title: Studies of the formation and properties of urea-formaldehyde resin adhesives

authors: Zeng, Huiyang

abstract: Urea-formaldehyde (UF) resin is used primarily as an adhesive for manufacturing wood panels (medium density fiberboard, particleboard and plywood). These are important New Zealand export products. A better understanding of the formation of UF resin will allow maximisation of its adhesive properties (high bonding strength) and minimisation of formaldehyde emissions (an adverse environmental effect). These improvements will enhance the competitive advantage of New Zealand resin products.

The research reported here has been directed primarily towards monitoring the UF reaction by Nuclear Magnetic Resonance spectroscopy (NMR), preparing UF resins, determining the performance of the resins produced and characterising the resins by high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) methods.

The development of a dynamic (RAPID) NMR acquisition method has contributed to the identification of optimum conditions for UF resin manufacture. A series of NMR "snap-shots" of the UF reaction system over the entire reaction period has been obtained. A wide range of reaction conditions, eg formaldehyde to urea molar ratio, formaldehyde concentration, initial addition pH, condensation pH, addition reaction time and reaction temperature, have been investigated. From the species present and the changes in their relative concentrations during the reaction, optimum reaction conditions have been determined as:

Formaldehyde concentration: 35-46%
F/U molar ratio: 1.8-2.0
Temperature: 88°C
Addition reaction time: 25-30 min
Initial addition pH: 8.0-9.0
Condensation pH: 4.5-5.0

The dynamic (RAPID) NMR studies were complemented by HPLC characterisation of samples taken during the different reaction stages. The main low molecular weight species present in the UF reaction system have been identified. In general the HPLC results were consistent with those obtained by the dynamic (RAPID) NMR method.

Low molecular weight species were identified by electrospray mass spectrometry.

Molecular weight, molecular weight distribution and resin aging were investigated by the GPC method. The number average molecular weights of typical final UF resins were in the range of 600-800 Dalton. The weight average molecular weights of the same resins were in the range of 7000-10 000 Dalton.
A series of laboratory resins were prepared to test the appropriateness of the optimum reaction conditions predicted from the NMR and HPLC studies. Resin performance in wood panels was determined by measuring internal bond, formaldehyde emission and cold water swell. The effects of F/U molar ratio, resin loading and board thickness on the panel properties have also been determined. The results showed improvement in the internal bond and formaldehyde emissions.

Comparison of the experimental resin prepared under the optimum reactions with a commercial unmodified UF resin indicated that a 12% increase in internal bond. Formaldehyde emissions were similar.

It is clear from the results of this study that current manufacturing conditions for the production of unmodified UF resins are close to optimum. Future improvements are likely to be based upon structural and/or non-structural additives.

text: Studies of the formation and properties of urea-formaldehyde resin adhesives Urea-formaldehyde (UF) resin is used primarily as an adhesive for manufacturing wood panels (medium density fiberboard, particleboard and plywood). These are important New Zealand export products. A better understanding of the formation of UF resin will allow maximisation of its adhesive properties (high bonding strength) and minimisation of formaldehyde emissions (an adverse environmental effect). These improvements will enhance the competitive advantage of New Zealand resin products.

The research reported here has been directed primarily towards monitoring the UF reaction by Nuclear Magnetic Resonance spectroscopy (NMR), preparing UF resins, determining the performance of the resins produced and characterising the resins by high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) methods.

The development of a dynamic (RAPID) NMR acquisition method has contributed to the identification of optimum conditions for UF resin manufacture. A series of NMR "snap-shots" of the UF reaction system over the entire reaction period has been obtained. A wide range of reaction conditions, eg formaldehyde to urea molar ratio, formaldehyde concentration, initial addition pH, condensation pH, addition reaction time and reaction temperature, have been investigated. From the species present and the changes in their relative concentrations during the reaction, optimum reaction conditions have been determined as:

Formaldehyde concentration: 35-46%
F/U molar ratio: 1.8-2.0
Temperature: 88°C
Addition reaction time: 25-30 min
Initial addition pH: 8.0-9.0
Condensation pH: 4.5-5.0

The dynamic (RAPID) NMR studies were complemented by HPLC characterisation of samples taken during the different reaction stages. The main low molecular weight species present in the UF reaction system have been identified. In general the HPLC results were consistent with those obtained by the dynamic (RAPID) NMR method.

