Thermo-Gravimetric Analysis (TGA): a vital test for rubber fender chemical composition and quality control

By Mishra Kumar, Business Unit Director - R&D

High-quality fenders are essential to the safety and efficiency of port operations, protecting vessels and terminals alike. But, until recently, understanding chemical composition in rubber fenders was not practiced in the industry due to a lack of suitable tests and specifications.

The chemical composition of a rubber compound in a fender has a severe impact on Velocity Factor (VF), Temperature Factor (TF), efficiency, lifespan, energy absorption capacity and reaction force. The designer of a fender system must have prior knowledge of the chemical composition which must be specified in the purchase specifications.

PIANC suggests that no matter how good the theoretical fender arrangement may be, it will not last long if it’s poorly designed or made from low-grade materials. Large quantity of recycled rubber and Calcium Carbonate are not desirable in a superior rubber formulation. These ingredients not only impact the performance of a fender but also reduce the lifespan by severely deteriorating the aging properties of rubber compounds. It is of utmost importance to specify the optimum quantity of certain vital ingredients in a rubber formulation.

Specifying the minimum amount of vital ingredients (e.g. rubber percentage or ash percentage) in a fender formulation does not prevent manufacturers or compound designers from creating new formulations. An infinite number of rubber compounds can be developed, even if the compound designer has to stick to a particular chemical composition with a specified minimum percentage of ingredients.

Thermo-Gravimetric Analysis (TGA) is a useful test in rubber industry. It assists in:

1. Determining the chemical composition

The TGA test can be used to ensure undesirable materials are not used in rubber formulations during the fender manufacturing process. This test is valuable to determine the percentage of the vital ingredients in an uncured or cured rubber compound.

2. Assures the quality of rubber compounds in samples versus final products

The TGA test, which is increasingly being built into specifications by consultants, acts as a proof point for consultants in helping to establish the consistency of rubber samples taken from the rubber compounds (intended to use for manufacturing a fender) and the commercial fender supplied to project sites.

It also enables consultants to examine and compare the chemical composition of a rubber compound sample (used for manufacturing and testing of physical properties), model (sample) fenders (used for durability testing), against that of a commercial fender. Thus, guaranteeing the chemical composition of the rubber compound they have specified, tested and supplied to their clients.