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الأجهزة القابلة للارتداء

Otis Ray McIntire · Public domain (expired patent)

أنشأه

Emma

22. سبتمبر 2026

Extruded Polystyrene Foam

Carl Munters had shown that polystyrene heated with methyl chloride under pressure puffs into a closed-cell foam when let out of the vessel (US 2,023,204) - but only in small pieces; with larger outlets the mass collapsed into brittle, irregular lumps. Otis Ray McIntire at Dow found the fix: keep the mass BELOW the critical temperature of methyl chloride, about 143 °C, so the gas stays dissolved, and let its own evaporation cool the foam fast enough to freeze the cells. **US 2,450,436**, "Manufacture of cellular thermoplastic products", McIntire, assigned to Dow Chemical, filed 26. July 1947, granted 5. October 1948. Its drawing is the pressure vessel with the bottom valve the foam flows out of. Dow sold the result as blue insulation board; the white bead foam of packaging is a later process. **Methyl chloride is toxic; you start from foam board.** You build a hot-wire cutter, cut an insulated box, and measure how long it keeps ice.

مبتدئ

3 hours plus an ice test

التعليمات

The cutter

Base on two feet, a post and an arm; the wire runs from the arm tip down through the base to a spring underneath.

ملف التصميمBLENDCC0 - Free

تنزيل النموذج

Build the frame

From 18 mm plywood cut a 300 x 300 mm base, two 300 x 40 mm feet, a 280 x 50 mm post and a 200 x 50 mm arm. Glue and screw the post to the back edge and the arm square on top.

المواد لهذه الخطوة:

لوح خشب رقائقي1 قطعة

براغي خشب10 قطع

غراء خشب20 مل

الأدوات المطلوبة:

منشار يدوي

مثقاب لاسلكي

طقم مفكات

مسطرة فولاذية

String the wire

Drill 2 mm through the arm tip and the base directly below. Fix the wire to an eye bolt on top of the arm, run it down through the base, and tie it to a spring under the base so it stays taut when it expands hot. Check it is square to the table.

المواد لهذه الخطوة:

سلك نيكروم 80/20 قطر 0,64 مم1 متر

مسمار ملولب بعين1 قطعة

مجموعة نوابض ضغط1 طقم

الأدوات المطلوبة:

مثقاب لاسلكي

طقم لُقم ثقب في علبة

Power it

Clip leads to the wire at the arm and below the base. Set the bench supply to 1.5 V with a 4 A limit and raise it slowly (notebook) until the wire slides through a scrap cleanly. Ventilate.

الأدوات المطلوبة:

مصدر تغذية مختبري قابل للضبط

Alligator to Alligator Cables

كمامة تنفّس N95

نظارة أمان شفافة

Cut the box

From 25 mm foam board cut a base and lid 200 x 200 mm, two sides 200 x 150 mm and two 150 x 150 mm. Feed slowly - let the wire do the work. Tape the box together.

المواد لهذه الخطوة:

لوح رغوة بوليسترين مبثوق1 ورقة

شريط لاصق ورقي1 لفة

الأدوات المطلوبة:

مسطرة فولاذية

Weigh a cube

Cut a 50 mm cube from an offcut and weigh it for the notebook.

الأدوات المطلوبة:

ميزان مطبخ رقمي

The ice test

Put 500 g of ice in a bag in the foam box and another 500 g in a cardboard box of the same size, side by side in the same room. Note the room temperature and check both every hour until the ice is gone.

المواد لهذه الخطوة:

مكعبات ثلج1000 غ

صندوق كرتون مضلّع1 قطعة

الأدوات المطلوبة:

ميزان مطبخ رقمي

مقياس حرارة الغرفة

Wire, density, heat leak

جارٍ تحميل دفتر Jupyter…

History & Context

**What the patent specifies:** polystyrene with methyl chloride dissolved under pressure below the gas's critical temperature, released through an outlet so evaporation expands and cools it into uniform closed cells, in blocks 2 inches thick or more. **Modern build (derived):** commercial extruded foam board, today made with other blowing agents. The patent names its target plainly: blocks big enough to cut into insulating panels for refrigerators. Its limits: it melts at low heat, burns unless treated, dissolves in many solvents (and in some glues and paints), and breaks down in sunlight.