Aqueous injection moulding

An important aspect of this enhancement strategy is its compatibility with current fabrication techniques, in particular polymer processing technology. The technique of micro-injection moulding was employed to produce polystyrene chips with an integrated array of cone structures intended for use in an aqueous environment. 

The susceptibility of PHB to attack in aqueous environments is part of the wider consideration of the polymer s general chemical resistance. This is summarized in Table 14 and is represented as the time taken for an injection-moulded PHB homopolymer bar to fracture when immersed at room temperature in the particular solvent and placed under a constant 1% strain. As expected, the resistance to acid and... 

PCL was also blended with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymers on a small two-roll mill for 5 min at 140 °C (12% HV) or 128 °C (20% HV). The blends were injection moulded to produce tensile test samples. Samples were prepared in the presence of 1 wt % hydroxyapatite as a crystal nucleating agent and to reduce sample preparation time. For both copolymers, the addition of PCL (10 wt %) reduced the initial modulus and tensile strength (Table 12). Samples containing 90 wt % of PCL exhibited properties very similar to those of PCL and the effects were attributed to phase separation from the blends brought about by PHBV crystallisation at temperatures exceeding T for PCL. That is, the samples show immiscibility. Even blends containing 10 wt % PCL samples aimealed in aqueous media or in an oven showed the presence of crystalline PCL. 

Comments All flame retardant, ext = extrusion, inj = injection moulding, tm = transfer moulding, ADG = aqueous dispersion grade. Coloured grades available. ... 

Preservatives may inelude disinfeetant and antiseptic chemicals together with eertain compounds used almost exclusively as preservatives. They are added to mar industrial, including pharmaceutical, products which may, by their nature, support the growth of bacteria and moulds causing spoilage of the product and possibly infection of the user. In the field of pharmaceutical preservation, addition of an inhibitory substance to a multidose injection (Chapter 21) or the prevention of growth in aqueous suspensions ofdmgs intended for oral administration (Chapter 18) are prime examples. 

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