Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 2
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

It is nearly impossible to study behaviour effectively without any reference to its context. This is because it is generally known in the psychological literature that behaviour is partially a product of its environment. This suggests that many behavioural processes may be universal but there are significant variations in their manifestations. For instance, love may be a universal process but its manifestation varies from one society to another. Given that ethical decision-making is a behavioural process, it stands to reason that its manifestation will vary from one culture to another. It is against this premise that this paper seeks to demonstrate that despite the existence of the ‘universal’ normative ethical principles, ethical decisions will be expected to vary across cultural space and even evolve with time. This paper achieves this objective by employing typical ethical dilemmas that Ghanaian psychologists and other health professionals encounter to show how and why what is ethical in one culture becomes unethical in the Ghanaian context and what is unethical in the Ghanaian context becomes ethical in another culture.

Go to article

Authors and Affiliations

Seth Oppong
Download PDF Download RIS Download Bibtex

Abstract

APNB (alkaline phenolic no bake), widely known as Alphaset is one of the major sand binder systems used in foundries to make molds and cores without application of heat or gas. This is a two part system comprising of a phenol-formaldehyde resin in alkaline medium as binder and range of esters of dibasic acids and/or polyhydric alcohols as hardeners.

Resin performance varies depending upon formulations. Major variables in formulations are mole ratio of phenol: formaldehyde, total alkali content, ratio of two alkalis (NaOH & KOH) and molecular weight of polymers i.e. chain length.

In present work, one mole ratio of phenol & formaldehyde has been chosen to prepare 8 resins with following details.

Table 1.

Physical and chemical properties of eight (fresh) resins, A to H

Properties A B C D E F G H
Viscosity at 30°C (mPs-a) 56 47 66 51 39 44 49 52
Na (%) 5.94 3.21 5.94 3.21 nil 2.73 nil 2.73
K (%) nil 3.31 nil 3.31 7.18 3.87 7.18 3.87
Molecular weight Low Low High High Low Low High High
Gel Time at 121°C, mt-sec 27-0 29-30 24-0 30-0 30-0 27-30 26-30 26-0
Moisture (%) 52.43 52.42 53.01 53.75 55.58 54.12 51.61 54.03
Non-volatile Content (%) 48.74 47.25 49.10 49.35 47.63 47.32 48.06 48.29
Specific Gravity 1.182 1.177 1.183 1.180 1.172 1.184 1.178 1.188
Free Phenol (%) 0.47 0.42 0.44 0.43 0.37 0.27 0.41 0.20

Properties of these 8 formulations have been studied for strength and viscosity over a period of 12 weeks in 4 week interval.

Attempt has been made to develop a simple test for simulating hot & retained strength of molds in laboratory. Process followed for chasing hot and retained strength is described under clause 2.

With more and more understanding of the chemistry of alphaset system in last three & half decades it has been possible to identify role of variables contributing towards specific properties vis a vis developing tailor made formulations to fulfill requirements of individual foundries right from mold making to de coring.

Go to article

Authors and Affiliations

D.K. Ghosh

This page uses 'cookies'. Learn more