Plastiblends India Limited has introduced a range of Photo Degradable, Thermally Degradable and Compostible Additive Masterbatches. Besides the advantage of being environmentally friendly, Bio-D-Plast Additive Masterbatches are also cost effective and can be processed on existing machinery/equipments. The degradation speed and intensity can be controlled without sacrificing the strength, clarify and physical properties of the film.

Biodegradable Degradation refers to starch based biodegradable additive masterbatches, wherein, in the first phase of degradation, the strength of the plastic increases as starch absorbs atmospheric moisture, making it more flexible. This starch serves as a food source and activates the oxidative mechanism. When bacteria, algae fungi, etc, consume the starch in thin film, the plastic is weakened and perforated leaving behind a plastic matrix that continues to degrade. In the second phase, the plastic piece become brittle, fragment and start powdering. In the last phase, these pieces continue to break down to molecular sizes and become food for surface bacteria. This results in low molecular weight paraffin like waxes, soil type mulch and finally carbon dioxide and water. Thicker film needs more starch to degrade. Photo Degradable, Thermally Degradable and Compostible Additive Masterbatches introduced by PBI have the oxidative mechanism, as well as free radicals serving "double duty" in the degradation process. The oxidation process is similar to burning the plastic and consumes the carbon elements in the plastic backbone.

The degradation speed is mainly dependent on:

Concentration of Bio-D-Plast Additive Masterbatch, thickness of film, type of resin carrier - PE or PP, level of antioxidant/UV absorber present in the resin carrier, presence and level of coloured pigments such as carbon black, titanium dioxide, opacifiers and colourants, temperature of processing and type of exposure - underground/overground.

Processing of Bio -D-Plast Additive Masterbatches

Tumble blending in resin carrier is adequate for satisfactory dispersion. Very little or no process parameter changes will be required for the production of blown film, cast film, oriented film, injection moulded and blow moulded products. The carrier resins can be LDPE, LLDPE, HDPE, HMHDPE and PP. Processing can be at temperatures ranging from 180° C to 230° C. Bio-D-Plast MBs in unopened bags can be stored indoors for 6 to 9 months without any problems.
The introductory range comprises of:

Performance tests

Film samples representating control, D48/BL/21 (10% dosage level) and D48/10/402 (10% dosage level have been tested as per :

	ASTM D3826-98 : Standard practice for determing Degradation End point in Degradable Polyethylene and Propylene using a Tensile Test
	Astm D5208-01: Standard Practice for Fluorescent UV Exposure of Photodegradable plastics.
	Astm D2565-99 : Practice for Xenon ARC Exposure of plastics intended for outdoor applications.

Degradation can be defined as a change in the chemical structure of a plastic involving a change in properties - physical and mechanical. A degradable plastic undergoes significant change in its chemical structure under specific environmental conditions resulting in loss of some properties. In Photodegradation, the plastic is made to become more sensitive to the sun's UV rays with the introduction of trace quantities of activated non-toxic elements, creating free radicals which randomly attack the polymer chain. These free radicals sever molecular bonds of the plastic and allow bacteria to consume the plastic.

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