title: Reprocessing of wood fibre reinforced polypropylene composites. Part I: Effects on physical and mechanical properties

authors: Beg, Mohammad Dalour Hossen

subjects: natural fibre composites

abstract: This paper describes the effects of reprocessing on the physical and mechanical properties of composites based on radiata pine (Pinus radiata) fibre in a polypropylene (PP) matrix. Composites, containing either 40 wt% or 50 wt% fibre with 4 wt% maleated polypropylene (MAPP) as a coupling agent, were reprocessed up to eight times. For composites with 40 wt% fibre, tensile strength (TS) and Young’s modulus (YM) were found to decrease with increased reprocessing by up to 25% for TS and 17% for YM (after reprocessed eight times). Flexural tests were also carried out for 40 wt% fibre composites and flexural strength and modulus were found to decrease with increased reprocessing. Although, TS was lower for virgin composites with 50 wt% fibre than for those with 40 wt% fibre, this initially increased with reprocessing by up to 14% (after reprocessed two times), but then decreased with further reprocessing, and an overall 11% reduction of TS was found after reprocessing eight times compared to the virgin composites. YM was higher for virgin composites with 50 wt% than those with for 40 wt% fibre and also initially increased with reprocessing but decreased upon further reprocessing. Reprocessing was found to increase thermal stability. The TS of composites made by combining reprocessed with virgin materials was also assessed.

text: Reprocessing of wood fibre reinforced polypropylene composites. Part I: Effects on physical and mechanical properties This paper describes the effects of reprocessing on the physical and mechanical properties of composites based on radiata pine (Pinus radiata) fibre in a polypropylene (PP) matrix. Composites, containing either 40 wt% or 50 wt% fibre with 4 wt% maleated polypropylene (MAPP) as a coupling agent, were reprocessed up to eight times. For composites with 40 wt% fibre, tensile strength (TS) and Young’s modulus (YM) were found to decrease with increased reprocessing by up to 25% for TS and 17% for YM (after reprocessed eight times). Flexural tests were also carried out for 40 wt% fibre composites and flexural strength and modulus were found to decrease with increased reprocessing. Although, TS was lower for virgin composites with 50 wt% fibre than for those with 40 wt% fibre, this initially increased with reprocessing by up to 14% (after reprocessed two times), but then decreased with further reprocessing, and an overall 11% reduction of TS was found after reprocessing eight times compared to the virgin composites. YM was higher for virgin composites with 50 wt% than those with for 40 wt% fibre and also initially increased with reprocessing but decreased upon further reprocessing. Reprocessing was found to increase thermal stability. The TS of composites made by combining reprocessed with virgin materials was also assessed.

year: 2008

title: The development of multiplicative thinking and proportional reasoning: Models of conceptual learning and transfer

authors: Wright, Vincent John

subjects: proportional reasoning

abstract: This thesis considers the development of multiplicative thinking and proportional reasoning from two perspectives. Firstly, it examines the research literature on progressions in conceptual understanding to create a Hypothetical Learning Trajectory (HLT). Secondly, it surveys modern views of how transfer by learners occurs in and between situations, contrasting object views of abstraction with knowledge in pieces views.
Case studies of six students aged 11-13 years illustrate conceptual changes that occur during the course of a school year. The students are involved in a design experiment in which I (the researcher) co-teach with the classroom teacher. The students represent a mix of gender, ethnicity and level of achievement. Comparison of the HLT with the actual learning trajectory for each student establishes its validity as a generic growth path.
Examination of the data suggests that two models of learning and by inference, transfer, describe the conceptual development of the students. There is consideration of students’ use of anticipated actions on physical and imaged embodiments as objects of thought with a focus on the significance of object creation for conceptual growth, and the encapsulation, completeness and contextual detachment of objects. 
There is broad consistency in students’ progress through the phases of the HTL within each sub-construct though the developmental patterns of individual are variable and temporal alignment across the sub-constructs does not uniformly hold. Some consistency of order effect in concept development is noted. Discussion on the limitations of the HTL includes the difference between knowledge types from a pedagogical perspective, absence of significant model-representation-situation transfer, and order relations in conceptual development.
Considerable situational variation occurs as students solve problems that involve applications of the same concepts. Partial construction of concepts is common. This was true of all learners, irrespective of level of achievement. High-achieving students more readily anticipate actions and trust these anticipations as objects of thought than middle and low achievers. The data supports knowledge in pieces views of conceptual development. Complexity for learners in observing affordances in situations, and in co-ordinating the fine-grained knowledge required, explains the difficulty of transfer. While supporting the anticipation of action as significant from a learning perspective the research suggests that expertise in applying concepts involves a process of noticing similarity across contextually bound situations and cueing appropriate knowledge resources.

