This paper described the tensile, thermal, and moisture absorption characteristic of polyvinyl alcohol (PVA) / bengkuang (Pachyrhizuserosus) starch blend films. The film was produced through the solution casting method. Tensile, thermogravimetric analysis and moisture test were studied to determine the tensile strength, thermal stability, and moisture absorption, respectively. The highest tensile strength (TS) was 15.86 ± 0.69 MPa for pure PVA film. This result was higher than bengkuang starch and its blends film. Tensile elongation (TE) decreased as increased bengkuang starch content in PVA. The thermal degradation of PVA film was higher 10°C than bengkuang starch films in range temperature 200-380°C. The addition of bengkuang starch in PVA also increased moisture absorption. The highest moisture absorption was in the bengkuang starch film. This blend film’s tensile, thermal, and moisture properties probably suggested it could be suitable for food packaging.
Penelitian ini bertujuan untuk mengetahui karakteristik dari material serat karbon TC35-12K tipe woven dipadukan dengan resin epoksi sebagai matrik. Orientasi serat yang diterapkan adalah 00 dan 450 pada masing-masing layer dan menemukan susunan layer yang paling optimal. Metode dalam penelitian ini yaitu dengan simulasi matematis dan komputasi menggunakan software finite element Analysis (FEA). Hasil dari penelitian menemukan bahwa orientasi serat 450 serat karbon serat karbon TC35-12K/epoksi woven memiliki kemampuan sangat baik terhadap torsi dengan nilai total deformation 1,38 mm apabila diberikan torsi 120 N.m. Selain itu orientasi serat 00 memiliki kemampuan lebih baik terhadap beban tarik dan bending. Orientasi serat 00 juga meningkatkan nilai natural frequency 151,65 Hz karena kakakuan menjadi lebih baik. Konfigurasi orientasi serat dan urutan susunan layer optimal adalah 45/45/0/0 yang mampu terhadap torsi, tarik, bending, dan putaran kritis. Putaran kritis berdampak pada punca getaran, semakin tinggi angka putaran kritis akan lebih baik. Konfigurasi yang dipilih mampu hingga putaran 9000 rpm
A weakness of unsaturated polyester is brittle due to the cross-linking of the UP chain network. Improving the toughness may be carried out by blending with appropriate additives. This work aims to characterize the fracture surface of unsaturated polyester (UP)/vinyl ester (VE) blends with a ratio of 70% and 30% respectively. Addition of VE in UP increases the toughness of the blends resulting from disruption of the cross-linking of the UP chain network. The disrupted network was characterized by the FESEM morphology from fracture surface of the blend which exhibits three different regions i.e., the smooth zone corresponding to the slow crack growth rate (1); a transition zone, where the surface roughness steadily increases (2); a final failure zone with much rougher marks (3). The presence of more nanovoids in region 2 and 3 confirmed the bigger disruption of the crosslinking in UP networks increasing UP chain mobility and toughness of the blends. The nanovoids result in a dimpled appearance of the fracture surface and become points of high-stress concentration from which cracks can initiate. When subjected to a sudden load, many cracks can grow simultaneously forming beach marks where the cleavage from several cracks meets.
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