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حِرَف

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العلوم

رياضة

التقنية

الأجهزة القابلة للارتداء

أنشأه

Woody

22. سبتمبر 2026

Epoxy Resin

Pierre Castan, a Swiss chemist at the dental firm De Trey Frères, was looking for a resin for dentures. He reacted a phenol carrying two hydroxy groups with epichlorohydrin, then hardened the product with an acid anhydride, and got a hard, clear, unusually adherent solid. Ciba licensed it and sold it as Araldite; in the US Sylvan Greenlee developed epoxies independently. **US 2,324,483**, "Process of preparing synthetic resins", Castan, granted 20. July 1943, claims condensing "a polybasic carboxylic acid anhydride" with the product of "a phenol having at least two phenolic hydroxy groups and of an epichlorhydrine". It does not single out bisphenol A, the phenol most epoxies use today. **Epichlorohydrin is a carcinogen; you start from a two-part kit.** You glue pine lap joints at the right ratio and four wrong ones, then test hardness and break the joints.

مبتدئ

2 hours plus 24 h cure

التعليمات

Cut the joint pieces

Saw ten pine strips 100 x 25 mm. Sand one face of each end with 120 grit and dust off. Label five pairs 1:1, 1.25:1, 1:1.25, 1.5:1 and 1:1.5.

المواد لهذه الخطوة:

لوح صنوبر1 قطعة

ورق صنفرة1 ورقة

شريط لاصق ورقي1 لفة

الأدوات المطلوبة:

منشار يدوي

مسطرة فولاذية

قلم رصاص

Measure by syringe

Gloves on. For each ratio draw resin and hardener in separate syringes (1:1 = 2 ml + 2 ml; 1.25:1 = 2.5 + 2; and so on) into its own cup. This assumes a 1:1-by-volume kit - scale to your label.

المواد لهذه الخطوة:

إيبوكسي ثنائي المكوّن25 مل

الأدوات المطلوبة:

قفازات نتريل

طقم محاقن

أكواب خلط مدرّجة

نظارة أمان شفافة

Mix thoroughly

Stir each cup 2 minutes, scraping the walls and bottom. Unmixed streaks behave like a wrong ratio.

الأدوات المطلوبة:

قضيب تحريك

Glue and pour

Spread each mix on the sanded ends of its pair, overlap them 25 mm and spring-clamp over wax paper. Pour the rest as a coin-sized puddle on wax paper beside it.

المواد لهذه الخطوة:

ورق مشمّع1 ورقة

الأدوات المطلوبة:

ملزمة زنبركية

Cure 24 hours

Leave everything at room temperature, 20 °C or warmer, for 24 hours. Cold slows the cure.

Pencil hardness

Sharpen pencils 6B to 6H and flatten the tips on 400 grit. Push each at 45° across a puddle, from hard down, until one no longer scratches. Record that grade.

الأدوات المطلوبة:

طقم أقلام غرافيت

عدسة صائغ

Break the joints

Clamp one strip of a joint in the vise and tap the free end sideways with the mallet until it breaks. Estimate how much of the bond face is torn wood.

الأدوات المطلوبة:

ملزمة منضدة

مطرقة مطاطية

نظارة أمان شفافة

Ratio, leftovers, results

جارٍ تحميل دفتر Jupyter…

History & Context

**What the patent specifies:** a resin from a two-hydroxy phenol and epichlorohydrin, hardened by a polybasic acid anhydride. **Modern build (derived):** a two-part kit, most with an amine hardener that cures at room temperature. Epoxy became the glue that holds metal, the matrix of fibreglass and carbon-fibre parts, and the boat-builder's resin. Its limits: it yellows in sunlight, softens with heat, and uncured resin and hardener sensitise skin - which is why the gloves stay on every time.