Can i do plastic engineering after diploma mechanical
Let me get this clear. Are you asking whether you can do a degree in plastic engineering at Maharaja Sayajirao University? Actually you will have to appear for GUJCET which allows for vocational technical students even for this university. However I dont see the Maharaja Sayajirao University offering plastic engineering. I can see only two institutes in GUJCET offering Plastic Technology and they are:
Central Institute of Plastic Engineering & Technology, Ahmedabad and L. D. Engineering College, Ahmedabad.
For details on GUJCET, check here