Thursday, March 14, 2013

Dr. Shah G.D., submitted to Modern Plastics & Polymers- Plastics @ Gujarat, for supplement March 2011 edition.

Published as 
Skill development- Fostering new talent  by Kymberlee Fernandes, rewiew interview of Dr. Shah G.D., Modern Plastics & Polymers- Plastics @ Gujarat, supplement March 2011 edition. pp 50-52.

Dr. Mrs.G.D.Shah (PhD. Chemical Engg.) 
I/C Head Of Plastics Engg. Dept. 
Govt. Polytechnic.
Lord Krishna preferred Gujarat as the place to live in by residing at Dwarika. Since then, Gujarat has been a favoured state to live in and do business. Consequently, with the blessings of Mahatma Gandhi, Sardar Vallbhbhai Patel the Technology and Gujarat has so developed that the Mountain is compelled to come to the Mohamed. No one can bypass the achievements of Gujarat. This is because both the CMs – The Chief Minister and the Common Man -- in Gujarat think for the development of Gujarat. The Chief Minister of Gujarat, H’ble Shri Narendra Modi, having the heart of Common Man of Gujarat has made the Gujarat State the most favoured destination of India for sharing technology and do Global business.
The Plastics Industry in Gujarat has also joined hands to hands with the vibrant drive of development of Gujarat. Gujarat has approximately 15,000 units of which @80% are in small scale sector having annual turnover of @10,000 crores. This happens to be @one fifth of the total industrial units of plastics in India. Gujarat is the second highest exporter of India in Plastic sector. The availability of raw material is the key asset of Gujarat plastic industry. More than 70% of polymers are manufactured in Gujarat which is @ 60% of total output of the Indian Petrochemical Industry. Gujarat plastic industry has achieved annual growth of @15-20% in past years. Looking to the present per capita plastic consumption of 8-10 kg in India as against 25-30 kg in the developed economies and 85-100kg in the highly developed economies, the potential of growth of plastic industry in Gujarat is massive. Today major international companies from various segments of industry like automobile, food processing and packaging have set up their large manufacturing plants in Gujarat. With the growth of per capita income and favourable government support the Gujarat entrepreneurs are motivated to acquire/hire technical expertise, to achieve high quality standards.
The growing market of the technology will increase the requirement of technical expertise in the industry. In order to meet the requirements of industry the intake capacity of Government Polytechnic Ahmedabad is increased to double its original capacity i.e. from 30 to 60 since academic year 2008. The proposal was made well in advance in year 2007. Also the syllabus is revised on regular basis. The Diploma Plastics Engineering is the only Diploma course having tenure of 4 years—8 semesters. It is sandwich pattern course offering two industrial training of 24 weeks each under Apprenticeship act at the 5th and 8th semester level. The student placement is almost 100% with a start of 5000/- to 10,000/- per month. The students also get an opportunity to serve abroad in countries like South Africa, Saudi Arabia, Malaysia, Singapore, Australia, U.S., etc. They also can opt for higher studies in India as lateral entry in 2nd year degree engineering. As the tenure of this Diploma is of 4 years the students can get direct admissions at the Masters courses after obtaining credits of certain courses as may be prescribed by individual Universities/Program in various countries mentioned. Most of the Diploma pass outs find professional opportunities in various fields of plastics industry like servicing/maintenance, marketing, processing, machine manufacturing, testing and quality assurance, mould designing and fabrication field.
To satisfy the industrial needs of constant skill up gradation the department conducts special self sustaining short term programs under continuing education centre. The duration and contents for these programs are designed as per the industrial need.
The Department, through the community Polytechnic wing of the institute also conduct various skill based short term program for the development of rural community through technology transfer. The rural community is imparted skills like fibre reinforced plastics product manufacturing, acrylic fabrication, screen printing technology etc. These skills require low investment and have high market generating self employment.
The Department, through SPPWD Study centre of the institute runs various non formal courses of 3 months duration. These courses are designed to impart technical skill to the physically challenged persons. The duration of the courses is of 3 months. After 3 months the persons with disability acquire technical skill and professional competency related to various miscellaneous plastic processing techniques like fibre reinforced plastics product manufacturing, acrylic fabrication, screen printing technology etc. After completion of the course they are assisted for their employment and/or are motivated for self employment. The students are paid a monthly stipend as per the Government Norms. To satisfy the industrial and social needs the Department has well equipped laboratories and highly qualified, intelligent and dedicated faculty/staff.
ack of Well established and proven plastic recycling line for plastics, and ignorance towards the disposal of plastic waste has become an issue of major concern. This has lead to a worldwide drive for the development of biodegradable plastics. To deal with this and other such issues in future, the Department plans to start a plastics testing cum research centre. The major beneficiaries of the plan are the industries, who strive for the international/national standards, and the young/upcoming researchers, as they can get the research facility under one roof. The Department also observe a continuous recycling line in the department itself.


