Poly(lactic acid) or PLA bio‐composite is prepared by filling with micro‐graphite via solution blending. The micro‐graphite loading is varied from 0–15 wt%. The objectives of this research are to investigate the influence of micro‐graphite loading on PLA bio‐composite, on the viscoelasticity and thermal stability. The viscoelasticity behavior exhibits a considerable dependence on the melt properties of the PLA/micro‐graphite bio‐composites on the percentage micro‐graphite. The complex viscosity |η*|, storage modulus (G’), and loss modulus (G″) tend to improve with increasing micro‐graphite loading. Thermogravimetric analyses indicate that the micro‐graphite slightly stabilizes the PLA. The decomposition reaction is shifted to a higher temperature in the range 7–9 °C. This reaction leads to the loss of volatile byproducts, which occur at temperatures higher than 310 °C. It means far from the melt processing conditions. The differential scanning calorimetry thermogram shows that the glass transition temperature (Tg) and the melting temperature are close to that of neat PLA with changes only around 2–4 °C.
In this research, a low molecular weight poly(lactic acid) (or PLA) synthesized from direct polycondensation was melt compounded with urea to formulate slow-release fertilizer (SRF). We studied the influence of the molecular weight (MW) of PLA as a matrix and the urea composition of SRF towards release kinetics in water at 30 °C. The physical appearance of solid samples, the change in urea concentration, and acidity (pH) of water were monitored periodically during the release test. Three studied empirical models exhibited that diffusion within the matrix dominated the urea release process, especially when the release level was less than 60%. Thus, a lower MW of PLA and a higher urea content of SRF showed a faster release rate. For the entire length of the release experiment, a combination of diffusion and degradation mechanisms exhibited the best agreement with the experimental data. The hydrolytic degradation of PLA may begin after 96 h of immersion (around 60% release level), followed by the appearance of some micro-holes and cracks on the surface of the SRF samples. Generally, this research revealed the good release performance of urea without residues that damage the soil structure and nutrient balance.
In a specific range of electrical conductivity, poly(lactic acid)/PLA has the potential to be developed into environmentally friendly antistatic packaging after a modification process. PLA was blended in a mini single screw extruder at 180oC with different compositions of micro-graphite (0, 0.5, 1, and 1.5 %wt.). This report discusses the degradability of PLA composite, i.e., photo-oxidative degradation and hydrolytic degradation. The weight loss, thermal properties, and cross-section morphology of the tested specimens were monitored periodically. During the degradation test, micro-graphite could be released from the composite, leaving a rough surface and reducing the weight of the composite. Differential scanning calorimetry (DSC) test exhibited that the presence of micro-graphite did not influence the melting temperature of the composition studied. However, the onset temperature of the melting point showed a slight shift of about 2-4oC. Bulk crystallinity demonstrated a considerable dependence on the micro-graphite loading (0-1.5%wt). However, there were two contradictory phenomena after both degradation tests. UV exposure could stimulate the fragmentation of PLA chains, break the crystal structure and increase the embrittlement. Thus, crystallinity tended to decrease during photo-oxidative degradation. In hydrolytic degradation, degradation firstly occurred in the amorphous regions and was ongoing within the studied range of time (0-20 weeks). Thus, the bulk crystallinity of composite tended to increase.
<p><strong>ABSTRAK.</strong> Kewirausahaan merupakan salah satu tuntutan kompetensi lulusan siswa di SMK Negeri 1 Mojosongo. Kompetensi tersebut menjadi salah satu indikator kualitas sumber daya manusia lulusan SMK. Tim Manajemen sekolah selalu berusaha meningkatkan kualitas sumber daya siswa dan tenaga pengajarnya. Salah satu terobosan yang dilakukan adalah bekerjasama dengan Prodi D3 Teknik Kimia Universitas Sebelas Maret untuk meningkatkan wawasan siswanya. Konsep kerjasama ini berupa transfer keilmuan yang dikemas dalam kegiatan pengabdian masyarakat. Kegiatan ini memiliki beberapa tahapan dimulai dari identifikasi masalah mitra yaitu perlunya pemahaman konsep kewirausahaan, business plan, pemodalan dana hibah, konsep desain dan inovasi produk dan pemasaran usaha. Pada tahap awal kegiatan siswa diminta mengikuti pretest untuk mengetahui tingkat mula pemahaman. Tahap kedua paparan materi kewirausahaan dan diskusi, tahap ketiga demo sekaligus praktik langsung pembuatan inovasi produk pangan dari buah nipah. Kegiatan diakhiri dengan post test dan testimoni hasil kegiatan. Dari kegiatan yang telah dilakukan, menunjukkan hasil bahwa terdapat peningkatan pemahaman peserta tentang kewirausahaan dan inovasi produk menggunakan teknologi sederhana. </p><p> </p><p><strong>ABSTRACT. </strong>Entrepreneurship is one of the required competencies for students' graduation at SMK Negeri 1 Mojosongo. Thus, this competency is one of the indicators to determine the quality of graduates from SMK N 1 Mojosongo. The School management has been trying to improve the quality of students and teaching staff. Collaboration between SMK N 1 Mojosongo and Diploma 3 of the Chemical Engineering Study Program of Universitas Sebelas Maret is one of the breakthroughs to increase students' insight. The concept of this collaboration is in the form of knowledge transfer which is packaged in community service activities. This activity begins with identifying the problems experienced by partners such as the need to understand the concept of entrepreneurship, business plans, grant funding, design concepts, product innovation, and business marketing. Before the main agenda begins, students are asked to take a pretest to determine their initial level of understanding. After a presentation on entrepreneurship, the students practice making food product innovations from Nypa fruticans. Finally, the students took the post-test and gave testimonials on the results of the activities. The results of this activity indicate that there is an increase in participants' understanding of entrepreneurship and product innovation with simple technology.</p>
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