By Miss Valeritta Lodin
| 1 | Question from Ms. Nor Sayzwani Sukri | From Jury XXXX: - What is the main reason for using PU as the plywood binder? - Increasing NCO/OH ratio had enhance the shear strength of the plywood. But, why the shear strength for the highest ratio of NCO/OH (2.6) had been dropped? | Answer from presenter | 1. Due to increasing concerns related formaldehyde emissions as a potential risk to the environment and human health. One alternative binding agent that can be used is PU adhesive because, PU adhesive provide non-formaldehyde emitting solutions. 2. Less bonding between hydroxyl group and isocyanate group correspond might be the reason shear strength for 2.6 NCO/OH ratio decreased. At high isocyanate index, the free unreacted isocyanate group tends to form more allophanate linkage with the urethane bond caused the adhesive layer to be brittle and crack easily when shear strength force is applied. |
| 2 | Comment from Ms. Nor Sayzwani Sukri | From Jury XXXX: Very good study but less graphic presentation not fully utilized. The sound is not too clear. | Answer from presenter | Thank you, I will improve in the future. |