Structural characterisation of pre-processed thermoplastic protein derived from bloodmeal

Additives are required to convert bloodmeal powder into an extrudable thermoplastic protein-based bioplastic. These include a protein denaturant, a surfactant, a reducing agent and plasticisers. The objective of this work was to assess the structural changes induced in bloodmeal by these additives prior to extrusion. Structure was investigated using Fourier transform infrared (FT-IR) spectroscopy, wide angle X-ray scattering (WAXS) and synchrotron light based FT-IR microspectroscopy. FT-IR results suggested the additives reduced α-helical content. The shape of the amide I region (1600 – 1700 cm⁻¹, representing carbonyl group stretching in the protein backbone) is known to depend on protein secondary structures. Bloodmeal showed a broad, convoluted peak in this region, with a maximum in the range 1648 – 1658 cm⁻¹, associated with α-helices. With processing additives, a dip was seen in the α-helix region, with twin peaks emerging either side of it. Urea, one of the additives, also absorbs in the amide I region and may also contribute to a change in its shape. Analysis of the amide 3 region supported a reduction in the ratio of α helices to β sheets. Further support of structural changes was shown by WAXS. The additives decreased the sharpness of peaks corresponding to 4.8 Å and 10 Å, thought to represent intra-helix spacing and inter-helix packing respectively. FT-IR microspectroscopy at the Australian Synchrotron enabled spatial variations in secondary structure to be explored using peaks in the amide 3 region. Spatial distribution of secondary structure was detected in bloodmeal and thermoplastically modified bloodmeal prior to extrusion (PPM-TEG). Bloodmeal showed domain separation on the approximate order of 10 μm, whilst PPM-TEG appeared to have larger phases and overall reduced α-helical content, relative to beta sheets

Plasticization of Bloodmeal-based Thermoplastics

Water is the most common plasticizer for proteinbased thermoplastics, lowering the softening point to a allow processing without excessive degradation. The biggest drawback of using water a plasticizer is that water easily evaporates from the material during use or storage. This leads to embrittlement and loss of functionality over time. In this study a series of high molecular mass plasticizers were evaluated for their efficiency in plasticizing bloodmeal-based thermoplastics. It was found that propylene glycol, di and tri-ethylene glycol were most efficient in increasing the material’s ductility, as measured by elongation at break. Using 10 parts plasticizer per hundred bloodmeal (pphBM) in combination with 10 pphBM urea gave optimal results in terms of Young’s modulus, tensile strength and processability. The mechanical properties of plasticized samples showed a stronger dependency on moisture content, compared to unplasticized samples and reached higher equilibrium moisture content in a shorter time. Using 10 pphBM TEG as plasticizer in resulted in a plastic material with a Young’s modulus of 869 MPa, tensile strength of 14.7 MPa and an elongation at break of 46%

Effect of oxidative treatment on the secondary structure of decoloured bloodmeal

Bloodmeal can be decoloured using peracetic acid resulting in a material with a pale-yellow colour which only needs sodium dodecyl sulphate, water and triethylene glycol to extrude into a semi-transparent bioplastic. Fourier-transform infrared (FTIR) spectroscopy using Synchrotron light was used to investigate the effect of peracetic acid treatment at various concentrations on the spatial distribution of secondary structures within particles of bloodmeal. Oxidation caused aggregation of helical structures into sheets and acetic acid suppressed sheet formation. Decolouring with peracetic acid led to particles with a higher degree of disorder at the outer edges and higher proportions of ordered structures at the core, consistent with the expected diffusion controlled heterogeneous phase decolouring reaction. The degradation of stabilizing intra- and intermolecular interactions and the presence of acetate ions results in increased chain mobility and greater amorphous content in the material, as evidenced by reduction in Tg and greater enthalpy of relaxation with increasing PAA concentration

The effects of energy price changes: heterogeneous welfare impacts and energy poverty in Indonesia

We study the welfare and energy poverty implications of energy price change scenarios in Indonesia. Our analysis extends previous analyses of energy price impacts at the household level in three ways. First, by employing a household energy demand system (QUAIDS), we are able to distinguish between first- and second-order welfare effects over the income distribution. Second, our results point to the ownership of energy-processing durables as another source of impact heterogeneity. Third, we extend the welfare analysis beyond the money-metric utility effects and look at energy poverty, which is understood as the absence of or imperfect access to reliable and clean modern energy services. The analysis indicates that energy prices may serve as an effective instrument to reduce energy use but also have important adverse welfare effects. The latter can, however, be mitigated by appropriate compensation policies

Time dependent properties of thermoplastic protein produced from bloodmeal with sodium sulphite as an anti-crosslinking agent

