Choyamba, ndikofunikira kumvetsetsa zinthu zazikulu zomwe zimagwiritsidwa ntchito posindikiza mu 3D: ma polima.

A polima ndi molekyulu yaikulu, kapena macromolecule, yopangidwa ndi mayunitsi ambiri obwerezabwereza otchedwa monomers, yopangidwa kudzera mu njira yotchedwa kupolimaPa nthawi ya polymerization, ma monomers amalumikizidwa pamodzi ndi mankhwala kuti apange msana waukulu wa unyolo wa polima.

Mitundu yosiyanasiyana ya ma polima imapangidwa kutengera kapangidwe ka mankhwala ndi kapangidwe ka ma monoma awo. Ma bond omwe amapangidwa pakati pa ma monoma amatanthauzidwa kuti zomangira za covalent.

Ma polima amagawidwa m'magulu awiri akuluakulu: ma thermosets ndi thermoplastics.

Ma thermosets ndi ma polima omwe amachira mosasinthika kuchokera ku madzi ofewa olimba kapena okhuthala prepolymer kukhala cholimba cholimba. Njira yochiritsira iyi, yotchedwanso kulumikiza, mwa mankhwala amalumikiza ma monomers onse ndi ma prepolymers mu kapangidwe ka netiweki ya magawo atatu.

Akachira, ma thermosets sizingasungunuke kapena kusinthidwa ndi kutentha ndipo nthawi zambiri sizimalola kutentha kukonzanso.

Thermoplastics ndi zinthu zomwe chepetsani kutentha ndi kulimbitsa kutentha mukaziziraZitha kutenthedwa, kupangidwa mosiyanasiyana, komanso kuziziritsidwa mobwerezabwereza popanda kusintha kwambiri mphamvu zake za mankhwala kapena makina.

Mosiyana ndi ma thermosets, komwe maunyolo a polima amalumikizana pamodzi, maunyolo a thermoplastic amagwirizanitsidwa pamodzi chifukwa cha kusagwirizana kofooka komwe kumadziwika kuti zomangira zopanda covalent.

Njira ina yogawa ma thermoplastics ndi kapangidwe kake kakang'ono, zomwe zimatsimikizira makhalidwe ofunikira a magwiridwe antchito ndi khalidwe.

Ma polima a Amorphous amadziwika ndi palibe dongosolo lakutali — maunyolo awo a polima amakonzedwa mwachisawawa.

Kawirikawiri, mapulasitiki owonekera bwino monga PMMA, PS, ndi PC nthawi zambiri zimakhala zosasinthika.

Ma polima a semicrystalline ali ndi kapangidwe kokonzedwa bwino komwe kali ndi madera okonzedwa bwino otchedwa makhiristo.

Makristalo amakhala ndi unyolo wa polima wolumikizidwa bwino. Madera onse a kristalo ndi a amorphous amakhala pamodzi, ndichifukwa chake mawu akuti "semicrystalline".

Chiŵerengero cha madera a kristalo chimatanthauzidwa kuti kunyezimira, zomwe zimakhudza kwambiri mphamvu za makina ndi kutentha kwa zinthuzo.