Video Praktikum Pengukuran Kadar Karet Kering Lateks

Summary

This video provides a step-by-step practical guide for students at Politeknik Negeri Lampung on measuring the dry rubber content in latex. The demonstration, led by instructors, covers essential topics like the use of ammonia and formic acid, the process of measuring and preparing latex samples, grinding, drying, and oven-drying techniques. The aim is to determine the dry rubber content using both field and laboratory methods. Students are instructed on the importance of accurate measurements and calculations to determine the rubber's quality and how to report their findings in a formal lab report.

Takeaways

• 😀 The practical session is focused on measuring the dry rubber content in latex, a crucial parameter in rubber processing.
• 😀 The session is led by Ibu Widyarini Hartari, with assistance from Ibu Hydra and Pak Heri, both involved in the rubber processing course.
• 😀 The primary materials used in the practical include ammonia 5%, formic acid 5%, and Wantex latex, along with glass beakers, pipettes, and weighing scales.
• 😀 Ammonia is used in the field to prevent latex coagulation, but since Wantex latex is still fresh, it does not require ammonia in the lab.
• 😀 Formic acid 5% is added to latex samples in the laboratory to facilitate coagulation.
• 😀 The practical involves adding 50 ml of fresh latex for field samples and 25 ml for laboratory samples.
• 😀 After adding formic acid, the latex mixture is stirred to ensure thorough coagulation.
• 😀 The initial weight of the latex in the beaker is recorded to later calculate the dry rubber content.
• 😀 The latex is then ground using a grinder to break up the coagulated latex, with a minimum of 7 grinding passes to ensure consistency.
• 😀 After grinding, the latex is either air-dried (field samples) or oven-dried at 120°C for 1 hour (laboratory samples) before final weighing to determine the dry rubber content.

Q & A

What is the main objective of the practical session discussed in the transcript?

The main objective is to measure the dry rubber content in latex, which is a crucial parameter in rubber processing.

Who are the instructors involved in the practical session?

The instructors are Ibu Widyarini Hartari, a lecturer for the rubber product processing course, Ibu Hydra, a PLP senior in the same field, and Pak Heri, another PLP in the rubber product processing course.

What materials are used in the practical session?

The materials used include ammonia 5%, formic acid 5%, latex, a 250 ml beaker, and other laboratory tools such as pipettes and a stirrer.

Why is ammonia used in the latex processing for field samples?

Ammonia is used in field samples to prevent coagulation (or gelling) of the latex, as it helps to stabilize the latex before further processing.

What is the role of formic acid in the laboratory-based experiment?

Formic acid (5%) is used to help coagulate the latex in the laboratory-based experiment, as the latex used in this setting is fresh and does not require ammonia.

How much formic acid is added to the latex for the field samples?

For the field samples, 3 milliliters (60 drops) of formic acid are added to the latex.

What is the procedure after adding formic acid to the latex?

After adding formic acid, the latex is stirred thoroughly, and then it is allowed to coagulate. Once coagulated, it is weighed and processed further.

How is the dry rubber content measured in the laboratory?

In the laboratory, after coagulation and grinding, the latex is dried in an oven at 120°C for 1 hour, and the dry rubber content is calculated based on the weight difference before and after drying.

How is the dry rubber content measured for the field samples?

For the field samples, the dried latex is weighed, and the weight is multiplied by a correction factor (0.702072) to determine the dry rubber content, resulting in a percentage of 24.48%.

What is the correction factor used in the field sample dry rubber content calculation?

The correction factor used for the field sample dry rubber content calculation is 0.702072, which standardizes the result based on regional rubber processing standards.

What calculation method is used to determine the dry rubber content in the laboratory sample?

In the laboratory, the dry rubber content is calculated by dividing the dry weight (11 grams) by the initial wet weight (33 grams) and then multiplying by 100%, resulting in 33% dry rubber content.

What is the final step in the practical session after measuring the dry rubber content?

The final step is for students to compile their results and observations into a report, detailing the determination of the dry rubber content both for field and laboratory samples.