title: The effects of alkaline digestion, bleaching and ultrasonication treatment of fibre on 3D printed harakeke fibre reinforced polylactic acid composites

authors: Beg, Mohammad Dalour Hossen

subjects: Biocomposites

abstract: This paper documents an investigation of the effects of fibre treatment on New Zealand flax (harakeke) fibre reinforced polylactic acid (PLA) composites. The raw fibre was alkali digested, followed by bleaching and then modified with ultrasonication. Alkali treatment removed lignin and other non-cellulosic components and partially separated fibre bundles while bleaching further removed lignin and improved the separation of elementary fibres, resulting in microfibres with a cellulose content 92 wt%. With subsequent ultrasonication, microfibrils could be seen partially separated (defibrillation) at fibre surfaces. Treated fibres were compounded with PLA at a fibre loading of 30 wt% and extruded into composite filaments. Filaments from alkali, bleached and ultrasonication-treated fibres had smooth surfaces, which translated into high-quality printability along with good mechanical performance. The combination of chemically treated microfibres with selective surface defibrillation using ultrasonication and fibre alignment induced by the printing process resulted in 3D printed samples with a tensile strength of 79 MPa and Young’s modulus of 8.7 GPa, which are the highest values reported so far for 3D printed PLA-based composites reinforced with short fibres.

text: The effects of alkaline digestion, bleaching and ultrasonication treatment of fibre on 3D printed harakeke fibre reinforced polylactic acid composites This paper documents an investigation of the effects of fibre treatment on New Zealand flax (harakeke) fibre reinforced polylactic acid (PLA) composites. The raw fibre was alkali digested, followed by bleaching and then modified with ultrasonication. Alkali treatment removed lignin and other non-cellulosic components and partially separated fibre bundles while bleaching further removed lignin and improved the separation of elementary fibres, resulting in microfibres with a cellulose content 92 wt%. With subsequent ultrasonication, microfibrils could be seen partially separated (defibrillation) at fibre surfaces. Treated fibres were compounded with PLA at a fibre loading of 30 wt% and extruded into composite filaments. Filaments from alkali, bleached and ultrasonication-treated fibres had smooth surfaces, which translated into high-quality printability along with good mechanical performance. The combination of chemically treated microfibres with selective surface defibrillation using ultrasonication and fibre alignment induced by the printing process resulted in 3D printed samples with a tensile strength of 79 MPa and Young’s modulus of 8.7 GPa, which are the highest values reported so far for 3D printed PLA-based composites reinforced with short fibres.

year: 2023-03

title: Fatigue, work-rest cycles, and psychomotor performance of New Zealand truck drivers

authors: Charlton, Samuel G.

subjects: New Zealand

abstract: The goal of the present research programme was to find out how common driver fatigue is among New Zealand truck drivers and the degree to which they suffer from fatigue-related effects on their driving performance. To that end, 606 truck drivers were tested at a variety of sites throughout the North Island of New Zealand. The results showed that a considerable number of drivers are operating in excess of the hours of service regulations. The three fatigue measures in our survey indicated that there are significant levels of fatigue in the New Zealand transport industry. One out of four of the drivers' self-ratings of fatigue were in the "tired" range, even though many of them were surveyed at the beginning of their shift. A psychomotor test also indicated a very high level of fatigue in the sample. Overall, 24% of the sample failed the psychomotor performance criteria. Amount of rest and sleep, shift length, and number of driving days per week were all significantly related to psychomotor performance. The results of the daytime sleepiness inventory showed that the drivers in our sample had somewhat higher levels of daytime sleepiness than do heavy goods vehicle drivers in Great Britain. There was significant correspondence between drivers' self-ratings, psychomotor performance, and daytime sleepiness fatigue measures.

text: Fatigue, work-rest cycles, and psychomotor performance of New Zealand truck drivers The goal of the present research programme was to find out how common driver fatigue is among New Zealand truck drivers and the degree to which they suffer from fatigue-related effects on their driving performance. To that end, 606 truck drivers were tested at a variety of sites throughout the North Island of New Zealand. The results showed that a considerable number of drivers are operating in excess of the hours of service regulations. The three fatigue measures in our survey indicated that there are significant levels of fatigue in the New Zealand transport industry. One out of four of the drivers' self-ratings of fatigue were in the "tired" range, even though many of them were surveyed at the beginning of their shift. A psychomotor test also indicated a very high level of fatigue in the sample. Overall, 24% of the sample failed the psychomotor performance criteria. Amount of rest and sleep, shift length, and number of driving days per week were all significantly related to psychomotor performance. The results of the daytime sleepiness inventory showed that the drivers in our sample had somewhat higher levels of daytime sleepiness than do heavy goods vehicle drivers in Great Britain. There was significant correspondence between drivers' self-ratings, psychomotor performance, and daytime sleepiness fatigue measures.

year: 2006

title: Ko ngōku maumaharatanga i ahau i Te Whare Wānanga o Waikato

authors: Papesch, Te Rita

subjects: Tohu maumahara

abstract: Kua huri te rima ngahuru o ngā tau kua tū Te Whare Wānanga hei whakaruruhau mō rātou ka kuhu ki ngōna kuaha. Ko taku tāne tuatahi me taku tungāne pakeke ake i ahau ngētehi o ngā akonga tuatahi, ā, e maumahara ana ahau i tētehi wā i tae atu ahau ki reira ki te tiki i a rāua i waho tonu i te whare pukapuka. I taua wā ko A Block tērā, te wāhi e tū nei Te Puawānanga-ki-te Ao ināianei. Ko te Cowshed tonu te wāhi whakahaere i Te Whare Wānanga. Ka mīharo i tōna rerekētanga i ngēnei wā!

text: Ko ngōku maumaharatanga i ahau i Te Whare Wānanga o Waikato Kua huri te rima ngahuru o ngā tau kua tū Te Whare Wānanga hei whakaruruhau mō rātou ka kuhu ki ngōna kuaha. Ko taku tāne tuatahi me taku tungāne pakeke ake i ahau ngētehi o ngā akonga tuatahi, ā, e maumahara ana ahau i tētehi wā i tae atu ahau ki reira ki te tiki i a rāua i waho tonu i te whare pukapuka. I taua wā ko A Block tērā, te wāhi e tū nei Te Puawānanga-ki-te Ao ināianei. Ko te Cowshed tonu te wāhi whakahaere i Te Whare Wānanga. Ka mīharo i tōna rerekētanga i ngēnei wā!

year: 2016