Low molecular weight species were identified by electrospray mass spectrometry.

Molecular weight, molecular weight distribution and resin aging were investigated by the GPC method. The number average molecular weights of typical final UF resins were in the range of 600-800 Dalton. The weight average molecular weights of the same resins were in the range of 7000-10 000 Dalton.
A series of laboratory resins were prepared to test the appropriateness of the optimum reaction conditions predicted from the NMR and HPLC studies. Resin performance in wood panels was determined by measuring internal bond, formaldehyde emission and cold water swell. The effects of F/U molar ratio, resin loading and board thickness on the panel properties have also been determined. The results showed improvement in the internal bond and formaldehyde emissions.

Comparison of the experimental resin prepared under the optimum reactions with a commercial unmodified UF resin indicated that a 12% increase in internal bond. Formaldehyde emissions were similar.

It is clear from the results of this study that current manufacturing conditions for the production of unmodified UF resins are close to optimum. Future improvements are likely to be based upon structural and/or non-structural additives.

year: 2001

title: Examining work-family practice use and employee attitudes in a New Zealand local government organisation

authors: Haar, Jarrod M.

abstract: Work-family practices have proliferated in response to major changes in the workplace, including the increased participation rates of women and mothers, the rise in dual-career families and single parent families, and growth in the elderly population. These changes are seen as providing employees help in balancing work and family commitments. Work-family policies are purported to offer benefits to both employers and employees, for example reduced turnover, increased organisational commitment and greater job satisfaction.

The major focus of the present study was employee use of multiple work-family policies, as the majority of the work-family literature focuses upon single practices. The present study sought to examine the relationship between work-family practice use and work-family conflict, to determine whether work-family practices link with conflict. Also, in response to a failure of the literature in explaining the link between work-family policy use and employee attitudes, the present study used social exchange theory and the norm of reciprocity to better explain the relationship. The present study also use a set of organisational justice theories to examine perceptions of the fairness of work-family policies, and the link these perceptions may have with general employee attitudes. Also, for exploring work-family backlash, where the distribution of rewards suggests work-family non-users may hold negative attitudes compared to users.

A single local government organisation, with 203 employees, was the focus of this study. Surveys were distributed at two distinct time periods to reduce common method variance. A total of 100 paired survey responses were received. Findings supported a positive relationship between work-family practices and conflict between work and home, in both directions. Additionally, work → family conflict was associated with decreased job satisfaction and increased work strain. Findings also indicated that work-family practice use predicted work-family specific attitudes but not attitudes towards the job and organisation. Work-family practice use and perceived benefits of work-family programmes predicted fairness perceptions, however, fairness perceptions failed to predict attitudes towards the organisation and job. Lastly, there was no evidence of a work-family backlash, with users and non-users holding similar attitudes towards the work-family programmes, organisation and job.

Implications include the need for examining the causal nature of the work-family practice and conflict relationship, caution regarding the assumption that work-family policies are automatically beneficial, and encouragement for organisations to proactively test their work-family programmes. Lastly, the lack of a work-family backlash suggests media sensationalism, and, therefore, as non-users are not likely to hold negative attitudes towards the organisation, work-family backlash should not be seen as discouraging organisational adoption of work-family programmes.

Contributions of this research include the examination of multiple work-family practices, which is rare, and the elucidation of the work-family conflict – work-family practice use relationship, which is poorly understood. Theorising the influence that work-family practices have upon employee attitudes is another contribution. While the findings indicated no significant link between general attitudes and practice use, this might highlight a methodological limitation in examining practice use, rather than practice value or frequency of use. Lastly, this thesis indicates that work-family practices do link in multiple ways with employee attitudes under multiple theoretical approaches.

text: Examining work-family practice use and employee attitudes in a New Zealand local government organisation Work-family practices have proliferated in response to major changes in the workplace, including the increased participation rates of women and mothers, the rise in dual-career families and single parent families, and growth in the elderly population. These changes are seen as providing employees help in balancing work and family commitments. Work-family policies are purported to offer benefits to both employers and employees, for example reduced turnover, increased organisational commitment and greater job satisfaction.