text: The development of multiplicative thinking and proportional reasoning: Models of conceptual learning and transfer This thesis considers the development of multiplicative thinking and proportional reasoning from two perspectives. Firstly, it examines the research literature on progressions in conceptual understanding to create a Hypothetical Learning Trajectory (HLT). Secondly, it surveys modern views of how transfer by learners occurs in and between situations, contrasting object views of abstraction with knowledge in pieces views.
Case studies of six students aged 11-13 years illustrate conceptual changes that occur during the course of a school year. The students are involved in a design experiment in which I (the researcher) co-teach with the classroom teacher. The students represent a mix of gender, ethnicity and level of achievement. Comparison of the HLT with the actual learning trajectory for each student establishes its validity as a generic growth path.
Examination of the data suggests that two models of learning and by inference, transfer, describe the conceptual development of the students. There is consideration of students’ use of anticipated actions on physical and imaged embodiments as objects of thought with a focus on the significance of object creation for conceptual growth, and the encapsulation, completeness and contextual detachment of objects. 
There is broad consistency in students’ progress through the phases of the HTL within each sub-construct though the developmental patterns of individual are variable and temporal alignment across the sub-constructs does not uniformly hold. Some consistency of order effect in concept development is noted. Discussion on the limitations of the HTL includes the difference between knowledge types from a pedagogical perspective, absence of significant model-representation-situation transfer, and order relations in conceptual development.
Considerable situational variation occurs as students solve problems that involve applications of the same concepts. Partial construction of concepts is common. This was true of all learners, irrespective of level of achievement. High-achieving students more readily anticipate actions and trust these anticipations as objects of thought than middle and low achievers. The data supports knowledge in pieces views of conceptual development. Complexity for learners in observing affordances in situations, and in co-ordinating the fine-grained knowledge required, explains the difficulty of transfer. While supporting the anticipation of action as significant from a learning perspective the research suggests that expertise in applying concepts involves a process of noticing similarity across contextually bound situations and cueing appropriate knowledge resources.

year: 2011

title: Outdoor learning in Aotearoa New Zealand: voices past, present, and future

authors: Cosgriff, Marg

subjects: culture

abstract: Many of the principles and practices that have influenced outdoor education in Aotearoa New Zealand find their genesis in the United Kingdom and North America. In recent times, many of these foundational assumptions have been called into question. This paper highlights how emerging 'local' voices are questioning and reframing how outdoor education is conceptualised and practiced. In large part this is due to a sense of distinctiveness borne from the bicultural foundations that underpin governance and policy-making. This paper explores how outdoor educators are developing pedagogies that acknowledge the particularities of our context, particularly the bicultural foundation of Aotearoa New Zealand. The paper highlights how social and cultural influences shape educational policy and how outdoor educators are responding, both theoretically and practically, to meet the needs of learners in an increasingly diverse society.

text: Outdoor learning in Aotearoa New Zealand: voices past, present, and future Many of the principles and practices that have influenced outdoor education in Aotearoa New Zealand find their genesis in the United Kingdom and North America. In recent times, many of these foundational assumptions have been called into question. This paper highlights how emerging 'local' voices are questioning and reframing how outdoor education is conceptualised and practiced. In large part this is due to a sense of distinctiveness borne from the bicultural foundations that underpin governance and policy-making. This paper explores how outdoor educators are developing pedagogies that acknowledge the particularities of our context, particularly the bicultural foundation of Aotearoa New Zealand. The paper highlights how social and cultural influences shape educational policy and how outdoor educators are responding, both theoretically and practically, to meet the needs of learners in an increasingly diverse society.

year: 2012