the melting point of the thermoplastic phase and thermal gravimetric analysis (TGA) was used to measure the thermal stability of different formulation. The kinetics of crystallization and degradation were evaluated using results from DSC and TGA, respectively. The activation energy for thermal degradation and the percentage of crystallinity of the thermoplastic composites were correlated to mechanical properties using linear regression. It was found that fiber degradation had a significant effect on strength but the effects of percentage of crystallinity on composites strength were insignificant. On the other hand, the percentage of crystallinity affects stiffness and impact strength. The ductility was a function of both crystallinity and thermal stability

Continuous Modification of Polypropylene Via Photoinitiation

This is the peer reviewed version of the following article: Amintowlieh, Y., Tzoganakis, C., & Penlidis, A. (n.d.). Continuous modification of polypropylene via photoinitiation. Polymer Engineering & Science, 55(10), 2423–2432 which has been published in final form at https://doi.org/10.1002/pen.24133 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.A twin screw extruder was used for continuous modification of polypropylene (PP) via UV radiation. Long chain branches were incorporated in the PP backbone to modify its rheological properties. Benzophenone (BPH) as photoinitiator and trimethylolpropane triacrylate (TMPTA) as coagent were utilized during PP photomodification. Radiation was carried out after mixing in the extruder on solid stretched strands with approximately 0.3 mm thickness. The effects of photoinitiator concentration, radiation time and coagent presence were studied via a replicated two-level full factorial design of experiments. It was shown that photomodification of PP can be done continuously. Formation of long chain branches (LCBs) in the experimental runs was confirmed via rheological measurements. Gel content of the samples was also measured. It was found that long chain branches can be formed in PP with and without TMPTA at certain processing conditions. The amount of gel in the samples prepared with TMPTA was higher; however, the gel content could be controlled by manipulating BPH concentration and radiation time.Natural Sciences and Engineering Research Council (NSERC) of Canada Canada Research Chair (CRC) progra

Resposta à flexão e análise de tenacidade de argamassas reforçadas com fibra de Curauá

O desenvolvimento e comercialização de materiais compósitos produzidos a partir de fibras naturais são considerados extremamente importante, uma vez que essas fibras reduzirão a dependência dos materiais produzidos com recursos não renováveis. Dentre essas fibras naturais destaca-se a fibra do curauá, sua utilização na produção de compósitos melhora de forma notável as propriedades do conjunto fibra matriz, logo o presente artigo objetiva estudar as propriedades mecânicas de compósitos reforçados com fibra de curauá, em especial sua resistência à flexão e tenacidade. Para isso foram confeccionadas cinco famílias de argamassas, uma de referência sem utilização da fibra e as outras quatro reforçada com fibra variando o comprimento da fibra e sua fração volumétrica. Verificou-se que a fibra do curauá ao ser adicionada em matriz cimentícia melhora suas propriedades mecânicas comparada a um compósito não reforçado com fibra, sua deformação, resistência à flexão e tenacidade são melhoradas

An Overview of the Potential of UV Modification of Polypropylene

This is the peer reviewed version of the following article: Amintowlieh, Y., Tzoganakis, C., & Penlidis, A. (2016). An Overview of the Potential of UV Modification of Polypropylene. Macromolecular Symposia, 360(1), 96–107, which has been published in final form at https://doi.org/10.1002/masy.201500110. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.UV radiation with a photoinitiator has been utilized to modify polypropylene (PP). Factors affecting solid state photomodification were studied and the optimal processing conditions for formation of three different structures (degraded, long chain branched and crosslinked) in PP were determined. A long radiation time (more than 5 minutes) is required to form long chain branched PP (LCBPP) and this exposure time is even higher for production of crosslinked PP (XPP). Trimethylolpropane triacrylate (TMPTA) was utilized to decrease UV radiation duration. Optimal concentrations of TMPTA and photoinitiator for formation of long chain branched and crosslinked PP were determined. Finally, a setup was suggested for continuous photomodification of PP using a twin screw extruder. In this design, PP strands are irradiated directly after the die. Optimal photoinitiator (benzophenone) concentration, coagent (TMPTA) concentration and radiation time required to form controlled rheology (CRPP) or long chain branched PP or crosslinked PP were identified.Natural Sciences and Engineering Research Council (NSERC) of Canada Canada Research Chair (CRC) progra