Casparus Johan R. Verbeek

Recent Developments in Thermo-Mechanical Processing of Proteinous Bioplastics

Proteinous bioplastics have received renewed interest over the last decade due to an awareness of the environmental impact of conventional plastics. In the second half of the previous century, further development of proteinous bioplastics was overshadowed by the fast growth in synthetic polymer technology. Today, proteins are considered a sustainable source for producing biodegradable alternatives to conventional plastics. Proteins are complex hetero-polymers, offering a number of different functional side groups capable of forming strong intermolecular bonds. Denaturing, cross-linking and plasticization are the most important aspects of protein processing. Typically, proteins and plasticizers are blended prior to thermo-processing, during which a highly viscous melt should be formed. The softening temperature of proteins is often above their decomposition temperatures, thereby making processability dependant on the type and amount of plasticizer. Generally, increasing the amount of plasticizer will lower the softening temperature and viscosity of the blend. Extrusion is particularly suitable for processing proteins, but excessive aggregation should be avoided by judicial use of chemicals, such as denaturants, plasticizers and reducing agents. Current technology described in recent patents mostly involves chemical modification of protein structures, incorporation of novel plasticizers and developing new process and specialized equipment. These are discussed further in the text.

Recent Developments in Polymer Consolidated Composites

Polymer matrix composites (PMCs) are used extensively in industry, varying from high performance structural composites used in the aerospace industry, to products such as insulation boards used in the construction industry. At either end of this spectrum, the matrix could be regarded to have a different functionality. In high performance composites, the polymer forms a continuous phase around the reinforcement, whereas, in products such as particle boards, the matrix may no longer be continuous. Therefore, PMCs could be considered to be divided into continuous polymer matrix composites (CPMCs) and polymer consolidated composites (PCCs), the latter referring to where commonly the matrix might be regarded as simply a binder. Although the field of PMCs is well established, this has commonly not been extended to PCCs. This paper evaluates recent literature on materials used in PCCs, the factors that influence their behavior and how they can be defined as a subset of PMCs.

An ecoprofile of thermoplastic protein derived from blood meal Part 2: thermoplastic processing

PurposeThe purpose of this research was to develop a nonrenewable energy and greenhouse gas emissions ecoprofile of thermoplastic protein derived from blood meal (Novatein thermoplastic protein; NTP). This was intended for comparison with other bioplastics as well as identification of hot spots in its cradle-to-gate production. In Part 1 of this study, the effect of allocation on the blood meal used as a raw material was discussed. The objective of Part 2 was to assess the ecoprofile of the thermoplastic conversion process and to compare the cradle-to-gate portion of the polymers life cycle to other bioplastics.MethodsInventory was collected to aggregate nonrenewable primary energy use and greenhouse gas emissions. Data were collected from a variety of sources including published papers, reports to government agencies, engineering models and information from a single blood meal production facility. Several assumptions regarding the thermoplastic conversion process were evaluated by way of a sensitivity analysis.ResultsThe allocation procedure chosen for the impacts of farming and meat processing had the greatest effect on results. Excluding farming and meat processing, blood drying had the greatest contribution to nonrenewable energy use and GHGs, followed by the petrochemical plasticizer used. Other assumptions, such as scarcity of water or inclusion of pigments, although significant when considered for blood meal conversion to NTP alone, were found not to be significant when production of blood meal was included in the analysis. Qualitative differences were observed between NTP and other bioplastics. For example, the profiles of some other bio-based polymers were dominated by fermentation and polymer recovery processes. In the case of NTP, it is the production of the raw material used that is most significant, and thermoplastic modification has a relatively low contribution to GHGs and nonrenewable energy use.ConclusionsFor a truly attributional scenario, production of any ruminant animal products does have an associated GHG. Deriving this for blood meal on a mass-based allocation seems to indicate that NTP is less favorable than other cradle-to-gate bioplastic production systems from a global warming perspective.On the other hand, the motivation for developing the material in the first place was to make use of an existing waste product. If it is assumed that the magnitude of blood meal production is independent of fertilizer or plastics demand and, instead, reflects demand for major products such as meat, further development of NTP is justified.