The major focus of the present study was employee use of multiple work-family policies, as the majority of the work-family literature focuses upon single practices. The present study sought to examine the relationship between work-family practice use and work-family conflict, to determine whether work-family practices link with conflict. Also, in response to a failure of the literature in explaining the link between work-family policy use and employee attitudes, the present study used social exchange theory and the norm of reciprocity to better explain the relationship. The present study also use a set of organisational justice theories to examine perceptions of the fairness of work-family policies, and the link these perceptions may have with general employee attitudes. Also, for exploring work-family backlash, where the distribution of rewards suggests work-family non-users may hold negative attitudes compared to users.

A single local government organisation, with 203 employees, was the focus of this study. Surveys were distributed at two distinct time periods to reduce common method variance. A total of 100 paired survey responses were received. Findings supported a positive relationship between work-family practices and conflict between work and home, in both directions. Additionally, work → family conflict was associated with decreased job satisfaction and increased work strain. Findings also indicated that work-family practice use predicted work-family specific attitudes but not attitudes towards the job and organisation. Work-family practice use and perceived benefits of work-family programmes predicted fairness perceptions, however, fairness perceptions failed to predict attitudes towards the organisation and job. Lastly, there was no evidence of a work-family backlash, with users and non-users holding similar attitudes towards the work-family programmes, organisation and job.

Implications include the need for examining the causal nature of the work-family practice and conflict relationship, caution regarding the assumption that work-family policies are automatically beneficial, and encouragement for organisations to proactively test their work-family programmes. Lastly, the lack of a work-family backlash suggests media sensationalism, and, therefore, as non-users are not likely to hold negative attitudes towards the organisation, work-family backlash should not be seen as discouraging organisational adoption of work-family programmes.

Contributions of this research include the examination of multiple work-family practices, which is rare, and the elucidation of the work-family conflict – work-family practice use relationship, which is poorly understood. Theorising the influence that work-family practices have upon employee attitudes is another contribution. While the findings indicated no significant link between general attitudes and practice use, this might highlight a methodological limitation in examining practice use, rather than practice value or frequency of use. Lastly, this thesis indicates that work-family practices do link in multiple ways with employee attitudes under multiple theoretical approaches.

year: 2002

title: A history of Māori literacy success

authors: Derby, Melissa

abstract: This article explores literacy in 19th century Māori society, and in particular, this work considers the initial interactions Māori tribal groups had with literacy following contact with British settlers. The overarching purpose of this article is to respond to the increasingly prevalent suggestion that literacy is a Western competency, and that to be concerned with ensuring Māori children are achieving well in reading and writing is an act of colonisation. This work illustrates that these narratives run counter to the history, behaviour, and values of many tribal groups in New Zealand. More specifically, the historical interactions Māori had with literacy illustrate that both the ability and the desire to succeed in reading and writing was a feature of Māori historical practices. Therefore, to ensure high levels of literacy achievement in contemporary times is not a colonising act but rather aligns with Māori history, behaviour, and values.

text: A history of Māori literacy success This article explores literacy in 19th century Māori society, and in particular, this work considers the initial interactions Māori tribal groups had with literacy following contact with British settlers. The overarching purpose of this article is to respond to the increasingly prevalent suggestion that literacy is a Western competency, and that to be concerned with ensuring Māori children are achieving well in reading and writing is an act of colonisation. This work illustrates that these narratives run counter to the history, behaviour, and values of many tribal groups in New Zealand. More specifically, the historical interactions Māori had with literacy illustrate that both the ability and the desire to succeed in reading and writing was a feature of Māori historical practices. Therefore, to ensure high levels of literacy achievement in contemporary times is not a colonising act but rather aligns with Māori history, behaviour, and values.

year: 2021