In this work, a smectite clay from the State of Paraiba, Brazil, was treated with six different types of ammonium salts, which is an usual method to enhance the affinity between the clay and polymer for the preparation of nanocomposites. The clays, before and after modification, were characterized by X ray diffraction. The conformation of the salts within the platelets of the clay depended on the number of long alkyl chains of the salt. The thermal stability of the clays was also studied. The ammonium salts thermal decomposition was explained in light of their position within the organoclays.

A tecnologia avançada de corte com jato de água pode ser usada em chapas de polipropileno. Os modernos sistemas são compostos por: bomba de alta pressão, mesa XY e computador. O corte no sistema cria uma ranhura com características próprias. A largura do sulco é maior na entrada que na saída do corte. No corte do polipropileno podem surgir rebarbas na base da chapa como pequenas fibras. Experiência adquirida na confecção de peneiras mostrou que o número de furos é decisivo no custo da peça. Ensaios preliminares simularam alternativas de corte com e sem abrasivo. A abertura de 900 furos numa área de 967 cm² revelou consumir 126 minutos para corte sem abrasivo, contra 201 no caso mais oneroso. A seguir, novos desenhos foram propostos diminuindo a malha, mas, preservando o índice de vazamento. Assim, 145, 218 ou 362 furos são possíveis. O corte de velocidade constante e com abrasivo mostrou-se o mais eficiente. Por outro lado, o modo de abrir o furo influi na qualidade da peneira. A seleção da alternativa adequada, os problemas surgidos durante a investigação e as soluções adotadas foram detalhadamente descritos no estudo.

Advanced technology of waterjet cut can be used in polypropylene tableware. The modern systems comprise a high-pressure pump, XY table and computer as controller. The cutting process may lead to kerfs with specific characteristics. The kerf width is larger in the entrance than in the jet exit. In cutting polypropylene, burrs in the base of the plate can appear as small staple fibers. Experience acquired in the confection of sieves showed that the number of punctures is decisive in the cost of the part. Preliminary assays simulated cut alternatives with and without abrasive. The opening of 900 punctures in an area of 967 cm² consumes 126 minutes for cutting without abrasive, in contrast to 201 minutes in the most costly case. New drawings were then considered with the meshes being decreased, but preserving the emptying index. Thus, 145, 218 or 362 punctures are possible. The cutting at a constant speed and using abrasive was the most efficient. On the other hand, the manner in which the puncture is opened influences the quality of the sieve. The selection of the optimal alternative, the problems appearing during the study and the solutions adopted are described in the paper.