In the synthesis of water-blown expandable polystyrene, granular starch as a carrier of water, the blowing agent, was grafted with polystyrene by radical initiated polymerization. Organic peroxides, such as tertbutyl perbenzoate or dibenzoyl peroxide were used as free radical initiators. The graft polymerization reaction was confirmed by FT-IR spectroscopy and SEM. The reaction leads to low level grafted starch. However, the amount of grafted polymer can be significantly increased using maleic anhydride in the monomer feed. The effect of concentration of maleic anhydride was studied. The reaction mechanism was proposed.
The compatibility of starch with the polystyrene matrix in the synthesis of water-blown expandable polystyrene (WEPS) was improved by making use of maleic anhydride. The foam morphology on the contrary is significantly changed after pre-expansion as the content of maleic anhydride is increased. It has been found that starch is grafted during the polymerization with styrene-maleic anhydride copolymer. Partial immscibility of polystyrene matrix and styrene-maleic anhydride grafts formed at higher concentrations of maleic anhydride causes the agglomeration of starch. Consequently, water, as the blowing agent, cannot be finely dispersed in the matrix, which is the reason of the irregular foam morphology. Different methods for the improvement of the compatibilization are discussed.
Fracture‐related infection (FRI) is a serious complication following musculoskeletal trauma. Accurate diagnosis and appropriate treatment depend on retrieving adequate deep tissue biopsies for bacterial culture. The aim of this cohort study was to compare intraoperative tissue cultures obtained by the Reamer‐Irrigator‐Aspirator system (RIA)‐system against standard tissue cultures obtained during the same surgical procedure. All patients had long bone fractures of the lower limbs and were assigned to the FRI or Control group based on the FRI consensus definition. The FRI group consisted of 24 patients with confirmed FRI and the Control group consisted of 21 patients with aseptic nonunion or chronic pain (in the absence of other suggestive/confirmatory criteria). Standard tissue cultures and cultures harvested by the RIA‐system showed similar results. In the FRI group, standard tissue cultures and RIA cultures revealed relevant pathogens in 67% and 71% of patients, respectively. Furthermore, in four FRI patients, cultures obtained by the RIA‐system revealed additional relevant pathogens that were not found by standard tissue culturing, which contributed to the optimization of the treatment plan. In the Control group, there were no false‐positive RIA culture results. As a proof‐of‐concept, this cohort study showed that the RIA‐system could have a role in the diagnosis of FRI as an adjunct to standard tissue cultures. Since scientific evidence on the added value of the RIA‐system in the management of FRI is currently limited, further research on this topic is required before its routine application in clinical practice.
The expansion of polystyrene using water as the blowing agent has been investigated. Hydrophilic particles are dispersed in styrene before the suspension polymerization. During this polymerization the necessary amount of water is absorbed and/or adsorbed by these additives. The different additives used in this work are ordinary corn starch and high-amylose starch, zeolite A and Y, and SiO2. Factors that influence the density and the morphology of the expanded product are the type of additive, the additive and water content, the polymerization conditions, and the expansion procedure. High frequency electric field heating and hot air have been used for the expansion. The lowest density is obtained with high frequency electric field heating.
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