title: Comparison of dynamic properties of magnetorheological elastomers with existing antivibration rubbers

authors: Shuib, Raa Khimi

subjects: Science & Technology

abstract: Tan δ and energy dissipated during hysteresis testing of isotropic and anisotropic MREs containing silane modified iron sand particles in a natural rubber matrix were compared with existing antivibration rubbers. Tan δ was measured using dynamic mechanical analysis (DMA) over a range of frequency (0.01–130 Hz), strain amplitude (0.1–4.5%), and temperature (−100–50 °C). Energy dissipated was measured using a universal tester under cyclic tensile loading. The chosen antivibration rubbers for comparison contained different contents of carbon black filler (30, 50 and 70 phr) in a natural rubber matrix. It was found that energy absorption for comparative samples was generally higher than isotropic and anisotropic MREs over the range of frequency and strain amplitude explored, as well as in hysteresis testing and this was believed to be largely due the presence of carbon black in the formulation. Further assessment was carried out on materials that were the same as anisotropic MREs except they had additions of carbon black. The energy absorption was found higher than comparative samples with the same carbon black contents, supporting the use of iron sand to improve damping. However, trends for energy absorption at around Tg were found to reverse which is considered to be due to the segmental motion of rubber chains being by far the most significant influence on energy absorption in the glass transition zone.

text: Comparison of dynamic properties of magnetorheological elastomers with existing antivibration rubbers Tan δ and energy dissipated during hysteresis testing of isotropic and anisotropic MREs containing silane modified iron sand particles in a natural rubber matrix were compared with existing antivibration rubbers. Tan δ was measured using dynamic mechanical analysis (DMA) over a range of frequency (0.01–130 Hz), strain amplitude (0.1–4.5%), and temperature (−100–50 °C). Energy dissipated was measured using a universal tester under cyclic tensile loading. The chosen antivibration rubbers for comparison contained different contents of carbon black filler (30, 50 and 70 phr) in a natural rubber matrix. It was found that energy absorption for comparative samples was generally higher than isotropic and anisotropic MREs over the range of frequency and strain amplitude explored, as well as in hysteresis testing and this was believed to be largely due the presence of carbon black in the formulation. Further assessment was carried out on materials that were the same as anisotropic MREs except they had additions of carbon black. The energy absorption was found higher than comparative samples with the same carbon black contents, supporting the use of iron sand to improve damping. However, trends for energy absorption at around Tg were found to reverse which is considered to be due to the segmental motion of rubber chains being by far the most significant influence on energy absorption in the glass transition zone.

year: 2015-12-15

title: Investigation of anti-fouling processing aids in the primary evaporation of whey permeate

authors: Harrison, Dylan

subjects: whey permeate

abstract: The production of lactose via the concentration of whey permeate is an important process in the dairy industry. Hautapu dairy factory, owned by Fonterra Cooperative Group, process milk into a range of dairy-based products including; Cheese, Milk Protein Concentrate and Lactose. This project was focused around reducing fouling during the evaporation of whey permeate for the production of lactose powder. As whey permeate is heated in evaporators, mineral salts precipitate and accumulate onto the stainless steel heat exchange surfaces. This layer of mineral scale, known as fouling, greatly reduces the amount of heat transfer used for evaporating the whey permeate. Once the fouling gets to a point where it is no longer achievable to reach the concentrated solids target, the evaporator is shut down and cleaned with chemicals to remove the scale build up.

To decrease the amount of scale build up, a process aid is added to the whey permeate. This process aid A , or PAA, is a polyphosphate that when added to the feed stream gives longer run times. This project was aimed at establishing the chemistry behind the inhibiting abilities of PAA and its interaction with whey permeate. It is known that PAA acts as a complexing agent with calcium when it is added to the permeate stream which prevents it from forming calcium phosphate, the main source of fouling.