The aim of this research was to investigate how the time dependent mechanical behaviour of bloodmeal-based thermoplastic was affected by varying sodium sulphite content at two injection moulding temperatures (120°C at exit or 140°C at exit). Thermoplastic protein was prepared by extrusion with 2, 3 or 4g sodium sulphite (SS), 3g sodium dodecyl sulphate, 10 g urea, 20 g triethylene glycol and 40 g water per 100 g bloodmeal, then injection moulded into test specimens. Pull to break, creep and stress relaxation tests were performed on conditioned samples and glass transition temperature (Tg) was determined by dynamic mechanical analysis. Ultimate tensile strength was 7.9, 7.6 and 5.6 MPa for samples moulded at 120°C and 7.6, 6.3 and 5.7 MPa when moulded at 140°C with 2, 3 and 4 g SS respectively. Experimental creep data was modelled with a 4 element model, consisting of a spring and dashpot in parallel, in series with an additional spring and dashpot. Plotting creep compliance versus time showed increasing chain mobility as SS content increased. Relaxation was modelled with the Struik equation for short-time experiments. Relaxation times were 530, 360 and 250 s with 2, 3 and 4 g SS respectively when moulded at the lower temperature. At 140°C, relaxation times were 440, 430 and 190 s for these SS contents. Tg was in the range 57-65°C (1 Hz peak in tanδ) for all samples, but was lowest for samples with 4 g SS. These results show that both increased sodium sulphite and the higher moulding temperature increased chain mobility in the processed plastic

Constrained firms, not subsistence activities : Evidence on capital returns and accumulation in Peruvian microenterprises.

We present a multi-period model of capital accumulation in order to investigate microenterprise (ME) production dynamics in a developing country context characterized by credit constraints and risk. These constraints are reflected in marginal returns to capital above market interest rates and we show that capital accumulation is faster in MEs with higher productivity, higher initial wealth and less risk exposure. We test our predictions using panel data for Peruvian MEs from 2002 to 2006. We indeed find high marginal returns to capital and sizable effects of household non-business wealth and, in contrast to previous studies, risk on capital accumulation in MEs. The findings of this paper can serve as a basis for the promotion of combined credit and risk management devices to enhance private sector development

Credit‐constrained in risky activities? The determinants of the capital stocks of micro and mall firms in Western Africa

Micro and small enterprises (MSEs) in developing countries are typically considered to be severely credit constrained. Additionally, high business risks may partly explain why the capital stocks of MSEs remain low. This article analyzes the determinants of the capital stocks of MSEs in poor economies focusing on credit constraints and risk. The analysis is based on a unique, albeit cross-sectional but backward‐looking, micro data set on MSEs covering the economic capitals of seven West‐African countries. The main result is that capital market imperfections indeed seem to explain an important part of the variation in capital stocks in the early lifetime of MSEs. Furthermore, the analyses show that risk plays a key role in capital accumulation. Risk-averse individuals seem to adjust their initially low capital stocks upwards when enterprises grow older. MSEs in risky activities owned by wealthy individuals even seem to over-invest when they start their business and subsequently adjust capital stocks downwards. As other firms simultaneously suffer from capital shortages, such behavior may imply large inefficiencies

Credit-constrained in risky activities? The determinants of the capital stocks of micro and small firms in Western Africa

Micro and small enterprises (MSEs) in developing countries are typically considered to be severely credit constrained. Additionally, high business risks may partly explain why the capital stocks of MSEs remain low. This article analyzes the determinants of the capital stocks of MSEs in poor economies focusing on credit constraints and risk. The analysis is based on a unique, albeit cross‐sectional but backward‐looking, micro data set on MSEs covering the economic capitals of seven West‐African countries. The main result is that capital market imperfections indeed seem to explain an important part of the variation in capital stocks in the early lifetime of MSEs. Furthermore, the analyses show that risk plays a key role in capital accumulation. Risk‐averse individuals seem to adjust their initially low capital stocks upwards when enterprises grow older. MSEs in risky activities owned by wealthy individuals even seem to over‐invest when they start their business and subsequently adjust capital stocks downwards. As other firms simultaneously suffer from capital shortages, such behaviour may imply large inefficiencies

Constrained firms, not subsistence activities: evidence on capital returns and accumulation in Peruvian microenterprises

We investigate the returns to capital and capital accumulation using panel data of Peruvian micro enterprises (MEs). Marginal returns to capital are found to be very high at low levels of capital, but rapidly decreasing at higher levels. The dynamic analyses of capital accumulation in MEs suggest that credit constraints explain a major part of the variation in firm growth. We find a very large positive effect of household non-business wealth on capital stocks of MEs. We also show a sizable effect of risk on accumulation and pronounced interactions between wealth and risk. The presented evidence is consistent with poorly endowed entrepreneurs who operate in imperfect capital markets and a very risky environment