The palatability of flavoured novel floating pellets made with brewer's spent grain to captive carp

Abstract The palatability to common carp, Cyprinus carpio L. of three newly developed differently flavoured floating pellets made from a high proportion (40%) of brewers spent grain (BSG) was tested using a multiple-offer feeding experiment. The addition of ‘bold’ flavours, such as vanilla or strawberry essence, may help mask the unpleasant taste of some piscicides; however, their inclusion must not compromise uptake by carp. There were no significant differences between the consumption rates of the three varieties, and all flavours were readily consumed. Therefore, it is suggested that highly flavoured pellets made with BSG have a strong potential to mask the flavour of an unpalatable toxin, and further research is now needed to test this hypothesis.

Prediction of the Flexural Modulus of Fibre Reinforced Thermoplastics for use as Kayak Paddle Blades

It can be shown that there is a strong link between paddler performance and paddle stiffness. Despite the fact that composite materials are often chosen to enable design of more rigid sporting equipment, readily available flexural modulus values for composites other than proprietary blends are not easily obtained. Therefore, when composition deviates from proprietary blends, accurate prediction of material properties becomes necessary. A mathematical model for predicting the flexural modulus of short fibre reinforced composite materials is developed based on the application of simple beam theory. The flexural modulus can be modelled by considering a small section of the composite comprising a finite number of polymer and reinforcement layers. Simple beam theory assumes that there is perfect bonding between these layers, but it is well known that interfacial adhesion plays a significant role in composite properties. To account for the interfacial layer and interfacial bonding the second moment of area of the composite beam element was modified by assuming that the contribution to the second moment of area from the matrix layer is reduced by an amount representing the nonbonded interfacial layer. The flexural modulus values obtained from the model are compared to experimental values for glass-fibre reinforced linear low density polyethylene. It has been found that the use of non-contact regions in the model resulted in improved accuracy over the model with perfect bonding for short fibre reinforced LLDPE.

Properties of Blends of Novatein Thermoplastic Protein from Bloodmeal and Polybutylene Succinate Using Two Compatibilizers

The use of dual compatibilizers, poly (2-ethyl-2-oxazoline) (PEOX) and polymeric methylene diphenyl diisocyanate (pMDI) in Novatein thermoplastic protein from bloodmeal (NTP) and PBS blends were investigated. A composition of 50% of NTP was used for all formulations with different percentage compatibilizer. Mechanical, morphology, thermal and water absorption were used as analysis methods to study blend properties. To improve compatibility, two different approaches to blending the compatibilizers were used. Firstly, PEOX was added before extrusion this has improved the blends tensile strength. Secondly, addition of PEOX during NTP production followed by pMDI added before injection molding, showed a futher improvement in tensile strength. SEM revealed that PEOX has improved the dispersion of NTP and pMDI has strengthened the adhesion between phases consistent with mechanical property results. A broad tan δ peak in DMA analysis was obtained indicated improved compatibility in blends using two compatibilizers. In spite of that, the addition of dual compatibilizer has reduced the water resistance of PBS.

The Use of Aqueous Urea as Chemical Denaturant in Processing CGM into a Biodegradable Polymer Material

Corn gluten meal (CGM) has potential as a bioderived polymer for use in composite materials. Previous work to improve the processability of CGM has focused on the use of plasticisers including water, polyethylene glycol, glycerol and octanoic acid, however, a common problem is that these leach from the material subsequent to processing [1]. It has been raised that a certain degree of denaturation must occur in order to make proteins processable [2]. The current work explores the use of aqueous urea as chemical denaturant in processing CGM into a biodegradable polymer material. Consolidated materials were obtained which showed increased resistance to cracking with higher urea concentration. FTIR analysis revealed that processing CGM with increased concentrations of aqueous urea resulted in the progressive transformation of the protein secondary structure from an ordered, clustered conformation to that of extended chains. Aqueous urea is assumed to promote protein-solvent interactions which stabilise the extended chain conformations.

