Reactive blends of metallocene polyolefin elastomers (POE)/polypropylene (PP) with 60/40 composition were prepared with an organic peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, and a bis-azide derivative, diphenyloxid-4,4'-bis(sulfonylazide) (BSA). Ethylene-1-butene (EB) and ethylene-1-octene (EO) copolymers and elastomeric polypropylene (ePP) were used as the elastomeric phase. The effect of elastomeric phase on the thermal, rheological, morphological and mechanical properties of the thermoplastic vulcanizates (TPVs) or dynamic vulcanizates were studied. All TPVs depicted pseudoplastic behavior and blends cured with azide curative showed higher viscosities. The TPVs showed both dispersed and continuous phase morphology that depends on the elastomeric phase type revealing a limited degree of compatibility between PP and the elastomers EO or EB. On the other hand, the TPV PP/ePP showed a uniform morphology suggesting an improved compatibility. Substantial changes observed in physical properties were explained on the basis of blends' morphology and dynamic vulcanization. The results confirm that the mechanical properties are more influenced by the elastomeric phase than by the curative agent. This study revealed a broad new range of opportunities for POE-based TPVs.

Este trabalho apresenta o estudo do comportamento de compostos de PVC com adição de amido para aplicação especialmente na indústria calçadista. As propriedades mecânicas dos compostos nas proporções de 5, 7,5 e 10% foram estudadas através de ensaios de tração. Também foram verificados os índices de fluidez, alterações de propriedades quando submetidos ao envelhecimento artificial em estufa e natural ao expor às intempéries e enterrar no solo. A viabilidade da aplicação na indústria calçadista foi feita por injeção em gáspeas e tiras de sandálias, com testes de resistência, flexão e testes de campo. Os resultados demonstraram que o acréscimo de amido ao PVC provoca perda nas propriedades mecânicas, justificado pela baixa resistência mecânica do amido em relação ao PVC. Após envelhecimento em estufa o processo de retrogradação do amido deixa os compostos mais rígidos e com menor fluidez. Quando expostos às intempéries e ao solo, o PVC pode ser degradado com perda de HCl, o que leva à acidificação do solo. Nas aplicações em calçados e sandálias a resistência mecânica não atende aos requisitos do mercado. Apesar do baixo custo, o fraco comportamento mecânico dificulta sua viabilização para substituição em escala.

This paper deals with the behavior of PVC compounds with addition of starch for applications, especially in the footwear industry. The mechanical properties of the compounds in the proportions of 5, 7.5 and 10% were studied using tensile tests. Also investigated were the flow rates, in addition to changes in properties when the material was subjected to artificial aging in an oven and exposed to natural weather and buried in the soil. The feasibility of application in the industry was evaluated with tests of endurance, strength and field tests in injection uppers and straps of sandals. The results showed that the addition of starch to PVC causes loss of mechanical properties, owing to the lower mechanical strength of starch compared to PVC. After aging in an oven, starch is degraded, thus causing the compound more rigid and less fluid. When exposed to weather and soil, PVC can be degraded with loss of HCl, which leads to soil acidification. In conclusion, for applications in footwear and sandals, the mechanical strength does not meet the market requirements. Despite the low cost, the poor mechanical behavior makes them unviable for mass scale production.