 The development of biodegradable polymer is dealt in my personal capacity by developing a degradable polymer/theory while pursuing the doctorate degree in chemical engineering. Various study and research articles have been published in various national and international journals with a mention of recycling trends, biodegradability and eco friendly use of plastics.
Looking to the growth rate of plastics industry the Department would like to develop a processing, mould fabrication and testing laboratory possessing   modern equipments. Although the Department has a well equipped laboratory, the equipments with modern technology are still missing.

Saturday, February 18, 2012

Blow molding materials

Theoretically any thermoplastic material can be used for a blow molding operation. but practically only those material which show high hot strength and good stretch property at extrusion temperature are suitable for blow molding. The most common materials which show these properties are HDPE, LDPE, PP, medium impact PS, PVC, and PC.  Acetal, nylon, ionomers and acrylonitrile styrene are other materials which may be used. But because of their cost and/or sharp melting point or other properties, they have not been proved to be as suitable as the materials mentioned earlier.
1.       It has greater rigidity of the material which permits the use of thinner bottle walls and thus provide light weight, low cost packaging.
2.       It has lower water vapor permeability
3.       It has ability to withstand higher working temperature.
4.       HDPE pack can be decorated with high speed silk screen printing method.
Considerable knowhow is required for the correct design of HDPE bottle. On an average a bottle requires approximately 2years development period and 30% of its production costs are usually accounted for R&D.
It is used for more flexible items.
It is used for high gloss, heat resistance, stiffness and good strength.
It exhibits good color, high glass like clarity, decorative finish pack and it will not damage sinks, glass shelves and other delicate bathroom fittings and it will not rust. Also it has a moderate cost.
With the advances in the understanding of PVC compound chemistry, new blow molding equipments are developed; which can manufacture bottles and packs of very light weight and at a high production rate. These bottles are rigid, strong and of comparatively low permeability. It can possess glass like clarity. Thin walled PVC products have extremely competitive material cost. Main problem with PVC is its toxicity when used for the packaging of edible and potable substances. To overcome this thicker walls are necessary. This results in the increased cost.
 It is used where transparency and strength are required. But this is availed at somewhat higher cost.
Other thermoplastics materials which are now coming into use for blow molding and which increase their application as blow molding material are:
Phenoxy material is  used for eye wash bottles.
Methyl pentene polymer used for experimental bottles.
Cellulose acetate butyrate used for Sun Tan oil bottles.
ABS for pressure containers used for spray.
This material though expensive is used due to technical consideration like freedom of corrosion, light weight etc.

Tuesday, September 20, 2011


Any design that improves the part function should be considered.
Letterings in plastic product are required to include permanent detail or designs. These letterings may be raised or depressed on the plastic part.
Raised letters:
 This can be included by indenting the mirror image of desired letters/ designs in the mold. The mold surface should be highly finished to prevent any mold sticking. Also the letters should be checked periodically for any imperfections and some mold releasing agents should be applied.
Depressed letters:
This can be included by incorporating raised letters in the mold or post molding indentation. The raised letters can be incorporated in the mold by spark erosion or by assembling the required design on the mold surface. Both this methods involve higher cost for the part production due to the following reasons:
·         Increased mould fabrication cost.
·         Increased difficulties in part ejection.
·         Depressed letters either remove the material (reduce wall thickness and strength of part) or reduce the volume of the container.
Texturing in plastics means to display (create) effects on the plastic surface which simulates the fibrous structure of meat. Mould in or formed in textured surfaces on plastic can be obtained by variation in integral coloring methods.
Some decorative filler are added to the base resin at the compounding levels so as to produce such visual effects of wood, metallic finish etc.


·         The tolerances specified for any molded or machined plastic part should be as loose as possible because extremely tight tolerances require more expensive molds, special controls during the molding operation and possibly the use of shrink fixtures during cooling. All these result in a part which is more expensive.
·         In many plastic, the dimensional changes due to temperature variation from –550 C to 1200 C is considerably more than the allowable tolerances.
·         For thermoplastics injection molding, compression molding generally results in parts with best dimensional tolerances. The dimensional tolerances for thermoplastic parts made by any method vary from part to part and material to material.
·         The tolerances for thermoset plastic parts depend on the type of resin, filler, molding condition and the type of mold used.
·         Parts made with thermoset plastic can be designed with a tighter tolerances than corresponding thermoplastic parts because thermoset plastic are more stable under thermal condition than the unfilled thermoplastic, when used for the same part.
·         Filled thermoplastic depending on the amount and type of filler can approach or be equal to the dimensional stability of thermoset plastic.
·         Tolerances vary depending on the location of the parting line and the depth of the flash. The molder should be informed by the critical dimension.
·         The flash can affect the dimension in one plane and not in the other.
·         Tolerances suggested by the resin manufacturer are given in inches/inch at the ambient temperature and 50%RH.
·         Shrinkage of parts made by thermoforming, blow molding, rotational molding etc. (except compression molding and transfer molding) will show higher variation in tolerance than injection molding. This variation is determined empirically.
·         Glass reinforced thermoplastic have considerably tighter tolerances than unreinforced material.
·         The molder can make slight changes in the finished dimension of a molded part without the cost and trouble of re-matching, re-heat-treating, and re-plating the mold.
·         The molder can increase or decrease the dimension or prevent the warpage.