Comparative Rheology Techniques for Assessment of MIM Titanium Metal Powder Feedstocks.

In this work standard industrial processing equipment, the torque mixer and twin screw extruder, are used to measure the melt flow of several titanium metal powder feedstocks. The study was to determine whether test data from specialised rheology equipment might be reproduced with standard processing equipment used by the MIM industry.Considering the wide range of flow defects possible with MIM there is a valid assumption that flow behaviour measurement will be better represented by a number of processes, especially those most representative of the injection moulding process.In this study process data was collected and analysed based on mixing torque, screw work, specific mechanical energy and viscosity. Viscosity was further calculated relative to (L/D) ratio and strain rates during extrusion. Subsequently the data was compared with viscosity values from a capillary rheometer both without, and with, account for end effects and slip.The results showed that all the techniques provide similar ranking for the feedstocks with regard to melt flow during processing. The results also showed an inversion of the ranking where the shear rate increased from (1000 to 5000) s-1 as a result of shear sensitivity. The agreement of results from the different techniques clearly show that conventional processing equipment may provide valid feedstock assessment. The results if not definitive will provide good comparative measure where upper and lower bounds can be determined.

The Role of Extrusion Conditions on the Mechanical Properties of Thermoplastic Protein

Abstract Mechanical properties of Novatein thermoplastic protein compounded at different extrusion temperatures and processing water contents have been examined in a factorial experiment. Thermoplastic proteins are moisture sensitive and can be prone to thermal degradation during processing. Processing water was varied between 30 and 45 parts per hundred parts bloodmeal while the extrusion temperature was varied between 120 and 150 °C to identify a processing window suitable for process scale up. To resolve any effects processing water had on protein-protein interactions from its plasticising effect, injection molded specimens were mechanically tested both as molded and after conditioning at controlled temperature and humidity. Despite all conditioned samples having approximately the same moisture content, mechanical properties were different. Tensile strength and modulus decreased with increasing processing water at the same equilibrium moisture content. DMA and WAXS suggested this was due to changes in chain mobility within the amorphous phase of the material, rather than conformational change towards a more ordered state. Properties of unconditioned specimens were mostly dependent on the plasticising effect of different amounts of processing water remaining in the material after injection molding. Extrusion temperature had very little effect on mechanical properties, suggesting that Novatein is robust enough to handle some temperature variations during processes such as injection molding.

Morphology and Mechanical Properties of Itaconic Anhydride Grafted Poly(lactic acid) and Thermoplastic Protein Blends

Abstract Blends between Novatein thermoplastic protein and polylactic acid (PLA) have been prepared by reactive extrusion using itaconic anhydride grafted PLA. At equal proportions of Novatein and PLA, the absence of a compatibilizer formed a dispersed phase morphology of Novatein in PLA and the incorporation of compatibilizer formed a co-continuous morphology. Incorporating PLA in Novatein can improve the tensile strength of Novatein by 42% and the impact strength by 36% at an equal proportion blend (50/50) in the presence of a compatibilizer. Thermal analysis revealed that 50/50 was the phase inversion point, above and below this composition the material behaved similarly. The effect of compatibilizer was evident in wide-angle X-ray scattering. In the absence of compatibilizer three phases were detected: crystalline Novatein, amorphous Novatein, and amorphous PLA phases. With compatibilizer, the blend was moving towards two phases: crystalline Novatein, and an amorphous blend of Novatein and PLA. Itaconic anhydride grafted PLA improved miscibility between Novatein and PLA, and its use can potentially lead to the production of Novatein/PLA foams.