In the course of the research, it was fortuitously discovered that PAA works very inefficiently as an inhibitor in whey permeate because of its ability to form an insoluble salt with free calcium ions. The consequence of this was that high calcium levels in whey permeate lead to PAA precipitating out of solution rendering it an ineffective anti-fouling agent to prevent further scale build up. As a result of this, alternative inhibitors were considered and tested for their calcium tolerance and calcium phosphate inhibiting properties. From these considerations, carboxymethyl inulin was regarded as the most favourable replacement candidate for PAA. This resulted in plans being set down for a future industrial trial involving the carboxymethyl inulin.

text: Investigation of anti-fouling processing aids in the primary evaporation of whey permeate The production of lactose via the concentration of whey permeate is an important process in the dairy industry. Hautapu dairy factory, owned by Fonterra Cooperative Group, process milk into a range of dairy-based products including; Cheese, Milk Protein Concentrate and Lactose. This project was focused around reducing fouling during the evaporation of whey permeate for the production of lactose powder. As whey permeate is heated in evaporators, mineral salts precipitate and accumulate onto the stainless steel heat exchange surfaces. This layer of mineral scale, known as fouling, greatly reduces the amount of heat transfer used for evaporating the whey permeate. Once the fouling gets to a point where it is no longer achievable to reach the concentrated solids target, the evaporator is shut down and cleaned with chemicals to remove the scale build up.

To decrease the amount of scale build up, a process aid is added to the whey permeate. This process aid A , or PAA, is a polyphosphate that when added to the feed stream gives longer run times. This project was aimed at establishing the chemistry behind the inhibiting abilities of PAA and its interaction with whey permeate. It is known that PAA acts as a complexing agent with calcium when it is added to the permeate stream which prevents it from forming calcium phosphate, the main source of fouling.

In the course of the research, it was fortuitously discovered that PAA works very inefficiently as an inhibitor in whey permeate because of its ability to form an insoluble salt with free calcium ions. The consequence of this was that high calcium levels in whey permeate lead to PAA precipitating out of solution rendering it an ineffective anti-fouling agent to prevent further scale build up. As a result of this, alternative inhibitors were considered and tested for their calcium tolerance and calcium phosphate inhibiting properties. From these considerations, carboxymethyl inulin was regarded as the most favourable replacement candidate for PAA. This resulted in plans being set down for a future industrial trial involving the carboxymethyl inulin.

year: 2009

title: Who owns native nature? Discourses of rights to land, culture, and knowledge in New Zealand

authors: Goldsmith, Michael

subjects: indigenous cultures

abstract: Michael Brown famously asked ‘Who owns native culture?’ This paper revisits that question by analyzing what happens to culture when the culturally defined boundary between it and nature becomes salient in the context of disputes between indigenous and settler populations. My case study is the dispute between the New Zealand government and Maori tribal groupings concerning ownership of the foreshore and seabed. Having been granted the right to test their claims in court in 2003, Maori groups were enraged when the government legislated the right out of existence in 2004. Though the reasons for doing so were clearly political, contrasting cultural assumptions appeared to set Maori and Pakeha (New Zealanders of European origin) at odds. While couching ownership of part of nature as an IPR issue may seem counter-intuitive, I argue that as soon as a property claim destabilizes the nature/culture boundary, IPR discourse becomes pertinent.

text: Who owns native nature? Discourses of rights to land, culture, and knowledge in New Zealand Michael Brown famously asked ‘Who owns native culture?’ This paper revisits that question by analyzing what happens to culture when the culturally defined boundary between it and nature becomes salient in the context of disputes between indigenous and settler populations. My case study is the dispute between the New Zealand government and Maori tribal groupings concerning ownership of the foreshore and seabed. Having been granted the right to test their claims in court in 2003, Maori groups were enraged when the government legislated the right out of existence in 2004. Though the reasons for doing so were clearly political, contrasting cultural assumptions appeared to set Maori and Pakeha (New Zealanders of European origin) at odds. While couching ownership of part of nature as an IPR issue may seem counter-intuitive, I argue that as soon as a property claim destabilizes the nature/culture boundary, IPR discourse becomes pertinent.

year: 2009